T Clausen

C Dearlove

P Jacquet

Internet Engineering Task Force (IETF)

This specification describes version 2 of the Optimized Link State Routing Protocol (OLSRv2) for Mobile Ad Hoc Networks (MANETs).

Introduction

The Optimized Link State Routing Protocol version 2 (OLSRv2) is the successor to OLSR (version 1) as published in [START_REF] Clausen | Optimized Link State Routing Protocol (OLSR)[END_REF]. Compared to [START_REF] Clausen | Optimized Link State Routing Protocol (OLSR)[END_REF], OLSRv2 retains the same basic mechanisms and algorithms, enhanced by the ability to use a link metric other than hop count in the selection of shortest routes. OLSRv2 also uses a more flexible and efficient signaling framework and includes some simplification of the messages being exchanged.

OLSRv2 is developed for Mobile Ad Hoc Networks (MANETs). It operates as a table-driven, proactive protocol, i.e., it exchanges topology information with other routers in the network regularly. OLSRv2 is an optimization of the classic link state routing protocol. Its key concept is that of multipoint relays (MPRs). Each router selects two sets of MPRs, each being a set of its neighbor routers that "cover" all of its symmetrically connected 2-hop neighbor routers. These two sets are "flooding MPRs" and "routing MPRs", which are used to achieve flooding reduction and topology reduction, respectively.

Flooding reduction is achieved by control traffic being flooded through the network using hop-by-hop forwarding, but with a router only needing to forward control traffic that is first received directly from one of the routers that have selected it as a flooding MPR (its "flooding MPR selectors"). This mechanism, denoted "MPR flooding", provides an efficient mechanism for information distribution within the MANET by reducing the number of transmissions required [MPR].

Topology reduction is achieved by assigning a special responsibility to routers selected as routing MPRs when declaring link state information. A sufficient requirement for OLSRv2 to provide shortest routes to all destinations is that routers declare link state information for their routing MPR Thus, the use of MPRs allows reduction of the number and the size of link state messages and reduction in the amount of link state information maintained in each router. When possible (in particular if using a hop count metric), the same routers may be picked as both flooding MPRs and routing MPRs.

A router selects both routing and flooding MPRs from among its onehop neighbors connected by "symmetric", i.e., bidirectional, links. Therefore, selecting routes through routing MPRs avoids the problems associated with data packet transfer over unidirectional links (e.g., the problem of not getting link-layer acknowledgments at each hop, for link layers employing this technique).

OLSRv2 uses and extends the MANET Neighborhood Discovery Protocol (NHDP) defined in [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF] and also uses the Generalized MANET Packet/Message Format [START_REF] Clausen | Generalized Mobile Ad Hoc Network (MANET) Packet/Message Format[END_REF], the TLVs specified in [START_REF] Clausen | Representing Multi-Value Time in Mobile Ad Hoc Networks (MANETs)[END_REF] and, optionally, message jitter as specified in [START_REF] Clausen | Jitter Considerations in Mobile Ad Hoc Networks (MANETs)[END_REF]. These four other protocols and specifications were all originally created as part of OLSRv2 but have been specified separately for wider use.

OLSRv2 makes no assumptions about the underlying link layer. OLSRv2, through its use of [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF], may use link-layer information and notifications when available and applicable. In addition, OLSRv2 uses link metrics that may be derived from link layer or any other information. OLSRv2 does not specify the physical meaning of link metrics but specifies a means by which new types of link metrics may be specified in the future but used by OLSRv2 without modification.

OLSRv2, like OLSR [START_REF] Clausen | Optimized Link State Routing Protocol (OLSR)[END_REF], inherits its concept of forwarding and relaying from the High Performance Radio Local Area Network (HIPERLAN) (a MAC-layer protocol), which is standardized by ETSI [HIPERLAN] [HIPERLAN2]. This document does not obsolete [START_REF] Clausen | Optimized Link State Routing Protocol (OLSR)[END_REF], which is left in place for further experimentation.

Terminology

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119].

All terms introduced in [RFC5444], including "packet", "Packet Header", "message", "Message Header", "Message Body", "Message Type", "message sequence number", "hop limit", "hop count", "Address Block", "TLV Block", "TLV", "Message TLV", "Address Block TLV", "type" (of TLV), "type extension" (of TLV), "value" (of TLV), "address", "address prefix", and "address object" are to be interpreted as described there.

All terms introduced in [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF], including "interface", "MANET interface", "network address", "link", "symmetric link", "symmetric 1-hop neighbor", "symmetric 2-hop neighbor", "symmetric 1-hop neighborhood" "constant", "interface parameter", "router parameter", "Information Base", and "HELLO message" are to be interpreted as described there.

Additionally, this specification uses the following terminology:

Router: A MANET router that implements this protocol.

OLSRv2 interface:

A MANET interface running this protocol. A router running this protocol MUST have at least one OLSRv2 interface.

Routable address:

A network address that may be used as the destination of a data packet. A router that implements this protocol will need to distinguish a routable address from a non-routable address by direct inspection of the network address, based on global-scope address allocations by IANA and/or administrative configuration (consistently across the MANET). Broadcast and multicast addresses, and addresses that are limited in scope to less than the entire MANET, MUST NOT be considered as routable addresses.

Anycast addresses may be considered as routable addresses.

Originator address: An address that is unique (within the MANET) to a router. A router MUST select an originator address; it MAY choose one of its interface addresses as its originator address; and it MAY select either a routable or non-routable address. A broadcast, multicast, or anycast address MUST NOT be chosen as an originator address. If the router selects a routable address, then it MUST be one that the router will accept as destination. An originator address MUST NOT have a prefix length, except when included in an Address Block where it MAY be associated with a prefix of maximum prefix length (e.g., if the originator address is an IPv6 address, it MUST have either no prefix length or have a prefix length of 128). The originator address of the router that created a message, as deduced from that message by its recipient. For all messages used in this specification, including HELLO messages defined in [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF], the recipient MUST be able to deduce an originator address. The message originator address will usually be included in the message as its <msg-orig-addr> element as defined in [START_REF] Clausen | Generalized Mobile Ad Hoc Network (MANET) Packet/Message Format[END_REF]. However, an exceptional case, which does not add a <msg-orig-addr> element to a HELLO message, may be used by a router that only has a single address.

Willingness:

A numerical value between WILL_NEVER and WILL_ALWAYS (both inclusive) that represents the router's willingness to be selected as an MPR. A router has separate willingness values to be a flooding MPR and a routing MPR.

Willing symmetric 1-hop neighbor:

A symmetric 1-hop neighbor that has willingness not equal to WILL_NEVER.

Multipoint relay (MPR):

A router, X, is an MPR for a router, Y, if router Y has indicated its selection of router X as an MPR in a recent HELLO message. Router X may be a flooding MPR for Y if it is indicated to participate in the flooding process of messages received from router Y, or it may be a routing MPR for Y if it is indicated to declare link state information for the link from X to Y. It may also be both at the same time.

MPR selector:

A router, Y, is a flooding/routing MPR selector of router X if router Y has selected router X as a flooding/routing MPR.

MPR flooding:

The optimized MANET-wide information distribution mechanism, employed by this protocol, in which a message is relayed by only a reduced subset of the routers in the network. MPR flooding is the mechanism by which flooding reduction is achieved.

EXPIRED:

Indicates that a timer is set to a value clearly preceding the current time (e.g., current time -1).

This specification employs the same notational conventions as [START_REF] Clausen | Generalized Mobile Ad Hoc Network (MANET) Packet/Message Format[END_REF] and [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF].

Clausen, et al.

Standards Track [Page 8]

RFC 7181

OLSRv2 April 2014

Applicability Statement

This document specifies OLSRv2, a proactive routing protocol intended for use in Mobile Ad Hoc Networks (MANETs) [RFC2501]. The protocol's applicability is determined by its characteristics, which are that this protocol:

o Is designed to work in networks with a dynamic topology and in which messages may be lost, such as due to collisions over wireless media.

o Supports routers that each have one or more participating OLSRv2 interfaces, which will consist of some or all of its MANET interfaces using [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF]. The set of a router's OLSRv2 interfaces, and the sets of its other MANET and non-MANET interfaces, may change over time. Each interface may have one or more network addresses (which may have prefix lengths), and these may also be dynamically changing.

o Enables hop-by-hop routing, i.e., each router can use its local information provided by this protocol to route packets.

o Continuously maintains routes to all destinations in the network, i.e., routes are instantly available and data traffic is subject to no delays due to route discovery. Consequently, no data traffic buffering is required.

o Supports routers that have non-OLSRv2 interfaces that may be local to a router or that can serve as gateways towards other networks.

o Enables the use of bidirectional additive link metrics to use shortest distance routes (i.e., routes with smallest total of link metrics). Incoming link metric values are to be determined by a process outside this specification.

o Is optimized for large and dense networks; the larger and more dense a network, the more optimization can be achieved by using MPRs, compared to the classic link state algorithm [MPR].

o Uses [START_REF] Clausen | Generalized Mobile Ad Hoc Network (MANET) Packet/Message Format[END_REF] as described in its "Intended Usage" appendix and by [START_REF] Chakeres | IANA Allocations for Mobile Ad Hoc Network (MANET) Protocols[END_REF].

o Allows "external" and "internal" extensibility (adding new Message Types and adding information to existing messages) as enabled by [START_REF] Clausen | Generalized Mobile Ad Hoc Network (MANET) Packet/Message Format[END_REF].

o Is designed to work in a completely distributed manner and does not depend on any central entity. The objectives of this protocol are for each router to:

o Identify all destinations in the network.

o Identify a sufficient subset of links in the network, in order that shortest routes can be calculated to all available destinations.

o Provide a Routing Set containing these shortest routes from this router to all destinations (routable addresses and local links).

Overview

These objectives are achieved, for each router, by: o Using NHDP [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF] to identify symmetric 1-hop neighbors and symmetric 2-hop neighbors.

o Reporting its participation in OLSRv2, and its willingness to be a flooding MPR and to be a routing MPR, by extending the HELLO messages defined in [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF] by the addition of an MPR_WILLING Message TLV. The router's "flooding willingness" indicates how willing it is to participate in MPR flooding. The router's "routing willingness" indicates how willing it is to be an intermediate router for routing. Note that a router is still able to be a routing source or destination, even if unwilling to perform either function.

o Extending the HELLO messages defined in [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF] to allow the addition of directional link metrics to advertised links with other routers participating in OLSRv2 and to indicate which link metric type is being used by those routers. Both incoming and outgoing link metrics may be reported, the former determined by the advertising router.

o Selecting flooding MPRs and routing MPRs from among its willing symmetric 1-hop neighbors such that, for each set of MPRs, all symmetric 2-hop neighbors are reachable either directly or via at least one selected MPR, using a path of appropriate minimum total metric for at least routing MPR selection. An analysis and examples of MPR selection algorithms are given in [MPR]; a suggested algorithm, appropriately adapted for each set of MPRs, is included in Appendix B of this specification. Note that it is not necessary for routers to use the same algorithm in order to interoperate in the same MANET, but each such algorithm must have the appropriate properties, described in Section 18. o Signaling its flooding MPR and routing MPR selections, by extending the HELLO messages defined in [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF] to report this information by the addition of MPR Address Block TLV(s) associated with the appropriate network addresses.

o Extracting its flooding MPR selectors and routing MPR selectors from received HELLO messages, using the included MPR Address Block TLV(s).

o Defining a TC (Topology Control) Message Type using the message format specified in [START_REF] Clausen | Generalized Mobile Ad Hoc Network (MANET) Packet/Message Format[END_REF]. TC messages are used to periodically signal links between routing MPR selectors and itself throughout the MANET. This signaling includes suitable directional neighbor metrics (the best link metric in that direction between those routers).

o Allowing its TC messages, as well as HELLO messages, to be included in packets specified in [START_REF] Clausen | Generalized Mobile Ad Hoc Network (MANET) Packet/Message Format[END_REF], using the "manet" IP protocol or UDP port as specified in [START_REF] Chakeres | IANA Allocations for Mobile Ad Hoc Network (MANET) Protocols[END_REF].

o Diffusing TC messages by using a flooding reduction mechanism, denoted "MPR flooding"; only the flooding MPRs of a router will retransmit messages received from (i.e., originated or last relayed by) that router.

Note that the indicated extensions to [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF] are of forms permitted by that specification.

This specification defines:

o The requirement to use [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF], its parameters, constants, HELLO messages, and Information Bases, each as extended in this specification.

o Two new Information Bases: the Topology Information Base and the Received Message Information Base.

o TC messages, which are used for MANET wide signaling (using MPR flooding) of selected topology (link state) information.

o A requirement for each router to have an originator address to be included in, or deducible from, HELLO messages and TC messages.

o The specification of new Message TLVs and Address Block TLVs that are used in HELLO messages and TC messages, including for reporting neighbor status, MPR selection, external gateways, link metrics, willingness to be an MPR, and content sequence numbers. Note that the generation of (incoming) link metric values is to be o The response to other events, such as the expiration of information in the Information Bases.

This protocol inherits the stability of a link state algorithm and has the advantage of having routes immediately available when needed, due to its proactive nature.

This protocol only interacts with IP through routing table management and the use of the sending IP address for IP datagrams containing messages used by this specification.

Routers and Interfaces

In order for a router to participate in a MANET using this protocol, it must have at least one, and possibly more, OLSRv2 interfaces. Each OLSRv2 interface:

o Is a MANET interface, as specified in [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF]. In particular, it must be configured with one or more network addresses; these addresses must each be specific to this router and must include any address that will be used as the sending address of any IP packet sent on this OLSRv2 interface.

o Has a number of interface parameters, adding to those specified in [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF].

o Has an Interface Information Base, extending that specified in [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF].

o Generates and processes HELLO messages according to [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF], extended as specified in Section 15. o Generates, receives, and processes TC messages.

Information Base Overview

Each router maintains the Information Bases described in the following sections. These are used for describing the protocol in this specification. An implementation of this protocol may maintain this information in the indicated form or in any other organization that offers access to this information. In particular, note that it is not necessary to remove Tuples from Sets at the exact time indicated, only to behave as if the Tuples were removed at that time.

Local Information Base

The Local Information Base is specified in [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF] and contains a router's local configuration. It is extended in this specification to also record an originator address and to include a router's:

Interface Information Base

The Interface Information Base for each OLSRv2 interface is as specified in [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF], extended to also record, in each Link Set, link metric values (incoming and outgoing) and flooding MPR selector information.

Neighbor Information Base

The Neighbor Information Base is specified in [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF] and is extended to also record, in the Neighbor Tuple for each neighbor:

o Its originator address.

o Neighbor metric values, these being the minimum of the link metric values in the indicated direction for all symmetric 1-hop links with that neighbor.

o Its willingness to be a flooding MPR and to be a routing MPR.

o Whether it has been selected by this router as a flooding MPR or as a routing MPR and whether it is a routing MPR selector of this router. (Whether it is a flooding MPR selector of this neighbor is recorded in the Interface Information Base.) o Whether it is to be advertised in TC messages sent by this router.

Topology Information Base

The Topology Information Base in each router contains:

o An Advertising Remote Router Set, recording each remote router from which TC messages have been received. This is used in order to determine if a received TC message contains fresh or outdated information; a received TC message is ignored in the latter case.

o A Router Topology Set, recording links between routers in the MANET, as described by received TC messages. The purpose of the Topology Information Base is to record information used, in addition to that in the Local Information Base, the Interface Information Bases, and the Neighbor Information Base, to construct the Routing Set (which is also included in the Topology Information Base).

This specification describes the calculation of the Routing Set based on a Topology Graph constructed in two phases. First, a "backbone" graph representing the routers in the MANET, and the connectivity between them, is constructed from the Local Information Base, the Neighbor Information Base, and the Router Topology Set. Second, this graph is "decorated" with additional destination network addresses using the Local Information Base, the Routable Address Topology Set, and the Attached Network Set.

