Preventing Routing Loops

RIPng is a distance vector routing protocol. Because RIPng devices advertise their routing tables to their neighbors, routing loops may occur.

RIPng prevents routing loops by using the following mechanisms:

Counting to infinity: RIPng defines the cost of 16 as infinity. If the cost of a route reaches 16 due to a routing loop, this route is considered unreachable.
Split horizon: Split horizon prevents a RIPng-enabled interface from sending back the routes it learns, which reduces bandwidth consumption and prevents routing loops.
Poison reverse: Poison reverse allows a RIPng-enabled interface to set the cost of the route that it learns from a neighbor to 16 (indicating that the route is unreachable) and then send the route back. After receiving this route, the neighbor deletes the useless route from its routing table, which prevents loops.
Suppression timers: Suppress timers can prevent routing loops and reduce the possibility that receiving incorrect routes results in incorrect routing information.

If both split horizon and poison reverse are configured, only poison reverse takes effect.

Before configuring RIPng to prevent routing loops on the network, complete the following tasks:

Configure IPv6 addresses for interfaces to ensure that neighboring nodes are reachable at the network layer.
Configuring Basic RIPng Functions

Perform one or more of the following configurations as required.

Configuring Split Horizon: You can configure split horizon to prevent routing loops.

Configuring Poison Reverse: You can configure poison reverse to prevent routing loops.

Configuring Suppression Timers: Suppression timers can prevent routing loops and reduce the possibility that receiving incorrect routes results in incorrect routing information.

Verifying the Configuration of Routing Loop Prevention: After configuring routing loop prevention, verify the running status of RIPng, information about interfaces, and RIPng routing information.