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62-474: An organizationally unique identifier ( OUI ) is a 24-bit number that uniquely identifies a vendor , manufacturer , or other organization. OUIs are purchased from the Institute of Electrical and Electronics (IEEE) Registration Authority by the assignee (IEEE term for the vendor, manufacturer, or other organization). Only assignment from MA-L registry assigns new OUI. They are used to uniquely identify

124-606: A 16 Mbit/s version that ran on unshielded twisted pair cable. IBM launched their own proprietary Token Ring product on October 15, 1985. It ran at 4 Mbit/s , and attachment was possible from IBM PCs, midrange computers and mainframes. It used a convenient star-wired physical topology and ran over shielded twisted-pair cabling. Shortly thereafter it became the basis for the IEEE 802.5 standard. During this time, IBM argued that Token Ring LANs were superior to Ethernet , especially under load, but these claims were debated. In 1988,

186-726: A token passing ring topology , and many teams worldwide began working on their own implementations. At the IBM Zurich Research Laboratory Werner Bux and Hans Müller, in particular, worked on the design and development of IBM's Token Ring technology, while early work at MIT led to the Proteon 10 Mbit/s ProNet-10 Token Ring network in 1981  – the same year that workstation vendor Apollo Computer introduced their proprietary 12 Mbit/s Apollo Token Ring (ATR) network running over 75-ohm RG-6U coaxial cabling . Proteon later evolved

248-541: A 'concentration' configuration by default, but later MAUs also supporting a feature to act as splitters and not concentrators exclusively such as on the IBM 8226. Later IBM would release Controlled Access Units that could support multiple MAU modules known as a Lobe Attachment Module . The CAUs supported features such as Dual-Ring Redundancy for alternate routing in the event of a dead port, modular concentration with LAMs, and multiple interfaces like most later MAUs. This offered

310-598: A Modified EUI-64 has the following format in significance order: Network Address Authority (NAA) Name_Identifier formats define the first nibble (4 bits) to define the format of the identifier: This encapsulation is used in Fibre Channel and SAS, and is also supported in iSCSI in RFC 3980. This addition requires either a shortened vendor-specific identifier field, or some OUI bits are assumed to be 0, such as when using EUI-64 Mapped format. An Individual Address Block (IAB)

372-418: A Token Ring network is wired as a star , with 'MAUs' in the center, 'arms' out to each station, and the loop going out-and-back through each. A MAU could present in the form of a hub or a switch; since Token Ring had no collisions many MAUs were manufactured as hubs. Although Token Ring runs on LLC , it includes source routing to forward packets beyond the local network. The majority of MAUs are configured in

434-690: A base 16 number as in FFFFFFFF 16 . The CDI-40 was historically recommended as context dependent identifier that was formed by concatenating the 24-bit OUI with a 16-bit extension or by concatenating a 36-bit OUI-36 with a 4-bit extension. In either case, the extension was assigned by the organization that purchased the OUI. The resulting identifier was generally represented as a set of octets separated by dashes (hexadecimal notation) or colons (bit-reversed notation) as in FF-FF-FF-FF-FF or FF:FF:FF:FF:FF, as

496-494: A block of EUI-48 and EUI-64 identifiers (while owner of IAB cannot assign EUI-64) by the IEEE Registration Authority. The owner of an already assigned OUI-36 registry product may continue to use the assignment. Example of EUI-48 created within an IAB: An EUI-48 identifier is formed by combining the 36-bit IEEE assigned IAB base value with a 12-bit extension identifier assigned by the organization – e.g., if

558-463: A more reliable setup and remote management than with an unmanaged MAU hub. Cabling is generally IBM "Type-1", a heavy two-pair 150 ohm shielded twisted pair cable. This was the basic cable for the "IBM Cabling System", a structured cabling system that IBM hoped would be widely adopted. Unique hermaphroditic connectors , referred to as IBM Data Connectors in formal writing or colloquially as Boy George connectors, were used. The connectors have

