ps drop caused by gtpu failure
DESCRIPTION
huawei ps dropTRANSCRIPT
PS drop call caused by GTPU failure【Phenomenon Description】In G country C project, We are reported that there
are some GTPU Failure caused call drop recently, but there is no such kind
of call drop before:
【Alarm Information:】none.
【Cause Analysis】 From log data and product code, we found it is caused by an inproper
process mechanism in the board GOUc. And this problem is triggered when
switch on Direct Tunnel (One Tunnel) in CN.
In the sceanario of Direct Tunnel, after RAB release due to User Inactive,
according to protocol, resoures of RAN side will be released, but PDP context
will be reserved between SGSN and GGSN. In the procedure of connection
reestablishment between SGSN and GGSN, GGSN will set the address of User
plane to SGSN. GTPU packet from GGSN will be sent via SGSN. Different to
single-core board, multi-core board GOUc will check the IP packet from source
at this time, and the result will be failure. So an Error Indication will be
triggered. Thus generate a GTPU Failure caused call drop.
【 Handling Process: 】 R&D had fixed this problem in the RNC version of
BSC6900V900R011C00SPH732 . After upgrade the RNC version, the problem solved.
【Suggestions and Summary】 When we meet some special value of drop calls, we should open
a ticket to R&D to analyze it. For us, it is better to read the document of precaution.