Cisco WAN Switching Modules

Field Notice: PXM-UI-S3 Clock not Working with PXM1 Resulting in CESM Failures

June 14, 2001

Products Affected




With PXM1

Problem Description

Clocking on a PXM-UI-S3 is not transferred to the MGX8250, MGX8230, or MGX8850 system.


The PXM-UI-S3 back card enables clock to be applied to the MGX8250, MGX8230 and MGX8850 shelves (equipped with PXM1). The clock source is used as a stable reference for the MGX shelf. This stable reference is used to clock Service Module Ports as well as the ports on the PXM1 card.

The anomaly displayed occurs when the following conditions are met:

  1. PXM-UI-S3 is installed in MGX8250, MGX8230 and MGX8850.

  2. PXM1 is also installed in MGX8250, MGX8230 and MGX8850.

It should be noted that this anomaly does not occur when the PXM-UI-S3 is installed in an MGX8850 equipped with a PXM45 or PXM45/B. If external clocking problems are encountered in these conditions, do not apply workarounds or solutions defined in this field notice.

Problem Symptoms

The symptom is card failure. However, clock-sensitive applications such as Circuit Emulation exhibit greater sensitivity to clocking anomalies. Hence, this trouble has been observed only on the circuit emulation service modules (CESMs) cards after a switch over of controller cards.



Replace PXM-UI-S3 with PXM-UI.


Currently, there is no solution that allows use of the PXM-UI-S3 with external clocking. The soonest available release that may contain a fix for this issue is 1.1.4x. Monitor the bug shown below to receive notification of the resolution of this issue.


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




Stratum3 clock - clock does not propagate to the Trunk card

Other Considerations

Cisco recommends verifying that the symptoms observed are due to the combination of circumstances outlined in the Background section of this field notice. Once this verification is complete, implement a workaround to resolve this isue as defined in the Workaround/Solution section.

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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