Page 146 - DCAP207_NETWORKS_DCAP406_COMPUTER_NETWORKS

Unit 9: Network Layer

Notes
Figure 9.2: Hierarchical Routing

Routing protocol in such an Internet system can be broadly divided into two types:
Intra-domain routing
Inter-domain routing.

Notes Each of these protocols is hierarchically organized. For communication within a
domain, only the former routing is used. However, both of them are used for
communication between two or more domains.

Two algorithms, Distance-Vector Protocol and Link-State Protocol, are available to update
contents of routing tables.

RIP

It is a simple protocol based on the distance vector routing which uses the Bellman Ford algorithm
for calculating the routing tables.

Distance Vector Routing

Distance Vector Routing comes under the category of dynamic routing. Modern computer
networks believe in dynamic routing algorithms as compared to static routing algorithms. This
routing algorithm along with link state routing is the popular. Distance vector protocols are
RIP, Interior Gateway Routing Protocol (IGPR). In distance vector algorithm each router maintains
a routing table and exchanges its routing table with each of its neighbors so that their routing
tables get updated. Each router will then merge the received routing tables with its own table,
and then transmit the merged table to its neighbors. This is shown in Figure 9.3. This occurs
dynamically after a fixed time interval by default, thus requiring significant link overhead.

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