route loop-detect ospf disable

Usage Scenario

When routes are imported to an OSPF process, routing loops may occur. To prevent this problem, run the undo route loop-detect ospf disable command to enable loop detection for imported routes.If the device detects that an imported route was advertised by itself, it encapsulates the route with a large link cost before advertising the route. After learning the route, other devices preferentially select another path to prevent routing loops.

Precautions

OSPF uses Opaque LSAs to detect routing loops imported. Therefore, you need to run the opaque-capability enable command to enable the Opaque LSA capability.

After the device enters the loop breaking state, it cannot automatically exit the routing loop state and the alarm cannot be automatically cleared. In this case, manual intervention is required. For example, after a routing policy or route tag is correctly configured, run the clear route loop-detect ospf alarm-state command to exit the routing loop state and clear the alarm.

A single process supports loop detection for a maximum of 100,000 routes. If more than 100,000 routes are imported, routing loops cannot be detected for the excess routes. The system checks the number of routes for loop detection at 03:00 every day. If the number of routes for loop detection is less than 100,000, the system performs loop detection on these imported routes and some excess routes. The maximum number of imported routes for loop detection is still 100,000.

When the device advertises a large cost during the routing loop period, the apply cost command does not take effect in the routing policy.

Summary and NSSA routes do not support loop detection.

The default route advertised using the default-route-advertise command supports only loop detection and does not support self-healing.

Only the loops that occur during inter-process route import between two devices can be detected. If more than two devices are involved during inter-process route import, loops cannot be detected.

Router ID conflicts, including intra-AS and inter-AS router ID conflicts, are not supported because a router ID conflict may trigger a false detection.

When the OSPF process that imports a route also calculates a route with the same prefix and the two routes implement inter-process route load balancing, loops cannot be detected.