Cisco IGX 8400 Series Switches

Field Notice: ALM/A to ALM/A Virtual Path PVC via ALM/B Trunks Fails in 9.1 and 9.2

December 3, 1999

Products Affected




Only Virtual Path Connections (VPCs) are affected.

Problem Description

ALM/A-terminated Virtual Path Connections (VPCs) routed over ALM/B trunks will not pass data after upgrading from 8.2.5x to 9.1.09. No alarm or event is created to notify the user. Virtual Circuit Connections (VCCs) will continue to work properly after the software upgrade.

Similarly, while running 9.1 or 9.2 switch software, adding a VPC to ALM/A ports and routing over ALM/B trunks will appear to work but the VPC will not pass data.

This is a defect in 9.1 and 9.2 software, thus replacing the ALM/A or the ALM/B will not resolve the problem.


After upgrading from 8.2.59 to 9.1.09 the customer is unable to pass traffic on his ALM/A Virtual Path Connection over an ALM/B trunk. These are Gateway Type 5 connections: Cell VPC simple gateway. Gateway Type 2 ATM connections: Cell Forwarding VCC connections work fine and are not affected.

This problem has been observed with 9.1.09, 9.1.10 software, ALM/B C.B.H Firmware, ALM/A C.A.E Firmware. The resolution to this problem will be included in releases of 9.1 and 9.2 software.

Problem Symptoms

ALM/A VPC connections discard 100% of traffic when routed over ALM/B trunks when running 9.2 or 9.1 switch software. Use the command clrchstats slot.port.vpi.vci at both ends of affected VPC and then use the command dspchstats slot.port.vpi.vci to see if the cells from one end of the VPC are arriving at the other end of the VPC. If the "network-to-port" cell counts are not incrementing but the "port-to-network" cells are incrementing at the opposite end of the VPC, then use the dsptrkerrs slot# to see the below errors:

NODENAME       TN    StrataCom       IGX 8420  9.1.10    May  12 1999 18:24 GMT 

TRK  7       Status:Clear - OK                           Clrd:05/12/99 18:24:03
Statistical Alarm Count ETS   Status    Integrated Alarm  Count ETS   Status
Out of Frms           0     0           Comm Fails            0     -
Loss of Sig           0     0           Loss of Sig (RED)     0     -
Tx Voice Pkt Drp      0     0           AIS         (BLUE)    0     -
Tx TS Pkt Drp         0     0           Out of Frms (RED)     0     -
Tx Non-TS Pkt Drp     0     0           Rmt OOF     (YEL)     0     -
Tx CC Pkt Drp         0     0
Tx BData A Pkt Drp    0     0
Tx BData B Pkt Drp    0     0
Packet Err           15     2
Line Code Errs        0     0
P-bit Parity Errs     0     0
C-bit Parity Errs     0     0
                                        Last failure time: Date/Time Not Set 

This Command: dsptrkerrs 7

If the "Packet Errors" count is incrementing, implement the workaround shown below.


Workaround: Route ALM/A VPC connections over NTM or UXM trunks.

Solution: Releases 9.1.15 and 9.2.21 include the fix for this problem. Use CCO Bug Navigator Bug Watcher Feature to receive automated e-mail notifications of changes in the below bug status.


This problem has Cisco bug IDs CSCdm75494 and CSCdm38356. To follow the bug ID link below and see detailed bug information, you must be a registered user and you must be logged in.


CSCdm75494 (registered customers only)

CSCdm38356 (registered customers only)

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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