The Topology Graph does not need to be recorded in the Topology Information Base; it can either be constructed as required when the Routing Set is to be changed or need not be explicitly constructed (as illustrated in Appendix C). An implementation may, however, construct and retain the Topology Graph if preferred.

Signaling Overview

This protocol generates and processes HELLO messages according to [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF]. HELLO messages transmitted on OLSRv2 interfaces are extended according to Section 15 of this specification to include an originator address, link metrics, and MPR selection information.

This specification defines a single Message Type, the TC message. TC messages are sent by their originating router proactively, at a regular interval, on all OLSRv2 interfaces. This interval may be fixed or dynamic, for example, it may be backed off due to congestion or network stability. TC messages may also be sent as a response to a change in the router itself, or its advertised symmetric 1-hop neighborhood, for example, on first being selected as a routing MPR.

Because TC messages are sent periodically, this protocol is tolerant of unreliable transmissions of TC messages. Message losses may occur more frequently in wireless networks due to collisions or other transmission problems. This protocol may use "jitter", randomized adjustments to message transmission times, to reduce the incidence of collisions, as specified in [START_REF] Clausen | Jitter Considerations in Mobile Ad Hoc Networks (MANETs)[END_REF].

This protocol is tolerant of out-of-sequence delivery of TC messages due to in-transit message reordering. Each router maintains an Advertised Neighbor Sequence Number (ANSN) that is incremented when its recorded neighbor information that is to be included in its TC messages changes. This ANSN is included in the router's TC messages.

The recipient of a TC message can use this included ANSN to identify which of the information it has received is most recent, even if TC messages may be "complete" or "incomplete". A complete TC message advertises all of the originating router's routing MPR selectors; it may also advertise other symmetric 1-hop neighbors. Complete TC messages are generated periodically (and also, optionally, in response to symmetric 1-hop neighborhood changes). Incomplete TC messages may be used to report additions to advertised information, without repeating unchanged information.

TC messages, and HELLO messages as extended by this specification, define (by inclusion or by deduction when having a single address) an originator address for the router that created the message. A TC message reports both the originator addresses and routable addresses of its advertised neighbors, distinguishing the two using an Address Block TLV (an address may be both routable and an originator address). TC messages also report the originator's locally attached networks.

TC messages are MPR flooded throughout the MANET. A router retransmits a TC message received on an OLSRv2 interface if and only if the message did not originate at this router and has not been previously forwarded by this router, this is the first time the message has been received on this OLSRv2 interface, and the message is received from (i.e., originated from or was last relayed by) one of this router's flooding MPR selectors.

Some TC messages may be MPR flooded over only part of the network, e.g., allowing a router to ensure that nearer routers are kept more up to date than distant routers, such as is used in Fisheye State Routing [FSR] and Fuzzy Sighted Link State routing [FSLS]. This is enabled using [START_REF] Clausen | Representing Multi-Value Time in Mobile Ad Hoc Networks (MANETs)[END_REF].

TC messages include outgoing neighbor metrics that will be used in the selection of routes.

Link Metrics

OLSRv1 [START_REF] Clausen | Optimized Link State Routing Protocol (OLSR)[END_REF] created minimum hop routes to destinations. However, in many, if not most, circumstances, better routes (in terms of quality of service for end users) can be created by use of link metrics. OLSRv2, as defined in this specification, supports metric-based routing, i.e., it allows links to each have a chosen metric. Link metrics as defined in OLSRv2 are additive, and the routes that are to be created are those with the minimum sum of the link metrics along that route.

Link metrics are defined to be directional; the link metric from one router to another may be different from that on the reverse link. The link metric is assessed at the receiver, as on a (typically) wireless link, that is the better informed as to link information.

Both incoming and outgoing link information is used by OLSRv2; the distinctions in this specification must be clearly followed.

This specification also defines both incoming and outgoing neighbor metrics for each symmetric 1-hop neighbor, these being the minimum value of the link metrics in the same direction for all symmetric links with that neighbor. Note that this means that all neighbor metric values are link metric values and that specification of, for example, link metric value encoding also includes encoding of neighbor metric values.

This specification does not define the nature of the link metric. However, this specification allows, through use of the type extension of a defined Address Block TLV, for link metrics with specific meanings to be defined and either allocated by IANA or privately used. Each HELLO or TC message carrying link (or neighbor) metrics thus indicates which link metric information it is carrying, allowing routers to determine if they can interoperate. If link metrics require additional signaling to determine their values, whether in HELLO messages or otherwise, then this is permitted but is outside the scope of this specification.

Careful consideration should be given to how to use link metrics. In particular, it is advisable to not simply default to use of all links with equal metrics (i.e., hop count) for routing without careful consideration of whether that is appropriate or not. The signaling in this specification has been designed so that a "backbone" Topology Graph of routers, each identified by its originator address, with at most one direct connection between any pair of routers, can be constructed (from the Neighbor Set and the Router Topology Set) using a suitable minimum path length algorithm. This Topology Graph can then have other network addresses (routable or of symmetric 1-hop neighbors) added to it (using the Interface Information Bases, the Routable Address Topology Set, and the Attached Network Set).

Protocol Parameters and Constants

The parameters and constants used in this specification are those defined in [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF] plus those defined in this section. The separation in [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF] into interface parameters, router parameters, and constants is also used in this specification.

Similarly to the parameters in [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF], parameters defined in this specification MAY be changed dynamically by a router and need not be the same on different routers, even in the same MANET, or, for interface parameters, on different interfaces of the same router.

Protocol and Port Numbers

This protocol specifies TC messages, which are included in packets as defined by [START_REF] Clausen | Generalized Mobile Ad Hoc Network (MANET) Packet/Message Format[END_REF]. These packets MUST be sent either using the "manet" protocol number or the "manet" UDP well-known port number, as specified in [START_REF] Chakeres | IANA Allocations for Mobile Ad Hoc Network (MANET) Protocols[END_REF].

Multicast Address

This protocol specifies TC messages, which are included in packets as defined by [START_REF] Clausen | Generalized Mobile Ad Hoc Network (MANET) Packet/Message Format[END_REF]. These packets MAY be transmitted using the Link-Local multicast address "LL-MANET-Routers", as specified in [START_REF] Chakeres | IANA Allocations for Mobile Ad Hoc Network (MANET) Protocols[END_REF].

Interface Parameters

A single additional interface parameter is specified for OLSRv2 interfaces only.

Received Message Validity Time

The following parameter manages the validity time of recorded received message information:

RX_HOLD_TIME:

The period after receipt of a message by the appropriate OLSRv2 interface of this router for which that information is recorded, in order that the message is recognized as having been previously received on this OLSRv2 interface.

The following constraints apply to this parameter:

o RX_HOLD_TIME > 0 o RX_HOLD_TIME SHOULD be greater than the maximum difference in time that a message may take to traverse the MANET, taking into account any message forwarding jitter as well as propagation, queuing, and processing delays.

Router Parameters

The following router parameters are specified for routers.

Local History Times

The following router parameter manages the time for which local information is retained: The time for which a recently used and replaced originator address is used to recognize the router's own messages.

The following constraint applies to this parameter: o O_HOLD_TIME > 0 5.4.2. Link Metric Parameters All routes found using this specification use a single link metric type that is specified by the router parameter LINK_METRIC_TYPE, which may take any value from 0 to 255, both inclusive.

Message Intervals

The following parameters regulate TC message transmissions by a router. TC messages are usually sent periodically but MAY also be sent in response to changes in the router's Neighbor Set and/or Local Attached Network Set. In a highly dynamic network, and with a larger value of the parameter TC_INTERVAL and a smaller value of the parameter TC_MIN_INTERVAL, TC messages MAY be transmitted more often in response to changes than periodically. However, because a router has no knowledge of, for example, routers remote to it (i.e., beyond two hops away) joining the network, TC messages MUST NOT be sent purely responsively.

TC_INTERVAL:

The maximum time between the transmission of two successive TC messages by this router. When no TC messages are sent in response to local network changes (by design or because the local network is not changing), then TC messages MUST be sent at a regular interval TC_INTERVAL, possibly modified by jitter, as specified in [START_REF] Clausen | Jitter Considerations in Mobile Ad Hoc Networks (MANETs)[END_REF].

TC_MIN_INTERVAL:

The minimum interval between transmission of two successive TC messages by this router. (This minimum interval MAY be modified by jitter, as specified in [START_REF] Clausen | Jitter Considerations in Mobile Ad Hoc Networks (MANETs)[END_REF].)

The following constraints apply to these parameters:

o TC_INTERVAL > 0 o 0 <= TC_MIN_INTERVAL <= TC_INTERVAL o T_HOLD_TIME MUST be representable by way of the exponent-mantissa notation described in Section 5 of [START_REF] Clausen | Representing Multi-Value Time in Mobile Ad Hoc Networks (MANETs)[END_REF].

Processing and Forwarding Validity Times

The following parameters manage the processing and forwarding validity time of recorded message information:

P_HOLD_TIME:

The period after receipt of a message that is processed by this router for which that information is recorded, in order that the message is not processed again if received again. The period after receipt of a message that is forwarded by this router for which that information is recorded, in order that the message is not forwarded again if received again.

The following constraints apply to these parameters:

o P_HOLD_TIME > 0 o F_HOLD_TIME > 0
o Both of these parameters SHOULD be greater than the maximum difference in time that a message may take to traverse the MANET, taking into account any message forwarding jitter as well as propagation, queuing, and processing delays.

Jitter

If jitter, as defined in [START_REF] Clausen | Jitter Considerations in Mobile Ad Hoc Networks (MANETs)[END_REF], is used, then the governing jitter parameters are as follows:

TP_MAXJITTER: Represents the value of MAXJITTER used in [START_REF] Clausen | Jitter Considerations in Mobile Ad Hoc Networks (MANETs)[END_REF] for periodically generated TC messages sent by this router.

TT_MAXJITTER:

Represents the value of MAXJITTER used in [START_REF] Clausen | Jitter Considerations in Mobile Ad Hoc Networks (MANETs)[END_REF] for externally triggered TC messages sent by this router.

F_MAXJITTER:

Represents the default value of MAXJITTER used in [START_REF] Clausen | Jitter Considerations in Mobile Ad Hoc Networks (MANETs)[END_REF] for messages forwarded by this router. However, before using F_MAXJITTER, a router MAY attempt to deduce a more appropriate value of MAXJITTER, for example, based on any TLVs with Type = INTERVAL_TIME or Type = VALIDITY_TIME contained in the message to be forwarded.

For constraints on these parameters, see [START_REF] Clausen | Jitter Considerations in Mobile Ad Hoc Networks (MANETs)[END_REF].

Hop Limit

The parameter TC_HOP_LIMIT is the hop limit set in each TC message.

TC_HOP_LIMIT MAY be a single fixed value or MAY be different in TC messages sent by the same router. However, each other router, at any hop count distance, MUST see a regular pattern of TC messages in order that meaningful values of TLVs with Type = INTERVAL_TIME and Type = VALIDITY_TIME at each hop count distance can be included as defined in [START_REF] Clausen | Representing Multi-Value Time in Mobile Ad Hoc Networks (MANETs)[END_REF]. Thus, the pattern of TC_HOP_LIMIT MUST be If a router has a willingness value equal to WILL_ALWAYS (the highest possible value), then it will always be selected as a flooding or routing MPR, as appropriate, by all symmetric 1-hop neighbors.

In a MANET in which all routers have WILL_FLOODING = WILL_ALWAYS, flooding reduction will effectively be disabled, and flooding will perform as blind flooding.

In a MANET in which all routers have WILL_ROUTING = WILL_ALWAYS, topology reduction will effectively be disabled, and all routers will advertise all of their links in TC messages.

A + For each Link Tuple that is not removed, set:

-L_out_metric := UNKNOWN_METRIC;

-L_SYM_time := EXPIRED;

-L_MPR_selector := false.

+ Remove all Router Topology Tuples, Routable Address Topology Tuples, Attached Network Tuples, and Routing Tuples from their respective Protocol Sets in the Topology Information Base.

Constants

The following constants are specified for routers. Unlike router parameters, constants MUST NOT change and MUST be the same on all routers.

Link Metric Constants

The constant minimum and maximum link metric values are defined by:

o MINIMUM_METRIC := 1 o MAXIMUM_METRIC := 16776960
The symbolic value UNKNOWN_METRIC is defined in Section 6.1.

Link Metric Values

A router records a link metric value for each direction of a link of which it has knowledge. These link metric values are used to create metrics for routes by the addition of link metric values.

Link Metric Representation

Link metrics are reported in messages using a compressed representation that occupies 12 bits, consisting of a 4-bit field and an 8-bit field. The compressed representation represents positive integer values with a minimum value of 1 and a maximum value that is slightly smaller than the maximum 24-bit value. Only those values that have exact representation in the compressed form are used. Route metrics are the summation of no more than 256 link metric values and can therefore be represented using no more than 32 bits.

Link and route metrics used in the Information Bases defined in this specification refer to the uncompressed values, and arithmetic involving them does likewise and assumes full precision in the result. (How an implementation records the values is not part of this specification, as long as it behaves as if recording uncompressed values. An implementation can, for example, use 32-bit values for all link and route metrics.) In some cases, a link metric value may be unknown. This is indicated in this specification by the symbolic value UNKNOWN_METRIC. An implementation may use any representation of UNKNOWN_METRIC as it is never included in messages or used in any computation. (Possible representations are zero or any value greater than the maximum representable metric value.)

Link Metric Compressed Form

The 12-bit compressed form of a link metric uses a modified form of a representation with an 8-bit mantissa (denoted a) and a 4-bit exponent (denoted b). Note that if represented as the 12-bit value 256b+a, then the ordering of those 12-bit values is identical to the ordering of the represented values.

The value so represented is (257+a)2^b -256, where ^ denotes exponentiation. This has a minimum value (when a = 0 and b = 0) of MINIMUM_METRIC = 1 and a maximum value (when a = 255 and b = 15) of MAXIMUM_METRIC = 2^24 -256.

An algorithm for computing a and b for the smallest representable value not less than a link metric value v such that MINIMUM_METRIC <= v <= MAXIMUM_METRIC is:

1. Find the smallest integer b such that v + 256 <= 2^(b + 9).

2. Set a := (v -256(2^b -1)) / (2^b) -1, rounded up to the nearest integer.

Local Information Base

The Local Information Base, as defined for each router in [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF], is extended by this protocol by: o Recording the router's originator address. where:

AL_net_addr is the network address of an attached network that can be reached via this router. This SHOULD be a routable address. It is constrained as described below.

AL_dist is the number of hops to the network with network address AL_net_addr from this router.

AL_metric is the metric of the link to the attached network with address AL_net_addr from this router.

Interface Information Base

An Interface Information Base, as defined in [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF], is maintained for each MANET interface. The Link Set and 2-Hop Set in the Interface Information Base for an OLSRv2 interface are modified by this protocol. In some cases, it may be convenient to consider these Sets as also containing these additional elements for other MANET interfaces, taking the indicated values on creation but never being updated.

Link Set

The Link Set is modified by adding these additional elements to each Link Tuple:

L_in_metric is the metric of the link from the OLSRv2 interface with addresses L_neighbor_iface_addr_list to this OLSRv2 interface;

L_out_metric is the metric of the link to the OLSRv2 interface with addresses L_neighbor_iface_addr_list from this OLSRv2 interface;

L_mpr_selector is a boolean flag, describing if this neighbor has selected this router as a flooding MPR, i.e., is a flooding MPR selector of this router. o L_mpr_selector := false.

