Using RIPng in Your Network

The S- K- and 7100-Series device supports Routing Information Protocol Next Generation (RIPng). RIPng is a distance‐vector routing protocol for use in small networks; it is not intended for complex networks. RIPng is an Interior Gateway Protocol (IGP) in that it is used within a single Autonomous System (AS). RIPng is described in RFC 2080. A router, running RIPng broadcasts, updates at set intervals. Each update contains paired values where each pair consists of an IP network address and an integer distance to that network. RIPng uses a hop count metric to measure the distance to a destination and is not appropriate for situations where routes need to be chosen based on real-time parameters such as a measured delay, reliability, or load.

RIPng is conceptually the same as RIPv2 for IPv4. In essence, the IPv4 address is expanded into an IPv6 address. RIPng replaces the IPv4 subnet with an IPv6 prefix length. The next-hop header field is eliminated but the functionality is preserved. The route tag field is preserved. The maximum diameter (metric value) of the network is 15, assuming that a cost of 1 is used for each network; 16 still means the route is unreachable.

RIPng uses fixed metrics to compare alternative routes. The RIPng metric of a network is an integer value range of 1 - 15. Given that the maximum path limit is 15, the metric value is usually set to 1.

RIPng uses a UDP-based protocol and sends and receives datagrams on UDP port 521, which is used for all communications with another router‘s RIPng process. RIPng messages are either a request for all or a part of the receiving router‘s route table or a response that contains all or part of a sending router‘s route table.

Unsolicited response messages containing the complete routing table of the sending router are sent out every 30 seconds by default to every neighboring router. There are two timers associated with routing table entries. The expiration timer specifies when a route has expired. The expiration timer is initialized when a route is first established and each time an update is received for that route. The flush timer specifies when an expired route should be removed from the route table.

Each network has an IPv6 destination address prefix and prefix length associated with it.

Authentication has been removed from RIPng.