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MGCP traffic is dropped with log "Response to unknown Request. Bad Call-ID" after upgrade to R76 / R77 / R77.10 Technical Level
Symptoms
  • MGCP traffic is randomly dropped after upgrade to R76 / R77 / R77.10 with the following log:

    Protocol = udp
    Action = Drop
    Content Type = VoIP Session
    VoIP Log Type = Reject
    VoIP Reject Reason = MGCP content security violation
    VoIP Reject Reason Information = Response to unknown Request. Bad Call-ID
    

    Example:

  • Kernel debug ('fw ctl debug -m fw + mgcp drop') shows:

    ;mgcp_application_policy_validator: Entering;
    ;mgcp_validator: MGCP Syntax Validator finished successfully;
    ;mgcp_read_tid_table with tid=XXXX verb=XXX: getting data from tid table;
    ;mgcp_handle_response: trans_data: VerbString=XXX, CallID=XXX, isPortCommand=0;
    ;mgcp_verb_to_cmd_id: 5;
    ;mgcp_handle_response: Internal error, no call_id in mgcp_conn table ;
    ... ...
    ;fw_mgcp_manager: mgcp_analyze_packet returned 0;
    ... ...
    ;fw_mgcp_return_from_managers_func: ret from voip managers is: 0, mgcp_int_error_irrelevant=1 ;
    ;fw_conn_post_inspect: handler function returned action DROP;
    ;fw_log_drop_ex: Packet proto=17 ... dropped by fw_conn_post_inspect Reason: Handler 'mgcp_manager' drop;
    ;fw_filter_chain: fw_conn_post_inspect returned action DROP;
    ;fw_filter_chain: Final switch, action=DROP;
    ;After VM: <dir 0, ... IPP 17> (len=...) ;
    ;VM Final action=DROP;
    ; ----- Stateful VM inbound Completed -----
    
Solution
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