3Com Switch 8800 Advanced Software V5 Configuration Guide

28
RIP CONFIGURATION
n
The term "router" in this document refers to a router in a generic sense or an
Ethernet switch running routing protocols.
When configuring RIP, go to these sections for information you are interested in:
■ “RIP Overview” on page 269
■ “Configuring RIP Basic Functions” on page 274
■ “Configuring RIP Advanced Functions” on page 275
■ “Optimizing the RIP Network” on page 279
■ “Displaying and Maintaining RIP Configuration” on page 283
■ “RIP Configuration Examples” on page 283
■ “Troubleshooting RIP Configuration” on page 287
RIP Overview RIP is a simple Interior Gateway Protocol (IGP), mainly used in small-sized
networks, such as academic networks and simple structured 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.
RIP Working Mechanism Basic concept of RIP
RIP is a Distance-Vector-based 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 is
known as metric. The hop count from a router to its directly connected network is
0. The hop count from one 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 bigger) is considered infinite, which means the destination network is
unreachable. That is why RIP is not suitable for large-scaled networks.
RIP prevents routing loops by implementing the split horizon and poison reverse
functions.
RIP routing table
Each 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.