2-Hop Set

The 2-Hop Set is modified by adding these additional elements to each 2-Hop Tuple:

N2_in_metric is the neighbor metric from the router with address N2_2hop_iface_addr to the router with OLSRv2 interface addresses N2_neighbor_iface_addr_list;

N2_out_metric is the neighbor metric to the router with address N2_2hop_iface_addr from the router with OLSRv2 interface addresses N2_neighbor_iface_addr_list.

A 2-Hop Tuple created (but not updated) by [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF] MUST set:

o N2_in_metric := UNKNOWN_METRIC; o N2_out_metric := UNKNOWN_METRIC.

Neighbor Information Base

A Neighbor Information Base, as defined in [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF], is maintained for each router. It is modified by this protocol by adding these additional elements to each Neighbor Tuple in the Neighbor Set. In some cases, it may be convenient to consider these Sets as also containing these additional elements for other MANET interfaces, taking the indicated values on creation but never being updated.

N_orig_addr is the neighbor's originator address, which may be unknown. Note that this originator address does not include a prefix length; N_will_flooding is the neighbor's willingness to be selected as a flooding MPR, in the range from WILL_NEVER to WILL_ALWAYS, both inclusive, taking the value WILL_NEVER if no OLSRv2-specific information is received from this neighbor;

N_will_routing is the neighbor's willingness to be selected as a routing MPR, in the range from WILL_NEVER to WILL_ALWAYS, both inclusive, taking the value WILL_NEVER if no OLSRv2-specific information is received from this neighbor;

N_flooding_mpr is a boolean flag, describing if this neighbor is selected as a flooding MPR by this router;

N_routing_mpr is a boolean flag, describing if this neighbor is selected as a routing MPR by this router;

N_mpr_selector is a boolean flag, describing if this neighbor has selected this router as a routing MPR, i.e., is a routing MPR selector of this router.

N_advertised is a boolean flag, describing if this router has elected to advertise a link to this neighbor in its TC messages. (TR_from_orig_addr, TR_to_orig_addr, TR_seq_number, TR_metric, TR_time)

where:

TR_from_orig_addr is the originator address of a router that can reach the router with originator address TR_to_orig_addr in one hop (note that this does not include a prefix length);

TR_to_orig_addr is the originator address of a router that can be reached by the router with originator address TR_from_orig_addr in one hop (note that this does not include a prefix length);

TR_seq_number is the greatest ANSN in any TC message received that originated from the router with originator address TR_from_orig_addr (i.e., that contributed to the information contained in this Tuple);

TR_metric is the neighbor metric from the router with originator address TR_from_orig_addr to the router with originator address TR_to_orig_addr;

TR_time specifies the time at which this Tuple expires and MUST be removed.

Routable Address Topology Set

A router's Routable Address Topology Set records topology information about the routable addresses within the MANET, including via which routers they may be reached. It consists of Routable Address Topology Tuples:

(TA_from_orig_addr, TA_dest_addr, TA_seq_number, TA_metric, TA_time)

where:

TA_from_orig_addr is the originator address of a router that can reach the router with routable address TA_dest_addr in one hop (note that this does not include a prefix length); where:

R_dest_addr is the network address of the destination, either the network address of an interface of a destination router or the network address of an attached network;

R_next_iface_addr is the network address of the "next hop" on the selected path to the destination;

R_local_iface_addr is an address of the local interface over which an IP packet MUST be sent to reach the destination by the selected path.

R_dist is the number of hops on the selected path to the destination;

R_metric is the metric of the route to the destination with address R_dest_addr.

The Routing Set for a router is derived from the contents of other Protocol Sets of the router (the Link Sets, the Neighbor Set, the Router Topology Set, the Routable Address Topology Set, the Attached Network Set, and OPTIONAL use of the 2-Hop Sets). The Routing Set is updated (Routing Tuples added or removed, or the complete Routing Set recalculated) when routing paths are calculated, based on changes to these other Protocol Sets. Routing Tuples are not subject to timerbased expiration.

Received Message Information Base

The Received Message Information Base, defined by this specification, records information required to ensure that a message is processed at most once and is forwarded at most once per OLSRv2 interface of a router, using MPR flooding. Messages are recorded using their "signature", consisting of their type, originator address, and message sequence number. where:

F_type is the forwarded Message Type;

F_orig_addr is the originator address of the forwarded message (note that this does not include a prefix length);

F_seq_number is the message sequence number of the forwarded message;

F_time specifies the time at which this Tuple expires and MUST be removed.

Information Base Properties

This section describes some additional properties of Information Bases and their contents.

12.1.

Packets and Messages

The packet and message format used by this protocol is defined in [START_REF] Clausen | Generalized Mobile Ad Hoc Network (MANET) Packet/Message Format[END_REF]. Except as otherwise noted, options defined in [START_REF] Clausen | Generalized Mobile Ad Hoc Network (MANET) Packet/Message Format[END_REF] may be freely used, in particular alternative formats defined by packet, message, Address Block, and TLV flags.

This section describes the usage of the packets and messages defined in [START_REF] Clausen | Generalized Mobile Ad Hoc Network (MANET) Packet/Message Format[END_REF] by this specification and the TLVs defined by, and used in, this specification.

Messages

Routers using this protocol exchange information through messages. The Message Types used by this protocol are the HELLO message and the TC message. The HELLO message is defined by [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF] and extended by this specification (see Section 15). The TC message is defined by this specification (see Section 16).

Packets

One or more messages sent by a router at the same time SHOULD be combined into a single packet, subject to any constraints on maximum packet size (such as derived from the MTU over a local single hop) that MAY be imposed. These messages may have originated at the sending router or at another router and are being forwarded by the sending router. Messages with different originating routers MAY be combined for transmission within the same packet. Messages from other protocols defined using [START_REF] Clausen | Generalized Mobile Ad Hoc Network (MANET) Packet/Message Format[END_REF], including but not limited to NHDP [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF], MAY be combined for transmission within the same packet. This specification does not define or use any contents of the Packet Header.

Forwarded messages MAY be jittered as described in [START_REF] Clausen | Jitter Considerations in Mobile Ad Hoc Networks (MANETs)[END_REF], including the observation that the forwarding jitter of all messages received in a single packet SHOULD be the same. The value of MAXJITTER used in jittering a forwarded message MAY be based on information in that message (in particular any Message TLVs with Type = INTERVAL_TIME or Type = VALIDITY_TIME) or otherwise SHOULD be with a maximum delay of F_MAXJITTER. A router MAY modify the jitter applied to a message in order to more efficiently combine messages in packets, as long as the maximum jitter is not exceeded. All references in this specification to TLVs that do not indicate a type extension assume Type Extension = 0. TLVs in processed messages with a type extension that is neither zero as so assumed, nor a specifically indicated non-zero type extension, are ignored.

Note that, following [START_REF] Clausen | Generalized Mobile Ad Hoc Network (MANET) Packet/Message Format[END_REF] and network byte order, bits in an octet are numbered from 0 (most significant) to 7 (least significant).

Message TLVs

The MPR_WILLING TLV is used in HELLO messages. A message MUST NOT contain more than one MPR_WILLING TLV.

+-------------+--------------+--------------------------------------+ | Type | Value Length | Value | +-------------+--------------+--------------------------------------+ | MPR_WILLING | 1 octet | Bits 0-3 encode the parameter | | | | WILL_FLOODING; bits 4-7 encode the | | | | parameter WILL_ROUTING. | +-------------+--------------+--------------------------------------+ Table 1: MPR_WILLING TLV Definition
The CONT_SEQ_NUM TLV is used in TC messages. A message MUST NOT contain more than one CONT_SEQ_NUM TLV. -------------+--------------+------------------------------------- -------------+--------------+------------------------------------- -------------+--------------+------------------------------------- address MUST NOT be associated with more than one link metric value for any given type extension, kind (link or neighbor), and direction using this TLV. ------------+--------------+-------------------------------------- ------------+--------------+--------------------------------------+ Table 3: LINK_METRIC TLV Definition

+-

+ | Type | Value Length | Value | +-
+-------------+--------------+--------------------------------------+ | Type | Value Length | Value | +-
The exponent and mantissa use the representation defined in Section 6. Each bit of the types and directions sub-field, if set ('1'), indicates that the link metric is of the indicated kind and direction. Any combination of these bits MAY be used. +-----+-----------------+----------- ----+-----------------+-----------

+ | Bit | Kind | Direction | +-----+-----------------+-----------+ | 0 | Link metric | Incoming | | 1 | Link metric | Outgoing | | 2 | Neighbor metric | Incoming | | 3 | Neighbor metric | Outgoing | +-

+ Table 4: LINK_METRIC TLV Types and Directions

The MPR TLV is used in HELLO messages and indicates that an address with which it is associated is of a symmetric 1-hop neighbor that has been selected as an MPR. -----+--------------+--------------------------------------------- -----+--------------+--------------------------------------------- -----+--------------+--------------------------------------------- The NBR_ADDR_TYPE TLV is used in TC messages. --------------+--------------+------------------------------------+ | NBR_ADDR_TYPE | 1 octet | ORIGINATOR indicates that the The GATEWAY TLV is used in TC messages. An address MUST NOT be associated with more than one hop count value using this TLV. --------+--------------+------------------------------------- --------+--------------+-------------------------------------+ Table 7: GATEWAY TLV Definition All address objects included in a TC message according to this specification MUST be associated either with at least one TLV with Type := NBR_ADDR_TYPE or with a TLV with Type := GATEWAY, but not both. Any other address objects MAY be included in Address Blocks in a TC message but are ignored by this specification. The processing selection and forwarding mechanisms are designed to only need to parse the Message Header in order to determine whether a message is to be processed and/or forwarded and not to have to parse the Message Body even if the message is forwarded (but not processed). An implementation MAY only parse the Message Body if necessary or MAY always parse the Message Body and reject the message if it cannot be so parsed or any other error is identified.

+-

+ | Type | Value Length | Value | +-
+---------------+--------------+------------------------------------+ | Type | Value Length | Value | +-
+---------+--------------+-------------------------------------+ | Type | Value Length | Value | +-
An implementation MUST discard the message silently if it is unable to parse the Message Header or (if attempted) the Message Body, or if a message (other than a HELLO message) does not include a message sequence number.

Actions When Receiving a Message

On receiving, on an OLSRv2 interface, a message of a type specified to be using this mechanism, which includes the TC messages defined in this specification, a router MUST perform the following:

1. If the router recognizes from the originator address of the message that the message is one that the receiving router itself originated (i.e., the message originator address is the originator address of this router or is an O_orig_addr in an Originator Tuple), then the message MUST be silently discarded. 1. If the message is of a type that may be processed, then the message is considered for processing according to Section 14.2.

2. If the message is of a type that may be forwarded, AND:

+ <msg-hop-limit> is present and <msg-hop-limit> > 1; AND + <msg-hop-count> is not present or <msg-hop-count> < 255, then the message is considered for forwarding according to Section 14.3.

Message Considered for Processing

If a message (the "current message") is considered for processing, then the following tasks MUST be performed:

1. If the sending address (i.e., the source address of the IP datagram containing the current message) does not match (taking into account any address prefix) a network address in an L_neighbor_iface_addr_list of a Link Tuple, with L_status = SYMMETRIC, in the Link Set for the OLSRv2 interface on which the current message was received (the "receiving interface"), then processing the current message is OPTIONAL. If the current message is not processed, then the following steps are not carried out. 2. Process the current message according to its Message Type. For a TC message, this is as defined in Section 16.3.

If a

Message Considered for Forwarding

If a message (the "current message") is considered for forwarding, then the following tasks MUST be performed:

1. If the sending address (i.e., the source address of the IP datagram containing the current message) does not match (taking into account any address prefix) a network address in an L_neighbor_iface_addr_list of a Link Tuple, with L_status = SYMMETRIC, in the Link Set for the OLSRv2 interface on which the current message was received (the "receiving interface"), then the current message MUST be silently discarded. 3. The message is transmitted over all OLSRv2 interfaces, as described in Section 13.

HELLO Messages

The HELLO Message Type is owned by NHDP [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF], and HELLO messages are thus generated, transmitted, received, and processed by NHDP. This protocol, as permitted by [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF], also uses HELLO messages, including adding to HELLO message generation and implementing additional processing based on received HELLO messages. HELLO messages are not forwarded by NHDP [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF] or by OLSRv2.

HELLO Message Generation

HELLO messages sent over OLSRv2 interfaces are generated as defined in [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF] and then modified as described in this section. HELLO messages sent on other MANET interfaces are not modified by this specification.

HELLO messages sent over OLSRv2 interfaces are extended by adding the following elements:

o A message originator address, recording this router's originator address. This MUST use a <msg-orig-addr> element, unless:

* The message specifies only a single local interface address (i.e., contains only one address object that is associated with an Address Block TLV with Type = LOCAL_IF and that has no prefix length or a maximum prefix length) that will then be used as the message originator address; OR * The message does not include any local interface network addresses (i.e., has no address objects associated with an Address Block TLV with Type = LOCAL_IF), as permitted by the specification in [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF], when the router that generated the HELLO message has only one interface address and will use that as the sending address of the IP datagram in which the HELLO message is contained. In this case, that address will be used as the message originator address.

o A Message TLV with Type := MPR_WILLING MUST be included.

o The following cases associate Address Block TLVs with one or more addresses from a Link Tuple or a Neighbor Tuple if these are included in the HELLO message. In each case, the TLV MUST be associated with at least one address object for an address from the relevant Tuple; the TLV MAY be associated with more such addresses (including a copy of that address object, possibly not . This protocol MAY require that an additional HELLO message be sent on each OLSRv2 interface when either of the router's sets of MPRs changes, in addition to the cases specified in [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF] and subject to the constraints specified in [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF] (notably on minimum HELLO message transmission intervals).

HELLO Message Processing

When received on an OLSRv2 interface, HELLO messages are made available to this protocol in two ways, both as permitted by [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF]:

o Such received HELLO messages MUST be made available to this protocol on reception, which allows them to be discarded before being processed by NHDP [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF], for example, if the information added to the HELLO message by this specification is inconsistent.

o Such received HELLO messages MUST be made available to OLSRv2 after NHDP [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF] has completed its processing thereof, unless discarded as malformed by NHDP, for processing by OLSRv2.

HELLO Message Discarding

In addition to the reasons specified in [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF] for discarding a HELLO message on reception, a HELLO message received on an OLSRv2 interface MUST be discarded before processing by NHDP [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF] o Contains any address that will be processed by NHDP [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF] that is associated, using the same or different address objects, with two different values of link metric with the same kind and direction using a TLV with Type = LINK_METRIC and Type Extension = LINK_METRIC_TYPE. This also applies to different addresses that are both of the OLSRv2 interface on which the HELLO message was received.

o Contains any address object associated with an Address Block TLV with Type = MPR that is not also associated with an Address Block TLV with Type = LINK_STATUS and Value = SYMMETRIC (including using a different copy of that address object in the same or a different Address Block).

HELLO Message Usage

HELLO messages are first processed as specified in [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF]. That processing includes identifying (or creating) a Link Tuple and a Neighbor Tuple corresponding to the originator of the HELLO message (the "current Link Tuple" and the "current Neighbor Tuple"). After this, the following processing MUST also be performed if the HELLO message is received on an OLSRv2 interface and contains a TLV with Type = MPR_WILLING:

1. If the HELLO message has a well-defined message originator address, i.e., has an <msg-orig-addr> element or has zero or one network addresses associated with a TLV with Type = LOCAL_IF:

1. Remove any Neighbor Tuple, other than the current Neighbor Tuple, with N_orig_addr = message originator address, taking any consequent action (including removing one or more Link Tuples) as specified in [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF]. 4. All 2-Hop Tuples that were updated as described in [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF] are then updated according to:

The current

1. Update N2_in_metric and N2_out_metric as described in Section 15.3.2.1.

2. If there are any changes to the router's Information Bases, then perform the processing defined in Section 17.

Updating Metrics

For each address in a received HELLO message with an associated TLV with Type = LINK_STATUS and Value = HEARD or Value = SYMMETRIC, an incoming (to the message originator) link metric value is defined.

