[c-nsp] *** GMX Spamverdacht *** Re: Weird problem with 2960S and desktop switch

[Garry]

On 08.01.2014 09:57, Peter Rathlev wrote:
> On Wed, 2014-01-08 at 09:37 +0100, Garry wrote:
>> After shut/no shut, the port again went down due to BPDU.
>> Disabling BPDU guard caused the whole switch to lock up while the
>> desktop switch was connected, even though checking the logs after
>> removing the desktop switch (and a bit of additional waiting time, in
>> which I assume spanning tree came back up) did not show any errors or
>> messages between the int up and down of that port.
> Are you saying you had a loop (when BPDU Guard was disabled) or not?
I do not know what happened, apart from the fact that the whole switch
got unresponsive both for remote management, as well as local forwarding
when I put the "spanning-tree bpduguard disable" in the port and the
switch was connected to the port. According to the customer, there were
no additional lines connected to the desktop switch at that time. So,
assuming this was true, there shouldn't have been any loop effects been
caused.
>
> If you had a loop (confirmed by observing e.g. fully utilized links
> everywhere) even though the physical setup doesn't seem to contain loops
> you might have a malfunctioning switch among your devices.
>
> Otherwise it sound like BPDU Guard just does what you have asked it
> to. :-)
>
> If you don't have "spanning-tree bpduguard enable" configured on the
This is configured:

spanning-tree portfast bpduguard default
errdisable recovery cause bpduguard

Apart from the fact that the default BPDU guard does as it is supposed
to, my actual problem is why the switch goes down when I remove it on
that port, thus allowing the switch to be connected ... I reckon I might
have to go on site and check on the console when the switch is connected
(and BPDU guard disabled) to find out whether there are any hints as to
what is going wrong ...

Tnx, -gg