Bug #3937
Iu: verify handling of GMM Service Request (data)when no PDP Context present.
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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?
Related issues
History
#1 Updated by lynxis 6 months ago
- Related to Support #3920: PCAPs files of 3G PS for Osmocom network and Commercial one added
#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
#5 Updated by efistokl 6 months ago
- File sgsn-change-13744.zip sgsn-change-13744.zip added
#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/
#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
- File before.txt before.txt added
- File after.txt after.txt added
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.
