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Editors Note: This section is proposed for deletion because this is tied a specific network architecture.
[802.1Q tagging must be supported by the system (such that network egress traffic can be switched by a L2 device to the appropriate L2 termination device for managing backbone traffic or distinguishing traffic for wholesale partners in a wholesale environment).]
802.1q tagging should be supported by the 802.20 system or some other mechanism (i.e. policy routing). Tagging will support the L2 switching such that network egress traffic can be switched by a L2 device to the appropriate L2 termination device for managing backbone traffic or distinguishing traffic for wholesale partners in a wholesale environment. Tagging can also be used to facilitate a retail captive portal service model. By tagging traffic from a mobile terminal that is unknown (i.e. mobile terminal is un-provisioned) it can be switched at L2 to a system enabling a self provisioning system model. By tagging control and management traffic it to can be switched and separated as close to the base station as possible. All of these can be accomplished at a higher layer but are simpler to implement if 802.1Q tagging is supported.
The 802.1Q standard specifies that tags be appended to a MAC frame. The VLAN tag carries VLAN information. The VLAN tag has two parts: The VLAN ID (12-bit) and Prioritization (3-bit). The 802.1P implementation defines the prioritization field. 802.1p defines a 32-bit tag header that is inserted after a frame's normal destination and source address header info. Switches, routers, servers, desktop systems, mobile terminals, or base stations can set these priority bits. Switches and routers can prioritize traffic based on these tags.
By driving these functions to layer 2 a provider can build a flatter network supporting simple IP handoff over a larger 802.20 coverage area. These functions can be supported in other ways at a higher layer but are most efficiently handled at layer 2. The evaluation criteria group should report support for tagging so that the 802.20 group can factor support in the selection process.
David S. McGinniss
Sprint Broadband Wireless Group
Principal Engineer II