3Com WX4400 3CRWX440095A, WXR100 3CRWXR10095A manual Port Priority, Snmp Port Path Cost Defaults

Changing Standard Spanning Tree Parameters 353

Port Cost Port cost is a numeric value that STP adds to the total cost of a path to the root bridge. When a designated bridge has multiple equal-cost paths to the root bridge, the designated bridge uses the path with the lowest total cost. You can set this parameter on an individual port basis, for all VLANs the port is in, or for specific VLANs.

You can specify a value from 1 through 65,535 for the port cost. The default depends on the port speed and link type. Table 29 lists the defaults for STP port path cost.

Table 29 SNMP Port Path Cost Defaults

Port Speed	Link Type	Default Port Path Cost
1000 Mbps	Full Duplex Aggregate	19
	Link (Port Group)
1000 Mbps	Full Duplex	4
100 Mbps	Full Duplex Aggregate	19
	Link (Port Group)
100 Mbps	Full Duplex	18
100 Mbps	Half Duplex	19
10 Mbps	Full Duplex Aggregate	19
	Link (Port Group)
10 Mbps	Full Duplex	95
10 Mbps	Half Duplex	100

Port Priority

Changing the Bridge Priority

Port priority is the eligibility of the port to be the designated port to the root bridge, and thus part of the path to the root bridge. When the WX switch has more than one link to the root bridge, STP uses the link with the lowest priority value. You can set this parameter on an individual port basis, for all VLANs the port is in, or for specific VLANs.

Specify a priority from 0 (highest priority) through 255 (lowest priority). The default is 128.

To change the bridge priority, use the following command:

set spantree priority value {all vlan vlan-id}

Specify a bridge priority from 0 through 65,535. The default is 32,768. The all option applies the change globally to all VLANs. Alternatively, specify an individual VLAN.