Source Route Bridging Enhancements on Cisco 7200 Series Routers

Description

The following enhancements have been added to the Cisco 7200 series routers:

• Source route bridging (SRB) is now supported over Fiber Distributed Data Interface (FDDI).

• Particle-based switching is now supported for SRB packets (over FDDI and Token Ring) by default.

Particle-based switching adds scatter-gather capability to SRB to improve performance. Particles represent a communications data packet as a collection of noncontiguous buffers. The traditional Cisco IOS packet has a packet type control structure and a single contiguous data buffer. A particle packet has the same packet type control structure, but also maintains a queue of particle type structures, each of which manages its own block.

The scatter-gather architecture used by particle-based switching provides the following advantages:

• Allows drivers to use memory more efficiently (especially when using media that has a large maximum transmission unit [MTU]). For example, Token Ring buffers could be 512 bytes rather than 16 KB.

• Allows concurrent use of the same region of memory. For example, on IP multicast a single packet is received and sent out on multiple interfaces simultaneously.

• Allows insertion or deletion of memory at any location in a packet (not just at the beginning or end).

Configuration Task

To enable SRB over FDDI on the Cisco 7200 series routers, use the source-bridge interface command. For more information, refer to the "Configuring Source-Route-Bridging" chapter of the Bridging and IBM Networking Configuration Guide.

Configuration Example

For an example of configuring SRB over FDDI, refer to the "FDDI SRB Configuration Example" in the "Configuring Source-Route-Bridging" chapter of the Bridging and IBM Networking Configuration Guide.

Command Reference

For information on the source-bridge interface command, refer to the "Source-Route Bridging Commands" chapter in the Bridging and IBM Networking Command Reference.

What to Do Next

For information on FDDI, refer to the "Configuring Interfaces" chapter in the Configuration Fundamentals Configuration Guide and the "Interface Commands" chapter in the Configuration Fundamentals Command Reference.

For information on Cisco 7200 series routers, refer to the Cisco 7200 Installation and Configuration Guide.