IEEE 802.1Q-2005

For the purpose of compatible interconnection of information technology equipment using the IEEE 802 MAC Service supported by interconnected IEEE 802 standard LANs using different or identical media access control methods, this standard specifies the operation of MAC Bridges that support Virtual LANs (VLANs). To this end it a) Positions the support of VLANs within an architectural description of the MAC Sublayer; b) Defines the principles of operation of the VLAN-aware Bridge in terms of the support and preservation of the MAC Service, and the maintenance of Quality of Service; c) Specifies an Enhanced Internal Sublayer Service provided to the Media Access Independent functions that provide frame relay in a VLAN-aware Bridge; d) Establishes the principles and a model of Virtual Bridged Local Area Network operation; e) Identifies the functions to be performed by VLAN-aware Bridges, and provides an architectural model of the operation of a Bridge in terms of Processes and Entities that provide those functions; f) Specifies a frame format that allows a VLAN Identifier (VID) and priority information to be carried by VLAN tagged user data frames; g) Specifies the rules that govern the addition or removal of VLAN tags to and from user data frames; h) Specifies the rules that govern the ability to carry user data in either Canonical format or Noncanonical format in VLAN-tagged frames; i) Establishes the requirements for automatic configuration of VLAN topology; j) Establishes the requirements for VLAN-aware Bridge Management in a Virtual Bridged Local Area Network, identifying managed objects and defining management operations; k) Defines the operation of the Multiple Spanning Tree algorithm and protocol (MSTP); l) Describes the protocols and procedures necessary to support interoperation between MST and SST Bridges in the same Virtual Bridged Local Area Networks; m) Specifies the requirements to be satisfied by equipment claiming conformance to this standard.