Intel ER8100STUS - Express 8100 Router, Reference Manual

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Reference.bok : Chapter08 64 Wed Apr 22 10:58:08 1998
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Routing Information Protocol (RIP)
IP Routing
Routing Information Protocol (RIP)
Definition: RIP Routing information is exchanged by the Routing Information Protocol (RIP),
which is an Interior Gateway Protocol (IGP) based on a “Distance Vector Algo-
rithm”. RIP uses the User Datagram Protocol (UDP) to exchange routing infor-
mation.
RIP-1 and RIP-2
RIP based routing
Routers inform each other about present available paths (router links to other net-
works) by RIP updates. These are sent periodically (each 30 seconds) or trig-
gered by topology changes. Each router finds the best path to any known remote
network. If a router does not receive an update from an adjacent router for 180
seconds or more, it marks the routes served by the adjacent router as unusable.
RIP-1 and RIP-2
standards
The Intel Express 8100 Router supports both RIP-1 and RIP-2. RIP-1 is the orig-
inal standard as defined by RFC 1058. RIP-2 is an update of RIP-1 and is defined
by RFC 1723. RIP-1 and RIP-2 must be considered as separate protocols.
Important differences
between RIP-1 and RIP-
2 The most important differences between RIP-1 and RIP-2 are summarized as fol-
lows:
RIP-1 RIP-2
Network addresses must belong to
IP address class A, B or C. Supernet-
ting is not allowed and subnetting is
only allowed if the same subnet
mask is used throughout the net-
work. Network addresses are classless—vari-
able length network masks can be used
allowing supernetting and subnetting.
Routing updates do not contain sub-
net masks. Routing updates contain subnet masks.