Bug 10688 - ISDN outgoing calls often fails when used on satellite systems
Summary: ISDN outgoing calls often fails when used on satellite systems
Status: CLOSED OBSOLETE
Alias: None
Product: Drivers
Classification: Unclassified
Component: ISDN (show other bugs)
Hardware: All Linux
: P1 enhancement
Assignee: Karsten Keil
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2008-05-13 04:31 UTC by Goudal Francois
Modified: 2012-05-21 15:23 UTC (History)
2 users (show)

See Also:
Kernel Version: 2.6.18.8
Subsystem:
Regression: No
Bisected commit-id:


Attachments
Proposed patch for workaround (2.23 KB, patch)
2008-05-13 04:33 UTC, Goudal Francois
Details | Diff

Description Goudal Francois 2008-05-13 04:31:31 UTC
Latest working kernel version: none, as far as I know
Distribution: Debian 3.1
Hardware Environment: x86 machine + AVM Fritz! PCMCIA ISDN adapters
Problem Description:
When used on a satellite system, the I4L stack often fails to establish outgoing calls. This is due to timeouts in the I4L code that are more easily triggered because of the latency introduced by the satellite link. On an inmarsat system, I have faced more than 50% of failures, which is not really acceptable.

Steps to reproduce:
Buy an Inmarsat satcom system ;-) (Thrane M4, for example)
Connect your AVM Fritz ISDN card to it
Install the I4L driver (You probably prefer CAPI but you don't want the proprietary drivers from AVM so you don't have much choice)
Try to make linux dial a phone/dialup server on the ground using the satcom system.
Repeat the dialout several times, some of the attempts are probably going to fail.
Comment 1 Goudal Francois 2008-05-13 04:33:19 UTC
Created attachment 16123 [details]
Proposed patch for workaround

This patch proposes a workaround to the problem by multiplying by two the timeout values for the I4L subsystem.
This is proposed as a config option CONFIG_ISDN_SATELLITE.
Comment 2 Karsten Keil 2008-05-13 05:23:00 UTC
Yes this would be one possibility to address this. Maybe it would be better, if the general Dial timeout is configurable via a module parameter. I will have a look at this.

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