GSN Error Indication behavior

Pierre Kim admin at manateeshome.com
Sun Nov 11 06:00:50 UTC 2018


After some debugging I found that the intermittent data loss was caused
by the GSN not properly reacting to Error Indication packets.

>From GGSN:

<0002> ggsn.c:809 PDP(450091417013617:5): Packet received on
APN(internet): forwarding to tun apn0
<000d> gtp.c:2681 Packet from 192.168.27.49:2152, length: 24 content: 32
1a 00 10 00 00 00 00 40 8e 00 00 10 00 00 00 05 85 00 04 c0 a8 1b 31 :
Received Error Indication
<0002> ggsn.c:372 PDP(450091417013617:5): Deleting PDP context
<000d> pdp.c:255 Begin pdp_tiddel tid = 5716310714190054
<000d> pdp.c:262 End pdp_tiddel: PDP found


When the GGSN receives an error indication, isnt' it supposed to
acknowlege the SGSN and attempt to reinitialize the connection? In my
case the GGSN simply deleted the PDP context locally and both SGSN and
GGSN gets flooded by unknown PDP context error, while the phone keeps
trying to transmit data.

Tested on lastest git version and lastest release version: osmo-sgsn
1.3.0, osmo-ggsn 1.2.1


Regards,

Pierre




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