Routing Information Protocol (RIP) is a distance-vector routing protocol. The Deep Edge implementation of RIP supports RIP version 2 (see RFC 2453) and RIPng (see RFC 2080).

RIP was designed for small IP networks and relies on hop count to determine routes; the best routes have the fewest number of hops. RIP is based on UDP and uses port 520 for route updates. By limiting routes to a maximum of 15 hops, the protocol helps prevent routing loops, but also limits the supported network size. If more than 15 hops are required, traffic is not routed. RIP also can take longer to converge than OSPF and other routing protocols.

When RIP is enabled, Deep Edge multicast requests for RIP updates from each of its RIP-enabled interfaces. Neighboring routers respond with information from their routing tables. Deep Edge adds routes from neighbors to its own routing table only if those routes are not already recorded in the routing table. When a route already exists in the routing table, Deep Edge compares the advertised route to the recorded route and chooses the shortest route for the routing table.

RIP uses hop count as the metric for choosing the best route. A hop count of 1 represents a network that is connected directly to the unit, while a hop count of 16 represents a network that Deep Edge cannot reach. Each network that a packet travels through to reach its destination usually counts as one hop. When Deep Edge compares two routes to the same destination, it adds the route having the lowest hop count to the routing table.

Similarly, when RIP is enabled on an interface, Deep Edge sends RIP responses to neighboring routers on a regular basis. The updates provide information about the routes in the Deep Edge routing table, subject to the rules that you specify for advertising those routes. You can specify how often Deep Edge sends updates, how long a route can be kept in the routing table without being updated, and, for routes that are not updated regularly, how long the unit advertises the route as unreachable before it is removed from the routing table.

When configuring RIP settings, make sure to specify the networks running RIP and any additional settings needed to adjust RIP operation on the Deep Edge interfaces connected to the RIP-enabled network.