Cisco IGX 8400 Series Switches

Field Notice 980925: The tstport Command on Frame Relay Modules (FRMs) Causes Port to Lock Up

October 12, 1998

Products Affected




The following two conditions must be met for this problem to occur:

  1. The FRM or Frame Relay PAD (FRP) Card port must be configured as V.35 DCE.

  2. The node must be operating with one of the following software releases:

    1. 8.4.21 or earlier 8.4 release

    2. 8.5.06 or earlier 8.5 release

    3. 9.1.03 or earlier 9.1 release

Problem Description

The tstport command leaves the remote ends of the connections stuck in test mode. The connections do not pass customer data while in this mode. Subsequent attempts to run tstport are not successful because the test aborts.


In addition to the two conditions required above, this issue does not occur on:

  • all connections that terminate on the tested Frame Relay port.

  • connections with both ends terminating in the same node. These are known as "daxed" or "daccsed" connections.

Problem Symptoms

The most obvious symptoms of this issue are user connections failing to resume passing data after the tstport command is issued. User applications time out and access to remote network resources over the affected connections is denied.

Issuing dspcons command results in a flashing "T" for the connections at the remote end, as shown in the sample output below:

6.1.102        igx         24.1.200       TOk     fst      0 
6.1.103        igx         24.1.400       TOk     fst      0

In addition to the above symptoms, the tstdelay command executed at the remote end of the affected connection returns the following message:

Cannot run while connection is looped.
Next Command:

Executing the tstdelay command at the near end of the connection results in an aborted delay test with the following error message:

Test delay aborted.
Next Command:


Two workarounds are available:

  • Issue a switchcc command on the node where the tstport command was executed to clear this condition, or

  • Delete and add the affected connections using the delcon and addcon commands.

As an alternative to using the tstport command, you can loop up the port using the addloclp slot.port command. Then, check the state of port using the dspportstats slot.port command. These two commands can serve the same purpose as tstport by verifying traffic flow through the port. Utilizing both of these commands can provide more details to help you better diagnose a port connectivity problem.


Upgrade the network to the appropriate maintenance release containing the fix. The maintenance releases containing the fix are not yet determined.


This defect is logged under bug ID CSCdk43947.

If you are a registered CCO user and you have logged in, you can view bug details.

CSCdk43947 (registered customers only)

Related Bug:

A related bug ID is CSCdj83509, which records that the tstport command works once after the upgrade to 8.4.16, but aborts on every subsequent attempt.

CSCdj83509 (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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