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

[Gert Doering]

Hi,

I have this AS5300 that is handling incoming X.75/LAPB-TA calls, and
every few weeks, it seems to get stuck in weird ways.

Incoming calls connect fine, and the initial few bytes ("username, password")
are exchanged fine.  After that, nothing sent by the AS5300 to the ISDN
side arrives at the caller location - but "debug lapb-ta packets" *does*
log the packets just fine...:

Oct  2 12:56:01: %LINK-3-UPDOWN: Interface Serial0:0, changed state to up
Oct  2 12:56:01: %ISDN-6-CONNECT: Interface Serial0:0 is now connected to 8912003682 N/A
Oct  2 12:56:04: LAPB-TA: Autodetect trying to detect LAPB on Se0:0
Oct  2 12:56:04:   sampled pkt:  2 bytes:  1 3F.. match
Oct  2 12:56:04: LAPBTA: get_ll_config: Serial0:0
Oct  2 12:56:04: LAPBTA127: vty allocated for Se0:0
Oct  2 12:56:04: LAPBTA127: process 81
Oct  2 12:56:04: Se0:0: LAPB-TA started
Oct  2 12:56:04: LAPBTA: service change: LAPB physical layer up, context 62CC3A58 interface up, protocol down
Oct  2 12:56:04: LAPBTA: service change: , context 62CC3A58 up
Oct  2 12:56:04: LAPB-TA: Se0:0, 14 sent
Oct  2 12:56:04: LAPB-TA: Se0:0, 1 rcvd
Oct  2 12:56:04: LAPB-TA: Se0:0, 3 rcvd
Oct  2 12:56:04: LAPB-TA: Se0:0, 4 rcvd
Oct  2 12:56:04: LAPB-TA: Se0:0, 3 sent
Oct  2 12:56:04: LAPB-TA: Se0:0, 5 rcvd
Oct  2 12:56:04: LAPB-TA: Se0:0, 5 sent
Oct  2 12:56:04: LAPB-TA: Se0:0, 2 rcvd
Oct  2 12:56:04: LAPB-TA: Se0:0, 6 sent
Oct  2 12:56:04: LAPB-TA: Se0:0, 10 sent
Oct  2 12:56:05: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0:0, changed state to up
Oct  2 12:56:07: LAPB-TA: Se0:0, 5 sent
Oct  2 12:56:07: LAPB-TA: Se0:0, 21 sent

- about here, it breaks.  Nothing ever arrives at the calling side anymore
(and nothing the other side shows up as "rcvd" either).

Oct  2 12:56:07: LAPB-TA: Se0:0, 4 sent
Oct  2 12:56:17: LAPB-TA: Se0:0, 21 sent
Oct  2 12:56:17: LAPB-TA: Se0:0, 4 sent
Oct  2 12:56:27: LAPB-TA: Se0:0, 21 sent
Oct  2 12:56:27: LAPB-TA: Se0:0, 4 sent
Oct  2 12:56:37: LAPB-TA: Se0:0, 21 sent
Oct  2 12:56:37: LAPB-TA: Se0:0, 4 sent
Oct  2 12:57:11: LAPBTA127: stopped, removing lapb
Oct  2 12:57:11: LAPBTA: service change: LAPB deleted, context 62CC3A58 interface up, protocol down, disconnecting
Oct  2 12:57:11: LAPBTA: removing context 62CC3A58
Oct  2 12:57:11: %ISDN-6-DISCONNECT: Interface Serial0:0  disconnected from 8912003682 , call lasted 70 seconds
Oct  2 12:57:11: LAPBTA: close 62DDA294, line 127
Oct  2 12:57:11: %LINK-3-UPDOWN: Interface Serial0:0, changed state to down

... nothing unusual in the log, it just seems as if "LAPB-TA" loses contact
to "the ISDN side of things".  No real idea how to debug this further...


If I reboot the box, everything is back to working.  "shut / no shut" on
the serial0:15 interface did *not* change anything.

This is currently running 12.3(26), which is the latest 12.3 release.


I'd bet willing to try an upgrade to 12.4, but this brings up the next
question - is the 5300 supported in 12.4?  The IOS files that can be
found on the FTP server in 12.4/12.4.25b/as5300/ are all named "as5350-...",
so I'm wondering whether they will work on the 5300 as well, or whether
this is incompatible, and the directory naming is just weird.

(We could also downgrade to 12.2, if this is a new problem in 12.3...)

gert

-- 
USENET is *not* the non-clickable part of WWW!
                                                           //www.muc.de/~gert/
Gert Doering - Munich, Germany                             gert at greenie.muc.de
fax: +49-89-35655025                        gert at net.informatik.tu-muenchen.de
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