620-561: A number of information sources typically used by buyers to help them select suppliers, including suppliers' reputation, their own supplier evaluation processes, records of suppliers used previously, and approved lists of suppliers. De-listing refers to withdrawal of a supplier or their products from a company's supply chain. The UK's Groceries Supply Code of Practice also includes "significant" reductions in volumes purchased and supplied within its definition of "de-listing", and sets out good practice to be followed when de-listing occurs. At

682-666: A particular piece of equipments through derived identifiers such as MAC addresses , Subnetwork Access Protocol protocol identifiers, World Wide Names for Fibre Channel devices or vendor blocks in EDID . In MAC addresses, the OUI is combined with a 24-bit number (assigned by the assignee of the OUI) to form the address. The first three octets of the address are the OUI. The following terms are defined (either implicitly or explicitly) in IEEE Standard 802-2001 for use in referring to

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744-436: A shared transmission medium. They differed in their channel access methods . These differences have become immaterial, as modern Ethernet networks consist of switches and point-to-point links operating in full-duplex mode. Token Ring and legacy Ethernet have some notable differences: Stations on a Token Ring LAN are logically organized in a ring topology with data being transmitted sequentially from one ring station to

806-453: A standby monitor. All stations must be capable of becoming an active monitor station if necessary. The active monitor performs a number of ring administration functions. The first function is to operate as the master clock for the ring in order to provide synchronization of the signal for stations on the wire. Another function of the AM is to insert a 24-bit delay into the ring, to ensure that there

868-551: A start delimiter, an access control octet, and an end delimiter. Used by the sending station to abort transmission. Data frames carry information for upper-layer protocols, while command frames contain control information and have no data for upper-layer protocols. Data and command frames vary in size, depending on the size of the Information field. Frame type – 01 indicates LLC frame IEEE 802.2 (data) and ignore control bits; 00 indicates MAC frame and control bits indicate

930-627: A string of 5 bytes as in {FF,FF,FF,FF,FF}, or as a base 16 number as in FFFFFFFFFF 16 . Note: There were also IAB based CDI-40 sequences that were formed by combining the 36-bit IEEE assigned IAB base value with the 4-bit extension identifier assigned by the organization – e.g., if the IEEE assigned IAB base value is 0x0050C257A and the 4-bit extension identifier is 0xF, then the CDI-40 values generated by combining these two numbers are from 0x0050C257AF00 to 0x0050C257AFFF The IEEE now considers

992-409: A vendor compliance checklist or vendor quality audits , and these activities can be effectively managed by software tools. Purchase orders are usually used as a contractual agreement with vendors to buy goods or services. Vendors may or may not function as distributors or manufacturers of goods. If vendors are also manufacturers, they may either build to stock or build to order . "Vendor"

1054-443: A vendor relationship with a supplier if a small firm or a major organization wants to resell a product. Vendor registration entails several steps in the process, including completing a credit application, placing a company credit card on file for payments, giving them your company phone number, and establishing payment terms. Selection of vendors or suppliers is a key function within a procurement organization. Baily et al. refer to

1116-416: Is a physical and data link layer computer networking technology used to build local area networks . It was introduced by IBM in 1984, and standardized in 1989 as IEEE 802.5 . It uses a special three-byte frame called a token that is passed around a logical ring of workstations or servers . This token passing is a channel access method providing fair access for all stations, and eliminating

1178-407: Is always sufficient buffering in the ring for the token to circulate. A third function for the AM is to ensure that exactly one token circulates whenever there is no frame being transmitted, and to detect a broken ring. Lastly, the AM is responsible for removing circulating frames from the ring. Token Ring stations must go through a 5-phase ring insertion process before being allowed to participate in

1240-574: Is an inactive registry activity which has been replaced by the MA-S registry product as of 1 January 2014. The IAB uses a MA-L (and OUI) belonging to the IEEE Registration Authority, concatenated with 12 additional IEEE-provided bits (for a total of 36 bits), leaving only 12 bits for the IAB owner to assign to their (up to 4096) individual devices. An IAB is ideal for organizations requiring not more than 4096 unique 48-bit numbers (EUI-48). Unlike an OUI, which allows

