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Cisco Bug: CSCus63874 - Assertion at Function: mme_app_send_s11_modify_brr_req()

Last Modified

Feb 15, 2017

Products (1)

  • Cisco ASR 5000 Series

Known Affected Releases

18.0.0.58717

Description (partial)

Assertion failure at sess/mme/mme-app/app/mme_app_util.c:13704
Function: mme_app_send_s11_modify_brr_req()
Expression: sn_status != SN_STATUS_FAILURE

Symptom:
Assertion failure at sess/mme/mme-app/app/mme_app_util.c:13704
  Function: mme_app_send_s11_modify_brr_req()
  Expression: sn_status != SN_STATUS_FAILURE
  Proclet: sessmgr (f=87000,i=89)
  Process: card=8 cpu=1 arch=X pid=7874 cpu=~23% argv0=sessmgr
  Crash time: 2015-Jan-25+07:34:14 UTC
  Recent errno: 11 Resource temporarily unavailable
  Stack (60168@0xfffef000):
    [ffffe430/X] __kernel_vsyscall() sp=0xfffefef8
    [0b06c5cf/X] sn_assert() sp=0xfffeff38
    [08036da2/X] mme_app_send_s11_modify_brr_req() sp=0xffffcd08
    [080dd87a/X] mme_s1ho_to4g_arca_handle_reloc_complete_ack() sp=0xffffcd98
    [080ddde0/X] mme_s1ho_to4g_arca_handle_peer_path_failure() sp=0xffffcdb8
    [0808a0a2/X] mme_fsm_event_handler() sp=0xffffd268
    [080b90f3/X] mme_event_handler_s1ho_gen_to_4g_procedure() sp=0xffffd2a8
    [07f853a0/X] mme_procedure_handle_event() sp=0xffffd328
    [080bc921/X] mme_disp_handle_emm_evt() sp=0xffffd428
    [080bcf06/X] mme_s1ho_to4g_peer_path_failure_tmr_expiry() sp=0xffffd4a8
    [0536c414/X] tlib_serv() sp=0xffffd4f8
    [0536c054/X] tlib_tmr_tick() sp=0xffffd548
    [048d4262/X] snx_timer_service() sp=0xffffd558
    [048d216f/X] snx_fast_service() sp=0xffffd588
    [05fc153a/X] sessmgr_snx_tick_callback() sp=0xffffd5c8
    [0b10e3ba/X] sn_loop_run() sp=0xffffda88
    [0ae1236d/X] main() sp=0xffffdaf8
  Registers:

Conditions:
MME received HO Notify as part of S1 Handover progress over S3 interface with same SGW (2 PDNS - 1 being emergency PDN). MME sent Forward Relocation complete awaiting Acknowledgement.
Internal Peer (s3) path failure timeout fires.
MME treats S3 path failure as Fwd Reloc Complete Ack and attempts to send Modify Bearer Request to SGW.

However, the MME app SGW bearer state is MME_EGTPC_STATE_INACTIVE (21). This was not expected and thus, resulted in a failure.

QA testing environment:
After overnight run, chassis gets reloaded, and stargen and sitt instances does not stop. Also, after chassis comes up, sitt instances automatically start because it is running and call comes up (2G and 3G). No MME calls come up because lattice process loses association with chassis. Therefore, all lattice instances, which ran earlier stops and the call-models start again. This brings up 10k ENBs immediately, which results in a crash. This is a timing based crash, which is not easily reproducible.
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