What are Router Protocols?

A routing protocol specifies how routers communicate with each other. Each router only has prior knowledge of networks attached to it directly. Routing protocols facilitate router communication and overall network topology understanding.

A routing protocol specifies how routers communicate with each other and distributes information that enables them to select routes between any two notes on a computer network. Routing algorithms determine the specific choice route. A routing protocol shares information first with immediate neighbors and then throughout the network. Over time, the routers “learn” the topology of the network.

Routing Protocols:

  • IS-IS: The Intermediate System - Intermediate System protocol is an Interior Gateway Protocol (IGP) for the Internet, used to distribute IP routing information throughout a single Autonomous System (AS) in an IP network and runs on the data link layer (Layer 2).
  • OSPF: The Open Shortest Path First protocol is an Interior Gateway Protocol (IGP) for the Internet, used to distribute IP routing information throughout a single Autonomous System (AS) in an IP network. It only runs on the IPv4 subnet, while the IPv6 version runs on the link using link-local addressing.
  • IGRP: Interior Gateway Routing Protocol is a distance vector interior gateway protocol (IGP) used by routers to exchange routing data within an autonomous system.
  • EIGRP: Enhanced Interior Gateway Routing Protocol is an advanced distance-vector routing protocol for automating routing decisions and configuration.
  • RIP: Routing Information Protocol is one of the oldest distance-vector routing protocols which employ the hop count as a routing metric. RIP prevents routing loops by implementing a limit on the number of hops (15 total) allowed in a path from source to destination.
  • BGP: A protocol that manages how packets are routed across the Internet through the exchange of routing and reachability information between edge routers.