text:
IEEE 802.11

IEEE 802.11 is part of the IEEE 802 set of local area network (LAN) technical standards, and specifies the set of medium access control (MAC) and physical layer (PHY) protocols for implementing wireless local area network (WLAN) computer communication. The standard and amendments provide the basis for wireless network products using the Wi-Fi brand and are the world's most widely used wireless computer networking standards. IEEE 802.11 is used in most home and office networks to allow laptops, printers, smartphones, and other devices to communicate with each other and access the Internet without connecting wires. IEEE 802.11 is also a basis for vehicle-based communication networks with IEEE 802.11p.

The standards are created and maintained by the Institute of Electrical and Electronics Engineers (IEEE) LAN/MAN Standards Committee (IEEE 802). The base version of the standard was released in 1997 and has had subsequent amendments. While each amendment is officially revoked when it is incorporated in the latest version of the standard, the corporate world tends to market to the revisions because they concisely denote the capabilities of their products. As a result, in the marketplace, each revision tends to become its own standard. 802.11x is a shorthand for "any version of 802.11", to avoid confusion with "802.11" used specifically for the original 1997 version.

IEEE 802.11 uses various frequencies including, but not limited to, 2.4 GHz, 5 GHz, 6 GHz, and 60 GHz frequency bands. Although IEEE 802.11 specifications list channels that might be used, the allowed radio frequency spectrum availability varies significantly by regulatory domain.

The protocols are typically used in conjunction with IEEE 802.2, and are designed to interwork seamlessly with Ethernet, and are very often used to carry Internet Protocol traffic.

General description
The 802.11 family consists of a series of half-duplex over-the-air modulation techniques that use the same basic protocol. The 802.11 protocol family employs carrier-sense multiple access with collision avoidance (CSMA/CA) whereby equipment listens to a channel for other users (including non 802.11 users) before transmitting each frame (some use the term "packet", which may be ambiguous: "frame" is more technically correct).

802.11-1997 was the first wireless networking standard in the family, but 802.11b was the first widely accepted one, followed by 802.11a, 802.11g, 802.11n, 802.11ac, and 802.11ax. Other standards in the family (c–f, h, j) are service amendments that are used to extend the current scope of the existing standard, which amendments may also include corrections to a previous specification.

802.11b and 802.11g use the 2.4-GHz ISM band, operating in the United States under Part 15 of the U.S. Federal Communications Commission Rules and Regulations. 802.11n can also use that 2.4-GHz band. Because of this choice of frequency band, 802.11b/g/n equipment may occasionally suffer interference in the 2.4-GHz band from microwave ovens, cordless telephones, and Bluetooth devices. 802.11b and 802.11g control their interference and susceptibility to interference by using direct-sequence spread spectrum (DSSS) and orthogonal frequency-division multiplexing (OFDM) signaling methods, respectively.

802.11a uses the 5 GHz U-NII band which, for much of the world, offers at least 23 non-overlapping, 20-MHz-wide channels. This is an advantage over the 2.4-GHz, ISM-frequency band, which offers only three non-overlapping, 20-MHz-wide channels where other adjacent channels overlap (see: list of WLAN channels). Better or worse performance with higher or lower frequencies (channels) may be realized, depending on the environment. 802.11n and 802.11ax can use either the 2.4 GHz or 5 GHz band; 802.11ac uses only the 5 GHz band.

The segment of the radio frequency spectrum used by 802.11 varies between countries. In the US, 802.11a and 802.11g devices may be operated without a license, as allowed in Part 15 of the FCC Rules and Regulations. Frequencies used by channels one through six of 802.11b and 802.11g fall within the 2.4 GHz amateur radio band. Licensed amateur radio operators may operate 802.11b/g devices under Part 97 of the FCC Rules and Regulations, allowing increased power output but not commercial content or encryption.

Generations
In 2018, the Wi-Fi Alliance began using a consumer-friendly generation numbering scheme for the publicly used 802.11 protocols. Wi-Fi generations 1–8 use the 802.11b, 802.11a, 802.11g, 802.11n, 802.11ac, 802.11ax, 802.11be and 802.11bn protocols, in that order.

History
802.11 technology has its origins in a 1985 ruling by the U.S. Federal Communications Commission that released the ISM band for unlicensed use.

In 1991 NCR Corporation/AT&T (now Nokia Labs and LSI Corporation) invented a precursor to 802.11 in Nieuwegein, the Netherlands. The inventors initially intended to use the technology for cashier systems. The first wireless products were brought to the market under the name WaveLAN with raw data rates of 1 Mbit/s and 2 Mbit/s.

Vic Hayes, who held the chair of IEEE 802.11 for 10 years, and has been called the "father of Wi-Fi", was involved in designing the initial 802.11b and 802.11a standards within the IEEE. He, along with Bell Labs Engineer Bruce Tuch, approached IEEE to create a standard.

In 1999, the Wi-Fi Alliance was formed as a trade association to hold the Wi-Fi trademark under which most products are sold.

The major commercial breakthrough came with Apple's adoption of Wi-Fi for their iBook series of laptops in 1999. It was the first mass consumer product to offer Wi-Fi network connectivity, which was then branded by Apple as AirPort. One year later IBM followed with its ThinkPad 1300 series in 2000.

802.11-1997 (802.11 legacy)
The original version of the standard IEEE 802.11 was released in 1997 and clarified in 1999, but is now obsolete. It specified two net bit rates of 1 or 2 megabits per second (Mbit/s), plus forward error correction code. It specified three alternative physical layer technologies: diffuse infrared operating at 1 Mbit/s; frequency-hopping spread spectrum operating at 1 Mbit/s or 2 Mbit/s; and direct-sequence spread spectrum operating at 1 Mbit/s or 2 Mbit/s. The latter two radio technologies used microwave transmission over the Industrial Scientific Medical frequency band at 2.4 GHz. Some earlier WLAN technologies used lower frequencies, such as the U.S. 900 MHz ISM band.

Legacy 802.11 with direct-sequence spread spectrum was rapidly supplanted and popularized by 802.11b.

802.11a (OFDM waveform)
802.11a, published in 1999, uses the same data link layer protocol and frame format as the original standard, but an OFDM based air interface (physical layer) was added.

It operates in the 5 GHz band with a maximum net data rate of 54 Mbit/s, plus error correction code, which yields realistic net achievable throughput in the mid-20 Mbit/s. It has seen widespread worldwide implementation, particularly within the corporate workspace.

Since the 2.4 GHz band is heavily used to the point of being crowded, using the relatively unused 5 GHz band gives 802.11a a significant advantage. However, this high carrier frequency also brings a disadvantage: the effective overall range of 802.11a is less than that of 802.11b/g. In theory, 802.11a signals are absorbed more readily by walls and other solid objects in their path due to their smaller wavelength, and, as a result, cannot penetrate as far as those of 802.11b. In practice, 802.11b typically has a higher range at low speeds (802.11b will reduce speed to 5.5 Mbit/s or even 1 Mbit/s at low signal strengths). 802.11a also suffers from interference, but locally there may be fewer signals to interfere with, resulting in less interference and better throughput.

802.11b
The 802.11b standard has a maximum raw data rate of 11 Mbit/s (Megabits per second) and uses the same media access method defined in the original standard. 802.11b products appeared on the market in early 2000, since 802.11b is a direct extension of the modulation technique defined in the original standard. The dramatic increase in throughput of 802.11b (compared to the original standard) along with simultaneous substantial price reductions led to the rapid acceptance of 802.11b as the definitive wireless LAN technology.

Devices using 802.11b experience interference from other products operating in the 2.4 GHz band. Devices operating in the 2.4 GHz range include microwave ovens, Bluetooth devices, baby monitors, cordless telephones, and some amateur radio equipment. As unlicensed intentional radiators in this ISM band, they must not interfere with and must tolerate interference from primary or secondary allocations (users) of this band, such as amateur radio.

802.11g
In June 2003, a third modulation standard was ratified: 802.11g. This works in the 2.4 GHz band (like 802.11b), but uses the same OFDM based transmission scheme as 802.11a. It operates at a maximum physical layer bit rate of 54 Mbit/s exclusive of forward error correction codes, or about 22 Mbit/s average throughput. 802.11g hardware is fully backward compatible with 802.11b hardware, and therefore is encumbered with legacy issues that reduce throughput by ~21% when compared to 802.11a.

The then-proposed 802.11g standard was rapidly adopted in the market starting in January 2003, well before ratification, due to the desire for higher data rates as well as reductions in manufacturing costs. By summer 2003, most dual-band 802.11a/b products became dual-band/tri-mode, supporting a and b/g in a single mobile adapter card or access point. Details of making b and g work well together occupied much of the lingering technical process; in an 802.11g network, however, the activity of an 802.11b participant will reduce the data rate of the overall 802.11g network.

Like 802.11b, 802.11g devices also suffer interference from other products operating in the 2.4 GHz band, for example, wireless keyboards.

802.11-2007
In 2003, task group TGma was authorized to "roll up" many of the amendments to the 1999 version of the 802.11 standard. REVma or 802.11ma, as it was called, created a single document that merged 8 amendments (802.11a, b, d, e, g, h, i, j) with the base standard. Upon approval on 8 March 2007, 802.11REVma was renamed to the then-current base standard IEEE 802.11-2007.

