STP Question

phantasm

I was working on a practice exam the other night and came across a question that stumped me. They gave the output from a sh spanning-tree command asked which version of STP was running.

I've not been able to figure out how to tell from looking at the output. Anyone know? So far, I'v estudied the Networking Academy material, flash cards, and am now readding Lammle's book. Can't find an answer. Thanks.

Netwurk

It's running the IEEE version which is shown by this output from the "show spanning-tree" command:

Spanning tree enabled protocol ieee

The "show spanning-tree summary" command will give you the mode, which will probably be PVST

There is also the somewhat related VTP version, which would be shown by the "show vtp status" command

bighornsheep

In the output of show spanning-tree,

If you see all the interfaces listed, and the states they're in, the switch is running the original 802.1D STP.

If you see all the VLANs listed, with the active ports listed under each VLAN and the states they're in, it is running PVST/PVST+, the protocol will say "ieee"

If the protocol says rstp, the switch is running rapid-pvst+.

phantasm

Ok, let me wire this up and see what it looks like. Sounds like I've been overlooking it. Thanks.