34

BRF

 

Bridge No. B1

 

Backup BRF

 

Inactive

 

A

A

T

T

M

M

BRF

 

 

Bridge No. B2

 

 

Backup BRF

 

 

Bridge No. B1

 

 

Active

A

A

 

 

T

T

 

M

M

Figure 10. Example of Dynamic Source Route Recovery, Switch 1 Failed

Note that since a separate link is required for forwarding traffic with a given Route Descriptor, one switch can only carry backup traffic for one failed switch at a time. This means that a total of 2n switches is required to handle simultaneous failure of n switches.

While the above example shows redundancy for a BRF with two CRFs, it is also possible to provide (partial) redundancy for a BRF with more than two CRFs. This must, however, be accomplished by creating separate DSRR instances for selected CRF pairs. Note that since at least one of the CRFs must be connected to a legacy Token-Ring, it is not possible to provide full redundancy for a BRF with more than one ATM CRF.

SmartStack STS16-20D/STS16-20R Token Ring Switches Installation and User Guide

Switch Overview

Page 48
Image 48
Cabletron Systems STS16-20D, STS16-20R manual Example of Dynamic Source Route Recovery, Switch 1 Failed