Cisco Signaling Controllers

Field Notice: Access Servers Require Redundant Link Manager V1 for RLM Connection to SC2200 Release 4.2(x)

Revised August 22, 2002

August 15, 2002

Products Affected



SC2200 Running 4.2(x)

The procedure below is for network access servers connected to an SC2200 system that is utilizing Redundant Link Management (RLM).

Problem Description

RLM does not function correctly when used with an SC2200 running software Release 4.2(x). This happens after upgrading to Cisco IOS version 12.0(6) or later in network access servers (AS5200, AS5300, or AS5800) using an RLM connection to the SC2200.


Cisco IOS 12.0(6) has a default RLM version that is not supported on the SC2200 running software release 4.2(x). It is therefore necessary to change the RLM version if Cisco IOS 12.0(6) is being used in this configuration.

Problem Symptoms

RLM may appear to operate with the default setting in Cisco IOS (RLM V2) to the level of 95%+ success rate. However, in error conditions where circuits or RLM signalling links have disruptions or short breaks, the RLM sessions can become confused and the network access servers effectively stop taking new calls.

The Cisco IOS show run command can show RLM V2 as part of the configuration.

Using the Cisco IOS debug rlm group x detail command can show "Invalid priority" errors.


For sites running Cisco IOS 12.0(6) or later in network access servers connected to the SC2200 running software release 4.2(x), the site will need to change the RLM configuration level in the network access servers from RLM V2 to RLM V1.

The following procedure should be used to migrate a network access server from using RLM V2 to RLM V1.

Note:?Clearing or restarting an RLM group may likely result in all calls present on the network access server being terminated.

  1. Enter configuration mode.

  2. Enter the rlm group 0 command.

  3. Enter the shutdown command.

  4. Enter the exit command.

  5. Enter the rlm version 1 command.

  6. Enter the rlm group 0 command.

  7. Enter the no shutdown command.

This will restart the RLM group. It can then be confirmed that RLM is operating in V1 mode by looking at the output of the sh rlm group stat command.

This procedure should be done on each network access server running Cisco IOS 12.0(6) or later connected to an SC2200 running release 4.2(x).

RLM V2 should be used for sites running software release 7.x(x) on their SC2200s.

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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