If the HELLO message contains a TLV with Type = LINK_METRIC and Type Extension = LINK_METRIC_TYPE that associates that address value with a metric value of the appropriate kind (link) and direction (incoming) of metric, then the incoming link metric is that metric value; otherwise, the incoming link metric is defined as UNKNOWN_METRIC.

For each address in a received HELLO message with an associated TLV with Type = LINK_STATUS and Value = SYMMETRIC, an outgoing (from the message originator) link metric value is defined. If the HELLO message contains a TLV with Type = LINK_METRIC and Type Extension = LINK_METRIC_TYPE that associates that address value with a metric value of the appropriate kind (link) and direction (outgoing) of metric, then the outgoing link metric is that metric value; otherwise, the outgoing link metric is defined as UNKNOWN_METRIC.

For each address in a received HELLO message with an associated TLV with Type = LINK_STATUS or Type = OTHER_NEIGHB and Value = SYMMETRIC, an incoming (to the message originator) neighbor metric value is defined. If the HELLO message contains a TLV with Type = LINK_METRIC and Type Extension = LINK_METRIC_TYPE that associates that address value with a metric value of the appropriate kind (neighbor) and direction (incoming) of metric, then the incoming neighbor metric is that metric value; otherwise, the incoming neighbor metric is defined as UNKNOWN_METRIC. * The router MAY also set N_advertised := false.

TC Messages

This protocol defines, and hence owns, the TC Message Type (see Section 24). Thus, as specified in [START_REF] Clausen | Generalized Mobile Ad Hoc Network (MANET) Packet/Message Format[END_REF], this protocol generates and transmits all TC messages, receives all TC messages, and is responsible for determining whether and how each TC message is to be processed (updating the Topology Information Base) and/or forwarded, according to this specification.

TC Message Generation

A TC message is a message as defined in [START_REF] Clausen | Generalized Mobile Ad Hoc Network (MANET) Packet/Message Format[END_REF] MUST specify times that vary with the number of hops appropriate to the chosen pattern of TC message hop limits, as specified in [START_REF] Clausen | Representing Multi-Value Time in Mobile Ad Hoc Networks (MANETs)[END_REF]; these times MUST be appropriate multiples of TC_INTERVAL. The options included in [START_REF] Clausen | Representing Multi-Value Time in Mobile Ad Hoc Networks (MANETs)[END_REF] for representing zero and infinite times MUST NOT be used.

TC Message Transmission

A router with one or more OLSRv2 interfaces, and with any Neighbor Tuples with N_advertised = true, or with a non-empty Local Attached Network Set MUST generate TC messages. A router that does not have such information to advertise MUST also generate "empty" TC messages for a period A_HOLD_TIME after it last generated a non-empty TC message.

Complete TC messages are generated and transmitted periodically on all OLSRv2 interfaces, with a default interval between two consecutive TC message transmissions by the same router of TC_INTERVAL.

TC messages MAY be generated in response to a change in the information that they are to advertise, indicated by a change in the ANSN in the Neighbor Information Base. In this case, a router MAY send a complete TC message and, if so, MAY restart its TC message schedule. Alternatively, a router MAY send an incomplete TC message with at least the newly advertised network addresses (i.e., not previously, but now, an N_orig_addr or in an N_neighbor_addr_list in a Neighbor Tuple with N_advertised = true or an AL_net_addr) in its Address Blocks, with associated Address Block TLV(s). Note that a router cannot report removal of advertised content using an incomplete TC message.

When sending a TC message in response to a change of advertised network addresses, a router MUST respect a minimum interval of TC_MIN_INTERVAL between sending TC messages (complete or incomplete) and a maximum interval of TC_INTERVAL between sending complete TC messages. Thus, a router MUST NOT send an incomplete TC message if within TC_MIN_INTERVAL of the next scheduled time to send a complete TC message.

The generation of TC messages, whether scheduled or triggered by a change of contents, MAY be jittered as described in [START_REF] Clausen | Jitter Considerations in Mobile Ad Hoc Networks (MANETs)[END_REF] On receiving a TC message on an OLSRv2 interface, the receiving router MUST then follow the processing and forwarding procedures defined in Section 14.

If the message is considered for processing (Section 14.2), then a router MUST first check if the message is invalid for processing by this router, as defined in Section 16.3.1. A router MAY make a similar check before considering a message for forwarding; it MUST check the aspects that apply to elements in the Message Header.

If the TC message is not invalid, then the processing specific to TC Message Type, described in Section 16.3.2, MUST be applied. This will update its appropriate Interface Information Bases and its Router Information Base. Following this, if there are any changes in these Information Bases, then the processing in Section 17 MUST be performed.

TC Message Discarding

A received TC message is invalid for processing by this router if the message:

o Has an address length specified in the Message Header that is not equal to the length of the addresses used by this router. o Has a message originator address that is partially owned by this router. A router MAY recognize additional reasons for identifying that a message is invalid. An invalid message MUST be silently discarded, without updating the router's Information Bases.

Note that a router that acts inconsistently, for example, rejecting TC messages "at random", may cause parts of the network to not be able to communicate with other parts of the network. It is RECOMMENDED that such "additional reasons for identifying that a message is invalid" be a consistent network-wide policy (e.g., as part of a security policy), implemented on all participating routers. + TR_from_orig_addr := message originator address;

+ TR_to_orig_addr := advertised address.

3. This Router Topology Tuple (existing or new) is then modified as follows:

+ TR_seq_number := received ANSN;

+ TR_metric := associated link metric;

+ TR_time := current time + validity time.

Populating the Routable Address Topology Set

The router MUST update its Routable Address Topology Set as follows:

1. For each network address (henceforth, advertised address) that corresponds to one or more address objects with an associated Address Block TLV with Type = NBR_ADDR_TYPE and Value = ROUTABLE or Value = ROUTABLE_ORIG and that is not partially owned by this router, perform the following processing:

1. If the associated metric is UNKNOWN_METRIC, then remove any Routable Address Topology Tuple such that:

+ TA_from_orig_addr = message originator address; AND + TA_dest_addr = advertised address. + TA_from_orig_addr := message originator address;

Otherwise

+ TA_dest_addr := advertised address.

3. This Routable Address Topology Tuple (existing or new) is then modified as follows:

+ TA_seq_number := received ANSN;

+ TA_metric := associated link metric;

+ TA_time := current time + validity time.

Populating the Attached Network Set

The router MUST update its Attached Network Set as follows:

1. For each network address (henceforth, attached address) that corresponds to one or more address objects with an associated Address Block TLV with Type = GATEWAY and that is not fully owned by this router, perform the following processing: The TC message is processed as follows:

1. The Router Topology Set is updated according to Section 16.3.4.1. The Attached Network Set MUST be updated as follows:

The Routable Address

1. Any Attached Network Tuples with:

* AN_orig_addr = message originator address; AND * AN_seq_number < received ANSN, MUST be removed.

Information Base Changes

The changes described in the following sections MUST be carried out when any Information Base changes as indicated.

Originator Address Changes

If the router changes its originator address, then: The more neighbors that are advertised, the larger TC messages become, but the more redundancy is available for routing. A router SHOULD consider the nature of its network in making such a decision and SHOULD avoid unnecessary changes in advertising status, which may result in unnecessary changes to routing.

Advertised Neighbor Changes

The router MUST increment the ANSN in the Neighbor Information Base whenever:

1. Any Neighbor Tuple changes its N_advertised value, or any Neighbor Tuple with N_advertised = true is removed.

Any Neighbor

Neighborhood Changes and MPR Updates

The sets of symmetric 1-hop neighbors selected as flooding MPRs and routing MPRs MUST satisfy the conditions defined in Section 18. To ensure this: If either set of MPRs of a router is recalculated, this MUST be as described in Section 18.

Routing Set Updates

The Routing Set MUST be updated, as described in o The Attached Network Set of the router.

Selecting MPRs

Each router MUST select, from among its willing symmetric 1-hop neighbors, two subsets of these routers, as flooding and routing MPRs. This selection is recorded in the router's Neighbor Set and reported in the router's HELLO messages. Routers MAY select their MPRs by any process that satisfies the conditions that follow, which may, but need not, use the organization of the data described. Routers can freely interoperate whether they use the same or different MPR selection algorithms.

Only flooding MPRs forward control messages flooded through the MANET, thus effecting a flooding reduction, an optimization of the flooding mechanism, known as MPR flooding. Routing MPRs are used to effect a topology reduction in the MANET. (If no such reduction is required, then a router can select all of its relevant neighbors as routing MPRs.) Consequently, while it is not essential that these two sets of MPRs are minimal, keeping the numbers of MPRs small ensures that the overhead of this protocol is kept to a minimum. o A specification as to when MPRs MUST be calculated is given.

When a router selects its MPRs, it MAY consider any characteristics of its neighbors that it is aware of. In particular, it SHOULD consider the willingness of the neighbor, as recorded by the corresponding N_will_flooding or N_will_routing value, as appropriate, preferring neighbors with higher values. (Note that willingness values equal to WILL_NEVER and WILL_ALWAYS are always considered, as described.) However, a router MAY consider other characteristics to have a greater significance.

Each router MAY select its flooding and routing MPRs independently of each other or coordinate its selections. A router MAY make its MPR selections independently of the MPR selection by other routers, or it MAY, for example, give preference to routers that either are, or are not, already selected as MPRs by other routers.

Neighbor Graph

A Neighbor Graph is a structure defined here as consisting of sets N1 and N2 and some associated metric and willingness values. Elements of set N1 represent willing symmetric 1-hop neighbors, and elements of set N2 represent addresses of a symmetric 2-hop neighbor. o For each element x in N1, there is an associated willingness value W(x) such that WILL_NEVER < W(x) <= WILL_ALWAYS.

o For each element x in N1, there is an associated metric d1(x) > 0.

o For some elements y in N2, there is an associated metric d1(y) > 0. (Other elements y in N2 have undefined d1(y); this may be considered to be infinite.)

o For each element x in N1, there is a subset N2(x) of elements of N2; this subset may be empty. For each x in N1 and each y in N2(x), there is an associated metric d2(x,y) > 0. (For other x in N1 and y in N2, d2(x,y) is undefined and may be considered infinite.) o N2 is equal to the union of all the N2(x) for all x in N1, i.e., for each y in N2, there is at least one x in N1 such that y is in N2(x).

It is convenient to also define:

o For each y in N2, the set N1(y) that contains x in N1 if and only if y is in N2(x). From the final property above, N1(y) is not empty.

o For each x in N1 and y in N2, if d2(x,y) is defined, then d(x,y) := d1(x)+d2(x,y); otherwise, d(x,y) is not defined. (Thus, d(x,y) is defined if y is in N2(x) or, equivalently, if x is in N1(y).)

o For any subset S of N1 and for each y in N2, the metric d(y,S) is the minimum value of d1(y), if defined, and of all d(x,y) for x in N1(y) and in S. If there are no such metrics to take the minimum value of, then d(y,S) is undefined (may be considered to be infinite). From the final property above, d(y,N1) is defined for all y.

MPR Properties

Given a Neighbor Graph as defined in Section 18.2, an MPR Set for that Neighbor Graph is a subset M of the set N1 that satisfies the following properties: o For any y in N2 that does not have a defined d1(y), there is at least one element in M that is also in N1(y). This is equivalent to the requirement that d(y,M) is defined.

o For any y in N2, d(y,M) = d(y,N1).

These properties reflect that the MPR Set consists of a set of symmetric 1-hop neighbors that cover all the symmetric 2-hop neighbors and that they do so retaining a minimum distance route (1-hop, if present, or 2-hop) to each symmetric 2-hop neighbor.

Note that if M is an MPR Set, then so is any subset of N1 that contains M; also note that N1 is always an MPR Set. An MPR Set may be empty but cannot be empty if N2 contains any elements y that do not have a defined d1(y).

Flooding MPRs

Whenever flooding MPRs are to be calculated, an implementation MUST determine and record a set of flooding MPRs that is equivalent to one calculated as described in this section.

The calculation of flooding MPRs need not use link metrics or, equivalently, may use link metrics with a fixed value, here taken to be 1. However, links with unknown metric (L_out_metric = UNKNOWN_METRIC) MUST NOT be used even if link metrics are otherwise not used.

Routers MAY make individual decisions as to whether to use link metrics for the calculation of flooding MPRs. A router MUST use the same approach to the choice of whether to use link metrics for all links, i.e., in the cases indicated by A or B, the same choice MUST be made in each case.

For each OLSRv2 interface (the "current interface"), define a Neighbor Graph as defined in Section 18.2 according to the following:

o Define a reachable Link Tuple to be a Link Tuple in the Link Set for the current interface with L_status = SYMMETRIC and L_out_metric != UNKNOWN_METRIC.

o Define an allowed Link Tuple to be a reachable Link Tuple whose corresponding Neighbor Tuple has N_will_flooding > WILL_NEVER.

Clausen o Define an element of N2 for each network address that is the N2_2hop_addr of one or more allowed 2-Hop Tuples. This then defines the corresponding address for each element of N2.

o For each element y in N2, if the corresponding address is in the N_neighbor_addr_list of a Neighbor Tuple that corresponds to one or more reachable Link Tuples, then define d1(y) as either:

A. the minimum value of the L_out_metric of those Link Tuples; OR B. 1.

Otherwise, d1(y) is not defined. In the latter case, where d1(y) := 1, all such y in N2 may instead be removed from N2.

o For each element x in N1, define N2(x) as the set of elements y in N2 whose corresponding address is the N2_2hop_addr of an allowed 2-Hop Tuple that has N2_neighbor_iface_addr_list = L_neighbor_iface_addr_list of the Link Tuple corresponding to x. For all such x and y, define d2(x,y) as either:

A. N2_out_metric of that 2-Hop Tuple; OR B. 1.

It is up to an implementation to decide how to label each element of N1 or N2. For example, an element of N1 may be labeled with one or more addresses from the corresponding L_neighbor_iface_addr_list or with a pointer or reference to the corresponding Link Tuple. A router MAY select its flooding MPRs for each OLSRv2 interface independently, or it MAY coordinate its MPR selections across its OLSRv2 interfaces, as long as the required condition is satisfied for each OLSRv2 interface. One such coordinated approach is to process the OLSRv2 interfaces sequentially and, for each OLSRv2 interface, start with flooding MPRs selected (and not removable) if the neighbor has been already selected as an MPR for an OLSRv2 interface that has already been processed. The algorithm specified in Appendix B can be used in this way.

Routing MPRs

Whenever routing MPRs are to be calculated, an implementation MUST determine and record a set of routing MPRs that is equivalent to one calculated as described in this section. o Define an element of N2 for each network address that is the N2_2hop_addr of one or more allowed 2-Hop Tuples. This then defines the corresponding address for each element of N2.

o For each element y in N2, if the corresponding address is in the N_neighbor_addr_list of a reachable Neighbor Tuple, then define d1(y) to be the N_in_metric of that Neighbor Tuple; otherwise, d1(y) is not defined.

o For each element x in N1, define N2(x) as the set of elements y in N2 whose corresponding address is the N2_2hop_addr of an allowed 2-Hop Tuple that has N2_neighbor_iface_addr_list contained in N_neighbor_addr_list of the Neighbor Tuple corresponding to x. For all such x and y, define d2(x,y) := N2_out_metric of that 2-Hop Tuple.

It is up to an implementation to decide how to label each element of N1 or N2. For example, an element of N1 may be labeled with one or more addresses from the corresponding N_neighbor_addr_list or with a pointer or reference to the corresponding Neighbor Tuple.

