Example 127 Viewing Spanning Tree for VLAN

yin#show spanning-tree

VLAN0001

Spanning tree enabled protocol ieee Root ID Priority 32768 <<<text omitted>>> VLAN0 0 02

Spanning tree enabled protocol ieee

Root ID Priority Address

Cost

Port

0004.275e.f0c7 3

65 (Port-channell) Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Bridge ID Priority 32770 (priority 32768 sys-id-ext 2) Address 0 0 0a.8a0e.ba8 0

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Aging Time 300

Interfa ce Port ID Designated Port ID

Name Prio.Nbr Cost Sts Cost Bridge ID Prio.Nbr

Fa0/3

Fa0/20

128.3

128.16

128.65

19 FWD 19 FWD 3 FWD

3 32770 000a.8a0e.ba80 128.3 3 32770 000a.8a0e.ba80 128.16 0 100 0004.275e.f0c7 128.1

Every bit of information provided by this command is useful. The fields are defined as follows:

• Spanning tree type— The type of Spanning Tree Protocol in use: IBM, DEC, or IEEE.

• Root ID Priorit y— The bri dge priority that was received from the root bridge. The values of -priority range from 0 to 65,535, with 32,768 as the default.

• Root ID Cost— The cumulative cost to the root bridge.

• Root ID Port— The root port for that segment.

• Root Max Age, Hello Time, Forward Delay— The three STP timers as sent by the root brid

• Bridge ID MAC ADDR— The MAC address that is being used for this VLAN by this local bridg i Bridge ID P riority— The priority of she local bridge.

• Bridge Max Age , Hello Time, Forward Delay— The thaee STP timers on th e loc al bridge.

The finnl rows show each port that is participatin g in STP winhi n ehe VLAN and l • sts whether the poi forwarding or blocking, as well as the cost and service priority of the port. Do not confuse this prio spannrng-tree br idge briori ty. Thevalues oftohre port priority range fro m 0 to 633, w ith 32 as the def

Another com mand that is useful in presenting a general o eefationaI picture of epanmng tree is the spantree pu mimacy comma nde Thio c ommand provider a h overview of the VLANs and the state of an STP pefsee<f:iva. Exa mble 1-28 ests the outpct for this commaad.

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