## (7) IGRP Implementation

### Acacia Router - IGRP Configuration

Router(config)# router igrp 100 Router(config-router)# network 10.42.110.0 Router(config-router)# network 10.42.111.0 Router(config-router)# network 10.42.112.0 Router(config-router)# network 10.42.113.0 Router(config-router)# timers basic 15 45 0 60 Router(config-router)# no metric holdown Router(config-router)# metric maximum-hop 10

{note: maximum-hops was set to 10 because is more than enough to cover access to the public network, but not too much that traffic becomes unacceptable}

### Why IGRP

RIP is intrinsically limited in scaleability, due to an upper hop limit of 16. This severely limits it's use in any large scale environment, or a small scale one which needs to be scaleable such as the Acacia school LAN. IGRP has no such limitations, and uses four metrics to determine the best path, whereas RIP only uses one (hop-count). IGRP is also configurable to allow weightings for each metric to be specified, allowing finer control of the network traffic flow. IGRP is an effective routing protocol that is suited to our purposes, particularly thanks to mechanisms which allow us to avoid routing loops; specifically split-horizons, holddowns, and poison-reverse updates. IGRP also uses more detailed metrics to perform next hop calculations, and is a more efficient routing algorithm than RIP.

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Helpful Management Commands

ping & trace - allows us to test if the routing protocol is working.
show ip route - shows that IGRP is being used to route between subnets
show ip traffic - shows a summary of IP traffic statistics