Using these Neighbor Graphs, routing MPRs are selected and recorded according to the following:

o Determine an It SHOULD be preferred, where possible, to select R = S and to select X from the Local Interface Tuple corresponding to the Link Tuple from which R was selected. The metric for such an edge is the corresponding N_out_metric.

o All edges W -> V such that: * W is the TA_from_orig_addr of a Routable Address Topology Tuple; AND * V is the TA_dest_addr of the same Routable Address Topology Tuple.

The metric for such an edge is the corresponding TA_metric.

o All edges W -> T such that: * W is the AN_orig_addr of an Attached Network Tuple; AND * T is the AN_net_addr of the same Attached Network Tuple.

The metric for such an edge is the corresponding AN_metric. A path terminating with such an edge MUST NOT be used in preference to any other path. The metric for such an edge is the corresponding N2_out_metric.

Any part of the Topology Graph that is not connected to a local network address X is not used. Only one selection X SHOULD be made from each I_local_iface_addr_list, and only one selection R SHOULD be made from any L_neighbor_iface_addr_list. All edges have a hop count of 1, except edges W -> T that have a hop count of the corresponding value of AN_dist.

Populating the Routing Set

The Routing Set MUST contain the shortest paths for all destinations from all local OLSRv2 interfaces using the Network Topology Graph. This calculation MAY use any algorithm, including any means of choosing between paths of equal total metric. (In the case of two paths of equal total metric but differing hop counts, the path with the lower hop count SHOULD be used.)

Using the notation of Section 19.1, initially "backbone" paths using only edges X -> Y and W -> U need be constructed (using a minimum distance algorithm). Then paths using only a final edge of the other types may be added. These MUST NOT replace backbone paths with the same destination (and paths terminating in an edge Y -> Z SHOULD NOT replace paths with any other form of terminating edge).

Each path will correspond to a Routing Tuple. These will be of two types. The first type will represent single edge paths, of type X -> S or X -> Y, by: o R_metric := the total metric of all edges in the path.

Finally, Routing Tuples of the second type whose R_dest_addr is not routable MAY be discarded.

An example algorithm for calculating the Routing Set of a router is given in Appendix C.

Proposed Values for Parameters

This protocol uses all parameters defined in [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF] and additional parameters defined in this specification. All but one (RX_HOLD_TIME) of these additional parameters are router parameters as defined in [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF]. The proposed values of the additional parameters defined in the following sections are appropriate to the case where all parameters (including those defined in [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF]) have a single value. Proposed values for parameters defined in [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF] are given in that specification.

The following proposed values are based on experience with [START_REF] Clausen | Optimized Link State Routing Protocol (OLSR)[END_REF] deployments (such as documented in [McCabe]) and are considered typical. They can be changed to accommodate different deployment requirements --for example, a network with capacity-limited network interfaces would be expected to use greater values for message intervals, whereas a highly mobile network would be expected to use lower values for message intervals. When determining these values, the constraints specified in Section 5 MUST be respected. Note that routers in a MANET need not all use the same set of parameters, and those parameters that are indicated as interface parameters need not be the same on all OLSRv2 interfaces of a single router. Sequence numbers are used in this specification for the purpose of discarding "old" information, i.e., messages received out of order. However, with a limited number of bits for representing sequence numbers, wraparound (in which the sequence number is incremented from the maximum possible value to zero) will occur. To prevent this from interfering with the operation of this protocol, the following MUST be observed when determining the ordering of sequence numbers.

The term MAXVALUE designates in the following one more than the largest possible value for a sequence number. For a 16-bit sequence number (like those defined in this specification), MAXVALUE is 65536.

The sequence number S1 is said to be "greater than" the sequence number S2 if:

o S1 > S2 AND S1 -S2 < MAXVALUE/2, OR o S2 > S1 AND S2 -S1 > MAXVALUE/2
When sequence numbers S1 and S2 differ by MAXVALUE/2, their ordering cannot be determined. In this case, which should not occur, either ordering may be assumed.

Thus, when comparing two messages, it is possible --even in the presence of wraparound --to determine which message contains the most recent information.

Extensions

An extension to this protocol will need to interact with this specification and possibly also with [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF]. This protocol is designed to permit such interactions, in particular: o Through accessing, and possibly extending, the information in the Information Bases. All updates to the elements specified in this specification are subject to the normative constraints specified in [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF] o Through requesting that a message be generated at a specific time.

In that case, message generation MUST still respect the constraints in [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF] and Section 5.4.3.

Security Considerations

As a proactive routing protocol, OLSRv2 is a potential target for various attacks. This section presents the envisioned security architecture for OLSRv2 and gives guidelines on how to provide integrity, confidentiality, and integration into external routing domains. Separately specified mandatory security mechanisms are summarized, and some observations on key management are given.

Security Architecture

OLSRv2 integrates into the architecture specified in Appendix A of [START_REF] Clausen | Generalized Mobile Ad Hoc Network (MANET) Packet/Message Format[END_REF], in [START_REF] Chakeres | IANA Allocations for Mobile Ad Hoc Network (MANET) Protocols[END_REF], and in Section 16 of [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF], the latter by using and extending its messages and Information Bases.

As part of this architecture, OLSRv2 and NHDP [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF] recognize that there may be external reasons for rejecting messages that would be considered "badly formed" or "insecure", e.g., if an Integrity Check Value (ICV) included in a message by an external mechanism cannot be verified. This architecture allows options as to whether and how to implement security features, reflecting the situation that MANET routing protocol deployment domains have varying security requirements, ranging from "practically unbreakable" to "virtually none". This approach allows MANET routing protocol specifications to remain generic, with extensions to them and/or extensions to the The following sections provide guidelines on how to provide integrity, confidentiality, and integration with external routing domains in such extensions.

Integrity

Each router injects topological information into the network by transmitting HELLO messages and, for some routers, also TC messages.

If some routers for some reason (malice or malfunction) inject invalid control traffic, network integrity may be compromised. Therefore, message, or packet, authentication is strongly advised.

Different such situations may occur, for example: Authentication of the originator router for control messages (for situations 2, 4, and 5) and of the individual links announced in the control messages (for situations 1 and 3) may be used as a countermeasure. However, to prevent routers from repeating old (and correctly authenticated) information (situation 9), additional information is required (e.g., a timestamp or sequence number), allowing a router to positively identify such replayed messages. In general, ICVs (e.g., digital signatures) and other required security information can be transmitted within the HELLO and TC messages or within a packet header using the TLV mechanism. Either option permits different levels of protection to coexist in the same network, if desired.

An important consideration is that all control messages (HELLO messages and TC messages) are transmitted to all routers in the 1-hop neighborhood and some control messages (TC messages) are flooded to all routers in the network. This is done in a packet that is transmitted to all routers in the 1-hop neighborhood, the current set of which may not be known. Thus, a control message or packet used by this protocol is always contained in a transmission destined for multiple destinations, and it is important that the authentication mechanism employed permits any receiving router to validate the authenticity of a message or packet.

[RFC7182] specifies a common exchange format for cryptographic information in the form of Packet TLVs, Message TLVs, and Address Block TLVs, as specified in [START_REF] Clausen | Generalized Mobile Ad Hoc Network (MANET) Packet/Message Format[END_REF]. These may be used (and shared) among MANET routing protocol security extensions. In particular, [START_REF] Herberg | Integrity Check Value and Timestamp TLV Definitions for Mobile Ad Hoc Networks (MANETs)[END_REF] specifies the format of TLVs for containing Integrity Check Values (ICVs), i.e., signatures, for providing integrity, as well as TLVs for containing temporal information for preventing replay attacks. [START_REF] Herberg | Integrity Check Value and Timestamp TLV Definitions for Mobile Ad Hoc Networks (MANETs)[END_REF] specifies registries for using different ciphers and formats of temporal information. When using ICV TLVs in an OLSRv2 deployment, failure to verify an included ICV mandates rejection of an incoming message or packet as "invalid", according to Section 12.1 of [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF] and according to Section 16.3.1 of this specification when using the multiplexing and demultiplexing process described in Appendix A of [START_REF] Clausen | Generalized Mobile Ad Hoc Network (MANET) Packet/Message Format[END_REF].

[RFC7182] specifies how to insert ICVs into generated messages, how to verify incoming messages, and to reject "insecure" messages (i.e., messages without an ICV or with an ICV that cannot be verified). Different MANET deployments may, as a result of the purpose for which they are used and the possibility and nature of their configuration, require different ICV algorithms and timestamps or multiple keys, and thus, a security extension may use any of the different options provided in [START_REF] Herberg | Integrity Check Value and Timestamp TLV Definitions for Mobile Ad Hoc Networks (MANETs)[END_REF].

Confidentiality

OLSRv2 periodically MPR floods topological information to all routers in the network. Hence, if used in an unprotected network, in particular, an unprotected wireless network, the network topology is revealed to anyone who successfully listens to the control messages. This information may serve an attacker to acquire details about the topology and therefore to initiate more effective attacks against routers in the routing domain, e.g., by spoofing addresses of routers in the network and attracting traffic for these addresses. Note that this is independent of the data traffic and purely protects the control traffic, i.e., information about the network topology.

In situations where the confidentiality of the network topology is of importance, regular cryptographic techniques, such as use of OLSRv2 multicast control packets encrypted using IPsec (e.g., with a shared secret key), can be applied to ensure that control traffic can be read and interpreted by only those authorized to do so. Alternatively, a security extension may specify a mechanism to provide confidentiality for control messages and/or packets. However, unless the information about the network topology itself is confidential, integrity of control messages (as specified in Section 23.2) is sufficient to admit only trusted routers (i.e., routers with valid credentials) to the network.

Interaction with External Routing Domains

This protocol provides a basic mechanism for injecting external routing information into this protocol's routing domain. Routing information can also be extracted from this protocol's Information Bases, in particular the Routing Set, and injected into an external routing domain, if the routing protocol governing that routing domain permits this.

When operating routers connecting a routing domain using this protocol to an external routing domain, care MUST be taken not to allow potentially insecure and untrustworthy information to be injected from this routing domain to an external routing domain.

Care MUST also be taken to validate the correctness of information prior to it being injected, so as to avoid polluting routing tables with invalid information.

A recommended way of extending connectivity from an external routing domain to this routing domain, which is routed using this protocol, is to assign an IP prefix (under the authority of the routers/ gateways connecting this routing domain with the external routing domain) exclusively to this routing domain and to configure the gateways to advertise routes for that IP prefix into the external routing domain.

Mandatory Security Mechanisms

A conformant implementation of OLSRv2 MUST, at minimum, implement the security mechanisms specified in [START_REF] Herberg | Integrity Protection for the Neighborhood Discovery Protocol (NHDP) and Optimized Link State Routing Protocol Version 2 (OLSRv2)[END_REF], providing integrity and replay protection of OLSRv2 control messages, including of HELLO Bootstrapping a key is hard in a radio network, where it is, in general, not possible to determine from where a received signal was transmitted or if two transmissions come from the same or from different sources.

The widespread use of radio networks and mobile phone networks works under the assumptions that (i) secret information is embedded in mobile phones at manufacture, and (ii) a centralized database of this is accessible during the network lifetime.

As a primary use case of a MANET is to provide connectivity without centralized entities and with minimal management, a solution such as described in the previous paragraph is not feasible. In many instances, a cryptographic authority may not be present in the MANET at all, since such a cryptographic authority would be too vulnerable. Due to the potentially dynamic topology of a MANET, a cryptographic authority may also become unreachable (to some or all of the MANET routers) without prior warning.

[BCP107] provides guidelines for cryptographic key management. Specifically, Section 2.1 sets forth requirements for when AKM is required, and Section 2.2 sets forth conditions under which manual key management is acceptable. For the registries where an Expert Review is required, the designated expert SHOULD take the same general recommendations into consideration as are specified by [START_REF] Clausen | Generalized Mobile Ad Hoc Network (MANET) Packet/Message Format[END_REF].

Message Types

This specification defines one Message Type, allocated from the 0-223 range of the "Message Types" namespace defined in [START_REF] Clausen | Generalized Mobile Ad Hoc Network (MANET) Packet/Message Format[END_REF], as specified in Table 8. -----+----------------------------------------------+ | 1 | TC : Topology Control (MANET-wide signaling) | +- -----+----------------------------------------------+ Table 8: Message Type Assignment 24.3. Message-Type-Specific TLV Type Registries IANA has created a registry for Message-Type-specific Message TLVs for TC messages, in accordance with Section 6.2.1 of [START_REF] Clausen | Generalized Mobile Ad Hoc Network (MANET) Packet/Message Format[END_REF] and with initial assignments and allocation policies as specified in Table 9. --------+-------------+------------------- --------+-------------+------------------- --------+-------------+-------------------+ Table 9: TC Message-Type-Specific Message TLV Types IANA has created a registry for Message-Type-specific Address Block TLVs for TC messages, in accordance with Section 6.2.1 of [START_REF] Clausen | Generalized Mobile Ad Hoc Network (MANET) Packet/Message Format[END_REF] and with initial assignments and allocation policies as specified in Table 10. +---------+-------------+------------------- --------+-------------+------------------- This specification defines two Message TLV Types, which have been allocated from the "Message TLV Types" namespace defined in [START_REF] Clausen | Generalized Mobile Ad Hoc Network (MANET) Packet/Message Format[END_REF]. IANA has made allocations in the 0-127 range for these types. Two new Type Extension registries have been created with assignments as specified in Table 11 and Table 12. Specifications of these TLVs are in Section 13.3.1. Each of these TLVs MUST NOT be included more than once in a Message TLV Block. o If N2_out_metric != UNKNOWN_METRIC, then N2_out_metric MUST be representable in the defined compressed form.

+------+----------------------------------------------+ | Type | Description | +-

+-

In o AN_metric MUST be representable in the defined compressed form.

Appendix B. Example Algorithm for Calculating MPRs

The following specifies an algorithm that MAY be used to select an MPR Set given a Neighbor Graph, as defined in Section 18.2 and Section 18.3.

This algorithm selects an MPR Set M that is a subset of the set N1 that is part of the Neighbor Graph. This algorithm assumes that a subset I of N1 is pre-selected as MPRs, i.e., that M will contain I.

B.1. Additional Notation

The following additional notation, in addition to that in Section 18.2, will be used by this algorithm:

N: A subset of N2, consisting of those elements y in N2 such that either d1(y) is not defined, or there is at least one x in N1 such that d(x,y) is defined and d(x,y) < d1(y).

D(x):

For an element x in N1, the number of elements y in N for which d(x,y) is defined and has minimal value among the d(z,y) for all z in N1.

R(x,M):

For an element x in N1, the number of elements y in N for which d(x,y) is defined has minimal value among the d(z,y) for all z in N1 and no such minimal values have z in M. (Note that, denoting the empty set by 0, D(x) = R(x,0).)

B.2. MPR Selection Algorithm

To create the MPR Set M, starting with M := I:

1. Add all elements x in N1 that have W(x) = WILL_ALWAYS to M.

2. For each element y in N for which there is only one element x in N1 such that d2(x,y) is defined, add that element x to M.

3. While there exists any element x in N1 with R(x,M) > 0:

1. Select an element x in N1 with R(x,M) > 0 in the following order of priority, and then add to M: + greatest W(x), THEN + greatest R(x,M), THEN + greatest D(x), THEN + any choice, which MAY be based on other criteria (for example, a router MAY choose to prefer a neighbor as an MPR if that neighbor has already selected the router as an MPR of the same type, MAY prefer a neighbor based on information freshness, or MAY prefer a neighbor based on length of time previously selected as an MPR) or MAY be random.

4. OPTIONAL: consider each element x in M, but not in I, in turn and if x can be removed from M while still leaving it satisfying the definition of an MPR Set, then remove that element x from M. Elements MAY be considered in any order, e.g., in order of increasing W(x).

