The Circular Route Detection Test (CRDT) is designed to detect circular routing and loops in MTP3 routeset lists that may not be prevented by Preventive TFP Procedures and associated checks. This test detects circular routes at runtime after configuration and closes the loop to minimize damaging effects to the network. The test is especially relevant in complex network configurations, where it is possible for loops to consist of several hops.
The CRDT is only defined for ANSI in SS7 networks and is only applicable for member routesets.
For more information about CRDT, see the GR-246-CORE, Issue T1.111.7 with additional details in GR-82-CORE, Issue 10, Section 4.2.6.
For more information about the SS7 Variant Specific Configuration, refer to Configuring SS7 Variant Specific Configuration Attributes.
Configure the CRDT Support attribute to ENABLED.
This attribute is ENABLED by default.
When the CRDT is enabled, the CRDT is triggered automatically if the link congestion level increases.
To manually perform a CRDT, navigate to the Routeset Details screen, and click CRDT under the Actions heading (refer to Configuring a Routeset). Following this instruction ensures that the CRDT is performed on the selected routeset.
When the CRDT is completed, if the current routes cause circular routing, this route is marked as ‘PROHIBITED_CRDT’ and no traffic is carried on the route.