GPRS unreliable: long lasting connection fail

Tom Yates madhatter at
Mon Jan 12 10:41:57 CET 2009

On Mon, 12 Jan 2009, Niccolo Rigacci wrote:

> On Mon, Jan 12, 2009 at 08:13:56AM +0000, Tom Yates wrote:
>> i use 2008.12 with gsm0710uxd, and i've had fairly long travelling GPRS
>> calls (15-20 minutes on the train back from london).
> Please tell me: with gsm0710uxd the connection is still done by
> pppd/chat?

it definitely is.  read my writeup at if you want to see 
exactly what i'm doing (my writeup's about 2008.09, but it's identical to 
the setup i just did for 2008.12 save that gsm0710muxd was in the 
repository so i didn't have to get the packages manually.

> I hope to last 12 hours or so, because I do GPS live tracking
> with position upload to the internet every 5/10 seconds.

my battery won't last that long!

> But the real problem is that if the connection fails, it will not
> restart again. I can add a cronjob to test connection and restart
> it, but I know that pppd should manage the fault.

i have *definitely* had pppd drop and autorecover the connection on 
shorter calls (eg, on the train - the cambridge-london line has tunnels on 
it, which provide a handy means of testing drop/recover).

i'm not sure that pppd is handling the autorecovery, though; i have a 
vague feeling it's the call handling between the calypso chip and the base 
station(s) that are responsible for setting up my GPRS connection again). 
i can post my ppp and ping logs next time i see this behaviour, if you'd 
like, so we can see if ppp even appears to notice the outage?


   Tom Yates  -

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