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Switch thinks it's root while it's actually not

C

Cooky

Golden Member
Our server guys got two new c7000 blade enclosures, and I set up the blade switches (3120X) that came w/ them.

I set them up as a single VBS.
After connecting the switch stack to our DC aggr 6513, it somehow says it's the root of EVERY vlan!

Checked the priority of the new switch, it's got the higher number than the actual root.
I hardcode the priority to 64400 (or something close to it), same thing.

Has anyone seen anything like this?

I sent show tech to HP's blade support, but haven't heard from them...
 
How are you doing the trunking and are you using DTP? If there is no good L2 connectivity of course the 3120s will think they are the root because they're not getting BPDUs for all the other VLANs.

Also, what about VTP and hopefully you're running transparent?
 
We hardcode speed/duplex, and trunk mode on all ports between network devices.
I'll do some debugging on the 3120 to see if it's receiving BPDUs.

We've had some debate on VTP.
In the DMZ, and all new L3 subnets / areas, we're running transparent.
In the inside network, we're running VTP server / client. (which may change down the road, but just don't have the time to change every switch yet)
 
Well then if the appropriate VLANs are allowed on the trunk and native VLAN is good then something is really awry - check your mac-address tables on those ports to truly see if you're receiving BPDUs at L2. If the blade switch really thinks it's the root then it MUST not be receiving bpdu's for whatever vlan it believes it's root for.

So that could still be a trunking problem on either end, for example the VLANs aren't allowed on the trunk on the 6513 side. show int trunk is a great command as well to see what the trunk is doing as is "show interface g3/4 switchport" to see how the port is really operating.
 
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