Configuring The Pvst+ Port Cost; Configuring Pvst+ Port Priority - Cisco WS-C2948G-GE-TX Configuration Manual

Chapter 7 Configuring Spanning Tree

Configuring the PVST+ Port Cost

You can configure the port cost of switch ports. 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 range of cost is from
1–65535. The default differs for different media. Typically, the path cost is 1000 ÷ LAN speed in
megabits per second.
To configure the port cost for a port, perform this task in privileged mode:
Task
Step 1
Configure the port cost for a switch port.
Step 2 Verify the port cost setting.
This example shows how to configure the port VLAN priority 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
------------------------ ---- ------------- --------- ---- -------- ----------
1/1
1/2
2/1
2/2
2/3
2/4

Configuring PVST+ Port Priority

You can configure the port priority of switch ports in PVST+ mode. The port with the lowest priority
value forwards frames for all VLANs. The possible port priority value is from 0–63. The default is 32.
If all ports have the same priority value, the port with the lowest port number forwards frames.
To configure the port priority for a port, perform this task in privileged mode:
Task
Step 1 Configure the port priority for a switch port.
Step 2 Verify the port priority setting.
This example shows how to configure the port priority for a port:
Console> (enable) set spantree portpri 2/3 16
Bridge port
Console> (enable) show spantree 2/3
VLAN 1
.
.
.
Catalyst 4500 Series, Catalyst 2948G, Catalyst 2948G-GE-TX, and Catalyst 2980G Switches Software Configuration Guide—Release 8.2GLX
78-15908-01
Vlan Port-State
1 not-connected
1 not-connected
1 not-connected
1 not-connected
1 forwarding
1 not-connected
2/3 port priority set to 16.
Command
set spantree portcost {mod/port} cost
show spantree mod/port
Cost Prio Portfast Channel_id
4 32 disabled 0
4 32 disabled 0
100 32 disabled 0
100 32 disabled 0
12 32 disabled 0
100 32 disabled
Command
set spantree portpri mod_num/port_num priority
show spantree mod/port
Using PVST+
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