8-17
Catalyst 6000 Family Software Configuration Guide—Releases 6.3 and 6.4
78-13315-02
Chapter 8 Configuring Spanning Tree
Using PVST+
Designated Root 00-60-70-4c-70-00
Designated Root Priority 16384
Designated Root Cost 19
Designated Root Port 2/3
Root Max Age 14 sec Hello Time 2 sec Forward Delay 10 sec
Bridge ID MAC ADDR 00-d0-00-4c-18-00
Bridge ID Priority 32769 (bridge priority: 32768, sys ID ext: 1)
Bridge Max Age 20 sec Hello Time 2 sec Forward Delay 15 sec
Port Vlan Port-State Cost Prio Portfast Channel_id
------------------------ ---- ------------- --------- ---- -------- ----------
1/1 1 not-connected 4 32 disabled 0
1/2 1 not-connected 4 32 disabled 0
2/1 1 not-connected 100 32 disabled 0
2/2 1 not-connected 100 32 disabled 0
Configuring the PVST+ Port Cost
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
“Calculating and Assigning Port Costs” section on page 8-4
.
To configure the PVST+ port cost for a port, perform this task in privileged mode:
Note
When you enter the
set channel cost
command, it does not appear in the configuration file.
The command causes a “set spantree portcost” entry to be created for each port in the
channel. See the
“Setting the EtherChannel Port Path Cost”
section in
Chapter 6,
“Configuring EtherChannel,”
for information on using the
set channel cost
command.
This example shows how to configure the PVST+ port cost on a port and verify the configuration:
Console> (enable)
set spantree portcost 2/3 12
Spantree port 2/3 path cost set to 12.
Console> (enable)
show spantree 2/3
VLAN 1
.
.
.
Port Vlan Port-State Cost Prio Portfast Channel_id
------------------------ ---- ------------- --------- ---- -------- ----------
1/1 1 not-connected 4 32 disabled 0
1/2 1 not-connected 4 32 disabled 0
2/1 1 not-connected 100 32 disabled 0
2/2 1 not-connected 100 32 disabled 0
2/3 1 forwarding 12 32 disabled 0
Task
Command
Step 1
Configure the PVST+ port cost for a switch
port.
set spantree portcost
{
mod/port
}
cost
Step 2
Verify the port cost setting.
show spantree
mod
/
port
