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RIP Information
- Router interworking. Some routers do not support OSPF, and RIP may be the only common
dynamic discovery protocol in a heterogeneous environment. This often applies to
workstations, Unix machines or PC file servers used as routers.
- Router discovery. Many end user devices listen to RIP traffic to discover the local
router interface(s).
- Simplicity. RIP is simple to set up, and if a router has no complex choices to make on
alternate paths, then RIP is good enough.
Note that some of these "advantages" cause problems in real networks.
Misconfiguration of a Unix machine may generate illegal routes, and RIP will propagate
these through the internet unless route filters are used.
- Trust. The RIP protocol does not support checking for common faults and errors. All
routes sent by a router to others are assumed correct, even if no traffic can flow on the
return path.
- Slow convergence. RIP does not find new routes quickly when known routes fail. In
addition, more complex topologies with resilient routers can produce count to infinity
problems, where a spurious route is used and not discovered for several minutes.
- Poor metrics. RIP only supports a hop count metric, with a maximum value of 15 hops. It
is not practical to cost different speed links to bias traffic towards better routes
unless the network is simple and small.
In practise, a common requirement is to keep RIP for "local" routing (such as
router discovery), but use OSPF between routers to gain faster response.
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