Chapter 27. Routing Information Protocol; Distance Vector Protocol; Stability - Lenovo Flex System Fabric CN4093 Application Manual

Chapter 27. Routing Information Protocol

Distance Vector Protocol

Stability

© Copyright Lenovo 2015
In a routed environment, routers communicate with one another to keep track of
available routes. Routers can learn about available routes dynamically using the
Routing Information Protocol (RIP). Lenovo N/OS software supports RIP version 1
(RIPv1) and RIP version 2 (RIPv2) for exchanging TCP/IPv4 route information with
other routers.
Note: Lenovo N/OS 8.2 does not support IPv6 for RIP.
RIP is known as a distance vector protocol. The vector is the network number
and next hop, and the distance is the cost associated with the network number.
RIP identifies network reachability based on metric, and metric is defined as hop
count. One hop is considered to be the distance from one switch to the next, which
typically is 1.
When a switch receives a routing update that contains a new or changed
destination network entry, the switch adds 1 to the metric value indicated in the
update and enters the network in the routing table. The IPv4 address of the sender
is used as the next hop.
RIP includes a number of other stability features that are common to many routing
protocols. For example, RIP implements the split horizon and hold‐down
mechanisms to prevent incorrect routing information from being propagated.
RIP prevents routing loops from continuing indefinitely by limiting the number of
hops allowed in a path from the source to a destination. The maximum number of
hops in a path is 15. The network destination network is considered unreachable if
increasing the metric value by 1 causes the metric to be 16 (that is infinity). This
limits the maximum diameter of a RIP network to less than 16 hops.
RIP is often used in stub networks and in small autonomous systems that do not
have many redundant paths.
385