RFC 7181

OLSRv2

April 2014

Appendix E. Flow and Congestion Control

Due to its proactive nature, this protocol has a natural control over the flow of its control traffic. Routers transmit control messages at predetermined rates specified and bounded by message intervals.

This protocol employs [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF] for local signaling, embedding MPR selection advertisement through a simple Address Block TLV and router willingness advertisement (if any) as a single Message TLV. Local signaling, therefore, shares the characteristics and constraints of [START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF].

Furthermore, the use of MPRs can greatly reduce the signaling overhead from link state information dissemination in two ways, attaining both flooding reduction and topology reduction. First, using MPR flooding, the cost of distributing link state information throughout the network is reduced, as compared to when using blind flooding, since only MPRs need to forward link state declaration messages. Second, the amount of link state information for a router to declare is reduced; it only needs to contain that router's MPR selectors. This reduces the size of a link state declaration as compared to declaring full link state information. In particular, some routers may not need to declare any such information. In dense networks, the reduction of control traffic can be of several orders of magnitude compared to routing protocols using blind flooding [MPR]. This feature naturally provides more bandwidth for useful data traffic and further pushes the frontier of congestion.

Since the control traffic is continuous and periodic, it keeps the quality of the links used in routing more stable. However, using some options, some control messages (HELLO messages or TC messages) may be intentionally sent in advance of their deadline in order to increase the responsiveness of the protocol to topology changes. This may cause a small, temporary, and local increase of control traffic; however, this is at all times bounded by the use of minimum message intervals.

A router that recognizes that the network is suffering from congestion can increase its message interval parameters. If this is done by most or all routers in the network, then the overall control traffic in the network will be reduced. When using this capability, routers will have to take care not to increase message interval parameters such that they cannot cope with network topology changes. Note that routers can make such decisions independently; it is not necessary for all routers to be using the same parameter values, nor is it necessary that all routers decide to change their intervals at the same time.

A

  Neighbor Tuple created (but not updated) by[START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF] MUST set:

  + | CONT_SEQ_NUM | 2 octets | The ANSN contained in the Neighbor | | | | Information Base. | +-

  + | GATEWAY | 1 octet | Number of hops to attached network. | +-

  Processed Tuple exists with: * P_type = the Message Type of the current message; AND * P_orig_addr = the originator address of the current message; AND * P_seq_number = the message sequence number of the current message, then the current message MUST NOT be processed. 3. Otherwise: 1. Create a Processed Tuple in the Processed Set with: + P_type := the Message Type of the current message; Clausen, et al. = the originator address of the current message; + P_seq_number := the sequence number of the current message; + P_time := current time + P_HOLD_TIME.

2. Otherwise: 1 .

 1 If a Received Tuple exists in the Received Set for the receiving interface, with: + RX_type = the Message Type of the current message; AND + RX_orig_addr = the originator address of the current message; AND + RX_seq_number = the sequence number of the current message, then the current message MUST be silently discarded. 2. Otherwise: 1. Create a Received Tuple in the Received Set for the receiving interface with: -RX_type := the Message Type of the current message; -RX_orig_addr := originator address of the current message= sequence number of the current message; -RX_time := current time + RX_HOLD_TIME. 2. If a Forwarded Tuple exists with: -F_type = the Message Type of the current message; AND -F_orig_addr = the originator address of the current message; AND -F_seq_number = the sequence number of the current message, then the current message MUST be silently discarded. 3. Otherwise, if the sending address matches (taking account of any address prefix), any network address in an L_neighbor_iface_addr_list of a Link Tuple in the Link Set for the receiving OLSRv2 interface that has L_status = SYMMETRIC and L_mpr_selector = true, then: 1. Create a Forwarded Tuple in the Forwarded Set with: o F_type := the Message Type of the current message; o F_orig_addr := originator address of the current message; o F_seq_number := sequence number of the current message; o F_time := current time + F_HOLD_TIME. 2. The Message Header of the current message is modified by: o Decrement <msg-hop-limit> in the Message Header by 1; AND o If present, increment <msg-hop-count> in the Message Header by 1.

Clausen*

  any other indicated TLVs, in the same or a different Address Block). These additional TLVs MUST NOT be associated with any other addresses in a HELLO message that will be processed by NHDP[START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF]. * For each Link Tuple for which L_in_metric != UNKNOWN_METRIC and for which one or more addresses in its L_neighbor_iface_addr_list are included as address objects with an associated Address Block TLV with Type = LINK_STATUS and Value = HEARD or Value = SYMMETRIC, at least one of these addresses MUST be associated with an Address Block TLV with Type := LINK_METRIC indicating an incoming link metric with value L_in_metric. * For each Link Tuple for which L_out_metric != UNKNOWN_METRIC and for which one or more addresses in its L_neighbor_iface_addr_list are included as address objects with an associated Address Block TLV with Type = LINK_STATUS and Value = SYMMETRIC, at least one of these addresses MUST be associated with an Address Block TLV with Type := LINK_METRIC indicating an outgoing link metric with value L_out_metric. * For each Neighbor Tuple for which N_symmetric = true and for which one or more addresses in its N_neighbor_addr_list are included as address objects with an associated Address Block TLV with Type = LINK_STATUS or Type = OTHER_NEIGHB and Value = SYMMETRIC, at least one of these addresses MUST be associated with an Address Block TLV with Type := LINK_METRIC indicating an incoming neighbor metric with value N_in_metric. * For each Neighbor Tuple for which N_symmetric = true and for which one or more addresses in its N_neighbor_addr_list are included as address objects with an associated Address Block TLV with Type = LINK_STATUS or Type = OTHER_NEIGHB and Value = SYMMETRIC, at least one of these addresses MUST be associated with an Address Block TLV with Type := LINK_METRIC indicating an outgoing neighbor metric with value N_out_metric. * For each Neighbor Tuple with N_flooding_mpr = true and for which one or more network addresses in its N_neighbor_addr_list are included as address objects in the HELLO message with an associated Address Block TLV with Type = LINK_STATUS and Value = SYMMETRIC, at least one of these addresses MUST be associated with an Address Block TLV with Type := MPR and Value := FLOODING or Value := FLOOD_ROUTE. Clausen, et al. For each Neighbor Tuple with N_routing_mpr = true and for which one or more network addresses in its N_neighbor_addr_list are included as address objects in the HELLO message with an associated Address Block TLV with Type = LINK_STATUS and Value = SYMMETRIC, at least one of these addresses MUST be associated with an Address Block TLV with Type := MPR and Value := ROUTING or Value := FLOOD_ROUTE. 15.2. HELLO Message Transmission HELLO messages are scheduled and transmitted by NHDP [RFC6130]

o

  Does not include a message originator address and a message sequence number. o Does not include a hop count and contains a multi-value TLV with Type = VALIDITY_TIME or Type = INTERVAL_TIME, as defined in [RFC5497]. o Does not have exactly one Message TLV with Type = VALIDITY_TIME. o Has more than one Message TLV with Type = INTERVAL_TIME. o Does not have a Message TLV with Type = CONT_SEQ_NUM and Type Extension = COMPLETE or Type Extension = INCOMPLETE and contains at least one address object associated with an Address Block TLV with Type = NBR_ADDR_TYPE or Type = GATEWAY. o Has more than one Message TLV with Type = CONT_SEQ_NUM and Type Extension = COMPLETE or Type Extension = INCOMPLETE.

1.

  If the associated metric is UNKNOWN_METRIC, then remove any Attached Network Tuple such that: + AN_net_addr = attached address; AND + AN_orig_addr = message originator address. 2. Otherwise, if there is no Attached Network Tuple such that: + AN_net_addr = attached address; AND + AN_orig_addr = message originator address, then create a new Attached Network Tuple with: + AN_net_addr := attached address; + AN_orig_addr := message originator address. 3. This Attached Network Tuple (existing or new) is then modified as follows: = the Value of the associated GATEWAY TLV; + AN_metric := associated link metric; + AN_time := current time + validity time. 16.3.4. Completing TC Message Processing

1.o

  If there is no Originator Tuple with: * O_orig_addr = old originator address then create an Originator Tuple with: * O_orig_addr := old originator address The Originator Tuple (existing or new) with: * O_orig_addr = new originator address is then modified as follows: * O_time := current time + O_HOLD_TIME 17.2. Link State Changes The consistency of a Link Tuple MUST be maintained according to the following rules, in addition to those in [RFC6130]: o If L_status = HEARD or L_status = SYMMETRIC, then L_in_metric MUST be set (by a process outside this specification). o If L_status != SYMMETRIC, then set L_mpr_selector := false. Clausen, et al. If L_out_metric = UNKNOWN_METRIC, then L_status MUST NOT equal SYMMETRIC; set L_SYM_time := EXPIRED if this would otherwise be the case. 17.3. Neighbor State Changes The consistency of a Neighbor Tuple MUST be maintained according to the following rules, in addition to those in [RFC6130]: 1. If N_symmetric = true, then N_in_metric MUST equal the minimum value of all L_in_metric of corresponding Link Tuples with L_status = SYMMETRIC and L_in_metric != UNKNOWN_METRIC. If there are no such Link Tuples, then N_in_metric MUST equal UNKNOWN_METRIC. 2. If N_symmetric = true, then N_out_metric MUST equal the minimum value of all L_out_metric of corresponding Link Tuples with L_status = SYMMETRIC and L_out_metric != UNKNOWN_METRIC. If there are no such Link Tuples, then N_out_metric MUST equal UNKNOWN_METRIC. 3. If N_symmetric = false, then N_flooding_mpr, N_routing_mpr, N_mpr_selector, and N_advertised MUST all be equal to false. 4. If N_mpr_selector = true, then N_advertised MUST be equal to true. 5. If N_symmetric = true, N_out_metric != UNKNOWN_METRIC and N_mpr_selector = false, then a router MAY select N_advertised = true or N_advertised = false.

1.

  The set of flooding MPRs of a router MUST be recalculated if: * A Link Tuple is added with L_status = SYMMETRIC and L_out_metric != UNKNOWN_METRIC; OR * A Link Tuple with L_status = SYMMETRIC and L_out_metric != UNKNOWN_METRIC is removed; OR Clausen, et al. Tuple with L_status = SYMMETRIC and L_out_metric != UNKNOWN_METRIC changes to having L_status = HEARD, L_status = LOST, or L_out_metric = UNKNOWN_METRIC; OR * A Link Tuple with L_status = HEARD or L_status = LOST changes to having L_status = SYMMETRIC and L_out_metric != UNKNOWN_METRIC; OR * The flooding MPR selection process uses metric values (see Section 18.4) and the L_out_metric of any Link Tuple with L_status = SYMMETRIC changes; OR * The N_will_flooding of a Neighbor Tuple with N_symmetric = true and N_out_metric != UNKNOWN_METRIC changes from WILL_NEVER to any other value; OR * The N_will_flooding of a Neighbor Tuple with N_flooding_mpr = true changes to WILL_NEVER from any other value; OR * The N_will_flooding of a Neighbor Tuple with N_symmetric = true, N_out_metric != UNKNOWN_METRIC, and N_flooding_mpr = false changes to WILL_ALWAYS from any other value; OR * A 2-Hop Tuple with N2_out_metric != UNKNOWN_METRIC is added or removed; OR * The N2_out_metric of any 2-Hop Tuple changes and either the flooding MPR selection process uses metric values (see Section 18.4) or the change is to or from UNKNOWN_METRIC. 2. Otherwise, the set of flooding MPRs of a router MAY be recalculated if the N_will_flooding of a Neighbor Tuple with N_symmetric = true changes in any other way; it SHOULD be recalculated if N_flooding_mpr = false and this is an increase in N_will_flooding or if N_flooding_mpr = true and this is a decrease in N_will_flooding. 3. The set of routing MPRs of a router MUST be recalculated if: * A Neighbor Tuple is added with N_symmetric = true and N_in_metric != UNKNOWN_METRIC; OR * A Neighbor Tuple with N_symmetric = true and N_in_metric != UNKNOWN_METRIC is removed; OR * A Neighbor Tuple with N_symmetric = true and N_in_metric != UNKNOWN_METRIC changes to having N_symmetric = false; OR Clausen, et al. Tuple with N_symmetric = false changes to having N_symmetric = true and N_in_metric != UNKNOWN_METRIC; OR * The N_in_metric of any Neighbor Tuple with N_symmetric = true changes; OR * The N_will_routing of a Neighbor Tuple with N_symmetric = true and N_in_metric != UNKNOWN_METRIC changes from WILL_NEVER to any other value; OR * The N_will_routing of a Neighbor Tuple with N_routing_mpr = true changes to WILL_NEVER from any other value; OR * The N_will_routing of a Neighbor Tuple with N_symmetric = true, N_in_metric != UNKNOWN_METRIC and N_routing_mpr = false changes to WILL_ALWAYS from any other value; OR * A 2-Hop Tuple with N2_in_metric != UNKNOWN_METRIC is added or removed; OR * The N2_in_metric of any 2-Hop Tuple changes. 4. Otherwise, the set of routing MPRs of a router MAY be recalculated if the N_will_routing of a Neighbor Tuple with N_symmetric = true changes in any other way; it SHOULD be recalculated if N_routing_mpr = false and this is an increase in N_will_routing or if N_routing_mpr = true and this is a decrease in N_will_routing.

Clauseno

  If x in N1 has W(x) = WILL_ALWAYS, then x is in M.

o

  Define an allowed 2-Hop Tuple to be a 2-Hop Tuple in the 2-Hop Set for the current interface for which N2_out_metric != UNKNOWN_METRIC and there is an allowed Link Tuple with L_neighbor_iface_addr_list = N2_neighbor_iface_addr_list.o Define an element of N1 for each allowed Link Tuple. This then defines the corresponding Link Tuple for each element of N1 and the corresponding Neighbor Tuple for each element of N1, being the Neighbor Tuple corresponding to that Link Tuple.o For each element x in N1, define W(x) := N_will_flooding of the corresponding Neighbor Tuple.o For each element x in N1, define d1(x) as either:A. L_out_metric of the corresponding Link Tuple; OR B. 1.

