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Webcast-Catalyst9k
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Spanning-Tree designated port id not correct

4507_SW1 is root bridge. 4506_SW2 is connected to SW1 via a trunk port. Trunk port native vlan is 1, and allowed vlans are 2 and 3. SW1 is running IOS XE 3.x; SW is running IOS 12.2x. Spanning tree mode is PVST. I am trying to map out the L1/L2 connections remotely, but the port IDs are displaying inconsistently as displayed below. The output is not real, but it simulates what I'm seeing when trying to track down the links.

 

SW1
Port 120 (GigabitEthernet7/2) of VLAN0002 is designated forwarding
   Port path cost 4, Port priority 128, Port Identifier 128.120
   Designated root has priority 24627, address 1111.1111.1111
   Designated bridge has priorty 24627, address 1111.1111.1111
   Designated port id is 128.120, designated path cost 0

 

SW2
Port 1 (GigabitEthernet1/1) of VLAN0002 is root forwarding
   Port path cost 4, Port priority 128, Port Identifier 128.1
   Designated root has priority 24627, address 1111.1111.1111
   Designated bridge has priorty 24627, address 1111.1111.1111
   Designated port id is 128.250, designated path cost 0


The main difference is SW2 says it's neighbor is 128.250, but SW1 says my port id is 128.120? I know for a fact that these two ports are connected to each other. Why is that? Is this a bug, or am I missing something?

2 REPLIES
New Member

Who is 128.250? is there any

Who is 128.250? is there any other siwtch in topology?

 

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Sajid Ali Pathan

New Member

On SW1 STP port id is 128.120

On SW1 STP port id is 128.120 is GigabitEthernet7/2

On SW2 STP port is is 128.250 is GigabitEthernet7/2 on SW1

There are other switches in the topology, and they are experiencing the same problem. The design is hub and spoke, so they only see each other thru the hub. 

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