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Bug #3937

Iu: verify handling of GMM Service Request (data)when no PDP Context present.

Added by lynxis 6 months ago. Updated 5 months ago.

Status:
In Progress
Priority:
Normal
Assignee:
-
Category:
Iu interface
Target version:
-
Start date:
04/16/2019
Due date:
% Done:

0%

Spec Reference:
TS 24.008
Tags:

Description

What should the SGSN answer to GMM Service Request (type=data) when no PDP Context are active?
If there would be PDP Context, it should activate RAB Assignment Request to the RNC.

Should it ask the UE for the PDP Context Status and invalidate unknown PDP Contexts?
Should it sent GMM Service Reject?

sgsn-change-13744.zip sgsn-change-13744.zip 297 KB efistokl, 04/23/2019 12:36 PM
before.txt before.txt 8.27 KB manatails, 05/21/2019 10:27 AM
after.txt after.txt 11 KB manatails, 05/21/2019 10:27 AM

Related issues

Related to OsmoSGSN - Support #3920: PCAPs files of 3G PS for Osmocom network and Commercial oneIn Progress04/12/2019

History

#1 Updated by lynxis 6 months ago

  • Related to Support #3920: PCAPs files of 3G PS for Osmocom network and Commercial one added

#2 Updated by efistokl 6 months ago

#3 Updated by efistokl 6 months ago

lynxis wrote:

What should the SGSN answer to GMM Service Request (type=data) when no PDP Context are active?
Should it sent GMM Service Reject?

Yes, GMM Service Reject with cause # 40 (No PDP Context) works fine.

The problem is that sometimes Osmo-SGSN "hard-drops" PDP context - deletes it from itself and from GGSN but it doesn't send Deactivate PDP Context to the phone. So, the phone thinks that the PDP context is still active and doesn't send Activate PDP Context requests to the SGSN. I will post a patch in a moment.

#4 Updated by efistokl 6 months ago

Posted a patch here: https://gerrit.osmocom.org/#/c/osmo-sgsn/+/13744/

Attaching traces and logs for the patch above.

GTP packets between 2196-2218 are related to "hard-dropping" PDP context.
Packet 2311 - Service Reject which forces MS to reset its PDP contexts. (3GPP TS 24.008 Section 4.7.13.4 Service request procedure not accepted by the network. Cause # 40.).

Description:
10.0.2.52: femtocell nano3g ip.access S8
10.0.2.51: Osmocom network (without HLR and GGSN)
10.0.1.123 or 192.168.14.16: GGSN
172.48.1.5: HLR

#6 Updated by laforge 6 months ago

  • Tags set to TTCN3

#7 Updated by efistokl 6 months ago

lynxis may I ask you for a review or your opinion on this solution if you have time for this? https://gerrit.osmocom.org/#/c/osmo-sgsn/+/13744/

#8 Updated by lynxis 6 months ago

efistokl thanks for your patch! Comments are in gerrit.

#9 Updated by efistokl 5 months ago

  • Status changed from New to In Progress

lynxis wrote:

efistokl thanks for your patch! Comments are in gerrit.

Shall we mark it as "Resolved"? The patch https://gerrit.osmocom.org/#/c/osmo-sgsn/+/13744/ is merged.

#10 Updated by manatails 5 months ago

Some phones like iPhone 4 is unable to open data connection after this patch.

Attached are the logs from osmo-sgsn before and after the patch.

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