Interior gateway protocol

{{short description|Class of routing protocols}}

{{More citations needed|date=August 2022}}

{{Use British English|date=December 2020}}

{{IPstack}}

An interior gateway protocol (IGP) or interior routing protocol is a type of routing protocol used for exchanging routing table information between gateways (commonly routers) within an autonomous system (for example, a system of corporate local area networks).{{Cite web |date=2015-02-11 |title=Interior Gateway Protocols |url=https://www.ibm.com/docs/en/zos/2.1.0?topic=terminology-interior-gateway-protocols |access-date=2022-08-07 |website=www.ibm.com |language=en-us}} This routing information can then be used to route network-layer protocols like IP.

Interior gateway protocols can be divided into two categories: distance-vector routing protocols and link-state routing protocols. Specific examples of IGPs include Open Shortest Path First (OSPF), Routing Information Protocol (RIP), Intermediate System to Intermediate System (IS-IS) and Enhanced Interior Gateway Routing Protocol (EIGRP).{{Cite web |title=Interior Gateway Protocol - an overview {{!}} ScienceDirect Topics |url=https://www.sciencedirect.com/topics/computer-science/interior-gateway-protocol |access-date=2022-08-07 |website=www.sciencedirect.com}}

By contrast, exterior gateway protocols are used to exchange routing information between autonomous systems and rely on IGPs to resolve routes within an autonomous system.