Bug #3937
open
Iu: verify handling of GMM Service Request (data)when no PDP Context present.
Added by lynxis over 4 years ago.
Updated over 4 years ago.
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?
Files
- Related to Support #3920: PCAPs files of 3G PS for Osmocom network and Commercial one added
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.
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
efistokl thanks for your patch! Comments are in gerrit.
- Status changed from New to In Progress
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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