Tuning Dynamically Routed Internet Protocol Networks to Achieve Controlled and Predictable Failover During Link Instability

Abstract

Internet Protocol (IP) based networks have evolved greatly in the past decade from small manually-configured networks connecting small numbers of sites into global self-healing dynamic networks that connect, literally, everyone. With the advent of network-centric warfare, the network has become more important than ever to our warfighters on the ground, in the air, and at domestic and international locations. To support such large, complex, and rapidly changing networks, dynamic routing was developed, including the Routing Information Protocol (RIP), Interior Gateway Routing Protocol (IGRP), Border Gateway Protocol (BGP), Open Shortest Path First, and finally, Enhanced IGRP (EIGRP). As networks have been extended from the strategic to the tactical levels, the speed at which the networks change has risen dramatically at the same time that the reliability of the links upon which they rely has dropped. Unfortunately, the networks that we rely upon have sometimes evolved faster than the dynamic routing technologies supporting them, resulting in network instability and configuration challenges as system operators scramble to keep things running in rapidly changing and unreliable environments. Dynamic routing is the obvious answer to this challenge, but several factors hamper its implementation in real-world, operational environments. One of these factors is the challenge of achieving consistent, reliable, predictable failover of routing from primary to secondary and tertiary paths when links become unavailable.