802.11n
802.11n is an amendment that improves upon the previous 802.11 standards; its first draft of certification was published in 2006. The 802.11n standard was retroactively labelled as Wi-Fi 4 by the Wi-Fi Alliance. The standard added support for multiple-input multiple-output antennas (MIMO). 802.11n operates on both the 2.4 GHz and the 5 GHz bands. Support for 5 GHz bands is optional. Its net data rate ranges from 54 Mbit/s to 600 Mbit/s. The IEEE has approved the amendment, and it was published in October 2009. Prior to the final ratification, enterprises were already migrating to 802.11n networks based on the Wi-Fi Alliance's certification of products conforming to a 2007 draft of the 802.11n proposal.

802.11-2012
In May 2007, task group TGmb was authorized to "roll up" many of the amendments to the 2007 version of the 802.11 standard. REVmb or 802.11mb, as it was called, created a single document that merged ten amendments (802.11k, r, y, n, w, p, z, v, u, s) with the 2007 base standard. In addition much cleanup was done, including a reordering of many of the clauses. Upon publication on 29 March 2012, the new standard was referred to as IEEE 802.11-2012.

802.11ac
IEEE 802.11ac-2013 is an amendment to IEEE 802.11, published in December 2013, that builds on 802.11n. The 802.11ac standard was retroactively labelled as Wi-Fi 5 by the Wi-Fi Alliance. Changes compared to 802.11n include wider channels (80 or 160 MHz versus 40 MHz) in the 5 GHz band, more spatial streams (up to eight versus four), higher-order modulation (up to 256-QAM vs. 64-QAM), and the addition of Multi-user MIMO (MU-MIMO). The Wi-Fi Alliance separated the introduction of ac wireless products into two phases ("waves"), named "Wave 1" and "Wave 2". From mid-2013, the alliance started certifying Wave 1 802.11ac products shipped by manufacturers, based on the IEEE 802.11ac Draft 3.0 (the IEEE standard was not finalized until later that year). In 2016 Wi-Fi Alliance introduced the Wave 2 certification, to provide higher bandwidth and capacity than Wave 1 products. Wave 2 products include additional features like MU-MIMO, 160 MHz channel width support, support for more 5 GHz channels, and four spatial streams (with four antennas; compared to three in Wave 1 and 802.11n, and eight in IEEE's 802.11ax specification).

802.11ad
IEEE 802.11ad is an amendment that defines a new physical layer for 802.11 networks to operate in the 60 GHz millimeter wave spectrum. This frequency band has significantly different propagation characteristics than the 2.4 GHz and 5 GHz bands where Wi-Fi networks operate. Products implementing the 802.11ad standard are being brought to market under the WiGig brand name. The certification program is now being developed by the Wi-Fi Alliance instead of the now defunct Wireless Gigabit Alliance. The peak transmission rate of 802.11ad is 7 Gbit/s.

IEEE 802.11ad is a protocol used for very high data rates (about 8 Gbit/s) and for short range communication (about 1–10 meters).

TP-Link announced the world's first 802.11ad router in January 2016.

The WiGig standard is not too well known, although it was announced in 2009 and added to the IEEE 802.11 family in December 2012.

802.11af
IEEE 802.11af, also referred to as "White-Fi" and "Super Wi-Fi", is an amendment, approved in February 2014, that allows WLAN operation in TV white space spectrum in the VHF and UHF bands between 54 and 790 MHz. It uses cognitive radio technology to transmit on unused TV channels, with the standard taking measures to limit interference for primary users, such as analog TV, digital TV, and wireless microphones. Access points and stations determine their position using a satellite positioning system such as GPS, and use the Internet to query a geolocation database (GDB) provided by a regional regulatory agency to discover what frequency channels are available for use at a given time and position. The physical layer uses OFDM and is based on 802.11ac. The propagation path loss as well as the attenuation by materials such as brick and concrete is lower in the UHF and VHF bands than in the 2.4 GHz and 5 GHz bands, which increases the possible range. The frequency channels are 6 to 8 MHz wide, depending on the regulatory domain. Up to four channels may be bonded in either one or two contiguous blocks. MIMO operation is possible with up to four streams used for either space–time block code (STBC) or multi-user (MU) operation. The achievable data rate per spatial stream is 26.7 Mbit/s for 6 and 7 MHz channels, and 35.6 Mbit/s for 8 MHz channels. With four spatial streams and four bonded channels, the maximum data rate is 426.7 Mbit/s for 6 and 7 MHz channels and 568.9 Mbit/s for 8 MHz channels.

802.11-2016
IEEE 802.11-2016 which was known as IEEE 802.11 REVmc, is a revision based on IEEE 802.11-2012, incorporating 5 amendments (11ae, 11aa, 11ad, 11ac, 11af). In addition, existing MAC and PHY functions have been enhanced and obsolete features were removed or marked for removal. Some clauses and annexes have been renumbered.

802.11ah
IEEE 802.11ah, published in 2017, defines a WLAN system operating at sub-1 GHz license-exempt bands. Due to the favorable propagation characteristics of the low-frequency spectra, 802.11ah can provide improved transmission range compared with the conventional 802.11 WLANs operating in the 2.4 GHz and 5 GHz bands. 802.11ah can be used for various purposes including large-scale sensor networks, extended-range hotspots, and outdoor Wi-Fi for cellular WAN carrier traffic offloading, whereas the available bandwidth is relatively narrow. The protocol intends consumption to be competitive with low-power Bluetooth, at a much wider range.

802.11ai
IEEE 802.11ai is an amendment to the 802.11 standard that added new mechanisms for a faster initial link setup time.

802.11aj
IEEE 802.11aj is a derivative of 802.11ad for use in the 45 GHz unlicensed spectrum available in some regions of the world (specifically China); it also provides additional capabilities for use in the 60 GHz band.

Alternatively known as China Millimeter Wave (CMMW).

802.11aq
IEEE 802.11aq is an amendment to the 802.11 standard that will enable pre-association discovery of services. This extends some of the mechanisms in 802.11u that enabled device discovery to discover further the services running on a device, or provided by a network.

802.11-2020
IEEE 802.11-2020, which was known as IEEE 802.11 REVmd, is a revision based on IEEE 802.11-2016 incorporating 5 amendments (11ai, 11ah, 11aj, 11ak, 11aq). In addition, existing MAC and PHY functions have been enhanced and obsolete features were removed or marked for removal. Some clauses and annexes have been added.

802.11ax
IEEE 802.11ax is the successor to 802.11ac, marketed as Wi-Fi 6 (2.4 GHz and 5 GHz) and Wi-Fi 6E (6 GHz) by the Wi-Fi Alliance. It is also known as High Efficiency Wi-Fi, for the overall improvements to Wi-Fi 6 clients in dense environments. For an individual client, the maximum improvement in data rate (PHY speed) against the predecessor (802.11ac) is only 39% (for comparison, this improvement was nearly 500% for the predecessors). Yet, even with this comparatively minor 39% figure, the goal was to provide 4 times the throughput-per-area of 802.11ac (hence High Efficiency). The motivation behind this goal was the deployment of WLAN in dense environments such as corporate offices, shopping malls and dense residential apartments. This is achieved by means of a technique called OFDMA, which is basically multiplexing in the frequency domain (as opposed to spatial multiplexing, as in 802.11ac). This is equivalent to cellular technology applied into Wi-Fi.

The IEEE 802.11ax2021 standard was approved on February 9, 2021.

802.11ay
IEEE 802.11ay is a standard that is being developed, also called EDMG: Enhanced Directional MultiGigabit PHY. It is an amendment that defines a new physical layer for 802.11 networks to operate in the 60 GHz millimeter wave spectrum. It will be an extension of the existing 11ad, aimed to extend the throughput, range, and use-cases. The main use-cases include indoor operation and short-range communications due to atmospheric oxygen absorption and inability to penetrate walls. The peak transmission rate of 802.11ay is 40 Gbit/s. The main extensions include: channel bonding (2, 3 and 4), MIMO (up to 4 streams) and higher modulation schemes. The expected range is 300-500 m.

802.11ba
IEEE 802.11ba Wake-up Radio (WUR) Operation is an amendment to the IEEE 802.11 standard that enables energy-efficient operation for data reception without increasing latency. The target active power consumption to receive a WUR packet is less than 1 milliwatt and supports data rates of 62.5 kbit/s and 250 kbit/s. The WUR PHY uses MC-OOK (multicarrier OOK) to achieve extremely low power consumption.

802.11bb
IEEE 802.11bb is a networking protocol standard in the IEEE 802.11 set of protocols that uses infrared light for communications.

802.11be
IEEE 802.11be Extremely High Throughput (EHT) is the potential next amendment to the 802.11 IEEE standard, and will likely be designated as Wi-Fi 7. It will build upon 802.11ax, focusing on WLAN indoor and outdoor operation with stationary and pedestrian speeds in the 2.4 GHz, 5 GHz, and 6 GHz frequency bands.

Common misunderstandings about achievable throughput

Across all variations of 802.11, maximum achievable throughputs are given either based on measurements under ideal conditions or in the layer-2 data rates. However, this does not apply to typical deployments in which data is being transferred between two endpoints, of which at least one is typically connected to a wired infrastructure and the other endpoint is connected to an infrastructure via a wireless link.

