Interior Gateway Routing Protocol (IGRP)
A routing protocol invented by Cisco to succeed RIP. It is a distant –vector routing protocol created to overcome the limitations of RIP, (hop counts and metric) when in used within a large network. IGRP supports multiple metrics for each route, including bandwidth, delay, load, and reliability. The maximum hop count of IGRP-routed packets is 255 (default 100), and routing updates are broadcast every 90 seconds (by default).
IGRP is considered to be a classful routing protocol,because of its Inability to contain field for a subnet masking, the router assumes that all interface addresses within the same Class and network have the same subnet mask as the subnet mask configured for the interfaces in question. This is in contrast with classless routing protocols that can use variable length subnet masks. Classful protocols have become less popular as they are wasteful of IP address space.
