Download Stack Command Line Interface User's Guide

Chapter 15: Spanning Tree Protocol Commands
The root bridge parameter specifies the bridge identifier of the root bridge
of the spanning tree domain. The identifier consists of the bridge priority
value and MAC address of the root switch, separated by a slash (/). This
parameter only appears when STP is activated on the stack.
The root path cost parameter displays the path cost from the stack to the
root bridge of the spanning tree domain. If the stack is the root bridge, the
path cost is 0. This parameter only appears when STP is activated on the
stack.
The PORT parameter allows you to view the STP parameter settings for
the stack ports: An example of the display is shown in Figure 29.
Port
State
Cost
Priority
---------------------------------------------1.1
Forwarding
4
128
1.2
Forwarding
4
128
1.3
Forwarding
4
128
1.4
Forwarding
4
128
1.5
Forwarding
4
128
1.6
Forwarding
4
128
1.7
Forwarding
4
128
1.8
Forwarding
4
128
1.9
Forwarding
4
128
1.10
Forwarding
4
128
1.11
Forwarding
4
128
Figure 29. SHOW STP PORT Command
The columns are defined here:
ˆ
Port is the port number.
ˆ
State is the current state of a port. The possible states are Listening,
Learning, Forwarding, or Blocking when spanning tree is enabled on
the stack. When spanning tree is not enabled on the stack or if a port is
not being used, its state will be disabled.
ˆ
Cost is the port cost of the port.
ˆ
Priority is the port’s priority value. The number is used as a tie breaker
when two or more ports have equal costs to the root bridge.
Examples
This command displays the stack’s STP settings:
show stp
This command displays the STP settings for ports 2.1 to 2.4:
show stp port=2.1-2.4
244
Section III: Spanning Tree Protocols