This means that, typically, data frames pass an 802.11 (WLAN) medium and are being converted to 802.3 (Ethernet) or vice versa. Due to the difference in the frame (header) lengths of these two media, the application's packet size determines the speed of the data transfer. This means applications that use small packets (e.g., VoIP) create dataflows with high-overhead traffic (i.e., a low goodput). Other factors that contribute to the overall application data rate are the speed with which the application transmits the packets (i.e., the data rate) and, of course, the energy with which the wireless signal is received. The latter is determined by distance and by the configured output power of the communicating devices.

The same references apply to the attached graphs that show measurements of UDP throughput. Each represents an average (UDP) throughput (please note that the error bars are there but barely visible due to the small variation) of 25 measurements. Each is with a specific packet size (small or large) and with a specific data rate (10 kbit/s – 100 Mbit/s). Markers for traffic profiles of common applications are included as well. These figures assume there are no packet errors, which, if occurring, will lower the transmission rate further.

Channels and frequencies
802.11b, 802.11g, and 802.11n-2.4 utilize the 2.400–2.500 GHz spectrum, one of the ISM bands. 802.11a, 802.11n, and 802.11ac use the more heavily regulated 4.915–5.825 GHz band. These are commonly referred to as the "2.4 GHz and 5 GHz bands" in most sales literature. Each spectrum is sub-divided into channels with a center frequency and bandwidth, analogous to how radio and TV broadcast bands are sub-divided.

The 2.4 GHz band is divided into 14 channels spaced 5 MHz apart, beginning with channel 1, which is centered on 2.412 GHz. The latter channels have additional restrictions or are unavailable for use in some regulatory domains.

The channel numbering of the 5.725–5.875 GHz spectrum is less intuitive due to the differences in regulations between countries. These are discussed in greater detail on the list of WLAN channels.

Channel spacing within the 2.4 GHz band
In addition to specifying the channel center frequency, 802.11 also specifies (in Clause 17) a spectral mask defining the permitted power distribution across each channel. The mask requires the signal to be attenuated a minimum of 20 dB from its peak amplitude at ±11 MHz from the center frequency, the point at which a channel is effectively 22 MHz wide. One consequence is that stations can use only every fourth or fifth channel without overlap.

Availability of channels is regulated by country, constrained in part by how each country allocates radio spectrum to various services. At one extreme, Japan permits the use of all 14 channels for 802.11b, and 1–13 for 802.11g/n-2.4. Other countries such as Spain initially allowed only channels 10 and 11, and France allowed only 10, 11, 12, and 13; however, Europe now allow channels 1 through 13. North America and some Central and South American countries allow only 1 through 11.

Since the spectral mask defines only power output restrictions up to ±11 MHz from the center frequency to be attenuated by −50 dBr, it is often assumed that the energy of the channel extends no further than these limits. It is more correct to say that the overlapping signal on any channel should be sufficiently attenuated to interfere with a transmitter on any other channel minimally, given the separation between channels. Due to the near–far problem a transmitter can impact (desensitize) a receiver on a "non-overlapping" channel, but only if it is close to the victim receiver (within a meter) or operating above allowed power levels. Conversely, a sufficiently distant transmitter on an overlapping channel can have little to no significant effect.

Confusion often arises over the amount of channel separation required between transmitting devices. 802.11b was based on direct-sequence spread spectrum (DSSS) modulation and utilized a channel bandwidth of 22 MHz, resulting in three "non-overlapping" channels (1, 6, and 11). 802.11g was based on OFDM modulation and utilized a channel bandwidth of 20 MHz. This occasionally leads to the belief that four "non-overlapping" channels (1, 5, 9, and 13) exist under 802.11g. However, this is not the case as per 17.4.6.3 Channel Numbering of operating channels of the IEEE Std 802.11 (2012), which states, "In a multiple cell network topology, overlapping and/or adjacent cells using different channels can operate simultaneously without interference if the distance between the center frequencies is at least 25 MHz." and section 18.3.9.3 and Figure 18-13.

This does not mean that the technical overlap of the channels recommends the non-use of overlapping channels. The amount of inter-channel interference seen on a configuration using channels 1, 5, 9, and 13 (which is permitted in Europe, but not in North America) is barely different from a three-channel configuration, but with an entire extra channel.

However, overlap between channels with more narrow spacing (e.g. 1, 4, 7, 11 in North America) may cause unacceptable degradation of signal quality and throughput, particularly when users transmit near the boundaries of AP cells.

Regulatory domains and legal compliance
IEEE uses the phrase regdomain to refer to a legal regulatory region. Different countries define different levels of allowable transmitter power, time that a channel can be occupied, and different available channels. Domain codes are specified for the United States, Canada, ETSI (Europe), Spain, France, Japan, and China.

Most Wi-Fi certified devices default to regdomain 0, which means least common denominator settings, i.e., the device will not transmit at a power above the allowable power in any nation, nor will it use frequencies that are not permitted in any nation.

The regdomain setting is often made difficult or impossible to change so that the end-users do not conflict with local regulatory agencies such as the United States' Federal Communications Commission.

Layer 2 – Datagrams
The datagrams are called frames. Current 802.11 standards specify frame types for use in the transmission of data as well as management and control of wireless links.

Frames are divided into very specific and standardized sections. Each frame consists of a MAC header, payload, and frame check sequence (FCS). Some frames do not have payloads.

The first two bytes of the MAC header form a frame control field specifying the form and function of the frame. This frame control field is subdivided into the following sub-fields:
 * Protocol Version: Two bits representing the protocol version. The currently used protocol version is zero. Other values are reserved for future use.
 * Type: Two bits identifying the type of WLAN frame. Control, Data, and Management are various frame types defined in IEEE 802.11.
 * Subtype: Four bits providing additional discrimination between frames. Type and Subtype are used together to identify the exact frame.
 * ToDS and FromDS: Each is one bit in size. They indicate whether a data frame is headed for a distribution system or it is getting out of it. Control and management frames set these values to zero. All the data frames will have one of these bits set.
 * ToDS = 0 and FromDS = 0
 * Communication within a basic service set or an independent basic service set (IBSS) network.
 * ToDS = 0 and FromDS = 1
 * A frame sent by a station and directed to an AP accessed via the distribution system.
 * ToDS = 1 and FromDS = 0
 * A frame exiting the distribution system for a station.
 * ToDS = 1 and FromDS = 1
 * Only kind of frame frame that uses all four MAC addresses in a DATA frame.
 * Address 1: access point address exiting from the distribution system.
 * Address 2: access point entrance to the distribution system (AP to which the source station is connected).
 * Address 3: final station address.
 * Address 4: address of the source station.
 * More Fragments: The More Fragments bit is set when a packet is divided into multiple frames for transmission. Every frame except the last frame of a packet will have this bit set.
 * Retry: Sometimes frames require retransmission, and for this, there is a Retry bit that is set to one when a frame is resent. This aids in the elimination of duplicate frames.
 * Power Management: This bit indicates the power management state of the sender after the completion of a frame exchange. Access points are required to manage the connection and will never set the power-saver bit.
 * More Data: The More Data bit is used to buffer frames received in a distributed system. The access point uses this bit to facilitate stations in power-saver mode. It indicates that at least one frame is available and addresses all stations connected.
 * Protected Frame: The Protected Frame bit is set to the value of one if the frame body is encrypted by a protection mechanism such as Wired Equivalent Privacy (WEP), Wi-Fi Protected Access (WPA), or Wi-Fi Protected Access II (WPA2).
 * Order: This bit is set only when the "strict ordering" delivery method is employed. Frames and fragments are not always sent in order as it causes a transmission performance penalty.

The next two bytes are reserved for the Duration ID field, indicating how long the field's transmission will take so other devices know when the channel will be available again. This field can take one of three forms: Duration, Contention-Free Period (CFP), and Association ID (AID).

An 802.11 frame can have up to four address fields. Each field can carry a MAC address. Address 1 is the receiver, Address 2 is the transmitter, Address 3 is used for filtering purposes by the receiver. Address 4 is only present in data frames transmitted between access points in an Extended Service Set or between intermediate nodes in a mesh network.

The remaining fields of the header are:
 * The Sequence Control field is a two-byte section used to identify message order and eliminate duplicate frames. The first 4 bits are used for the fragmentation number, and the last 12 bits are the sequence number.
 * An optional two-byte Quality of Service control field, present in QoS Data frames; it was added with 802.11e.

The payload or frame body field is variable in size, from 0 to 2304 bytes plus any overhead from security encapsulation, and contains information from higher layers.

The Frame Check Sequence (FCS) is the last four bytes in the standard 802.11 frame. Often referred to as the Cyclic Redundancy Check (CRC), it allows for integrity checks of retrieved frames. As frames are about to be sent, the FCS is calculated and appended. When a station receives a frame, it can calculate the FCS of the frame and compare it to the one received. If they match, it is assumed that the frame was not distorted during transmission.

