[cisco-nas] Dial-IN problems with an AS5200

[Aaron Leonard]

> > Your debugs show that the call connected at ISDN layer 3,
> > but that the sync PPP packets sent by each side failed
> > successfully to be received by the other side.
> >
> > Presumably if you were to do a "show interface WHATEVER:B-CHANNEL"
> > before and after the call, you would see packets transmitted
> > and input errors incrementing.

> No, there are no input or output errors increasing on serial 0:x during this
> failed calls. Only 'interface resets' and 'carrier transitions' are increasing
> by 1 after each failed call.
> Also there are no input or output errors on ser 0:15 and 'sh contr e1 0' shows
> no errors at all for the last 24h.

How about the router on the other side of the circuit - is it showing
input errors?

> > This is very likely simply caused by transmission problems
> > in your circuit network.

> Because of the above I doubt this.

If the far-side router is also not seeing input errors incrementing
on its B channel, then I would agree that this is unlikely to be 
a circuit error.

> > A less likely cause would be a problem in the AS5200, where
> > some particular timeslot in the E1 controller is misbehaving.
> > See if the failing calls are or are not associated with the
> > E1 timeslot.  If so, then this would be the 5200's fault,
> > not the PSTN's.

> When the problem occurs (about 24h after the last reboot??) about 9 out of 10
> dialins failed with the mentioned symptoms.
> Right after rebooting the AS5200 (almost?) every dialin-attempt is successful.

> During the first 3h on most B-channels were only succesful calls (21), on some
> were only failed calls (4) and on some were first succesful and later failed
> calls (3).

> The last thing we've changed before this problem was a RAM- and Flash-Upgrade
> combined with an IOS-Upgrade. Could this problem be related to a defective RAM
> chip?

No, I don't think so.  What IOS were you running before the upgrade?
Did you encounter this problem then?  What IOS are you running now?

It sounds like this may be CSCds23532, "PPP LCP negotiation doesnt 
start for ISDN calls after normal work", which was reported against
12.1(2) thru 12.1(4.2), but which reportedly did not happen with 
11.3(4)T or 12.0(9).  The problem went away when the AS5200 was replaced with
an AS5300, and the DDTS was marked unreproducible.

  Release-note: Modified 001030
  
  On a Cisco AS5200 series access server that is running Cisco IOS Release 
  12.1(2) and that has a PRI/E1 that receives only data calls that are PC 
  clients with a terminal adapter (TA), the access server may not receive 
  incoming PPP link control protocol (LCP) packets and cannot process any 
  further PPP LCP configuration requests. This situation occurs about once a 
  week. This situation does not affect Cisco access servers that are running 
  Cisco IOS Release 11.3(4)T.
  
  Workaround: Reboot the router.

Regards,

Aaron

---

> Memory seems OK before the reboot:
> ranke01#sh mem dead
>                 Head    Total(b)     Used(b)     Free(b)   Lowest(b)
> Largest(b)
> Processor      EA32C    15817940     3717648    12100292    11630320
> 12020164
>       I/O   20000000     4194304     1551900     2642404     2411572
> 2639100
> ...
> 2360 bytes dead Proceccor Mem

> Regards
>  Hauke Krull
> --
> Dipl.-Phys. Hauke Krull
> NetUSE AG
> Dr.-Hell-Straße, D-24107 Kiel, Germany
> Fon: +49 431 386435 00  --  Fax: +49 431 386435 99