Cisco WAN Switching Modules

Field Notice: Y-Redundant Universal Frame Relay Modules (UFMs) May Mismatch After 8.2.5 or 8.5 Upgrade to 9.1

Updated December 17, 1998

December 11, 1998

Products Affected




With Y.A.C. or later firmware loaded prior to upgrade to 9.1


With Z.A.H. or later firmware loaded prior to upgrade to 9.1


With Z.A.H. or later firmware loaded prior to upgrade to 9.1.

Problem Description

The Universal Frame Relay Module C (UFM-C) and Universal Frame Relay Module U (UFM-U) show mismatched backcards after upgrading from either 8.2.5 or 8.5 to the 9.1 release. The mismatch occurs when either an UFM-C or an UFM-U with firmware that supports the new Hot Standby 9.1 feature is installed in a node operating with either 8.2.5 or 8.5 switch software. The firmware that supports Hot Standby is listed in the Products Affected section of this Field Notice.

Problem Symptoms

The most observable symptom is seen in the dspcds or dspcd slot_number screens:

node            TN    StrataCom       IGX 8420  9.1.04    Nov. 20 1998 20:12 PST

Missing Cards: 2 UFMs, 2 E1Bs

FrontCard  BackCard                      FrontCard  BackCard

   Type  Rev  Type     Rev  Status          Type  Rev  Type     Rev  Status

1  NPM   BWJ                Active-T     9  Empty universal backplane   
2  NPM   BWP                Standby      10 CVM   BH13 E1       AN   Active
3  Empty universal backplane             11 Empty universal backplane
4  Empty universal backplane             12 UFMU  ADE  V35      AA   Active
5  Empty universal backplane             13 UFM   AE12 E1B      AB   Mismatch
6  BTM   BDL  BTM-E3   AF   Active       14 UFM   AE12 E1B      AA   Mismatch
7  Empty universal backplane             15 FRM   EHZ  FRI-T1   AL   Active-T
8  FRM   EJZ  FRI-E1   AF   Active-T     16 ARM   BA   ARI      ---  Standby


Switch Software Release 9.1 introduced an Availability feature on the UFM-C and the UFM-U called Hot Standby which allows Y-redundant pairs to switch over more quickly, thus reducing impact to customer data traversing the Y-redundant UFM when a switchover occurs. The Hot Standby feature on the UFM is implemented by upgrading both firmware and software.

Releases 8.2.5 and 8.5 do not support the Hot Standby feature. During an upgrade from these releases to 9.1, the flags for Hot Standby in 9.1 are set incorrectly, triggering the IGX to report the backcard mismatch state.


There are two workarounds.

  • Upgrade the UFM firmware (with Hot Standby support) only after upgrading the software to 9.1.

  • Delete the y-redundancy (delyred primary_slot_number) before upgrading the software to 9.1, and re-add (addyred primay_slot_number secondary_slot_number) it after upgrading to 9.1.

The first workaround is preferred and easier to implement. The second workaround should be used only if the user has already upgraded the UFM firmware, but has not yet upgraded the switch software to 9.1.

Bug Details

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View CSCdk68018 (registered customers only)

For More Information

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