Management frames
Management frames are not always authenticated, and allow for the maintenance, or discontinuance, of communication. Some common 802.11 subtypes include:
 * Authentication frame: 802.11 authentication begins with the wireless network interface controller (WNIC) sending an authentication frame to the access point containing its identity.
 * When open system authentication is being used, the WNIC sends only a single authentication frame, and the access point responds with an authentication frame of its own indicating acceptance or rejection.
 * When shared key authentication is being used, the WNIC sends an initial authentication request, and the access point responds with an authentication frame containing challenge text. The WNIC then sends an authentication frame containing the encrypted version of the challenge text to the access point. The access point confirms the text was encrypted with the correct key by decrypting it with its own key. The result of this process determines the WNIC's authentication status.
 * Association request frame: Sent from a station, it enables the access point to allocate resources and synchronize. The frame carries information about the WNIC, including supported data rates and the SSID of the network the station wishes to associate with. If the request is accepted, the access point reserves memory and establishes an association ID for the WNIC.
 * Association response frame: Sent from an access point to a station containing the acceptance or rejection to an association request. If it is an acceptance, the frame will contain information such as an association ID and supported data rates.
 * Beacon frame: Sent periodically from an access point to announce its presence and provide the SSID and other parameters for WNICs within range.
 * Deauthentication frame: Sent from a station wishing to terminate connection from another station.
 * Disassociation frame: Sent from a station wishing to terminate the connection. It is an elegant way to allow the access point to relinquish memory allocation and remove the WNIC from the association table.
 * Probe request frame: Sent from a station when it requires information from another station.
 * Probe response frame: Sent from an access point containing capability information, supported data rates, etc., after receiving a probe request frame.
 * Reassociation request frame: A WNIC sends a reassociation request when it drops from the currently associated access point range and finds another access point with a stronger signal. The new access point coordinates the forwarding of any information that may still be contained in the buffer of the previous access point.
 * Reassociation response frame: Sent from an access point containing the acceptance or rejection to a WNIC reassociation request frame. The frame includes information required for association such as the association ID and supported data rates.
 * Action frame: extending management frame to control a certain action. Some of the action categories are Block Ack, Radio Measurement, Fast BSS Transition, etc. These frames are sent by a station when it needs to tell its peer for a certain action to be taken. For example, a station can tell another station to set up a block acknowledgement by sending an ADDBA Request action frame. The other station would then respond with an ADDBA Response action frame.

The body of a management frame consists of frame-subtype-dependent fixed fields followed by a sequence of information elements (IEs).

The common structure of an IE is as follows:

Control frames
Control frames facilitate the exchange of data frames between stations. Some common 802.11 control frames include:
 * Acknowledgement (ACK) frame: After receiving a data frame, the receiving station will send an ACK frame to the sending station if no errors are found. If the sending station does not receive an ACK frame within a predetermined period of time, the sending station will resend the frame.
 * Request to Send (RTS) frame: The RTS and CTS frames provide an optional collision reduction scheme for access points with hidden stations. A station sends an RTS frame as the first step in a two-way handshake required before sending data frames.
 * Clear to Send (CTS) frame: A station responds to an RTS frame with a CTS frame. It provides clearance for the requesting station to send a data frame. The CTS provides collision control management by including a time value for which all other stations are to hold off transmission while the requesting station transmits.

Data frames
Data frames carry packets from web pages, files, etc. within the body. The body begins with an IEEE 802.2 header, with the Destination Service Access Point (DSAP) specifying the protocol, followed by a Subnetwork Access Protocol (SNAP) header if the DSAP is hex AA, with the organizationally unique identifier (OUI) and protocol ID (PID) fields specifying the protocol. If the OUI is all zeroes, the protocol ID field is an EtherType value. Almost all 802.11 data frames use 802.2 and SNAP headers, and most use an OUI of 00:00:00 and an EtherType value.

Similar to TCP congestion control on the internet, frame loss is built into the operation of 802.11. To select the correct transmission speed or Modulation and Coding Scheme, a rate control algorithm may test different speeds. The actual packet loss rate of Access points varies widely for different link conditions. There are variations in the loss rate experienced on production Access points, between 10% and 80%, with 30% being a common average. It is important to be aware that the link layer should recover these lost frames. If the sender does not receive an Acknowledgement (ACK) frame, then it will be resent.

Standards and amendments
Within the IEEE 802.11 Working Group, the following IEEE Standards Association Standard and Amendments exist:

 * IEEE 802.11-1997: The WLAN standard was originally 1 Mbit/s and 2 Mbit/s, 2.4 GHz RF and infrared (IR) standard (1997), all the others listed below are Amendments to this standard, except for Recommended Practices 802.11F and 802.11T.
 * IEEE 802.11a: 54 Mbit/s, 5 GHz standard (1999, shipping products in 2001)
 * IEEE 802.11b: 5.5 Mbit/s and 11 Mbit/s, 2.4 GHz standard (1999)
 * IEEE 802.11c: Bridge operation procedures; included in the IEEE 802.1D standard (2001)
 * IEEE 802.11d: International (country-to-country) roaming extensions (2001)
 * IEEE 802.11e: Enhancements: QoS, including packet bursting (2005)
 * IEEE 802.11F: Inter-Access Point Protocol (2003) Withdrawn February 2006
 * IEEE 802.11g: 54 Mbit/s, 2.4 GHz standard (backwards compatible with b) (2003)
 * IEEE 802.11h: Spectrum Managed 802.11a (5 GHz) for European compatibility (2004)
 * IEEE 802.11i: Enhanced security (2004)
 * IEEE 802.11j: Extensions for Japan (4.9-5.0 GHz) (2004)
 * IEEE 802.11-2007: A new release of the standard that includes amendments a, b, d, e, g, h, i, and j. (July 2007)
 * IEEE 802.11k: Radio resource measurement enhancements (2008)
 * IEEE 802.11n: Higher Throughput WLAN at 2.4 and 5 GHz; 20 and 40 MHz channels; introduces MIMO to Wi-Fi (September 2009)
 * IEEE 802.11p: WAVE—Wireless Access for the Vehicular Environment (such as ambulances and passenger cars) (July 2010)
 * IEEE 802.11r: Fast BSS transition (FT) (2008)
 * IEEE 802.11s: Mesh Networking, Extended Service Set (ESS) (July 2011)
 * IEEE 802.11T: Wireless Performance Prediction (WPP)—test methods and metrics Recommendation cancelled
 * IEEE 802.11u: Improvements related to HotSpots and 3rd-party authorization of clients, e.g., cellular network offload (February 2011)
 * IEEE 802.11v: Wireless network management (February 2011)
 * IEEE 802.11w: Protected Management Frames (September 2009)
 * IEEE 802.11y: 3650–3700 MHz Operation in the U.S. (2008)
 * IEEE 802.11z: Extensions to Direct Link Setup (DLS) (September 2010)
 * IEEE 802.11-2012: A new release of the standard that includes amendments k, n, p, r, s, u, v, w, y, and z (March 2012)
 * IEEE 802.11aa: Robust streaming of Audio Video Transport Streams (June 2012) - see Stream Reservation Protocol
 * IEEE 802.11ac: Very High Throughput WLAN at 5 GHz; wider channels (80 and 160 MHz); Multi-user MIMO (down-link only) (December 2013)
 * IEEE 802.11ad: Very High Throughput 60 GHz (December 2012) — see also WiGig
 * IEEE 802.11ae: Prioritization of Management Frames (March 2012)
 * IEEE 802.11af: TV Whitespace (February 2014)
 * IEEE 802.11-2016: A new release of the standard that includes amendments aa, ac, ad, ae, and af (December 2016)
 * IEEE 802.11ah: Sub-1 GHz license exempt operation (e.g., sensor network, smart metering) (December 2016)
 * IEEE 802.11ai: Fast Initial Link Setup (December 2016)
 * IEEE 802.11aj: China Millimeter Wave (February 2018)
 * IEEE 802.11ak: Transit Links within Bridged Networks (June 2018)
 * IEEE 802.11aq: Pre-association Discovery (July 2018)
 * IEEE 802.11-2020: A new release of the standard that includes amendments ah, ai, aj, ak, and aq (December 2020)
 * IEEE 802.11ax: High Efficiency WLAN at 2.4, 5 and 6 GHz; introduces OFDMA to Wi-Fi (February 2021)
 * IEEE 802.11ay: Enhancements for Ultra High Throughput in and around the 60 GHz Band (March 2021)
 * IEEE 802.11az: Next Generation Positioning (March 2023)
 * IEEE 802.11ba: Wake Up Radio (March 2021)
 * IEEE 802.11bb: Light Communications (November 2023)
 * IEEE 802.11bc: Enhanced Broadcast Service (February 2024)
 * IEEE 802.11bd: Enhancements for Next Generation V2X (see also IEEE 802.11p) (March 2023)

In process

 * IEEE 802.11be: Extremely High Throughput (see also IEEE 802.11ax) (May 2024)
 * IEEE 802.11bf: WLAN Sensing
 * IEEE 802.11bh: Randomized and Changing MAC Addresses
 * IEEE 802.11bi: Enhanced Data Privacy
 * IEEE 802.11bk: 320 MHz Positioning
 * IEEE 802.11bn: Ultra High Reliability
 * IEEE 802.11bp: Ambient Power Communication
 * IEEE 802.11me: 802.11 Accumulated Maintenance Changes

802.11F and 802.11T are recommended practices rather than standards and are capitalized as such.

