[c-nsp] Dialup problems on a AS5300

[Vinny Abello]

Justin Shore wrote:
> We appear to be having dialup issues on one of our AS5300s. 
> Unfortunately they are not covered under a SmartNet (and can't be added 
> to a contract beginning Summer 06).  I've been hoping these things would 
> keep on working until we could kill our dialup offering but apparently 
> this one may be shooting craps on us.
> 
> I am not a access server buff and I'm not really sure what to look for. 
>   I see 47 modems marked as bad, 18 stuck in the download pending state, 
> and 35 active out of 192 modems.  Our average success rate has dropped 
> to 79%.  Some modems not yet marked as bad are down to 5x% success. 
> I'll send the 'sh modem' to anyone interested off list (too long for here).
> 
> This problem was believed to have been solved this AM before I got to 
> the office by our CO guys.  They disconnected each of the circuits, let 
> it error out, and then reconnected.  They thought this fixed the 
> problem.  I believe they simply kicked off the live customers, thus 
> fixing the busy signal issue.
> 
> Does anyone have any ideas what I can check?  What causes the 5300 to 
> think a modem is bad and is it really, in fact, bad?  I'm rather stumped 
> on this one.  I hate to take the spare 5300 out of our primary POP to 
> replace it because it died in the Spring during a physical move in the 
> CO.  We had to buy a grey-market PRI module to get it back online since 
> you can't buy new or refurb parts anymore.  These things had been 
> powered up and running for numerous years until this Spring when we 
> redid both POPs and moved them around.

Hi Justin,

I'm assuming you have MICA modems, and you didn't mention which IOS version you are running. It could actually be bad modems, but in my experience these types of things tend to happen due to IOS bugs. Usually a quick fix would be just to reboot the box. Sometimes configuring modem recovery helps this as well. Something like this:

modem recovery maintenance window 90
modem recovery maintenance action drop-call
modem recovery maintenance time 2:00
modem recovery maintenance stop-time 4:00
modem recovery maintenance max-download 5
modem recovery threshold 10


This will reload the firmware on the modems which can help prevent them from "going bad". I still don't understand why the MICA modems on Cisco boxes have problems like this. We used to use Livingston/Lucent Portmasters prior to switching to Cisco and we never heard of such a thing as a modem going bad or needing firmware reloaded. I think the premise of how modems in those competing boxes worked was entirely different though. I think everything in the Portmaster was software vs. the firmware loading on the AS5xx0's... but whatever.

You may also want to pose the same question in cisco-nas list. I don't know how active it is, but someone there may have better answers than I.

Good luck!

-- 

Vinny Abello
Network Engineer
vinny at tellurian.com
(973)940-6100 (NOC)
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