3Com 3CRWX120695A, Configuration Manual

Page: 353 / 728

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.
Port 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.
Changing the Bridge
Priority
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.
Table 29 SNMP Port Path Cost Defaults
Port Speed Link Type Default Port Path Cost
1000 Mbps Full Duplex Aggregate
Link (Port Group) 19
1000 Mbps Full Duplex 4
100 Mbps Full Duplex Aggregate
Link (Port Group) 19
100 Mbps Full Duplex 18
100 Mbps Half Duplex 19
10 Mbps Full Duplex Aggregate
Link (Port Group) 19
10 Mbps Full Duplex 95
10 Mbps Half Duplex 100