802.11m is used for standard maintenance. 802.11ma was completed for 802.11-2007, 802.11mb for 802.11-2012, 802.11mc for 802.11-2016, and 802.11md for 802.11-2020.

Standard vs. amendment
Both the terms "standard" and "amendment" are used when referring to the different variants of IEEE standards.

As far as the IEEE Standards Association is concerned, there is only one current standard; it is denoted by IEEE 802.11 followed by the date published. IEEE 802.11-2020 is the only version currently in publication, superseding previous releases. The standard is updated by means of amendments. Amendments are created by task groups (TG). Both the task group and their finished document are denoted by 802.11 followed by one or two lower case letters, for example, IEEE 802.11a or IEEE 802.11ax. Updating 802.11 is the responsibility of task group m. In order to create a new version, TGm combines the previous version of the standard and all published amendments. TGm also provides clarification and interpretation to industry on published documents. New versions of the IEEE 802.11 were published in 1999, 2007, 2012, 2016, and 2020.

Nomenclature
Various terms in 802.11 are used to specify aspects of wireless local-area networking operation and may be unfamiliar to some readers.

For example, time unit (usually abbreviated TU) is used to indicate a unit of time equal to 1024 microseconds. Numerous time constants are defined in terms of TU (rather than the nearly equal millisecond).

Also, the term portal is used to describe an entity that is similar to an 802.1H bridge. A portal provides access to the WLAN by non-802.11 LAN STAs.

Security
In 2001, a group from the University of California, Berkeley presented a paper describing weaknesses in the 802.11 Wired Equivalent Privacy (WEP) security mechanism defined in the original standard; they were followed by Fluhrer, Mantin, and Shamir's paper titled "Weaknesses in the Key Scheduling Algorithm of RC4". Not long after, Adam Stubblefield and AT&T publicly announced the first verification of the attack. In the attack, they were able to intercept transmissions and gain unauthorized access to wireless networks.

The IEEE set up a dedicated task group to create a replacement security solution, 802.11i (previously, this work was handled as part of a broader 802.11e effort to enhance the MAC layer). The Wi-Fi Alliance announced an interim specification called Wi-Fi Protected Access (WPA) based on a subset of the then-current IEEE 802.11i draft. These started to appear in products in mid-2003. IEEE 802.11i (also known as WPA2) itself was ratified in June 2004, and uses the Advanced Encryption Standard (AES), instead of RC4, which was used in WEP. The modern recommended encryption for the home/consumer space is WPA2 (AES Pre-Shared Key), and for the enterprise space is WPA2 along with a RADIUS authentication server (or another type of authentication server) and a strong authentication method such as EAP-TLS.

In January 2005, the IEEE set up yet another task group "w" to protect management and broadcast frames, which previously were sent unsecured. Its standard was published in 2009.

In December 2011, a security flaw was revealed that affects some wireless routers with a specific implementation of the optional Wi-Fi Protected Setup (WPS) feature. While WPS is not a part of 802.11, the flaw allows an attacker within the range of the wireless router to recover the WPS PIN and, with it, the router's 802.11i password in a few hours.

In late 2014, Apple announced that its iOS 8 mobile operating system would scramble MAC addresses during the pre-association stage to thwart retail footfall tracking made possible by the regular transmission of uniquely identifiable probe requests. Android 8.0 "Oreo" introduced a similar feature, named "MAC randomization".

Wi-Fi users may be subjected to a Wi-Fi deauthentication attack to eavesdrop, attack passwords, or force the use of another, usually more expensive access point.

title: IEEE 802.11


text:
Irn-Bru

Irn-Bru ( "iron brew", ) is a Scottish carbonated soft drink, often described as "Scotland's other national drink" (after Scotch whisky). Introduced in 1901, the drink is produced in Westfield, Cumbernauld, North Lanarkshire, by A.G. Barr of Glasgow. As well as being sold throughout the United Kingdom, Irn-Bru is available throughout the world and can usually be bought where there is a significant community of people from Scotland. The brand also has its own tartan. It has been the top-selling soft drink in Scotland for over a century, competing directly with global brands such as Coca-Cola.

Originally sold as Iron Brew, the drinks makers A.G Barr were forced to change the name of the drink in 1946 following a change in the law that stipulated that the marketing of products required to be "literally true". As the drink did not contain much iron, nor was it brewed, led the company to changing the name to the presently used Irn-Bru. Irn-Bru has long been the most popularly consumed soft drink in Scotland, consistently beating rivals such as Coca-Cola, Pepsi and Fanta, and reportedly sells 20 cans every second throughout Scotland. Irn-Bru is sold in a number of international food and drink markets, including in countries such as the Netherlands, Spain, Belgium, Malta, certain countries of the African continent, the Middle East, and North America.

Appearance and overview
Irn-Bru is known for its bright orange colour and unique flavour. As of 1999, it contained 0.002% of ammonium ferric citrate, sugar, 32 flavouring agents including caffeine and quinine (but not in Australia), and two controversial colourings (Sunset Yellow FCF E110 and Ponceau 4R E124). On 27 January 2010, soft-drink manufacturer A.G. Barr agreed to a Food Standards Agency voluntary ban on these two colourings although no date was set for their replacement.

After lobbying by First Minister of Scotland Alex Salmond, a proposed restriction of Sunset Yellow to 10 mg/litre was eased to 20 mg/litre in 2011 – the same amount present in Irn-Bru. As of August 2021, Irn-Bru still contains these colourings.

Origins
The first Iron Brew drink was produced by the Maas & Waldstein chemicals company of New York in 1889 under the name IRONBREW. The drink was popular across North America and was widely copied. A similar beverage was launched in 1898 by London essence firm Stevenson & Howell that supplied soft drinks manufacturers in the UK and colonies. Many local bottlers around the UK began selling their own version of the beverage.

Despite the official launch date for Barr's Iron Brew being given as 1901, the firms AG Barr & Co (Glasgow) and Robert Barr (Falkirk) jointly launched their own Iron Brew drink at least two years earlier, according to a document in the firm's archives which indicates that the drink was already enjoying strong sales by May 1899. The strongman image which Barr's adopted for their bottle labels and advertising had been trademarked by the firm Stevenson & Howell in 1898. Barr's ordered their labels directly from Stevenson & Howell, which also sold Barr's many of the individual flavours with which they mixed their own drinks. An advertisement for Barr's Iron Brew dated 1900 featuring the original strongman label can be found in Falkirk's Local History Archives.

Trademark

Barr's trademark application for the brand name Irn-Bru dates from July 1946 when the drink was still off sale because of wartime regulations. The firm first commercialised their drink using this new name in 1948 once government SDI consolidation of the soft drinks industry had ended. The name change followed the introduction of new labelling restrictions which cracked down on spurious health claims and introduced minimum standards for drinks claiming to contain minerals such as iron. However, according to Robert Barr OBE (chairman 1947–1978), there was also a commercial rationale behind the unusual spelling. "Iron Brew" had come to be understood as a generic product category in the UK, whereas adopting the name "Irn-Bru" allowed the firm to have a legally protected brand identity that would enable the firm to benefit from the popularity of their wartime "Adventures of Ba-Bru" comic strip advertising. (The "Iron Brew" name has continued to be used for many versions of the drink sold by rival manufacturers.)

Popularity and new variants
1980 saw the introduction of Low Calorie Irn-Bru: this was re-launched in 1991 as Diet Irn-Bru and again in 2011 as Irn-Bru Sugar Free. The Irn-Bru 32 energy drink variant was launched in 2006.

Irn-Bru has long been the most popular soft drink in Scotland, with Coca-Cola second, but competition between the two brands brought their sales to roughly equal levels by 2003. It is also the third best selling soft drink in the UK, after Coca-Cola and Pepsi, outselling high-profile brands such as Fanta, Dr Pepper, Sprite and 7 Up. This success in defending its home market (a feat claimed only by Irn-Bru, Inca Kola and Thums Up; Thums Up sold out to Coca-Cola in 1993, and Inka Kola owners Corporación Lindley S.A. entered into a joint venture with Coca-Cola in 1999, giving up all rights to the name outside Peru) led to ongoing speculation that Coca-Cola, PepsiCo, Inc. or its UK brand franchisee Britvic would attempt to buy A.G. Barr. In November 2012 AG Barr and Britvic announced a merger proposal, but in July 2013 the merger collapsed when terms could not be agreed.

Irn-Bru's advertising slogans used to be 'Scotland's other National Drink', referring to whisky, and 'Made in Scotland from girders', a reference to the rusty colour of the drink; though the closest one can come to substantiating this claim is the 0.002% ammonium ferric citrate listed in the ingredients.

Fiery Irn-Bru, a limited edition variant, was released in autumn 2011. It was packaged with a black and orange design, and with the signature man icon with an added image of a fire. It featured the traditional Irn-Bru flavour with an aftertaste similar to ginger.

Irn-Bru was also sold in reusable 750 ml glass bottles which, like other Barr's drinks, were able to be returned to the manufacturer in exchange for a 30 pence (previously 20p) deposit paid on purchase. This scheme was widely available in shops across Scotland and led to the colloquial term for an empty: a "glass cheque". As a result of a 40% drop in returned bottles since the 1990s Barr deemed the washing and re-filling process uneconomical, and on 1 January 2016 ceased the scheme.

