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Configuring LAN Interfaces

Configuring a Token Ring Interface

IC-58

Cisco IOS Interface Configuration Guide

Configuring a Token Ring Interface

Cisco supports various Token Ring interfaces. Refer to the Cisco Product Catalog for information about

platform and hardware compatibility.

The Token Ring interface supports both routing (Layer 3 switching) and source-route bridging (Layer 2

switching) on a per-protocol basis. For example, IP traffic could be routed while SNA traffic is bridged.

Routing features enhance source-route bridges.

The Token Ring MIB variables support the specification in RFC 1231, “IEEE 802.5 Token Ring MIB.”

The mandatory Interface Table and Statistics Table are implemented, but the optional Timer Table of the

Token Ring MIB is not. The Token Ring MIB has been implemented for the Token Ring Interface

Processor (TRIP).

Use the show interfaces, show controllers token, and show controllers cbus EXEC commands to

display the Token Ring numbers. These commands provide a report for each ring that Cisco IOS

software supports.

Note If the system receives an indication of a cabling problem from a Token Ring interface, it

puts that interface into a reset state and does not attempt to restart it. It functions this way

because periodic attempts to restart the Token Ring interface drastically affect the stability

of routing tables. Once you have again plugged the cable into the MAU, restart the interface

by using the clear interface tokenring command, where the number argument is the

interface number.

By default, the Token Ring interface uses the SNAP encapsulation format defined in RFC 1042. It is not

necessary to define an encapsulation method for this interface.

Particle-Based Switching of Source-Route Bridge Packets on Cisco 7200

Series Routers

Particle-based switching is 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 it 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).

For information about configuring SRB over FDDI, refer to the “Configuring Source-Route Bridging”

chapter of the Cisco IOS Bridging and IBM Networking Configuration Guide.

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Cisco Systems IC-23 Manual de usuario Pagina 36