SCCP Loop Detection

This feature detects SCCP looping of UDT/UDTS and XUDT/XUDTS messages. The SCCP Loop Detection feature requires a feature access key (FAK) for part number 893-0165-01 to enable the feature.

Normally, an STP sends GTT messages to the capability point codes (CPCs) of mated nodes for load sharing. However, approach can result in SCCP looping if the destination point code is the same as the originating point code or the point code of any intermediate in the network.

This looping can be resolved by eliminating the use of CPCs and verifying at an intermediate STP whether the OPC of the incoming MSU is the same as the true point code (TPC) of the DPC after GTT. However, CPCs are often used to implement LNP in addition to the SCCP.

The SCCP Loop Detection feature resolves the looping issue by providing a correlation between the MTP-designated TPCs/secondary point codes (SPCs) and the CPCs for all concerned STPs.

The SCCP Loop Detection feature is provisioned by configuring the Loopset Table and adding a loopset to a to a Global Title Translation.

The loopset commands define the correlation between MTP-designated point codes and the capability point codes of the STPs that detect SCCP looping. The GTT commands allow the administration, deletion, and retrieval of loopset table entries for a particular Global Title Translation.

The SCCP Loop Detection feature operates in Regular or Discard modes. In the Regular (default) mode, the SCCP Loop Detection Feature generates a UIM when it detects SCCP looping but does not discard the MSU. This UIM allows the operator to capture and verify MSUs throughout the system for SCCP looping. In the Discard mode, the SCCP Loop Detection feature generates a UIM when it detects SCCP looping and discards the MSU.

Provisioning the SCCP Loop Detection Feature

1. Enable the SCCP Loop Detection feature using the enable-ctrl-feat command. Perform the Activating the SCCP Loop Detection Feature procedure.

   Note:

   The SCCP Loop Detection feature can be turned on in this step using the chg-ctrl-feat command. If the SCCP Loop Detection feature is not turned on in this step, provisioning for the SCCP Loop Detection feature can still be performed. When the provisioning is completed, the SCCP Loop Detection feature can be turned on. The SCCP Loop Detection feature will not work until the feature is turned on in this step.
2. Provision the loopset table using the ent-loopset command. Perform the Adding a Loopset procedure.
3. Add a loopset to the global title translation using the ent-gtt or ent-gta commands. Perform Adding a Global Title Translation or Adding Global Title Address Information.