| Unicast Routing Control Agent for Proactive Diverse Link Selection
Sumit Khurana, Gi Tae Kim, Moncef Elaoud and Sunil Samtani
Applied Research, Telcordia Technologies, One Telcordia Drive, Piscataway, NJ 08854
Aristides Staikos
U.S. Army CERDEC, Fort Monmouth, NJ 07703
ABSTRACT
Routing within a single Open Shortest Path First (OSPF) area is completely determined by computing shortest paths on a topology graph. In conventional routing the link cost assigned to each edge on the graph is statically determined a-priori before the network is deployed. If subsequently, link quality degrades or alternate links become available, routing paths may become sub-optimal. The Unicast Routing Control Agent (URCA) being developed as a part of the PILSNER program dynamically changes link costs reacting to dynamic network conditions.
The goals of URCA are two-fold: 1) To ensure that links are evenly loaded. URCA attempts to set link costs that ensure that most links are utilized for carrying traffic. This has the result of maximizing the effective capacity or increasing the number of users that can be supported by a given network infrastructure. 2) To ensure that effect of soft link failures is minimized. In dynamic tactical environment with wireless links, link quality can be degraded due to congestion, blockage, mobility etc. URCA tries to route around degraded links ensuring that critical sessions are not degraded increasing the chances of a successful mission. These goals must be balanced against frequent network routing re-configuration which can be disruptive and oscillations where traffic moves back and forth between a set of links due to the reconfiguration.
This paper describes the functionality and design of the Unicast Routing Control Agent. We discuss the trade-offs that must be considered in designing an effective heuristic. We support our findings with results from a simulation study to evaluate the performance gains, such as the increase in aggregate throughput, from deploying URCA compared to the case where conventional routing is used.
|