Dynamic routing protocols have been used in networks since the late 1980s. One of the first routing protocols was Routing Information Protocol (RIP). RIP version 1 (RIPv1) was released in 1988, but some of the basic algorithms within the protocol were used on the Advanced Research Projects Agency Network (ARPANET) as early as 1969.
As networks evolved and became more complex, new routing protocols emerged. The RIP routing protocol was updated to accommodate growth in the network environment, into RIPv2. However, the newer version of RIP still does not scale to the larger network implementations of today. To address the needs of larger networks, two advanced routing protocols were developed: Open Shortest Path First (OSPF) and Intermediate System-to-Intermediate System (IS-IS). Cisco developed the Interior Gateway Routing Protocol (IGRP) and Enhanced IGRP (EIGRP), which also scales well in larger network implementations.
Additionally, there was the need to connect different internetworks and provide routing between them. The Border Gateway Protocol (BGP) is now used between Internet service providers (ISPs). BGP is also used between ISPs and their larger private clients to exchange routing information.
Figure 1 displays the timeline of when the various protocols were introduced.
Figure 2 classifies the protocols.
With the advent of numerous consumer devices using IP, the IPv4 addressing space is nearly exhausted; thus, IPv6 has emerged. To support the communication based on IPv6, newer versions of the IP routing protocols have been developed, see the IPv6 row in the figure.
RIP is the simplest of dynamic routing protocols and is used in this section to provide a basic level of routing protocol understanding.