Cisco IGX 8400 Series Switches

Field Notice: UXM IMA with T1 Back Card Logs Trunk Failures upon Clock Switches of Node

October 30, 1998

Products Affected

IGX UXM with T1 backcard

Problem Description

The Universal Switching Module (UXM) inverse multiplexing for ATM (IMA) group using the T1 back card experiences "IMA Group Failure" when there is a clock switch on the node. This leads to temporary Communication Breaks and clock switches on downstream nodes if the failed trunk is the source of clock. This may result in unreachable nodes if there are no other types of trunks to the node. The IGX must experience a clock switch to trigger the "IMA Group Failure." This should not affect nodes using Internal Oscillator as the clock source.


Customers note network nodes being unreachable after a clock switch. The cause is unknown and is currently under investigation.

Problem Symptoms

Unreachability results if there are only IMA trunk groups to the node.


Remove IMA trunk group(s).

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: