H3C Technologies H3C SecPath F1000-E - Manual (Page 286)

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RIP Configuration
NOTE:
The term router in this document refers to both routers and Layer 3 switches.
RIP Overview
RIP is a simple Interior Gateway Protocol (IGP), mainly used in small-sized networks, such as academic
networks and simple LANs. RIP is not applicable to complex networks.
RIP is still widely used in practical networking due to easier implementation, configuration and
maintenance than OSPF and IS-IS.
Operation of RIP
Introduction
RIP is a distance vector routing protocol, using UDP packets for exchanging information through port
520.
RIP uses a hop count to measure the distance to a destination. The hop count from a router to a directly
connected network is 0. The hop count from a router to a directly connected router is 1. To limit
convergence time, the range of RIP metric value is from 0 to 15. A metric value of 16 (or greater) is
considered infinite, which means the destination network is unreachable. That is why RIP is not suitable
for large-scaled networks.
RIP routing table
A RIP router has a routing table containing routing entries of all reachable destinations, and each routing
entry contains:
• Destination address: IP address of a host or a network.
• Next hop: IP address of the adjacent router’s interface to reach the destination.
• Egress interface: Packet outgoing interface.
• Metric: Cost from the local router to the destination.
• Route time: Time elapsed since the routing entry was last updated. The time is reset to 0 every time
the routing entry is updated.
• Route tag: Identifies a route, used in a routing policy to flexibly control routes.
RIP timers
RIP employs four timers, update, timeout, suppress, and garbage-collect.
• The update timer defines the interval between routing updates.
• The timeout timer defines the route aging time. If no update for a route is received within the aging
time, the metric of the route is set to 16 in the routing table.
• The suppress timer defines how long a RIP route stays in the suppressed state. When the metric of
a route is 16, the route enters the suppressed state. In the suppressed state, only routes which come