Nortel Networks NN47200-503 manual Non-local static routes, Routing Information Protocol RIP

IP routing 23

Non-local static routes

The Nortel Ethernet Routing Switch 5500 Series supports the usage of non-local static routes. A non-local static route is almost identical to a static route with the exception that the next hop of the route is not directly connected to the network entity. Non-local static routes are useful in situations where there are multiple paths to a network and the number of static routes could be reduced by using only one route with a remote gateway.

Because of their static nature, this type of solution is not scalable. Thus, in a large or growing network this type of route management may not be desirable. Also, non-local static routes do not have the capacity to determine the failure of paths. Thus, a router can still attempt to use a path after it has failed.

Routing Information Protocol (RIP)

Routing Information Protocol (RIP) is a standard, dynamic routing protocol based on the Bellman-Ford (or distance vector) algorithm. It is used as an Interior Gateway Protocol (IGP). RIP allows routers to exchange information to compute routes through an IPv4-based network. The hop count, or distance, is used as a metric to determine the best path to a remote network or host. The hop count cannot exceed 15 hops (assuming a cost of one hop for each network).

RIP is defined in RFC 1058 for RIP version 1 and RFC 2453 for RIP version

2.The most significant difference between the two versions is that RIP version 2 supports subnet masks and next hop information in the RIP packet.

RIP operation

RIP uses User Datagram Protocol (UDP) data packets to exchange routing information. Each router maintains a routing table, which lists the optimal route to every destination in the system. Each router advertises its routing information by sending a routing information update at regular intervals. Neighboring routers use this information to recalculate their routing tables and retransmit the routing information. For RIP version 1, no mask information is exchanged; the natural mask is always applied by the router receiving the update. For RIP version 2, mask information is always included.

The sequence of processes governed by the routing algorithm is as follows:

1.When a router starts, it initializes the RIP data structures and then waits for indications from lower-level protocols that its interfaces are functional.

2.RIP advertisements are send on all the interfaces that are configured to send routing information.

Nortel Ethernet Routing Switch 5500 Series

Configuration-IP Routing Protocols

NN47200-503 03.01 Standard

5.127 August 2007

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