Just as the OUI is extended to create EUI-48 and EUI-64 identifiers, or a CID can be extended to create a locally administered MAC address, other extended identifiers can be created from an OUI or CID assignment. Such extended identifiers, referred to as context dependent identifiers, are not necessarily globally unique but are intended to only be unique within a well specified context.A Context Dependent Identifier (CDI) is an extended identifier based on either an OUI, CID, or OUI-36 and typically specified within a standard with additional specification to allow unambiguous interpretation of the identifier and parsing of other data. Some examples include (but are not limited to): Defining all fields of the context dependent identifier within a standard. For example, using an OUI or CID to identify a manufacturer of hardware with additional fields identifying the model and revision of the hardware. (The OUI or CID owner typically assigns the values for the additional fields within bounds specified by the standard.) Such an identifier, if properly defined, is unique within the context of the standard. Defining vendor-specific extensions to management information within a standard but allowing the assignee of the unique identifier to specify the additional fields. This extended identifier would be unique within the context of the defined management information base. A vendor-specific protocol could be identified with an OUI/CID, and a standard defined fixed field to allow identification of multiple protocols from the same vendor; or with the OUI/CID indicating which set of rules to parse the data following the OUI/CID. The legacy definition of CDI-32 and CDI-40 (see “Deprecated and Obsolete Identifiers”).
Just as the OUI is extended to create EUI-48 and EUI-64 identifiers, or a CID can be extended to create a locally administered MAC address, other extended identifiers can be created from an OUI or CID assignment. Such extended identifiers, referred to as context dependent identifiers, are not necessarily globally unique but are intended to only be unique within a well specified context.<br>A Context Dependent Identifier (CDI) is an extended identifier based on either an OUI, CID, or OUI-36 and typically specified within a standard with additional specification to allow unambiguous interpretation of the identifier and parsing of other data. Some examples include (but are not limited to): <br> Defining all fields of the context dependent identifier within a standard. <br>For example, using an OUI or CID to identify a manufacturer of hardware with additional fields identifying the model and revision of the hardware. (The OUI or CID owner typically assigns the values for the additional fields within bounds specified by the standard.) Such an identifier, if properly defined, is unique within the context of the standard. <br> Defining vendor-specific extensions to management information within a standard but allowing the assignee of the unique identifier to specify the additional fields. This extended identifier would be unique within the context of the defined management information base. <br> A vendor-specific protocol could be identified with an OUI/CID, and a standard defined fixed field to allow identification of multiple protocols from the same vendor; or with the OUI/CID indicating which set of rules to parse the data following the OUI/CID. <br> The legacy definition of CDI-32 and CDI-40 (see “Deprecated and Obsolete Identifiers”).
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