Allied Telesis AlliedWare Plus Operating System Version 5.4.4C (x310-26FT,x310-26FP,x310-50FT,x310-50FP) - Manual (Page 1502)

EPSR Introduction and Configuration
Software Reference for x310 Series Switches
57.20 AlliedWare Plus TM Operating System - Version 5.4.4C C613-50046-01 REV A
Configuration Rules for Superloop Protected EPSR Rings
The following configuration rules are advised when configuring EPSR rings that share one
or more common segments.
■ Allocate a priority order to each of the interconnected rings, with 127 being the
highest priority and 1 the lowest.
■ A higher priority ring can have its master node located in any position; although,
where possible, avoid connecting a common segment to the secondary port of a
master node.
■ Do not locate the master node on a segment that is shared with a higher priority ring,
but you “can” locate it on a common segment that is shared with a lower priority ring.
In this situation however, the port that connects to the common segment must be
configured as the primary port.
For example, in Figure 57-12 , the upper portion of Node D could be configured as a
Master Node of the upper ring (having a priority of 120), but its lower portion must be
configured as a Transit Node (having the lower priority of 60).
■ On the transit nodes that connect to shared links, allocate the ring’s priority to the
ports that connect to each ring. Note that both of these nodes “must” be set to the
same priority value.
Note For good practice, we advise that you set all nodes within a ring to the priority
assigned to that ring. So, for the network of
Figure 57-12 each of the nodes
that form part of the upper ring would be configured with a priority of 120, and
each of the nodes that form the lower ring would all be configured with a
priority of 60.