Troubleshooting Trunk Links and Spanning Tree using Dia - Part 4 of 5

Welcome back!

Continuing this series on using dia to troubleshoot trunk links and spanning tree instances, let's move on to VLAN 33.

Once again, here is the physical layer topology:

By now, we have our routine.  Start with the 'show spanning-tree vlan 33' command:

Here, we can see that DS1 is the root switch and that four of the six trunks have VLAN 33 allowed.  The first update to the map follows:

Over to DS2 next and the 'show spanning-tree vlan 33' command:

A very similar configuration here.  DS2 is utilizing the Gigabit connections back to DS1 (the root switch), and the connections to AS2 are forwarding traffic for VLAN 33 as well.  Gi0/1 i1 is the root port and Gi0/2 is blocking to prevent a loop.  The updated map is now:

Next, AS1 and the 'show spanning-tree vlan 33' command:

Here we see that only two of the four trunk links are utilized.  Fa0/11 is the root port back to DS1 and Fa0/12 is in the blocking state to prevent a loop.  Again, the updated map:

Last, let's head over to AS2 to finish the map:

And here we can see a similar configuration as AS1.  Two of the four uplinks are utilized, but this time up to DS2.  Fa0/23 is the root port and Fa0/24 is blocking to prevent a loop.

Now that we have the Layer 2 topology sorted, let's verify the HSRP Active router.

On DS1, we run the 'show standby vlan 33' command:

Right away we can see that DS1 is the Active HSRP router with the 'State is Active' and 'Active router is local' lines.

While this configuration is not the most efficient (unused trunk links directly connected to the two distribution switches), this VLAN is not in too bad of shape.  Again, AS2 has to use an extra switch in the path (DS2) in order to reach the Active router, but overall not too bad.

The obvious fixes would be to allow VLAN 33 on all the links and change all of these dual uplinks into Etherchannels.

Next post will cover VLAN 44 and then the final configuration to implement all the fixes.

Thank you for reading!