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Overview
RIP Versus OSPF
9-2
The distinction between RIP and OSPF lies in the fundamental
differences between distance-vector protocols and link-state
protocols. Using a distance-vector protocol, each router creates a
unique routing table from summarized information obtained from
neighboring routers. Using a link-state protocol, every router
maintains an identical routing table created from information
obtained from all routers in the autonomous system. Each router
builds a shortest path tree, using itself as the root. The link-state
protocol ensures that updates sent to neighboring routers are
acknowledged by the neighbors, verifying that all routers have a
consistent network map.
The biggest advantage of using RIP is that it is relatively simple to
understand and implement, and it has been the de facto routing
standard for many years.
RIP has a number of limitations that can cause problems in large
networks, including the following:
A limit of 15 hops between the source and destination
networks
A large amount of bandwidth taken up by periodic broadcasts
of the entire routing table
Slow convergence
Routing decisions based on hop count; no concept of link
costs or delay
Flat networks; no concept of areas or boundaries
OSPF offers many advantages over RIP, including the following:
No limitation on hop count
Route updates multicast only when changes occur
Faster convergence
Support for load balancing to multiple routers based on the
actual cost of the link
Support for hierarchical topologies where the network is
divided into areas
The details of RIP and OSPF are explained later in this chapter.
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