At the time, Internet inter-domain routing technology was fairly rudimentary, and included a number of restrictions that imposed practical limitations on the growth of the network. In 1989, Rekhter, who worked at IBM’s Thomas J. Watson Research Center at the time, together with Kirk Lougheed, from Cisco Systems, designed the Border Gateway Protocol (BGP) to eliminate those limitations and provide a fully functional inter-domain routing system. As many good ideas do, BGP initially came to life on the back of napkins (three, to be exact).
The soundness of the basic BGP design is evidenced by the fact that it has served as the inter-domain routing protocol since the days when the U.S. Internet was a 13-node NSFNET backbone, a handful of regional networks, and the Advanced Research Projects Agency Network (ARPANET). Over 30 years later it serves as the Internet’s inter-domain routing protocol.
Over the course of many years Rekhter continued his work on the evolution of BGP, including developing, with Tony Li, BGP4, which brought Classless Inter-Domain Routing (CIDR) to the Internet. CIDR and BGP4 are core components that have been necessary to scale the Internet to its current size and usability.
Rekhter has also significantly influenced the development of the Internet as the co-author of 85 RFCs. An avid collaborator through the several decades of advancing BGP, Rekhter was also a co-developer of tag switching and Multiprotocol Label Switching (MPLS), routing techniques still used today to implement a wide variety of networking services.