New logo
2016 saw the introduction of the current logo, conveying "strength" and an "industrial feel", and a new diet variant called Irn-Bru Xtra in different branding to the existing sugar free variety in a similar fashion to Coca-Cola Zero and Pepsi Max.

Barr changed the formula of Irn-Bru in January 2018 in response to a sugar tax implemented in the UK in April 2018, intended to combat obesity. By reducing the sugar content to less than 5g per 100ml, Barr has made Irn-Bru exempt from the tax. The manufacturer asserted that "most people will not be able to tell the difference in flavour between the old and new formulas", but fans of the drink launched an unsuccessful 'Save Real Irn-Bru' campaign to stop or reverse the change, and began stocking up on the more sugary formula.

In May 2019, Barr announced a new energy drink variant of Irn-Bru called Irn-Bru Energy, which was released on 1 July 2019.

In October 2019, Barr announced the launch of the "Irn-Bru 1901". The drink would be available for a limited time and use the original recipe from 1901.

Recent history

In March 2021, Barr announced the relaunch of "IRN-BRU 1901" as a permanent addition to the IRN-BRU lineup.

Irn-Bru was the only soft drink on sale at the 2021 United Nations Climate Change Conference (COP26) in Glasgow, Scotland, due to a sponsorship arrangement. Member of the US House of Representatives Alexandria Ocasio-Cortez tried Irn-Bru at COP26 and said she loved it, and that it tasted just like the Latino soda Kola Champagne. The response from others at the conference ranged from strong dislike to strong like. The volume of editorial and opinion publicity the drink gained on social and print media was described as "the summit's surprise", coverage worth millions. However, AG Barr's share price remained relatively flat at the time.

Production
It is produced in Westfield, Cumbernauld, North Lanarkshire, since Barr's moved out of their Parkhead, Glasgow factory in the mid-2000s. In 2011, Irn-Bru closed their factory in Mansfield, making the Westfield plant in Cumbernauld the main location for production. Other manufacturing locations include the English city of Sheffield.

Marketing

Barr's actively promoted their Irn-Bru from the outset, with some of their earliest ads featuring world champion wrestlers and Highland Games athletes Donald Dinnie and Alex Munro who endorsed the drink by means of personal testimonials. In the 1930s, the firm began a long-running series of comic strip ads entitled "The Adventures of Ba-Bru" which ran in various local papers from April 1939 until October 1970. The last traces of this campaign, a large neon sign featuring Ba-Bru which stood in Union St above Glasgow Central railway station, was removed in 1983 and replaced with an illuminated display featuring the tagline "Your Other National Drink".

Barr has a long-established gimmick associating Irn-Bru with Scottishness, stemming from the claim of its being Scotland's most popular soft drink. A tagline, "Made in Scotland from girders", was used for several years from the 1980s, usually featuring Irn-Bru drinkers becoming unusually strong, durable or magnetic.

An advertising campaign launched in Spring 2000 aimed to "dramatise the extraordinary appeal of Irn-Bru in a likeably maverick style". David Amers, Planning Director, said: "Irn-Bru is the likeable maverick of the soft drinks market and these ads perfectly capture the brand's spirit." One involved a grandfather (played by actor Robert Wilson) who removed his false teeth to spoil his grandson's interest in his can of Irn-Bru. A further TV advertisement featured a senior citizen in a motorised wheelchair robbing a local shopping market of a supply of Irn-Bru.

In 2004 the company created a new concept "Phenomenal". In 2006 the company launched its first Christmas adverts. This campaign consisted of a parody commercial of a popular Christmas Cartoon, The Snowman, and was effective in interesting American audiences in the Irn-Bru brand. A sequel to the commercial would later be released in December 2018. Further advertising campaigns for Irn-Bru appeared in conjunction with the release of Irn-Bru 32 in 2006.

A 2009 advertisement for the product featured a group of high school pupils performing a musical number, with the refrain "It's fizzy, it's ginger, it's phenomenal!" It was a parody of High School Musical, and starred Jack Lowden. In 2012 the company changed its slogan to "gets you through", which see a number of people drinking Irn-Bru to get through tough situations. In response to the Coca-Cola 'Share a Coke' campaign, Barr decided to produce thousands of limited edition 750 ml bottles of Irn-Bru with the names 'Fanny', 'Senga', 'Rab' and 'Tam' on the label, mimicking that by Coca-Cola. The use of the name 'Fanny' ties in with one of Irn-Bru's controversial marketing advertisements.

One of the most controversial Irn-Bru television adverts evoked 1950s entertainment. A mother plays the piano, while the father and two children deliver a song which ends with the mother singing: "...even though I used to be a man". This advertisement was broadcast in 2000, but when it was repeated in 2003, it led to seventeen complaints about it being offensive to members of the transgender community. Issue A14 of the Ofcom Advertising Complaints bulletin reports that the children's response to their mother's claim was not offensive. According to the advertising agency Leith, the advertisement was meant to "create a sense of humour while confirming the maverick nature of the brand". However, the scene involving the mother shaving at the end of the advertisement was deemed by Ofcom to be "capable of causing offence by strongly reinforcing negative stereotypes", and so it was taken off the air.

In 2003, an Irn-Bru commercial which showed a midwife trying to entice a baby from its mother's womb during a difficult delivery sparked fifty complaints. Some saw it as upsetting to women who had suffered miscarriages. One billboard that drew criticism featured a young woman in a bikini along with the slogan "Diet Irn-Bru. I never knew four-and-a-half inches could give so much pleasure". Another featured a picture of a cow with the slogan "When I'm a burger, I want to be washed down with Irn-Bru". This billboard resulted in over 700 complaints but was cleared by advertisement watchdogs. According to a 2003 BBC report, a billboard which featured a depressed goth and the slogan "Cheer up Goth. Have an Irn-Bru." was also criticised for inciting bullying.

Brand portfolio
McCowan's also produced Irn-Bru Bars, chewy, fizzy, bright orange confectionery bars which taste strongly of Irn-Bru, though production ended in late 2005. Irn-Bru sorbet is available in some speciality ice cream shops in Scotland.

The drink can be used as a mixer with alcoholic beverages, mainly vodka and whisky. Barr launched an alcopop drink combining Irn-Bru and Bell's whisky, although this proved to be unpopular and was discontinued.

Exports and foreign markets

Irn-Bru is manufactured under licence in Russia by the Moscow Brewing Company. Bru and other Barr products are exported to Spain, the Netherlands, Germany, Gibraltar, Greece, and Cyprus, as well as parts of Africa and Asia. It is available in the Republic of Ireland, increasingly being stocked in BWG and ADM Londis supplied stores, as well as in supermarkets owned by Dunnes Stores and Tesco Ireland. In Ireland generally, the drink mainly sells in County Donegal. It is also available in Malta, Belgium and in Poland. It is now sold in Iceland, as of 2011.

Australia
In Australia, Irn-Bru was manufactured and distributed under licence by Occasio Australia until 2009. It was available in 500 ml and 1.25-litre in both standard and diet. The drink enjoyed growing success in the country, with its first advertising campaign launched in Queensland in September 2007. It was initially available in major chains such as Coles and Woolworths, Caltex service stations and in many independent grocers and convenience stores. It was then delisted at Coles Supermarkets. Because of manufacturing and bottling issues, Occasio ceased local production in late 2009. It is now imported direct from the UK and distributed by British Provender, and can again be found in the international sections of major supermarket chains and some convenience stores.

Canada
Irn-Bru sold in Canada contained no caffeine until recently. In March 2010, Health Canada repealed the ban on caffeine in clear coloured soft drinks and now bottles of Irn-Bru have the label 'Now Contains caffeine' on the packaging. Irn-Bru in Canada is distributed by TFB & Associates Ltd from Markham, Ontario but is packaged by A.G. Barr in Glasgow, Scotland. Irn-Bru can be found at Sobeys, Co-Op and Walmart supermarkets.

The now-defunct McKinlay soft-drink company in Glace Bay, Cape Breton, Nova Scotia, Canada, for many years offered its own non-licensed beverage called Irn-Bru and later "Cape Breton's Irn-Bru". It was a brown carbonated soft-drink with a fruity cola taste.

The standard Irn-Bru distributed in Canada also contains the "Not a source of iron" disclaimer on the label. The UK version of the drink (with caffeine) is commonly imported by speciality retailers, particularly in areas with large Scottish populations.

In 2014, Irn-Bru was incorrectly reported to have been one of a number of imported products, including Marmite, banned in Canada as a result of its additives in its ingredients due to a shipment being confiscated; however, a statement released by the Government of Canada in October 2020 reiterated that "Irn-Bru and Marmite are not banned for sale in Canada. These products have been available on Canadian store shelves for more than a decade and will continue to be sold in stores across Canada. ...Imported products, including Irn Bru and Marmite, that meet Canadian requirements under Canada's Food and Drug Regulations are and will continue to be available for sale in Canada."

Middle East
Irn-Bru is available throughout the Middle East. It is found mostly in LuLu supermarkets.

Norway
Irn-Bru entered the Norwegian market in May 2008. They had to withdraw from the market again in 2009 as a result of problems with production agreements and lack of funding for marketing.

