HP 2920 Spanning Tree Priority

[Matt-NZ]

Hi

I’m in the process of upskilling my meagre networking knowledge and have got a little confused with spanning tree on my 2920. Can someone explain what this command is doing please?

On my core, stacked pair of 2920's I have this command in the running configuration

spanning-tree root primary force-version rstp-operation

What is the ‘root primary’ part of the command doing? Is it configuring the spanning tree priority? I would have expected to see the command ‘spanning-tree priority 0’ instead but this is not in my running configuration. I’ve not been able to find any reference to this command string in any of the ProCurve documentation I've looked through.

The show spanning-tree command shows the switch priority is still the default 32768.

(Was goingto put a screen shot here, but I don't seem to have permission so I've attached it instaed) 

I had a network outage recently caused by excessive broadcasts. I’m trying to figure out if I have a misconfiguration in the spanning tree as well as try and find the root cause of the broadcasts.

Cheers

Matt

[Michael Patmon]

Hello.  "Switch Priority" is the configured priority, also stored in the hpSwitchStpPriority MIB.  The show command is just reading that value and displaying it.

"spanning-tree root primary" overrides the configured priority and sets it to 0 (or 4096 for "root secondary") for the CST/IST instances.  The priority for the active root bridge (the current switch in your screen shot) is displayed under "CST Root Priority".

There's no configuration there that should cause a broadcast loop.  Might check all the switch logs for clues for that time period, STP related or otherwise.