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ATM Switch Router Software Configuration Guide
OL-7396-01
Chapter11 Configuring ATM Routing and PNNI
Basic PNNI Configuration
The control for election is done through the assignment of leadership priorities. We recommend that the
leadership priority space be divided into three tiers:
First tier: 1 to 49
Second tier: 100 to 149
Third tier: 200 to 205
This subdivision is used because when a node becomes PGL, it in creases the advertised leadership
priority by a value of50. This avoids instabilities after election.
The following guidelines apply when configuring the node election leadership priority:
Nodes that you do not want to become PGLs should remain with the default leadership priority value
of 0.
Unless you want to force one of the PGL candidates to be the PGL, you should assign all leadership
priority values within the first tier. After a node is elected PGL, it remains PGL until it goes down
or is configured to step down.
If certain nodes should take precedence over nodes in the first tier, even if one is already PGL,
leadership priority values can be assigned from the second tier. We recommend that you configure
more than one node with a leadership priority value from this tier. This prevents one unstable node
with a larger leadership priority value from repeatedly destabilizing the peer group.
If you need a strict master leader, use the third tier.
Note The election leadership-priority command does not take effect unless a parent node has already been
configured using the node and parent commands.
To configure the election leadership priority, perform these steps, beginning in global configuration
mode:
Example
The following example shows how to change the election leadership pri ority for node 1 to 100:
Switch(config)# atm router pnni
Switch(config-pnni-node)# node 1
Switch(config-pnni-node)# election leadership-priority 100
Command Purpose
Step1 Switch(config)# atm router pnni
Switch(config-atm-router)#
Enters ATM router PNNI mode from the
terminal.
Step2 Switch(config-atm-router)# node node-index
Switch(config-pnni-node)#
Enters node configuration mode.
Step3 Switch(config-pnni-node)# election
leadership-priority number
Configures the election leadership priority. The
configurable range is from 0to 205.