Installation and Getting Started Guide

The show span command shows the following information.

 

Table 5.3: CLI Display of STP Information

 

 

 

This Field...

 

Displays...

 

 

 

Global STP Parameters

 

 

 

 

 

VLAN ID

 

The port-based VLAN that contains this spanning tree (instance of

 

 

STP). VLAN 1 is the default VLAN. If you have not configured port­

 

 

based VLANs on this device, all STP information is for VLAN 1.

 

 

 

Root ID

 

The ID assigned by STP to the root bridge for this spanning tree.

 

 

 

Root Cost

 

The cumulative cost from this bridge to the root bridge. If this device

 

 

is the root bridge, then the root cost is 0.

 

 

 

Root Port

 

The port on this device that connects to the root bridge. If this device

 

 

is the root bridge, then the value is “Root” instead of a port number.

 

 

 

Priority Hex

 

This device or VLAN’s STP priority. The value is shown in

 

 

hexadecimal format.

 

 

Note: If you configure this value, specify it in decimal format. See

 

 

“Changing STP Bridge Parameters” on page 5-4.

 

 

 

Max age sec

 

The number of seconds this device or VLAN waits for a hello message

 

 

from the root bridge before deciding the root has become unavailable

 

 

and performing a reconvergence.

 

 

 

Hello sec

 

The interval between each configuration BPDU sent by the root

 

 

bridge.

 

 

 

Hold sec

 

The minimum number of seconds that must elapse between

 

 

transmissions of consecutive Configuration BPDUs on a port.

 

 

 

Fwd dly sec

 

The number of seconds this device or VLAN waits following a

 

 

topology change and consequent reconvergence.

 

 

 

Last Chang sec

 

The number of seconds since the last time a topology change

 

 

occurred.

 

 

 

Chg cnt

 

The number of times the topology has changed since this device was

 

 

reloaded.

 

 

 

Bridge Address

 

The STP address of this device or VLAN.

 

 

Note: If this address is the same as the Root ID, then this device or

 

 

VLAN is the root bridge for its spanning tree.

 

 

 

Port STP Parameters

 

 

 

 

 

VLAN ID

 

The VLAN that the port is in.

 

 

 

Port Num

 

The port number.

 

 

 

Priority Hex

 

The port’s STP priority, in hexadecimal format.

 

 

Note: If you configure this value, specify it in decimal format. See

 

 

“Changing STP Port Parameters” on page 5-5.

 

 

 

Path Cost

 

The port’s STP path cost.

 

 

 

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