1302-467: Is assigned by the organization that purchased the OUI – the resulting identifier is generally represented by a string of 15 nibbles, as a base 16 number as in FFFFFFFFFFFFFFF 16 , or as FF-FF-FF:F.F.F.F.F.F.F.F.F as an EUI-64 value. Note: This identifier was previously used as the worldwide name (WWN) identifier within some storage systems. Its use is now considered deprecated by the IEEE and

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1364-514: Is identical to the EUI-48 identifier and is an obsolete label for it, although some distinction is still made when encapsulating MAC-48 and EUI-48 identifiers within EUI-64 identifiers (but now, the encapsulating mechanism is also deprecated). The EUI-48 is an identifier that is formed by concatenating the 24-bit OUI with a 24-bit extension identifier that is assigned by the organization that purchased

1426-420: Is often a generic term, used for suppliers of industries from retail sales to manufacturers to city organizations. The term generally applies only to the immediate seller, or the organization that is paid for the goods, rather than to the original manufacturer or the organization performing the service if it is different from the immediate supplier. There are four basic sorts of vendors in the supply chain, and

1488-481: The Groceries Code Adjudicator 's annual conference with suppliers and retailers in 2024 detailed discussions took place about best practice and "fair and reasonable timeframe[s]" for issuing and implementing de-listing notifications. In property sales, the vendor is the name given to the seller of a property, while the buyer is referred to as the "purchaser". IEEE 802.5 Token Ring

1550-476: The collisions of contention -based access methods. Token Ring was a successful technology, particularly in corporate environments, but was gradually eclipsed by the later versions of Ethernet . Gigabit Token Ring was standardized in 2001. A wide range of different local area network technologies were developed in the early 1970s, of which one, the Cambridge Ring , had demonstrated the potential of

1612-463: The EUI-64 identifier should be used in the future for this and all other purposes for which the EUI-60 was previously used. Some of the storage systems in which an OUI based variant was used are Fibre Channel , and Serial Attached SCSI (SAS). The EUI-64 is an identifier that is formed by concatenating the 24-bit OUI with a 40-bit extension identifier that is assigned by the organization that purchased

1674-643: The IEEE assigned IAB base-16 value is 0x0050C257A and the 12-bit extension identifier is 0xFFF, then the EUI-48 value generated by combining these two numbers is 0x0050C257AFFF. Vendor A vendor is a supply chain management term that means anyone who provides goods or services of experience to another entity. Vendors may sell B2B ( business-to-business ; i.e., to other companies), B2C (business to consumers or direct-to-consumer ), or B2G (business to government). Some vendors manufacture inventoriable items and then sell those items to customers , while other vendors offer services or experiences. The term vendor and

1736-474: The OUI are reserved as flag bits for some protocols (e.g., 'M' bit and 'X' bit), flags to indicate whether the address is part of an individual (unicast) or group (multicast) address block (e.g., Individual/Group [I/G] bit or Unicast/Multicast [U/M] bit), flags to indicate whether an address is universally or locally administered (e.g., Universal/Local [U/L] bit), etc., and should not contain the values 1, 2, 3, 5, 6, 7, 9, a, b, d, e, or f, unless these values reflect

1798-407: The OUI of AC-DE-48 and that the organization has created the EUI-48 value of AC-DE-48-23-45-67 by concatenating the extension identifier 23-45-67, this EUI-48 identifier has the following format in significance order: The same EUI-48 identifier after encapsulation within an EUI-64 has the following format in significance order: Encapsulation of MAC-48 or EUI-48 within modified EUI-64 example: In

1860-574: The OUI of AC-DE-48 and that the organization has created the MAC-48 value of AC-DE-48-23-45-67 by concatenating the extension identifier 23-45-67, this MAC-48 identifier has the following binary transmission order: The same MAC-48 identifier after encapsulation within an EUI-64 has the following transmission order: The same MAC-48 identifier after encapsulation within an EUI-64 has the following significance order: Encapsulation of EUI-48 within EUI-64 example: Assuming that an organization has registered

