3Com Switch 7750 Configuration Guide

RRPP Overview 907

To avoid temporary data loops, when detecting the port through which it connects

to the ring network becomes UP again, a transit node blocks the port temporarily

(only control VLAN packets are permitted to pass), and keeps the port blocked

until it receives the Complete Flush packet from the master node.

The following details how to unblock the temporarily blocked port:

■ When the master node is in the Fail status, if the secondary port receives the

HEALTH sent by the primary port, the master node believes that the ring

network has been recovered. Thus, the node status is transited to the

Complete status and the master node sends the Complete Flush message

through the primary port to request the transit node to update the FDB and

unblock the temporarily blocked port. After the transit node receives the

Complete Flush message, it unblocks the temporarily blocked port.

■ If the transit node does not receive the Complete Flush message after the Fail

timer expires, it automatically unblocks the temporarily blocked port.

Typical Networking of

RRPP

To ensure normal RRPP operation, you must configure RRPP correctly. Here are

several typical networking applications.

Single ring network

Figure 251 Single ring network

There is only one ring in the network topology. In this case, only one RRPP domain

is to be defined.

Switch A Switch B

Switch C

Switch D

Master node

Transit node

Domain 1

Ring 1

Transit node