Interior Gateway Routing Protocol

The Interior Gateway Routing Protocol ( IGRP ) is a in the 1980s developed by Cisco proprietary distance-vector routing protocol that is used by routers to exchange routing information within an autonomous system.

The objectives in the development of IGRP were mainly to improve the scalability and overcoming the specified RIP maximum number of 15 network nodes, which may be removed a target network before the network is considered unreachable. The maximum number of hops in IGRP is 255

IGRP may be used to create the cost metrics for the available bandwidth, the resulting delay in the path, the line load and the line reliability. The metric is calculated by the formula in IGRP

, For example, in a T1 line is 1544kbps

Is the delay time in microseconds, 10 units, is, for example at 20,000 microseconds delay

By default, the cost metric of a route from the bandwidth and the delay line is formed, ie and and.

To avoid routing loops split horizon method, hold down timer, Route Poisoning and Triggered Updates are used.

IGRP is deprecated and is no longer supported as of Cisco IOS v12.3. The EIGRP protocol has been used by Cisco as his successor.