FLOODING: (STATIC ALGO)
- An incoming plot on one line is flooded on all other lines.
- A large no. of duplicate packet may be generated in this way.
- To control this duplication, a no. of methods may be used.
- Plot is discarded when count reaches Zero.
- A list of forwarded plot may be maintained & pkts flooded only once.
- A high probability of packets being delivered.
- Utilizes every path, Hence also uses shortest path.
- Wastes a lot of bandwidth.
- Looping of pkts.
- Static algo. Current b/w traffic & topology not taken into account.
- Distributed databases, military applications.
DISTANCE VECTOR ROUTING:
- Also called Bellman-ford algo.
- Each router maintains a distance table.
- The Null table contains a list of neighbour for a router say R, as well as the cost/distance to reach the neighbours.
- This knowledge is shared with all the neighbours & the neighbouring route is update their distance table accordingly.
- In this way, all routers discover the optional distance & the best total cost.
- Originally used in ARPA net, later replaced by link state & routing algorithm.
- Examples: RIPV1, RIPV2, IGRP.
- Bellman ford algo does not prevent routing loops.
- Suffers from Count-to-Infinity Problem.
DISTANCE VECTOR (contd):
- Routing info is only shared with immediate neighbours.
- A router can’t see beyond its neighbours so this aspect of distance-vector alog is called Routing by Rumour.