| Range extension, originally a radio communications term, refers to use of intermediate nodes or special communication techniques to provide connectivity between two nodes that otherwise cannot communicate. In this paper, we describe network architectures for providing range extension service through an IP-based external network such as the Global Information Grid (GIG). In addition to using an external network when it is the only means for providing connectivity, the scenario where a user network has complete intra-domain reachability yet may choose to use a route provided by an external network is also considered. The former application may arise when a user network consists of geographically disparate sites or when a user network that is initially connected may become disconnected due to mobility. The latter can arise for load sharing across internal and external routes to better utilize bandwidth or when the external route has better Quality of Service (QoS) characteristics.
A wide range of solutions developed by the Internet Engineering Task Force (IETF) can be adopted for IP-based range extension. Potential solutions include Layer 3 and Layer 2 Virtual Private Networks (VPNs), use of IP tunnels, and modifications to the way that routes are redistributed between IGPs (e.g. Open Shortest Path First – OSPF) and exterior routing protocols (e.g. BGP). In this paper these solution alternatives are described, and subsequently compared using an extensive criteria including, for example, how complexity is distributed between the user network and provider network and how scalable, robust, and easy to manage they are. |
| FERIT YEGENOGLU received B.S. degrees in electrical engineering and physics from Bogazici University, Istanbul, Turkey, in 1986, an M.S. degree in electrical engineering in 1989, and a Ph.D. in information technology and engineering in 1992, both from George Mason University, Fairfax, Virginia. His research interests include Internet routing, traffic engineering, interworking of space and ground based networks, network optimization, and traffic and performance modeling. He is currently with Lockheed Martin, Integrated Systems and Solutions. He is a member of Eta Kappa Nu. |