Cabletron Systems 9032578-05 manual Setting the Bridge Priority, Setting a Port Priority

Chapter 3: Bridging Configuration Guide

Setting the Bridge Priority

You can globally configure the priority of an individual bridge when two bridges tie for position as the root bridge, or you can configure the likelihood that a bridge will be selected as the root bridge. The lower the bridge's priority, the more likely the bridge will be selected as the root bridge. This priority is determined by default; however, you can change it.

To set the bridge priority, enter the following command in Configure mode:

Set the bridge priority for default	stp set bridging priority <num>
spanning tree.
Set the bridge priority for a	pvst set	bridging spanning-tree <string>
particular instance of spanning tree.	priority	<num>

Setting a Port Priority

You can set a priority for an interface. When two bridges tie for position as the root bridge, you configure an interface priority to break the tie. The bridge with the lowest interface value is elected.

To set an interface priority, enter the following command in Configure mode:

Establish a priority for a specified	stp set port <port-list>priority <num>
interface for default spanning tree.
Establish a priority for a specified	pvst set port <port-list>spanning-tree
interface for a particular instance of	<string> priority <num>
spanning tree.

Assigning Port Costs

Each interface has a port cost associated with it. By convention, the port cost is 1000/data rate of the attached LAN, in Mbps. You can set different port costs.

To assign port costs, enter the following command in Configure mode:

Set a different port cost other than	stp set port <port-list>port-cost <num>
the defaults for default spanning
tree.
Set a different port cost other than	pvst set port <port-list>spanning-tree
the defaults for a particular instance	<string> port-cost<num>
of spanning tree.

SmartSwitch Router User Reference Manual 29