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    Overriding LNS Out-of-Resource Result Codes 4 and 5

    When the number of L2TP sessions reaches the configured maximum value, the LNS sends an out-of-resource result code (4 or 5) in a CDN (Call-Disconnect-Notify) message to the LAC. This signals the LAC to fail over to another LNS that has the resources for more sessions.

    Some third-party LAC implementations fail over only when they receive result code 2 sent in the CDN from the LNS. You can override result codes 4 and 5 with result code 2 on the LNS to enable such routers to fail over to another LNS. These codes have the following meanings:

    • 2—Call disconnected for the reason indicated in error code
    • 4—Call failed due to lack of appropriate facilities being available (temporary condition)
    • 5—Call failed due to lack of appropriate facilities being available (permanent condition)

    The following sections describe how to override the result codes and how to display the current code values.

    Overriding the Result Codes

    You can override the out-of-resource result codes 4 and 5 by issuing the session-out-of-resource-result-code-override command on the LNS.

    • To override result codes 4 and 5:

    Displaying the Current Override Setting

    You can view the current override setting for the LNS result codes in the L2TP destination profile.

    • To display the current override setting:
    ERX(config)#show l2tp destination profile boston
    L2TP destination profile boston
      Destination address
        Transport ipUdp
        Virtual router default
        Peer address
      Destination profile current session count is 0
    Host profile attributes
      Remote host is LAC
          Tunnel password is TunnelPass
          Local host name is LNS
          Local ip address is
          Disconnect-cause avp is enabled
          Tunnels are single-shot
          Override out-of-resource-result-code is enabled       
          Current session count is 0
    1 L2TP host profile found

    Published: 2014-08-20