1922-415: The OUI value 00:50:C2 was used for IAB assignments. After September 2012, the value 40:D8:55 was used. The owners of an already assigned IAB may continue to use the assignment. The OUI-36 is a deprecated registry activity name, which has been replaced by the MA-S registry product name as of 1 January 2014. This registry activity includes both a 36-bit unique number used in some standards and the assignment of

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1984-546: The OUI – the resulting identifier is generally represented as a set of octets separated by dashes (hexadecimal notation) or colons (bit-reversed notation) as in FF-FF-FF-FF-FF-FF or FF:FF:FF:FF:FF:FF, as a string of 6 bytes as in {FF,FF,FF,FF,FF,FF}, or as a base 16 number as in FFFFFFFFFFFF 16 . The EUI-60 is an identifier that is formed by concatenating the 24-bit OUI with a 36-bit extension identifier that

2046-582: The OUI – the resulting identifier is generally represented as a set of octets separated by dashes (hexadecimal notation) or colons (bit-reversed notation) as in FF-FF-FF-FF-FF-FF-FF-FF or FF:FF:FF:FF:FF:FF:FF:FF, as a string of 8 bytes as in {FF,FF,FF,FF,FF,FF,FF,FF}, or as a base 16 number as in FFFFFFFFFFFFFFFF 16 . Note: According to the IEEE guidelines, the first four digits of the organizationally assigned identifier (i.e.,

2108-478: The Token Ring priority MAC, eight priority levels, 0–7, are used. When the station wishing to transmit receives a token or data frame with a priority less than or equal to the station's requested priority, it sets the priority bits to its desired priority. The station does not immediately transmit; the token circulates around the medium until it returns to the station. Upon sending and receiving its own data frame,

2170-425: The above conditions take place and a station decides that a new monitor is needed, it will transmit a claim token frame, announcing that it wants to become the new monitor. If that token returns to the sender, it is OK for it to become the monitor. If some other station tries to become the monitor at the same time then the station with the highest MAC address will win the election process. Every other station becomes

2232-574: The assignee to assign values in various different number spaces (for example, EUI-48, EUI-64, and the various context-dependent identifier number spaces), the Individual Address Block could only be used to assign EUI-48 identifiers. All other potential uses based on the OUI from which the IABs are allocated are reserved, and remain the property of the IEEE Registration Authority. It should also be noted that, between 2007 and September 2012,

2294-418: The companies and business owners play diverse responsibilities. Manufacturers : A raw material, when transformed into finished goods, is with the help of the manufacturers. Retailer : A retailer is a reseller who sells things in a store or online, such as apparel or office supplies. The term may include street vendors selling hot dogs, and so on. In a retail context, those companies who provide goods for

2356-468: The disadvantage of being quite bulky, requiring at least 3 cm × 3 cm (1.2 in × 1.2 in) panel space, and being relatively fragile. The advantages of the connectors being that they are genderless and have superior shielding over standard unshielded 8P8C. Connectors at the computer were usually DE-9 female. Several other types of cable existed such as type 2, and type 3 cable. In later implementations of Token Ring, Cat 4 cabling

2418-503: The encapsulation within a Modified EUI-64 a MAC-48 is treated as an EUI-48 and the U/L bit is inverted. Assuming that an organization has registered the OUI of AC-DE-48 and that the organization has created the MAC-48 or EUI-48 value of AC-DE-48-23-45-67 by concatenating the extension identifier 23-45-67, this MAC-48 or EUI-48 identifier has the following format in significance order: The same MAC-48 or EUI-48 identifier after encapsulation within

2480-473: The faster 16 Mbit/s Token Ring was standardized by the 802.5 working group. An increase to 100 Mbit/s was standardized and marketed during the wane of Token Ring's existence and was never widely used. While a 1000 Mbit/s standard was approved in 2001, no products were ever brought to market and standards activity came to a standstill as Fast Ethernet and Gigabit Ethernet dominated the local area networking market. Early Ethernet and Token Ring both used

