6513 stp root bridge and Dell powerconnect 5316 issue

[Tony JOrdan]

Hi everyone,

have this issue with root bridge on on a vlan being learnt incorrectly by itself from another vlan.

The topology is this

6513        vlan 10       interface f4/10   Dell 5316 interface g11   vlan 1

                vlan 20       interface f4/20                   interface g16   vlan 20

The 6513 vlan 10 priority 12228                 Dell configured with classic stp and priority 32768

                vlan 20 priority 8192

pvst+ used on ios 12.1 (i know really old, but going to be de-commissioned any way).

Now on the cisco switch a show spanning-tree vl 20 it is entered and reports its the root for this vlan, ok correct there.

But when this is done for vlan 10 it reports that the root brodge is via f4/10 with the priority and mac address of vlan 20.

Somehow this shows that vlan 10 is getting bpdu's via the Dell 5316 from vlan 20 . The blade server connectivity is fine. 

Thanks for any advice

Cheers

TJ.

[Reza Sharifi]

Hi TJ,

I see you have vlan 10 on the switch and vlan 1 on the dell server.  If the port is a trunk port the vlans should be the same on both sides.  Is the sever a VM host?

why do you have 2 vlans/subnet on the server instead of both ports in an Etherchannle?

HTH

[Tony JOrdan]

Hi Reza,

Inherited issue. The ports are set to access. The servers are regular Windows servers (2008).

I agree would have been a better configured setup done that way with an etherchanel.

Also I noted that the interfaces on the Dell are set to untagged.

Cheers

TJ.