Foundry Networks Switch and Router Installation And Configuration Manual page 180

Foundry Switch and Router Installation and Configuration Guide
Port Type
10 Mbps
100 Mbps
Gigabit
OC-3c
OC-12c
OC-48c
You can set a port's STP path cost to a value from 0 – 65535. If you want to bias STP's selection to favor one
POS port over another of the same speed, use the following CLI method.
USING THE CLI
To change the STP path cost on a POS port, enter a command such as the following:
BigIron(config)# vlan 10
BigIron(config-vlan-10)# spanning-tree pos 2/1 path-cost 100
These commands change the CLI to the VLAN configuration level for VLAN 10, then change the POS port's path
cost for that VLAN's spanning tree to 100.
Syntax: [no] spanning-tree ethernet | pos <portnum> path-cost <value> | priority <value>
The ethernet | pos <portnum> parameter specifies the interface.
The <num> specifies the path cost and can be from 0 – 65535.
Changing a POS Port's STP Priority
The STP priority of a port determines which port within a spanning tree STP prefers for forwarding traffic into and
out of the spanning tree. For a port-based VLAN, the port priorities determine the port that STP selects within that
VLAN to forward traffic out of the VLAN. STP prefers the port with the highest port priority. You can set a port's
STP priority to a value from 0 – 255. The default for all port types is 128. The default depends on the port type.
See Table 6.1.
To change a POS port's STP priority, use the following CLI method.
USING THE CLI
To change the STP priority for a POS port, enter a command such as the following:
BigIron(config)# vlan 10
BigIron(config-vlan-10)# spanning pos 2/1 priority 200
These commands change the CLI to the configuration level for the POS port, then change the POS port's priority
for that VLAN's spanning tree to 200.
Syntax: [no] spanning-tree ethernet | pos <portnum> priority <num>
The ethernet | pos <portnum> parameter specifies the interface.
The <num> specifies the priority and can be from 0 – 255. The default for all port types is 128.
Enabling or Disabling STP on the Port
Use the following CLI method to enable or disable STP on a POS port.
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Table 6.1: Default STP Port Path Costs
Default Path Cost
100
19
4
200
80
20
December 2000