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Bug #4616

closed

osmo-sgsn PS paging an MS on each DL ip packet received for it

Added by pespin almost 4 years ago. Updated almost 4 years ago.

Status:
Resolved
Priority:
Normal
Assignee:
Category:
-
Target version:
-
Start date:
06/16/2020
Due date:
% Done:

100%

Spec Reference:
TS 48.018 7.4 + 7.5

Description

2 phones attached to a network running current master of osmo-pcu, osmo-sgsn, osmo-ggsn, etc.

  1. phoneA (alcatel onetouch) is pinging 8.8.8.8 on a loop through adb shell.
  2. phoneB (motorola G something) calls phoneA, calls is established and works fine, and call is finished by phoneB.
  3. phoneB resumes ping (connecion becomes active) after call is finished, ping is working fine from MS point of view.

Then, at that point, each ICMP req (uplink) contains TLLI=0xABCD on bssgp, and SGSN forwards it to GGSN
When each ICMP REPLY is received from GGSN in the SGSN, the SGSN sends a PS-PAGING request in sgsn_libgtp.c:cb_data_ind() because it finds the MS in status ST_GMM_REGISTERED_SUSPENDED. At the same time it also allows the icmp reply to be forwarded back to the PCU so everything looks like working but the SGSN sends lots of PS-PAGING requests (one for each downlink icmp reply packet).

When each of these PS-PAGING requests arrive on the PCU, it sends a Paging Request Type 1 over CCCH, but the MS of course doesn't see those because it's already GPRS-attached and sending data....


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Related issues

Related to OsmoBSC - Bug #2249: RR GPRS suspension request is not forwarded to the GMM/SGSNResolvedosmith05/09/2017

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