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Authors:
James F. Kurose, Keith W. Ross
Chapter:
The Network Layer
Exercise:
Problems
Question:28 | ISBN:9780132856201 | Edition: 6

Question

Consider the network shown below, and assume that each node initially knows the costs to each of its neighbors. Consider the distance-vector algorithm and show the distance table entries at node z.


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Answer

Distance vector routing algorithm exchanges the information with the neighbors and works asynchronously.

 

According to the distance vector algorithm, any node m computes the distance vector using the following formulas:

 

 

Note: NA is used when there is no distance value.

 

Construct the distance vector table for node z from the network diagram:

Now update the table with costs of all the neighboring nodes.

Update the table with minimum costs using the distance vector routing algorithm:

 

Example: v to y, two paths are available. v-u-y and v-x-y with costs 3 and 6 respectively. So, v-u-y is the path with minimum cost. Hence update the table with this value.

 

Therefore, at node z, the above table will be computed by the distance vector routing algorithm.

 

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