Interior Gateway Routing Protocol

What Does Interior Gateway Routing Protocol Mean?

Interior Gateway Routing Protocol (IGRP) is a proprietary distance vector routing protocol used to communicate routing information within a host network. It was invented by Cisco.


IGRP manages the flow of routing information within connected routers in the host network or autonomous system. The protocol ensures that every router has routing tables updated with the best available path. IGRP also avoids routing loops by updating itself with the changes occurring over the network and by error management.

Techopedia Explains Interior Gateway Routing Protocol

Cisco created Interior Gateway Routing Protocol (IGRP) in response to the limitations in Routing Information Protocol (RIP), which handles a maximum hop count of 15. IGRP supports a maximum hop count of up to 255. The primary two purposes of IGRP are to:

  • Communicate routing information to all connected routers within its boundary or autonomous system
  • Continue updating whenever there is a topological, network or path change that occurs

IGRP sends a notification of any new changes, and information about its status, to its neighbors every 90 seconds.

IGRP manages a routing table with the most optimal path to respective nodes and to networks within the parent network. Because it is a distance vector protocol, IGRP uses several parameters to calculate the metric for the best path to a specific destination. These parameters include delay, bandwidth, reliability, load and maximum transmission unit (MTU).


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Margaret Rouse is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical, business audience. Over the past twenty years her explanations have appeared on TechTarget websites and she's been cited as an authority in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine and Discovery Magazine.Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages. If you have a suggestion for a new definition or how to improve a technical explanation, please email Margaret or contact her…