[cisco-nas] X.75 (LAPB-TA) sessions getting "stuck"? (AS5300, 12.3)

[Aaron Leonard]

Good sleuthwork, Gert.  Looks like you're suffering from a input buffer
leak.

"show buffer input-interface <interface-name> dump" would dump out the
packets which can then be hand decoded (or munged into a format amenable
to being read by Wireshark.)

As to whether we could figure out some kind of workaround or bugfix ...
at some point, you'd want to have a TAC case open (not that the 5300 is
supported any longer) and get a DE assigned to figure out the bug.

Aaron

------------------------------------------------------------------------

Gert Doering wrote:
> Hi,
>
> On Tue, Nov 03, 2009 at 05:16:35PM +0100, Gert Doering wrote:
>   
>> Like "remove lapb-ta autodetection from all ISDN interfaces" or so
>> (which didn't have any effect, btw)?
>>     
>
> Ah, now that's interesting.
>
> A "not-yet-messed-up" B-Channel interface has:
>
> AS53-k02-Test#sh int s0:3
> Serial0:3 is down, line protocol is down 
>   Input queue: 0/10/0/0 (size/max/drops/flushes); Total output drops: 0
>
> while a "messed-up" B-Channel interface has:
>
> AS53-k02-Test#sh int s0:1
> Serial0:1 is down, line protocol is down 
>   Input queue: 6/10/0/0 (size/max/drops/flushes); Total output drops: 58
>
> if I increase the input hold queue to 100, there is still a packet
> stuck in there:
>
>   Input queue: 6/100/0/0 (size/max/drops/flushes); Total output drops: 58
>
> ... but the X.75 calls are working again.
>
> After every further call, more packets get stuck in the input queue...
>
>   Input queue: 11/100/0/0 (size/max/drops/flushes); Total output drops: 58
>
> (I'm not sure yet whether it's "one stuck packet per call" or has some
> more random element to it).
>
>
> So.  Next question :-) - is there a way to figure out what sort of
> "packets" are hanging in the input queue, and to get rid of them?
>
> (I remember security advisories with input queues getting wedged, but
> that was related to IP protocols, not X.75 protocol handling...)
>
> gert
>