Configuring The Pvst+ Port Cost For A Vlan - Cisco WS-X6066-SLB-APC - Content Switching Module Software Manual

Chapter 8 Configuring Spanning Tree
The default port cost mode is set to short in PVST+ mode. For port speeds of 10 Gb and greater, the
default port cost mode must be set to long.
To configure the PVST+ default port cost mode, perform this task in privileged mode:
Task
Configure the PVST+ default port cost mode.
This example shows how to configure the PVST+ default port cost mode:
Console> (enable) set spantree defaultcostmode long
Portcost and portvlancost set to use long format default values.
Console> (enable)

Configuring the PVST+ Port Cost for a VLAN

You can configure the port cost of switch ports. The ports with lower port costs are more likely to be
chosen to forward frames. Assign lower numbers to ports that are attached to faster media (such as full
duplex) and higher numbers to ports that are attached to slower media. The possible cost is from 1 to
65535 when using the short method for calculating port cost and from 1 to 200000000 when using the
long method. The default cost differs for different media. For information about calculating port cost,
see the
To configure the PVST+ port VLAN cost for a port, perform this task in privileged mode:
Task
Configure the PVST+ port cost for a
VLAN on a port.
When you use the set channel cost command, it does not appear in the configuration file. The
Note
command causes a "set spantree portcost" entry to be created for each port in the channel. See the
"Setting the EtherChannel Port Path Cost"
information on using the set channel cost command.
This example shows how to configure the PVST+ port VLAN cost on port 2/3 for VLANs 1 through 5:
Console> (enable) set spantree portvlancost 2/3 cost 20000 1-5
Port 2/3 VLANs 6-11,13-1005,1025-4094 have path cost 12.
Port 2/3 VLANs 1-5,12 have path cost 20000.
This parameter applies to trunking ports only.
Console> (enable
78-13315-02
EtherChannel computes the cost of a bundle using the formula,
–
AVERAGE_COST/NUM_PORT
"Calculating and Assigning Port Costs" section on page
Command
set spantree defaultcostmode {short | long}
Command
set spantree portvlancost {mod/port} [cost cost]
[vlan_list]
section in Chapter 6, "Configuring EtherChannel,"
Catalyst 6000 Family Software Configuration Guide—Releases 6.3 and 6.4
Using PVST+
8-4.
for
8-19