A routing scheme for hierarchically structured LAN/WAN networks

The authors propose a routing scheme for multiorganizational networks structured hierarchically in a two-level LAN/WAN (local-area network/wide-area network) configuration. The targeted networks, besides being hierarchical, are small in size than the public internets. These two characteristics play a key role in identifying suitable routing mechanisms. The authors propose a simple area routing algorithm for the two-level LAN/WAN network. Its main features consist of a decentralized interarea routing algorithm, with centralized routing functions within areas for interarea routing only. The routing mechanism does not interfere with the operation of the local subnets. The operation of the routing centers is fairly simple and can easily be duplicated in all the gateway nodes for reliability. The gateway routing protocol is based on source routing and is very simple to implement, consisting of only a mapping function. It involves very little processing overhead at the transit gateways