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Cisco Bug: CSCus23820 - Issue in case of Collision of TAU on TAU procedure

Last Modified

Dec 25, 2016

Products (1)

  • Cisco ASR 5000 Series

Known Affected Releases

16.4.0.57696

Description (partial)

Symptom:
MME sending Modify bearer req to src sgw after sgw relocation

Conditions:
1. UE does combined TA/LA Update from 3G-->4G with AF not Set, MME does context information exchange successfully with SGSN
2. MME sends TAU ACCEPT in initial ctxt setup to UE/ENB.
3. eNB does not send initial ctxt setup successful outcome to MME immediately.
4. UE sends one more combined TA/LA update to MME having the same GUTI as received in TAU ACCEPT at step2 (but from a different eNB)
5. This new TAU from eNB2 is resulting in SGW relocation.
6. TAU with the new eNB proceeds until TAU COMPLETE after which MME seem to sending MODIFY BEARER REQ to SGW1 instead of sending to SGW2.
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