They were believed to be sponsoring the Norwegian First Division club Mjøndalen IF in 2009. This later turned out to be fraud carried out by a third-party company, and Mjøndalen IF never received any sponsorship from Irn-Bru, even though the team played the 2009 season with the Irn-Bru logo on their shirts.

Russia
Irn-Bru began being sold in Russia in 1997, and by 2002, it had become their third best selling soft drink. After its original bottler went out of business, a new deal was signed for the drink to be manufactured and distributed in larger quantities by the Pepsi Bottling Group of Russia in 2002. Its popularity has been attributed to the drink's apparent similarity to discontinued Soviet-era soft drinks. As of 2011, Irn-Bru sales in Russia were still growing.

On 4 March 2022, due to the ongoing 2022 Russian invasion of Ukraine, AG Barr cut ties with the Russian market.

Spain
Irn-Bru has been distributed in Spain since the early 1980s servicing primarily the large British communities residing in Spain. It can be found in key tourist areas such as the Balearic Islands, the Spanish coastal region and Canary Islands with both the regular and sugar-free variant available. Outside of the United Kingdom, Spain is among the top 10 Irn-Bru markets.

United States
Irn-Bru and Diet Irn-Bru have been formulated since 2002 by A.G. Barr to meet the regulations for food colouring of the Food & Drug Administration (FDA). Ponceau 4R, used in the UK formulation, is prohibited by the FDA. Barr uses alternative food and drink colourants manufactured by a US company approved by the FDA. The product labelling also meets US labelling standards on nutritional information and bar code. Compliant Irn-Bru is solely imported by Great Scot International in Charlotte, North Carolina, which supplies distributors and retailers throughout the USA.

Competitor and generic Iron Brews

 * Rivets was an iron brew drink launched in 1994 by Meri-Mate Ltd of Dundee as competition for A.G. Barr's popular Irn Bru soft drink.
 * Highland Brew was launched in 2000 by the Natural Fruit and Beverage Company
 * Several supermarkets including Aldi, Asda and Lidl sell own brand Iron Brews

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Irn-Bru


text:
Internet Standard

In computer network engineering, an Internet Standard is a normative specification of a technology or methodology applicable to the Internet. Internet Standards are created and published by the Internet Engineering Task Force (IETF). They allow interoperation of hardware and software from different sources which allows internets to function. As the Internet became global, Internet Standards became the lingua franca of worldwide communications.

Engineering contributions to the IETF start as an Internet Draft, may be promoted to a Request for Comments, and may eventually become an Internet Standard.

An Internet Standard is characterized by technical maturity and usefulness. The IETF also defines a Proposed Standard as a less mature but stable and well-reviewed specification. A Draft Standard was an intermediate level, discontinued in 2011. A Draft Standard was an intermediary step that occurred after a Proposed Standard but prior to an Internet Standard.

As put in RFC 2026: "In general, an Internet Standard is a specification that is stable and well-understood, is technically competent, has multiple, independent, and interoperable implementations with substantial operational experience, enjoys significant public support, and is recognizably useful in some or all parts of the Internet."

Overview
An Internet Standard is documented by a Request for Comments (RFC) or a set of RFCs. A specification that is to become a Standard or part of a Standard begins as an Internet Draft, and is later, usually after several revisions, accepted and published by the RFC Editor as an RFC and labeled a Proposed Standard. Later, an RFC is elevated as Internet Standard, with an additional sequence number, when maturity has reached an acceptable level. Collectively, these stages are known as the Standards Track, and are defined in RFC 2026 and RFC 6410. The label Historic is applied to deprecated Standards Track documents or obsolete RFCs that were published before the Standards Track was established.

Only the IETF, represented by the Internet Engineering Steering Group (IESG), can approve Standards Track RFCs. The definitive list of Internet Standards is maintained in the Official Internet Protocol Standards. Previously, STD 1 used to maintain a snapshot of the list.

History and the purpose of Internet Standards
Internet standard is a set of rules that the devices have to follow when they connect in a network. Since the technology has evolved, the rules of the engagement between computers had to evolve with it. These are the protocols that are in place used today. Most of these were developed long before the Internet Age, going as far back as the 1970s, not long after the creation of personal computers.

TCP/IP

The official date for when the first internet went live is January 1, 1983. The Transfer Control Protocol/Internet Protocol (TCP/IP) went into effect. ARPANET (Advanced Research Projects Agency Network) and the Defense Data Network were the networks to implement the Protocols. These protocols are considered to be the essential part of how the Internet works because they define the rules by which the connections between servers operate. They are still used today by implementing various ways data is sent via global networks.

IPsec

Internet Protocol Security is a collection of protocols that ensure the integrity of encryption in the connection between multiple devices. The purpose of this protocol is to protect public networks. According to IETF Datatracker the group dedicated to its creation was proposed into existence on 25 November 1992. Half a year later the group was created and not long after in the mid 1993 the first draft was published.

HTTP

HyperText Transfer Protocol is one of the most commonly used protocols today in the context of the World Wide Web. HTTP is a simple protocol to govern how documents, that are written in HyperText Mark Language(HTML), are exchanged via networks. This protocol is the backbone of the Web allowing for the whole hypertext system to exist practically. It was created by the team of developers spearheaded by Tim Berners-Lee. Berners-Lee is responsible for the proposal of its creation, which he did in 1989. August 6, 1991 is the date he published the first complete version of HTTP on a public forum. This date subsequently is considered by some to be the official birth of the World Wide Web. HTTP has been continually evolving since its creation, becoming more complicated with time and progression of networking technology. By default HTTP is not encrypted so in practice HTTPS is used, which stands for HTTP Secure.

TLS/SSL

TLS stands for Transport Layer Security which is a standard that enables two different endpoints to interconnect sturdy and privately. TLS came as a replacement for SSL. Secure Sockets Layers was first introduced before the creation of HTTPS and it was created by Netscape. As a matter of fact HTTPS was based on SSL when it first came out. It was apparent that one common way of encrypting data was needed so the IETF specified TLS 1.0 in RFC 2246 in January, 1999. It has been upgraded since. Last version of TLS is 1.3 from RFC 8446 in August 2018.

OSI Model

The Open Systems Interconnection model began its development in 1977. It was created by the International Organization for Standardization. It was officially published and adopted as a standard for use in 1979. It was then updated several times and the final version. It took a few years for the protocol to be presented in its final form. ISO 7498 was published in 1984. Lastly in 1995 the OSI model was revised again satisfy the urgent needs of uprising development in the field of computer networking.

UDP

The goal of User Datagram Protocol was to find a way to communicate between two computers as quickly and efficiently as possible. UDP was conceived and realized by David P. Reed in 1980. Essentially the way it works is using compression to send information. Data would be compressed into a datagram and sent point to point. This proved to be a secure way to transmit information and despite the drawback of losing quality of data UDP is still in use.

Standardization process
Becoming a standard is a two-step process within the Internet Standards Process: Proposed Standard and Internet Standard. These are called maturity levels and the process is called the Standards Track.

If an RFC is part of a proposal that is on the Standards Track, then at the first stage, the standard is proposed and subsequently organizations decide whether to implement this Proposed Standard. After the criteria in RFC 6410 is met (two separate implementations, widespread use, no errata etc.), the RFC can advance to Internet Standard.

The Internet Standards Process is defined in several "Best Current Practice" documents, notably BCP 9 ( RFC 2026 and RFC 6410). There were previously three standard maturity levels: Proposed Standard, Draft Standard and Internet Standard. RFC 6410 reduced this to two maturity levels.

Proposed Standard
RFC 2026 originally characterized Proposed Standards as immature specifications, but this stance was annulled by RFC 7127.

A Proposed Standard specification is stable, has resolved known design choices, has received significant community review, and appears to enjoy enough community interest to be considered valuable. Usually, neither implementation nor operational experience is required for the designation of a specification as a Proposed Standard.

Proposed Standards are of such quality that implementations can be deployed in the Internet. However, as with all technical specifications, Proposed Standards may be revised if problems are found or better solutions are identified, when experiences with deploying implementations of such technologies at scale is gathered.

Many Proposed Standards are actually deployed on the Internet and used extensively, as stable protocols. Actual practice has been that full progression through the sequence of standards levels is typically quite rare, and most popular IETF protocols remain at Proposed Standard.

Draft Standard
In October 2011, RFC 6410 merged the second and third maturity levels into one Draft Standard. Existing older Draft Standards retain that classification. The IESG can reclassify an old Draft Standard as Proposed Standard after two years (October 2013).

Internet Standard
An Internet Standard is characterized by a high degree of technical maturity and by a generally held belief that the specified protocol or service provides significant benefit to the Internet community. Generally Internet Standards cover interoperability of systems on the Internet through defining protocols, message formats, schemas, and languages. An Internet Standard ensures that hardware and software produced by different vendors can work together. Having a standard makes it much easier to develop software and hardware that link different networks because software and hardware can be developed one layer at a time. Normally, the standards used in data communication are called protocols.

All Internet Standards are given a number in the STD series. The series was summarized in its first document, STD 1 (RFC 5000), until 2013, but this practice was retired in RFC 7100. The definitive list of Internet Standards is now maintained by the RFC Editor.