Clausen

  Graphs, flooding MPRs are selected and recorded by: o For each OLSRv2 interface, determine an MPR Set as specified in Section 18.3. o A Neighbor Tuple represents a flooding MPR and has N_flooding_mpr := true (otherwise, N_flooding_mpr := false) if and only if that Neighbor Tuple corresponds to an element in an MPR Set created for any interface as described above. That is, the overall set of flooding MPRs is the union of the sets of flooding MPRs for all OLSRv2 interfaces.

o

  Define a single Neighbor Graph as defined in Section 18.2 according to the following: o Define a reachable Neighbor Tuple to be a Neighbor Tuple with N_symmetric = true and N_in_metric != UNKNOWN_METRIC. o Define an allowed Neighbor Tuple to be a reachable Neighbor Tuple with N_will_routing > WILL_NEVER. o Define an allowed 2-Hop Tuple to be a 2-Hop Tuple in the 2-Hop Set for any OLSRv2 interface with N2_in_metric != UNKNOWN_METRIC and for which there is an allowed Neighbor Tuple with N_neighbor_addr_list containing N2_neighbor_iface_addr_list. o Define an element of N1 for each allowed Neighbor Tuple. This then defines the corresponding Neighbor Tuple for each element of N1For each element x in N1, define W(x) := N_will_routing of the corresponding Neighbor Tuple. o For each element x in N1, define d1(x) := N_in_metric of the corresponding Neighbor Tuple.

  as defined in Section 19.1 for these types of edge.The second type will represent a multiple edge path, which will always have first edge of type X -> Y, and will have final edge of type W -> U, W -> V, W -> T, or Y -> Z. The Routing Tuple will be: o R_local_iface_addr := X; o R_next_iface_addr := Y; o R_dest_addr := U, V, T or Z; o R_dist := the total hop count of all edges in the path;

  + | 128-223 | Unassigned | Expert Review | +-

  + | 128-223 | Unassigned | Expert Review | +---------+-------------+-------------------+Table 10: TC Message-Type-Specific Address Block TLV Types Clausen, et al.

oo

  If N_orig_addr = unknown, then N_will_flooding = WILL_NEVER, N_will_routing = WILL_NEVER, N_flooding_mpr = false, N_routing_mpr = false, N_mpr_selector = false, and N_advertised = false. o N_in_metric MUST equal the minimum value of the L_in_metric values of all corresponding Link Tuples with L_status = SYMMETRIC and L_in_metric != UNKNOWN_METRIC, if any; otherwise, N_in_metric = UNKNOWN_METRIC. o N_out_metric MUST equal the minimum value of the L_out_metric values of all corresponding Link Tuples with L_status = SYMMETRIC and L_out_metric != UNKNOWN_METRIC, if any; otherwise, N_out_metric = UNKNOWN_METRIC. o N_will_flooding and N_will_routing MUST be in the range from WILL_NEVER to WILL_ALWAYS, inclusive. o If N_flooding_mpr = true, then N_symmetric MUST be true, N_out_metric MUST NOT equal UNKNOWN_METRIC, and N_will_flooding MUST NOT equal WILL_NEVER. o If N_routing_mpr = true, then N_symmetric MUST be true, N_in_metric MUST NOT equal UNKNOWN_METRIC, and N_will_routing MUST NOT equal WILL_NEVER. o If N_symmetric = true and N_flooding_mpr = false, then N_will_flooding MUST NOT equal WILL_ALWAYS. o If N_symmetric = true and N_routing_mpr = false, then N_will_routing MUST NOT equal WILL_ALWAYS. Clausen, et al. If N_mpr_selector = true, then N_advertised MUST be true. o If N_advertised = true, then N_symmetric MUST be true and N_out_metric MUST NOT equal UNKNOWN_METRIC. In each Lost Neighbor Tuple: o NL_neighbor_addr MUST NOT include this router's originator address, the O_orig_addr in any Originator Tuple, or equal or have as a sub-range the AL_net_addr in any Local Attached Network Tuple. In each 2-Hop Tuple: o N2_2hop_addr MUST NOT equal this router's originator address, equal the O_orig_addr in any Originator Tuple, or equal or have as a sub-range the AL_net_addr in any Local Attached Network Tuple.o If N2_in_metric != UNKNOWN_METRIC, then N2_in_metric MUST be representable in the defined compressed form.

  selectors, if any. Routers that as routing MPRs need not send any link state information. Based on this reduced link state information, routing MPRs are used as intermediate routers in multi-hop routes.

	RFC 7181	OLSRv2	April 2014
	are not selected
	Clausen, et al.	Standards Track	[Page 5]

  All routable addresses of the router for which it is to accept IP packets as destination MUST be included in the Local Interface Set or the Local Attached Network Set.

	RFC 7181	OLSRv2	April 2014
	7.1. Originator Set
	A router's Originator Set records addresses that were recently used
	as originator addresses by this router. If a router's originator
	address is immutable, then the Originator Set is always empty and MAY
	be omitted. It consists of Originator Tuples:
	(O_orig_addr, O_time)
	Clausen, et al.	Standards Track	[Page 29]

The originator address MUST be unique to this router. It MUST NOT be used by any other router as an originator address. It MAY be included in any network address in any I_local_iface_addr_list of this router; it MUST NOT be included in any network address in any I_local_iface_addr_list of any other router. It MAY be included in, but MUST NOT be equal to, the AL_net_addr in any Local Attached Network Tuple in this or any other router. o The addition of an Originator Set, defined in Section 7.1, and a Local Attached Network Set, defined in Section 7.2. where: O_orig_addr is a recently used originator address; note that this does not include a prefix length. O_time specifies the time at which this Tuple expires and MUST be removed. 7.2. Local Attached Network Set A router's Local Attached Network Set records its local non-OLSRv2 interfaces via which it can act as a gateway to other networks. The Local Attached Network Set MUST be provided to this protocol and MUST reflect any changes in the router's status. (In cases where the router's configuration is static, the Local Attached Network Set will be constant; in cases where the router has no such non-OLSRv2 interfaces, the Local Attached Network Set will be empty.) The Local Attached Network Set is not modified by this protocol. This protocol will respond to (externally provided) changes to the Local Attached Network Set. It consists of Local Attached Network Tuples: (AL_net_addr, AL_dist, AL_metric)

  Attached networks local to this router only (i.e., not reachable except via this router) SHOULD be treated as local non-MANET interfaces and added to the Local Interface Set, as specified in[START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF], rather than added to the Local Attached Network Set.Because an attached network is not specific to the router and may be outside the MANET, an attached network MAY also be attached to other routers. Routing to an AL_net_addr will use maximum prefix length matching; consequently, an AL_net_addr MAY include, but MUST NOT equal or be included in, any network address that is of any interface of any router (i.e., is included in any I_local_iface_addr_list) or equal any router's originator address.It is not the responsibility of this protocol to maintain routes from this router to networks recorded in the Local Attached Network Set.

	RFC 7181	OLSRv2	April 2014
	Clausen, et al.	Standards Track	[Page 30]

Local Attached Network Tuples are removed from the Local Attached Network Set only when the router's local attached network configuration changes, i.e., they are not subject to timer-based expiration or changes due to received messages.

  L_in_metric will be specified by a process that is external to this specification. Any Link Tuple with L_status = HEARD or L_status = SYMMETRIC MUST have a specified value of L_in_metric if it is to be used by this protocol.

	RFC 7181	OLSRv2	April 2014
	Clausen, et al.	Standards Track	[Page 31]

A Link Tuple created (but not updated) by

[START_REF] Clausen | Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)[END_REF]

MUST set: o L_in_metric := UNKNOWN_METRIC; o L_out_metric := UNKNOWN_METRIC;

  N_in_metric is the neighbor metric of any link from this neighbor to an OLSRv2 interface of this router, i.e., the minimum of all corresponding L_in_metric with L_status = SYMMETRIC and L_in_metric != UNKNOWN_METRIC, UNKNOWN_METRIC if there are no such Link Tuples; N_out_metric is the neighbor metric of any link from an OLSRv2 interface of this router to this neighbor, i.e., the minimum of all corresponding L_out_metric with L_status = SYMMETRIC and L_out_metric != UNKNOWN_METRIC, UNKNOWN_METRIC if there are no such Link Tuples;

	RFC 7181	OLSRv2	April 2014
	Clausen, et al.	Standards Track	[Page 32]

  The Neighbor Information Base also includes a variable, the Advertised Neighbor Sequence Number (ANSN), whose value is included in TC messages to indicate the freshness of the information transmitted. The ANSN is incremented whenever advertised information (the originator and routable addresses included in Neighbor Tuples with N_advertised = true and local attached networks recorded in the Local Attached Network Set in the Local Information Base) changes, including addition or removal of such information. Topology Set records topology information about the links between routers in the MANET. It consists of Router Topology Tuples:

	RFC 7181	OLSRv2	April 2014
	10.2. Router Topology Set
	A router's
	AR_time is the time at which this Tuple expires and MUST be
	removed.
	Clausen, et al.	Standards Track	[Page 34]

10. Topology Information Base

The Topology Information Base, defined for each router by this specification, stores information received in TC messages in the Advertising Remote Router Set, the Router Topology Set, the Routable Address Topology Set, and the Attached Network Set.

Additionally, a Routing Set is maintained, derived from the information recorded in the Local Information Base, the Interface Information Bases, the Neighbor Information Base, and the rest of the Topology Information Base.

10.1. Advertising Remote Router Set

A router's Advertising Remote Router Set records information describing each remote router in the network that transmits TC messages, allowing outdated TC messages to be recognized and discarded. It consists of Advertising Remote Router Tuples:

(AR_orig_addr, AR_seq_number, AR_time) where:

AR_orig_addr is the originator address of a received TC message, note that this does not include a prefix length; AR_seq_number is the greatest ANSN in any TC message received that originated from the router with originator address AR_orig_addr (i.e., that contributed to the information contained in this Tuple);

Table 2

 2 +

	: CONT_SEQ_NUM TLV Definition
	13.3.2. Address Block TLVs
	The LINK_METRIC TLV is used in HELLO messages and TC messages. It
	MAY use any type extension; only LINK_METRIC TLVs with type extension
	equal to LINK_METRIC_TYPE will be used by this specification. An
	Clausen, et al.	Standards Track	[Page 42]

Table 5 :

 5 + MPR TLV Definition

	Clausen, et al.	Standards Track	[Page 43]

Table 6 :

 6

NBR_ADDR_TYPE TLV Definition

If an address is both an originator address and a routable address, then it may be associated with either one Address Block TLV with Type := NBR_ADDR_TYPE and Value := ROUTABLE_ORIG, or with two Address Block TLVs with Type:= NBR_ADDR_TYPE, one with Value := ORIGINATOR and one with Value := ROUTABLE.

  This flooding mechanism is used by this protocol and MAY be used by extensions to this protocol that define, and hence own, other Message Types, to manage processing and/or forwarding of these messages. This specification contains elements (P_type, RX_type, F_type) required only for such usage. This flooding mechanism is always used for TC messages (see Section 16). Received HELLO messages (see Section 15) are, unless invalid, always processed and never forwarded by this flooding mechanism. They thus do not need to be recorded in the Received Message Information Base.

	RFC 7181	OLSRv2	April 2014
	14. Message Processing and Forwarding
	This section describes the optimized flooding operation (MPR
	flooding) used when control messages, as instances of [RFC5444], are
	intended for MANET-wide distribution. This flooding mechanism
	defines when a received message is, or is not, processed and/or
	forwarded.
	Clausen, et al.	Standards Track	[Page 44]

  Includes any address object associated with an Address Block TLV with Type = LINK_STATUS or Type = OTHER_NEIGHB that overlaps the message's originator address.

	RFC 7181	OLSRv2	April 2014
	o
			or
	this specification if it:
	o Has more than one Message TLV with Type = MPR_WILLING.
	o Has a message originator address, or a network address
	corresponding to an address object associated with an Address
	Block TLV with Type = LOCAL_IF, that is partially owned by this
	router. (Some of these cases are already excluded by [RFC6130].)
	Clausen, et al.	Standards Track	[Page 51]

  Section 19, when changes in the Local Information Base, the Neighborhood Information Base, or the Topology Information Base indicate a change (including of any potentially used outgoing neighbor metric values) of the known symmetric links and/or attached networks in the MANET, hence changing the Topology Graph. It is sufficient to consider only changes that affect at least one of: o The Local Interface Set for an OLSRv2 interface, if the change removes any network address in an I_local_iface_addr_list. In this case, unless the OLSRv2 interface is removed, it may not be necessary to do more than replace such network addresses, if used, by an alternative network address from the same I_local_iface_addr_list. The Local Attached Set, if the change removes any AL_net_addr that is also an AN_net_addr. In this case, it may not be necessary to do more than add Routing Tuples with R_dest_addr equal to that AN_net_addr.

	RFC 7181	OLSRv2	April 2014
	o o The Link Set of any OLSRv2 interface, considering only Link Tuples
	that have, or just had, L_status = SYMMETRIC and L_out_metric !=
	UNKNOWN_METRIC (including removal of such Link Tuples).
	o The Neighbor Set of the router, considering only Neighbor Tuples
	that have, or just had, N_symmetric = true and N_out_metric !=
	UNKNOWN_METRIC and do not have N_orig_addr = unknown.
	o The 2-Hop Set of any OLSRv2 interface, if used in the creation of
	the Routing Set and if the change affects any 2-Hop Tuples with
	N2_out_metric != UNKNOWN_METRIC.
	o The Router Topology Set of the router.
	Clausen, et al.	Standards Track	[Page 70]

o The Routable Address Topology Set of the router.

  The properties of an MPR Set derived from a Neighbor Graph are defined. Any algorithm that creates an MPR Set that satisfies these properties is a valid MPR selection algorithm. An example algorithm that creates such an MPR Set is given in Appendix B. o How to create a Neighbor Graph for each interface based on the corresponding Interface Information Base is defined, and how to combine the resulting MPR Sets to determine the router's flooding MPRs and record those in the router's Neighbor Set are described. o How to create a single Neighbor Graph based on all Interface Information Bases and the Neighbor Information Base is defined, and how to record the resulting MPR Set as the router's routing MPRs in the router's Neighbor Set is described.

	RFC 7181	OLSRv2	April 2014
	18.1. Overview
	MPRs are selected according to the following steps, defined in the
	following sections:
	o A data structure known as a Neighbor Graph is defined.
	Clausen, et al.	Standards Track	[Page 71]

o

  MPR Set as specified in Section 18.3. Changes to the Routing Set do not require any messages to be transmitted. The state of the Routing Set SHOULD, however, be reflected in the IP routing table by adding and removing entries from that routing table as appropriate. Only appropriate Routing Tuples (in particular only those that represent local links or paths to routable addresses) need be reflected in the IP routing table.

	RFC 7181 RFC 7181	OLSRv2 OLSRv2	April 2014 April 2014
	19. Routing Set Calculation o All edges W -> U such that:
	The Routing Set of a router is populated with Routing Tuples that * W is the TR_from_orig_addr of a Router Topology Tuple; AND
	represent paths from that router to all destinations in the network.
	These paths are calculated based on the Network Topology Graph, which * U is the TR_to_orig_addr of the same Router Topology Tuple.
	is constructed from information in the Information Bases, obtained
	via HELLO and TC message exchange. The metric of such an edge is the corresponding TR_metric.
	The Network Topology Graph is further "decorated" with the following
	edges. If a network address S, V, Z, or T equals a network address Y
	or W, then the edge terminating in the network address S, V, Z, or T
	MUST NOT be used in any path.
	o Edges X -> S for all possible S, and one X per S, such that:
	19.1. Network Topology Graph * S is in the N_neighbor_addr_list of a Neighbor Tuple; AND
	The Network Topology Graph is formed from information from the * X is in the I_local_iface_addr_list of a Local Interface Tuple;
	router's Local Interface Set, Link Sets for OLSRv2 interfaces, AND
	Neighbor Set, Router Topology Set, Routable Address Topology Set, and
	Attached Network Set. The Network Topology Graph MAY also use * There is a Link Tuple with L_status = SYMMETRIC and
	information from the router's 2-Hop Sets for OLSRv2 interfaces. The L_out_metric != UNKNOWN_METRIC such that this Neighbor Tuple
	Network Topology Graph forms the router's topological view of the and this Local Interface Tuple correspond to it. A network
	network in the form of a directed graph. Each edge in that graph has address from L_neighbor_iface_addr_list will be denoted R in
	a metric value. The Network Topology Graph has a "backbone" (within this case.
	which minimum total metric routes will be constructed) containing the
	following edges:
	o Edges X -> Y for all possible Y, and one X per Y, such that:
	* Y is the N_orig_addr of a Neighbor Tuple; AND
	o A Neighbor Tuple represents a routing MPR and has N_routing_mpr := * N_orig_addr is not unknown; AND
	true (otherwise, N_routing_mpr := false) if and only if that
	Neighbor Tuple corresponds to an element in the MPR Set created as * X is in the I_local_iface_addr_list of a Local Interface Tuple;
	described above. AND
	18.6. Calculating MPRs * There is a Link Tuple with L_status = SYMMETRIC and
	L_out_metric != UNKNOWN_METRIC such that this Neighbor Tuple
	A router MUST recalculate each of its sets of MPRs whenever the and this Local Interface Tuple correspond to it. A network
	currently selected set of MPRs does not still satisfy the required address from L_neighbor_iface_addr_list will be denoted R in
	conditions. It MAY recalculate its MPRs if the current set of MPRs this case.
	is still valid but could be more efficient. Sufficient conditions to
	recalculate a router's sets of MPRs are given in Section 17.6. It SHOULD be preferred, where possible, to select R = Y and to
	select X from the Local Interface Tuple corresponding to the Link
	Tuple from which R was selected. The metric for such an edge is
	the corresponding N_out_metric.
	Clausen, et al. Clausen, et al.	Standards Track Standards Track	[Page 77] [Page 78]

  and Appendix A. Note that the processing specified in this document ensures that these constraints are satisfied.