2542-444: The first four digits of the extension identifier) portion of an EUI-64 “shall not be FFFE 16 or FFFF 16 ” (i.e., EUI-64 identifiers of the form ccccccFFFEeeeeee and ccccccFFFFeeeeee are not allowed) – this is to support the encapsulation of EUI-48 (FFFE 16 ) and MAC-48 (FFFF 16 ) values into EUI-64 values (though now the encapsulation is deprecated). IPv6 uses a 64-bit Modified Extended Unique Identifier ( Modified EUI-64 ) in

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2604-449: The hexadecimal digits in each pair, and the mapping between the hexadecimal digits and the bits of the octet value, are derived by interpreting the bits of the octet value as a binary numeral using the normal mathematical rules for digit significance .” (See hexadecimal ). “The format of a MAC data frame in which the octets of any MAC addresses conveyed in the MAC user data field have

2666-434: The label MAC-48 to be an obsolete term which was previously used to refer to a specific type of EUI-48 identifier used to address hardware interfaces (e.g., Network Interface Controllers and other network hardware) within existing IEEE 802 based networking applications and should not be used in the future. Instead, the term EUI-48 should be used by manufacturers and others in the field for this purpose – i.e., MAC-48 identifier

2728-621: The larger identifier through a process of combining the smaller identifier with specified values placed in specified bit-positions within the larger identifier – this process is known as 'encapsulation' and is provided for the purpose of easing the transition from MAC-48 and EUI-48 to EUI-64 and to provide a mechanism for the conversion of MAC-48 and EUI-48 identifiers to EUI-64 in such a way that duplicate or conflicting values are avoided. Encapsulation of MAC-48 within EUI-64 Example: Assuming that an organization has registered

2790-435: The latter scenario is represented with bits reversed from the canonical representation. So for instance, an OUI whose canonical form is ACDE48 could be seen written as 357B12 if translation is done improperly or inconsistently. The latter form ( bit-reversed or noncanonical representation), may also be referred to in the literature as "MSB format", "IBM format", or "Token Ring format" for this reason. RFC2469 explains

2852-455: The lower half of some IPv6 addresses. A Modified EUI-64 is an EUI-64 with the U/L bit inverted. There are other identifiers that may be formed using the OUI but those listed above are the most commonly used. Mapping an EUI-48 to an EUI-64 is deprecated. The mapping is described here for historical reasons. Other identifiers, such as MAC-48 and EUI-48 values, can be contained within a larger identifier or 'container', such as EUI-64, by creating

2914-505: The next with a control token circulating around the ring controlling access. Similar token passing mechanisms are used by ARCNET , token bus , 100VG-AnyLAN (802.12) and FDDI , and they have theoretical advantages over the CSMA/CD of early Ethernet. A Token Ring network can be modeled as a polling system where a single server provides service to queues in a cyclic order. The data transmission process goes as follows: Physically,

2976-414: The octet value and interpreting the resulting bit sequence as a binary numeral using the normal mathematical rules for digit significance.” The bit-reversed representation corresponds to the convention of transmitting the least-significant-bit of each byte first in serial data communications . “The format of a MAC data frame in which the octets of MAC addresses conveyed in the MAC user data field have

3038-412: The output of the ifconfig command. Canonical form is the intended standard. However, since IEEE 802.3 (Ethernet) and IEEE 802.4 ( Token Bus ) send the bytes (octets) over the wire, left-to-right, with least significant bit in each byte first, while IEEE 802.5 ( Token Ring ) and IEEE 802.6 ( FDDI ) send the bytes over the wire with the most significant bit first, confusion may arise when an OUI in

3100-410: The problem in more detail. The OUI is normally discussed and represented as a set of octets in hexadecimal notation separated by dashes (i.e., FF-FF-FF) or as a set of octets separated by colons in bit-reversed notation (i.e., FF:FF:FF). The two least-significant-bits of the second nibble of the first octet of the hexadecimal representation (i.e., the two least significant bits of the first octet) of