Documents submitted to the IETF editor and accepted as an RFC are not revised; if the document has to be changed, it is submitted again and assigned a new RFC number. When an RFC becomes an Internet Standard (STD), it is assigned an STD number but retains its RFC number. When an Internet Standard is updated, its number is unchanged but refers to a different RFC or set of RFCs. For example, in 2007 RFC 3700 was an Internet Standard (STD 1) and in May 2008 it was replaced with RFC 5000. RFC 3700 received Historic status, and RFC 5000 became STD 1.

The list of Internet standards was originally published as STD 1 but this practice has been abandoned in favor of an online list maintained by the RFC Editor.

Organizations of Internet Standards
The standardization process is divided into three steps:

 * 1) Proposed standards are standards to be implemented and can be changed at any time
 * 2) The draft standard was carefully tested in preparation for riverside to form the future Internet standard
 * 3) Internet standards are mature standards.

There are five Internet standards organizations: the Internet Engineering Task Force (IETF), Internet Society (ISOC), Internet Architecture Board (IAB), Internet Research Task Force (IRTF), World Wide Web Consortium (W3C). All organizations are required to use and express the Internet language in order to remain competitive in the current Internet phase. Some basic aims of the Internet Standards Process are; ensure technical excellence; earlier implementation and testing; perfect, succinct as well as easily understood records.

Creating and improving the Internet Standards is an ongoing effort and Internet Engineering Task Force plays a significant role in this regard. These standards are shaped and available by the Internet Engineering Task Force (IETF). It is the leading Internet standards association that uses well-documented procedures for creating these standards. Once circulated, those standards are made easily accessible without any cost.

Till 1993, the United States federal government was supporting the IETF. Now, the Internet Society's Internet Architecture Board (IAB) supervises it. It is a bottom-up organization that has no formal necessities for affiliation and does not have an official membership procedure either. It watchfully works with the World Wide Web Consortium (W3C) and other standard development organizations. Moreover, it heavily relies on working groups that are constituted and proposed to an Area Director. IETF relies on its working groups for expansion of IETF conditions and strategies with a goal to make the Internet work superior. The working group then operates under the direction of the Area Director and progress an agreement. After the circulation of the proposed charter to the IESG and IAB mailing lists and its approval then it is further forwarded to the public IETF. It is not essential to have the complete agreement of all working groups and adopt the proposal. IETF working groups are only required to recourse to check if the accord is strong.

Likewise, the Working Group produce documents in the arrangement of RFCs which are memorandum containing approaches, deeds, examination as well as innovations suitable to the functioning of the Internet and Internet-linked arrangements. In other words, Requests for Comments (RFCs) are primarily used to mature a standard network protocol that is correlated with network statements. Some RFCs are aimed to produce information while others are required to publish Internet standards. The ultimate form of the RFC converts to the standard and is issued with a numeral. After that, no more comments or variations are acceptable for the concluding form. This process is followed in every area to generate unanimous views about a problem related to the internet and develop internet standards as a solution to different glitches. There are eight common areas on which IETF focus and uses various working groups along with an area director. In the "general" area it works and develops the Internet standards. In "Application" area it concentrates on internet applications such as Web-related protocols. Furthermore, it also works on the development of internet infrastructure in the form of PPP extensions. IETF also establish principles and description standards that encompass the Internet protocol suite (TCP/IP). The Internet Architecture Board (IAB) along with the Internet Research Task Force (IRTF) counterpart the exertion of the IETF using innovative technologies.

The IETF is the standards making organization concentrate on the generation of "standard" stipulations of expertise and their envisioned usage. The IETF concentrates on matters associated with the progress of current Internet and TCP/IP know-how. It is alienated into numerous working groups (WGs), every one of which is accountable for evolving standards and skills in a specific zone, for example routing or security. People in working groups are volunteers and work in fields such as equipment vendors, network operators and different research institutions. Firstly, it works on getting the common consideration of the necessities that the effort should discourse. Then an IETF Working Group is formed and necessities are ventilated in the influential Birds of a Feather (BoF) assemblies at IETF conferences.

Internet Engineering Task Force
The Internet Engineering Task Force (IETF) is the premier internet standards organization. It follows an open and well-documented processes for setting internet standards. The resources that the IETF offers include RFCs, internet-drafts, IANA functions, intellectual property rights, standards process, and publishing and accessing RFCs.

RFCs

 * Documents that contain technical specifications and notes for the Internet.
 * The acronym RFC came from the phrase "Request For Comments" - this is not used anymore today and is now simply referred to as RFCs.
 * The website RFC Editor is an official archive of internet standards, draft standards, and proposed standards.

Internet Drafts

 * Working documents of the IETF and its working groups.
 * Other groups may distribute working documents as Internet-Drafts

Intellectual property rights

 * All IETF standards are freely available to view and read, and generally free to implement by anyone without permission or payment.

Standards Process

 * The process of creating a standard is straightforward - a specification goes through an extensive review process by the Internet community and revised through experience.

Publishing and accessing RFCs

 * Internet-Drafts that successfully completed the review process.
 * Submitted to RFC editor for publication.

Types of Internet Standards
There are two ways in which an Internet Standard is formed and can be categorized as one of the following: "de jure" standards and "de facto" standards. A de facto standard becomes a standard through widespread use within the tech community. A de jure standard is formally created by official standard-developing organizations. These standards undergo the Internet Standards Process. Common de jure standards include ASCII, SCSI, and Internet protocol suite.

Internet Standard Specifications
Specifications subject to the Internet Standards Process can be categorized into one of the following: Technical Specification (TS) and Applicability Statement (AS). A Technical Specification is a statement describing all relevant aspects of a protocol, service, procedure, convention, or format. This includes its scope and its intent for use, or "domain of applicability". However, a TSs use within the Internet is defined by an Applicability Statement. An AS specifies how, and under what circumstances, TSs may be applied to support a particular Internet capability. An AS identifies the ways in which relevant TSs are combined and specifies the parameters or sub-functions of TS protocols. An AS also describes the domains of applicability of TSs, such as Internet routers, terminal server, or datagram-based database servers. An AS also applies one of the following "requirement levels" to each of the TSs to which it refers:

 * Required: Implementation of the referenced TS is required to achieve interoperability. For example, Internet systems using the Internet Protocol Suite are required to implement IP and ICMP.
 * Recommended:  Implementation of the referenced TS is not required, but is desirable in the domain of applicability of the AS. Inclusion of the functions, features, and protocols of Recommended TSs in the developments of systems is encouraged. For example, the TELNET protocol should be implemented by all systems that intend to use remote access.
 * Elective: Implementation of the referenced TS is optional. The TS is only necessary in a specific environment. For example, the DECNET MIB could be seen as valuable in an environment where the DECNET protocol is used.

Web Standards
TCP/ IP Model & associated Internet Standards Web standards are a type of internet standard which define aspects of the World Wide Web. They allow for the building and rendering of websites. The three key standards used by the World Wide Web are Hypertext Transfer Protocol, HTML, and URL. Respectively, they specify the transfer of data between a browser and a web server, the content and layout of a web page, and what web page identifiers mean.

Network Standards
Network standards are a type of internet standard which defines rules for data communication in networking technologies and processes. Internet standards allow for the communication procedure of a device to or from other devices.

In reference to the TCP/IP Model, common standards and protocols in each layer are as follows:

 * The Transport layer: TCP and SPX
 * Network layer: IP and IPX
 * Data Link layer: IEEE 802.3 for LAN and Frame Relay for WAN
 * Physical layer: 8P8C and V.92

The future of Internet Standards
The Internet has been viewed as an open playground, free for people to use and communities to monitor. However, large companies have shaped and molded it to best fit their needs. The future of internet standards will be no different. Currently, there are widely used but insecure protocols such as the Border Gateway Protocol (BGP) and Domain Name System (DNS). This reflects common practices that focus more on innovation than security. Companies have the power to improve these issues. With the Internet in the hands of the industry, users must depend on businesses to protect vulnerabilities present in these standards.

Ways to make BGP and DNS safer already exist but they are not widespread. For example, there is the existing BGP safeguard called Routing Public Key Infrastructure (RPKI). It is a database of routes that are known to be safe and have been cryptographically signed. Users and companies submit routes and check other users' routes for safety. If it were more widely adopted, more routes could be added and confirmed. However, RPKI is picking up momentum. As of December 2020, tech giant Google registered 99% of its routes with RPKI. They are making it easier for businesses to adopt BGP safeguards. DNS also has a security protocol with a low adoption rate: DNS Security Extensions (DNSSEC). Essentially, at every stage of the DNS lookup process, DNSSEC adds a signature to data to show it has not been tampered with.

Some companies have taken the initiative to secure internet protocols. It is up to the rest to make it more widespread.

title: Internet Standard


text:
ISOC

ISOC is an abbreviation which may refer to:

 * Information Security Operations Center, is a location where enterprise information systems are monitored, assessed, and defended.
 * Internet Society, ISOC, an international organization that promotes Internet use and access
 * Internal Security Operations Command, a unit of the Thai military devoted to national security issues
 * Islamic Society, various Islamic-based groups
 * Independent State of Croatia, a country that existed during WWII

title: ISOC