Cisco WAN Switching Modules

Field Notice 980819: IMATM Protocol on UXM Fails

August 26, 1998

Products Affected

IGX-UXM with AAB fw

Problem Description

Y-redundancy on UXM with IMATM trunks may fail with trunk errors. There are three manifestations of this problem:

  1. IMATM protocol will fail on an UXM configured for IMATM equipped with either the BC-UAI-8-T1-DB15, BC-UAI-8-E1-DB15 or the BC-UAI-8-E1-BNC, BC-UAI-4-T1-DB15, BC-UAI-4-E1-DB15 or the BC-UAI-4-E1-BNC when one of the E1 or T1 links is failed and the user attempts to add the IMATM trunk.

  2. If one or more links fail on a configured and operating IMATM trunk, configured for Y-redundancy, and a switch of the active UXM occurs, the IMATM protocol fails and does not recover even after the failed link is re-established.

  3. IMA failure also occurs without Y-Redundancy in the following scenario:

    • uptrk slot.startport#-endport#, with retain links set to a value between 1 and number of links-1 and make sure all lines are up.

    • addtrk slot.startport#

    • After trunk is successfully added, one of the links fails. The trunk should still be Clear-OK state. If the UXM card resets or the node rebuilds due to power outage the IMATM trunk will remain in IMA protocol failure.

Problem Symptoms

The obvious symptom is that the IMATM trunk will be in a Major Alarm. Use the dsptrks command to check for this symptom. If the trunk failure isolates one or more nodes, unreachable nodes may be observed using the dspnds command.



The only workaround available is to delete the IMATM trunk, repair the failed link, and than add the IMATM trunk back. Additionally, setting the parameter "Retained links" using the cnftrk slot.startport to "1" will reduce the possibility of IMATM protocol failure when multiple links fail but will not prevent the failure in every instance.


The fix for this problem will be released in Firmware Version AAC or later. It is recommended that this firmware be obtained from CCO: Log in at CCO, and go to the Software Center to download a zip or tar file.

Bug Information

To follow the bug ID link below and see detailed bug information, you must be a registered user and you must be logged in.

View bug details for CSCdj62776 (registered customers only) .

IMA trunk cannot be added if one trunk is in alarm.

For More Information

If you require further assistance, or if you have any further questions regarding this field notice, please contact the Cisco Systems Technical Assistance Center (TAC) by one of the following methods:

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