Cause value 102

Last Updated : Oct 15, 2014 |
[0x66/0xE6]

Recovery on timer Expiry

Cause

The equipment that sends this cause value sends or receives a Layer 3 Q.931 message. Sending or receiving this message has initiated a Layer 3 timer that has expired. This cause value is generated in conjunction with Q.931 protocol error handling procedures.

This cause value has local significance only. The ISDN network between the user and the equipment generating the cause value sends:

  • A no-cause indication through the network

  • A more generic cause value through the network

Communication Manager logs timer-expiry errors in the error log against the signaling group of the D-channel where the error occurred. The signaling group, ISDN-SGR, error is Error Type 1 and the Aux Data contains the identifier of the Layer-3 timer that expired.

Communication Manager does not generate the diagnostic information for the Cause value IE.

Proposed Solution

Procedure

  1. Check the diagnostic information for the timer number that has expired. See Event data 2.
  2. Check if the protocols at each end of the interface match, for example, both sides are AT&T Custom or both sides are NI-2.
    1. If the ends of the interface are using different protocols, then both ends are using the protocols with different values for their Layer-3 timers.
    2. If the protocols at each end of the interface match, the Communication Manager timer has expired because:

      • The remote end never processed the message because the message was corrupted by noise on the D-channel. Check for any type of T1/E1 facility errors.

      • The remote end experiences a high traffic condition, and due to time limitation, cannot parse the sent message before the timer expires.

      • Though the message is generated in an internal Communication Manager trace, the message never transmits out onto the D-channel. Perform an external protocol capture on the D-channel to confirm the transmission of the suspect message.

  3. To interpret the receipt of Cause Value 102 from the remote end, look at a trace/protocol capture of the messaging taking place, and locate the last message received from the remote end before Cause Value 102 is received.

    The timer that expired is most likely the Layer-3 timer associated with that last message. If Communication Manager generated a message in between those 2 events that must have stopped the timer, the cause is one of the following:

    1. The remote end never processed the message because the message was corrupted on the D-channel. Check for any type of T1/E1 facility errors.
    2. The remote end experiences a high traffic condition, and due to time limitation, cannot parse the sent message before the timer expires.
    3. Though the message is generated in an internal Communication Manager trace, the message never transmits out onto the D-channel. Perform an external protocol capture on the D-channel to confirm the transmission of the suspect message.

    If Communication Manager fails to respond to the last message received from the remote end, the internal hardware and software running Communication Manager must be checked before troubleshooting the problem.

    Communication Manager administration that can contribute to timer expiry errors:

    1. Trunk group form: Incoming call handling table. If you enter an incorrect value in the Per call CPN/BN field, Communication Manager sends a FACILITY message to the CO that causes CO to reject to the CPN/BN information. Communication Manager logs many timer expiry errors such as Error Type 1, Aux Data 13, against the signaling group.
    2. DS1 form: Protocol version: If Communication Manager uses protocol version A, and is connected to a Nortel DMS central office that uses custom protocol, Communication Manager logs timer expiry errors against signaling group for DISCONNECT problems (Error Type 1, Aux Data 4) during high traffic conditions.

    The DMS CO custom protocol implementation uses the ANSI-recommended timer values for their Layer-3 timers while Communication Manager uses the ITU-recommended timer values. The T305 timer in the Communication Manager is 4 seconds, while the same timer in the DMS is 30 seconds this difference causes timer expiry problems in high traffic conditions. Change the protocol version of Communication Manager to c to line up the timers.