3162-467: The retailer to sell may be referred to as their suppliers. A Service Provider provides a service, such as maintenance or labour, to customers. Examples include consulting and janitorial services. A Wholesaler sources products from manufacturers and resells them to retail establishments, distributors, and other buyers. They serve as a crucial intermediary in the supply chain, offering competitive pricing and convenient purchasing options. There must be

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3224-460: The ring network. If any of these phases fail, the Token Ring station will not insert into the ring and the Token Ring driver may report an error. In some applications there is an advantage to being able to designate one station having a higher priority. Token Ring specifies an optional scheme of this sort, as does the CAN Bus , (widely used in automotive applications) – but Ethernet does not. In

3286-550: The same bit ordering as in the Bit-reversed representation.” The order in which an octet or a sequence of octets is transmitted over the transmission medium – this order normally corresponds to the bit-reversed representation. Example: An OUI consisting of the hexadecimal digits ACDE48 16 would be represented as follows: The following figure shows the position of these bits in significance order: Notes: Ethernet users are used to seeing canonical form , such as in

3348-493: The same bit ordering as in the Hexadecimal Representation.” (See MAC data frame , MAC addresses ) This appears from the context of the IEEE Standard 802-2001 to be another term for the 'Hexadecimal Representation' – i.e., “by interpreting the bits of the octet value as a binary numeral using the normal mathematical rules for digit significance.” “The representation of a sequence of octet values in which

3410-610: The station downgrades the token priority back to the original priority. Here are the following eight access priority and traffic types for devices that support 802.1Q and 802.1p : Bridging solutions for Token Ring and Ethernet networks included the AT&;T StarWAN 10:4 Bridge, the IBM 8209 LAN Bridge and the Microcom LAN Bridge. Alternative connection solutions incorporated a router that could be configured to dynamically filter traffic, protocols and interfaces, such as

3472-400: The term supplier are often used indifferently. The difference is that the vendors sells the goods or services while the supplier provides the goods or services. In most business contexts, except retail, this difference has no impact and words are interchangeable. Typically vendors are tracked in either a finance system or a warehouse management system . Vendors are often managed with

3534-404: The true meaning of these flag bits – if the organization that owns the OUI does set one of these bits when creating an identifier, then the value of the second nibble of the first octet changes accordingly in representations of the OUI (e.g., if the hexadecimal value of the second nibble of the first octet is 'C' and the least-significant-bit is set, then the value becomes 'D'). Notes: The CDI-32

3596-417: The type of MAC control frame A = 1, Address recognized C = 1, Frame copied Every station in a Token Ring network is either an active monitor (AM) or standby monitor (SM) station. There can be only one active monitor on a ring at a time. The active monitor is chosen through an election or monitor contention process. The monitor contention process is initiated when the following happens: When any of

3658-404: The values of the individual octets are displayed in order from left to right, with each octet value represented as a two-digit hexadecimal numeral, and with the resulting pairs of hexadecimal digits separated by colons . The order of the hexadecimal digits in each pair, and the mapping between the hexadecimal digits and the bits of the octet value, are derived by reversing the order of the bits in

3720-401: The various representations and formats of OUIs and the identifiers that may be created using them. “The representation of a sequence of octet values in which the values of the individual octets are displayed in order from left to right, with each octet value represented as a two-digit hexadecimal numeral, and with the resulting pairs of hexadecimal digits separated by hyphens . The order of

3782-478: Was also supported, so 8P8C (RJ45) connectors were used on both of the MAUs, CAUs and NICs; with many of the network cards supporting both 8P8C and DE-9 for backwards compatibility. When no station is sending a frame, a special token frame circles the loop. This special token frame is repeated from station to station until arriving at a station that needs to send data. Tokens are three octets in length and consist of

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3844-498: Was historically recommended as context dependent identifier that was formed by concatenating the 24-bit OUI with an 8-bit extension identifier that is assigned by the organization that purchased the OUI – the resulting identifier was generally represented as a set of octets separated by dashes (hexadecimal notation) or colons (bit-reversed notation) as in FF-FF-FF-FF or FF:FF:FF:FF, as a string of 4 bytes as in {FF,FF,FF,FF}, or as

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