PVST+ Configuration Examples
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213
Alcatel-Lucent
Beta Beta
OmniAccess 5740 Unified Services Gateway CLI Configuration Guide
PROCEDURE
Consider a scenario with OA5740-A, OA5740-B and OA5740-C with MAC
address 32768.00-00-00-00-00-0a, 32768.00-00-00-00-00-0b, 32768.00-00-00-
00-00-0c respectively.
By enabling spanning tree,
• Default priority is taken as 32768 for all the three bridges.
• As the priority is the same for all the bridges, the next criteria considered is the
MAC address. OA5740-A becomes the Root Bridge as it has the lowest MAC
address.
• As the root path cost on OA5740-B and OA5740-C is same, and OA5740-B has
the lowest MAC address of the two, OA5740-B Switchport 1/2 becomes the
Designated Port for segment B-C.
By default, all switchports will be in bridged mode. They belong to one broadcast
domain. Spanning tree can be enabled by using the following command:
O
N OA5740-A
OA5740-A(config)#interface switchport1/1
OA5740-A(config-if switchport1/1)#no shutdown
OA5740-A(config)#interface switchport1/2
OA5740-A(config-if switchport1/2)#no shutdown
OA5740-A(config)# spanning-tree
O
N OA5740-B
OA5740-B(config)#interface switchport1/1
OA5740-B(config-if switchport1/1)#no shutdown
OA5740-B(config)#interface switchport1/2
OA5740-B(config-if switchport1/2)#no shutdown
OA5740-B(config)# spanning-tree
O
N OA5740-C
OA5740-C(config)#interface switchport1/1
OA5740-C(config-if switchport1/1)#no shutdown
OA5740-C(config)#interface switchport1/2
OA5740-C(config-if switchport1/2)#no shutdown
OA5740-C(config)# spanning-tree
VERIFICATION
Verify the spanning tree by using the following show commands:
• show spanning-tree brief
• show spanning-tree summary
• show spanning-tree