[c-nsp] Spanning tree issues

[Lincoln Dale]

Matthew Crocker wrote:
>
> I'm sure I'm being stupid here but I can't figure out what is going on.
>
> I have 2 switches connected together via 2 GigE links,  they are not 
> bonded (no EtherChannel).  I want link one to act as a backup to the 
> other link.  I don't care which link is primary
>
> one switch is a 3550-12G the other is a Paradyne IPD12000E 'dslam'.  
> When I connect both GigE links the traffic starts looping and in about 
> 30-40 seconds the 3550 melts and I lose console access/response.  
> yanking either of the links restores everything instantly.    I'm sure 
> it is a spanning tree problem but isn't looping exactly what it is 
> supposed to detect and protect against?
>
> The 3550-12G should always be the spanning tree route.
>
> Topology is
>
> 7206 ---- 3550-12G ==== Paradyne IPD12000E ----- Paradyne IPD12000E
suggest you open a support case with Paradyne, by the sounds of it, no 
STP is running at all, its not responding to/generating BPDUs.  does it 
support RPVST?

you can perhaps diagnose a bit more by bringing up the link between the 
3550 and it with just one GbE and then inspecting STP status on c3550 
with "show spanning-tree ..".
make sure that it is bringing up the link as a bridge port & not access 
port.


cheers,

lincoln.