	RFC 7181	OLSRv2	April 2014
	messages.) This may, for example, be to allow a security
	protocol, as suggested in Section 23, to add a TLV containing a
	cryptographic signature to the message.
	o Through accessing an incoming message and potentially discarding
	it prior to processing by this protocol. This may, for example,
	allow a security protocol, as suggested in Section 23, to perform
	verification of message signatures and prevent processing and/or
	forwarding of unverifiable messages by this protocol.
	o Through accessing an incoming message after it has been completely
	processed by this protocol. In particular, this may allow a
	protocol that has added information, by way of inclusion of
	appropriate TLVs or of network addresses associated with new TLVs,
	access to such information after appropriate updates have been
	recorded in the Information Bases in this protocol.
	o Through accessing an outgoing message prior to it being
	transmitted over any OLSRv2 interface and adding information to it
	as specified in [RFC5444]. This MAY include Message TLVs and/or
	network addresses with associated Address Block TLVs. (Network
	addresses without new associated TLVs SHOULD NOT be added to
	Clausen, et al.	Standards Track	[Page 83]

Table 16 :

 16 Address Block TLV Type Assignment: GATEWAY Type extensions indicated as Expert Review SHOULD be allocated as described in[START_REF] Clausen | Generalized Mobile Ad Hoc Network (MANET) Packet/Message Format[END_REF], based on Expert Review as defined in[START_REF] Narten | Guidelines for Writing an IANA Considerations Section in RFCs[END_REF]. This section does not require any IANA action, as the required information is included in the descriptions of the MPR and NBR_ADDR_TYPE Address Block TLVs allocated in Section 24.5. This information is recorded here for clarity and for use elsewhere in this specification. The Values that the MPR Address Block TLV can use are as follows: Cedric Adjih, INRIA, France, <Cedric.Adjih@inria.fr> o Emmanuel Baccelli, INRIA , France, <Emmanuel.Baccelli@inria.fr> o Thomas Heide Clausen, LIX, France, <T.Clausen@computer.org> o Justin Dean, NRL, USA, <jdean@itd.nrl.navy.mil> o Christopher Dearlove, BAE Systems, UK, <chris.dearlove@baesystems.com> o Ulrich Herberg, Fujitsu Laboratories of America, USA, <ulrich@herberg.name> o Satoh Hiroki, Hitachi SDL, Japan, <hiroki.satoh.yj@hitachi.com> o Philippe Jacquet, Alcatel Lucent Bell Labs, France, <philippe.jacquet@alcatel-lucent.fr> Monden Kazuya, Hitachi SDL, Japan, <kazuya.monden.vw@hitachi.com> o Kenichi Mase, Niigata University, Japan, <mase@ie.niigata-u.ac.jp> o Ryuji Wakikawa, Toyota, Japan, <ryuji@sfc.wide.ad.jp> Updates to the Local Information Base, the Neighborhood Information Base, or the Topology Information Base MUST ensure that all constraints specified in this appendix are maintained, as well as those specified in [RFC6130]. This is the case for the processing, specified in this document. Any protocol extension or outside process, which updates the Neighborhood Information Base or the Topology Information Base, MUST also ensure that these constraints are maintained. In each Originator Tuple: o O_orig_addr MUST NOT equal any other O_orig_addr. o O_orig_addr MUST NOT equal this router's originator address. In each Local Attached Network Tuple: o AL_net_addr MUST NOT equal any other AL_net_addr. o AL_net_addr MUST NOT equal or be a sub-range of any network address in the I_local_iface_addr_list of any Local Interface Tuple. o AL_net_addr MUST NOT equal this router's originator address or equal the O_orig_addr in any Originator Tuple. o AL_dist MUST NOT be less than zero. In each Link Tuple: o L_neighbor_iface_addr_list MUST NOT contain any network address that AL_net_addr of any Local Attached Network Tuple equals or is a sub-range of. o If L_in_metric != UNKNOWN_METRIC, then L_in_metric MUST be representable in the defined compressed form. o If L_out_metric != UNKNOWN_METRIC, then L_out_metric MUST be representable in the defined compressed form. o If L_mpr_selector = true, then L_status = SYMMETRIC. N_orig_addr MUST NOT be changed to unknown. o N_orig_addr MUST NOT equal this router's originator address or equal O_orig_addr in any Originator Tuple. o N_orig_addr MUST NOT equal the AL_net_addr in any Local Attached Network Tuple. o If N_orig_addr != unknown, then N_orig_addr MUST NOT equal the N_orig_addr in any other Neighbor Tuple. o N_neighbor_addr_list MUST NOT contain any network address that includes this router's originator address, the O_orig_addr in any Originator Tuple, or equal or have as a sub-range the AL_net_addr in any Local Attached Network Tuple.

	Clausen, et al.	Standards Track	[Page 95]

o

  each Advertising Remote Router Tuple: o AR_orig_addr MUST NOT be in any network address in the I_local_iface_addr_list in any Local Interface Tuple or be in the IR_local_iface_addr in any Removed Interface Address Tuple. o AR_orig_addr MUST NOT equal this router's originator address or equal the O_orig_addr in any Originator Tuple. o AR_orig_addr MUST NOT be in the AL_net_addr in any Local Attached Network Tuple. o AR_orig_addr MUST NOT equal the AR_orig_addr in any other Advertising Remote Router Tuple. In each Router Topology Tuple: o There MUST be an Advertising Remote Router Tuple with AR_orig_addr = TR_from_orig_addr. o TR_to_orig_addr MUST NOT be in any network address in the I_local_iface_addr_list in any Local Interface Tuple or be in the IR_local_iface_addr in any Removed Interface Address Tuple. TR_to_orig_addr MUST NOT equal this router's originator address or equal the O_orig_addr in any Originator Tuple. o TR_to_orig_addr MUST NOT be in the AL_net_addr in any Local Attached Network Tuple. o The ordered pair (TR_from_orig_addr, TR_to_orig_addr) MUST NOT equal the corresponding pair for any other Router Topology Tuple. o TR_seq_number MUST NOT be greater than AR_seq_number in the Advertising Remote Router Tuple with AR_orig_addr = TR_from_orig_addr. o TR_metric MUST be representable in the defined compressed form. In each Routable Address Topology Tuple: o There MUST be an Advertising Remote Router Tuple with AR_orig_addr = TA_from_orig_addr. o TA_dest_addr MUST be routable. o TA_dest_addr MUST NOT overlap any network address in the I_local_iface_addr_list in any Local Interface Tuple or overlap the IR_local_iface_addr in any Removed Interface Address Tuple. o TA_dest_addr MUST NOT include this router's originator address or include the O_orig_addr in any Originator Tuple. o TA_dest_addr MUST NOT equal or have as a sub-range the AL_net_addr in any Local Attached Network Tuple. o The ordered pair (TA_from_orig_addr, TA_dest_addr) MUST NOT equal the corresponding pair for any other Attached Network Tuple. o TA_seq_number MUST NOT be greater than AR_seq_number in the Advertising Remote Router Tuple with AR_orig_addr = TA_from_orig_addr. o TA_metric MUST be representable in the defined compressed form. AN_net_addr MUST NOT equal or be a sub-range of any network address in the I_local_iface_addr_list in any Local Interface Tuple or equal or be a sub-range of the IR_local_iface_addr in any Removed Interface Address Tuple. o AN_net_addr MUST NOT equal this router's originator address or equal the O_orig_addr in any Originator Tuple. o The ordered pair (AN_orig_addr, AN_net_addr) MUST NOT equal the corresponding pair for any other Attached Network Tuple. o AN_seq_number MUST NOT be greater than AR_seq_number in the Advertising Remote Router Tuple with AR_orig_addr = AN_orig_addr. o AN_dist MUST NOT be less than zero.

	RFC 7181 RFC 7181	OLSRv2 OLSRv2	April 2014 April 2014
	o In each Attached Network Tuple: o
	o There MUST be an Advertising Remote Router Tuple with AR_orig_addr
	= AN_orig_addr.
	Clausen, et al. Clausen, et al.	Standards Track Standards Track	[Page 102] [Page 103]

Acknowledgments

The authors would like to acknowledge the team behind OLSRv1, as listed in RFC 3626, including Anis Laouiti (INT), Pascale Minet (INRIA), Paul Muhlethaler (INRIA), Amir Qayyum (M.A. Jinnah University), and Laurent Viennot (INRIA) for their contributions.

The authors would like to gratefully acknowledge the following people for intense technical discussions, early reviews, and comments on the specification and its components (listed alphabetically): Khaldoun Al Agha (LRI), Teco Boot (Infinity Networks), Ross Callon (Juniper), Song-Yean Cho (Samsung), Alan Cullen (BAE Systems), Louise Lamont (CRC), Li Li (CRC), Joseph Macker (NRL), Richard Ogier (SRI), Charles E. Perkins (Futurewei), Henning Rogge (Frauenhofer FKIE), and the entire IETF MANET Working Group.

Finally, the authors would like to express their gratitude to the Area Directors for providing valuable review comments during the IESG evaluation, in particular (listed alphabetically) Benoit Claise, Adrian Farrel, Stephen Farrell, Barry Leiba, Pete Resnick, and Martin Stiemerling.

+--------------+------+-----------+--------------------+------------+ -------------+------+-----------+--------------------+------------

Table 12: Message TLV Type Assignment: CONT_SEQ_NUM Type extensions indicated as Expert Review SHOULD be allocated as described in [START_REF] Clausen | Generalized Mobile Ad Hoc Network (MANET) Packet/Message Format[END_REF], based on Expert Review as defined in [START_REF] Narten | Guidelines for Writing an IANA Considerations Section in RFCs[END_REF].

Address Block TLV Types

This specification defines four Address Block TLV Types, which have been allocated from the "Address Block TLV Types" namespace defined in [START_REF] Clausen | Generalized Mobile Ad Hoc Network (MANET) Packet/Message Format[END_REF]. IANA has made allocations in the 8-127 range for these types. Four new Type Extension registries have been created with assignments as specified in Tables 13, 14, 15, and 16. Specifications of these TLVs are in Section 13.3.2.

The registration procedure for the "LINK_METRIC Address Block TLV Type Extensions" registry is Expert Review.

+-------------+------+-----------+---------------------------------- ------------+------+-----------+---------------------------------- All LINK_METRIC TLVs, whatever their type extension, MUST use their value field to encode the kind and value (in the interval MINIMUM_METRIC to MAXIMUM_METRIC, inclusive) of a link metric as specified in Sections 6 and 13.3.2. An assignment of a LINK_METRIC TLV type extension MUST specify the physical meaning of the link metric and the mapping of that physical meaning to the representable values in the indicated interval.

Example Algorithm for Calculating the Routing Set

The following procedure is given as an example for calculating the Routing Set using a variation of Dijkstra's algorithm. First, all Routing Tuples are removed, and then, using the selections and definitions in Appendix C.1, the procedures in the following sections (each considered a "stage" of the processing) are applied in turn. The following selections and definitions are made:

1. For each Local Interface Tuple, select a network address from its I_local_iface_addr_list. This is defined as the selected address for this Local Interface Tuple.

2. For each Link Tuple, the selected address of its corresponding Local Interface Tuple is defined as the selected local address for this Link Tuple.

3. For each Neighbor Tuple with N_symmetric = true and N_out_metric != UNKNOWN_METRIC, select a Link Tuple with L_status = SYMMETRIC for which this is the corresponding Neighbor Tuple and has L_out_metric = N_out_metric. This is defined as the selected Link Tuple for this Neighbor Tuple.

4. For each network address (N_orig_addr or in N_neighbor_addr_list, the "neighbor address") from a Neighbor Tuple with N_symmetric = true and N_out_metric != UNKNOWN_METRIC, select a Link Tuple (the "selected Link Tuple") from those for which this is the corresponding Neighbor Tuple, have L_status = SYMMETRIC, and have L_out_metric = N_out_metric, by:

1. If there is such a Link Tuple whose L_neighbor_iface_addr_list contains the neighbor address, select that Link Tuple.

2. Otherwise, select the selected Link Tuple for this Neighbor Tuple.

Then for this neighbor address:

3. The selected local address is defined as the selected local address for the selected Link Tuple.

4. The selected link address is defined as an address from the L_neighbor_iface_addr_list of the selected Link Tuple, if possible equal to this neighbor address.

5. Routing Tuple preference is decided by preference for minimum R_metric, then for minimum R_dist, and then for preference for corresponding Neighbor Tuples in this order: * For greater N_will_routing.

* For N_mpr_selector = true over N_mpr_selector = false.

C.2. Add Neighbor Routers

The following procedure is executed once.

C.3. Add Remote Routers

The following procedure is executed once.

1. Add a label that may be "used" or "unused" to each Routing Tuple, with all initial values equal to unused. (Note that this label is only required during this algorithm.)

2. If there are no unused Routing Tuples, then this stage is complete; otherwise, repeat the following until that is the case.

1. Find the unused Routing Tuple with minimum R_metric (if more than one, pick any) and denote it the "current Routing Tuple".

2. Mark the current Routing Tuple as used.

C.5. Add Remote Routable Addresses

The following procedure is executed once. There may be more than one Routing Tuple that may be added for an R_dest_addr in this stage. If so, then for each such R_dest_addr, a Routing Tuple with minimum R_metric MUST be added; otherwise, a Routing Tuple that is preferred SHOULD be added. There may be more than one Routing Tuple that may be added for an R_dest_addr in this stage. If so, then for each such R_dest_addr, a Routing Tuple with minimum R_metric MUST be added; otherwise, a Routing Tuple that is preferred SHOULD be added.

C.7. Add 2-Hop Neighbors

The following procedure is OPTIONAL according to Section 19.1 and MAY be executed once. There may be more than one Routing Tuple that may be added for an R_dest_addr in this stage. If so, then for each such R_dest_addr, a Routing Tuple with minimum R_metric MUST be added; otherwise, a Routing Tuple that is preferred SHOULD be added.

Appendix D. TC Message Example

TC messages are instances of [START_REF] Clausen | Generalized Mobile Ad Hoc Network (MANET) Packet/Message Format[END_REF] messages. This specification requires that TC messages contain <msg-hop-limit> and <msg-orig-addr> fields. It supports TC messages with any combination of remaining message header options and address encodings enabled by [START_REF] Clausen | Generalized Mobile Ad Hoc Network (MANET) Packet/Message Format[END_REF] that convey the required information. As a consequence, there is no single way to represent how all TC messages look. This appendix illustrates a TC message; the exact values and content included are explained in the following text.

The TC message's four-bit Message Flags (MF) field has a value of 15, indicating that the message header contains originator address, hop limit, hop count, and message sequence number fields. Its four-bit Message Address Length (MAL) field has value 3, indicating addresses in the message have a length of four octets, here being IPv4 addresses. The overall message length is 75 octets.

The message has a Message TLV Block with a content length of 17 octets containing four TLVs. The first two TLVs are validity and interval times for the message. The third TLV is the content sequence number TLV used to carry the 2-octet ANSN and (with default type extension zero, i.e., COMPLETE) indicates that the TC message is complete. The fourth TLV contains forwarding and routing willingness values for the originating router (FWILL and RWILL, respectively

OLSRv2

April 2014 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+