Page 148 - DCAP406_DCAP_207_Computer Networks

Unit 9: Network Layer

Notes
Did u know? In link-state protocols, there are no restrictions in number of hops as in
distance-vector protocols, and these are aimed at relatively large networks such as Internet
backbones. The load on routers will be large however, since processing is complex.

Figure 9.4: Routing Method - Link State Type

Dijkstra Algorithm: It calculates the shortest path between two points on network. The Dijkstra
graph is consisted of nodes and arches and nodes. It first selects a node tentatively. The algorithm
checks the tentative node against certain criteria to declare it as permanent node. The algorithm
starts with the roots of the tree, which is the local router and termed as local node. This node is
declared as permanent node and assigned a cost of 0. Thereafter, each neighbor node of this node
is examined to declare it last permanent node. And this node is assigned a cumulative cost .
Briefly, the link state routing deals with:

discovering its neighbor and learn their network addresses,
measuring the delay or cost to each of its neighbors,
constructing a packet indicating all it has just learned,

sending this packet to all other routers for their learning and
computing the shortest path to every other router.

Self Assessment

Fill in the blanks:
6. Distance Vector Routing comes under the category of ………………… routing.
7. Dijkstra’s algorithm is used to find the ………………. path to every other router.
8. …………………….. a simple protocol based on the distance vector routing which uses the
Bellman Ford algorithm.
9. Routing protocol in such an Internet system can be broadly divided into …………. types.
10. Routing inside an AS is called as ………………… routing.

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