Routing and multicasting in satellite IP networks.

摘要

Satellite networks are envisioned as integral parts of the future global communications infrastructure. Satellite networks can enable network connectivity in remote areas, be deployed very fast by simply adding satellite network interfaces, and utilized as primary or back-up connection medium by geographically separated communications parties. However, the dynamic network topology of satellite networks that involve non-geostationary satellites turns routing into a very challenging problem. Although predictable, the satellite movements cause the connection structure to change within the network. In this thesis, the routing problem in satellite IP networks with dynamic connectivity is addressed. First, the issue of internal IP-based routing in the LEO satellite IP networks is addressed. The solution presented in this thesis forwards datagram packets between two points in the satellite network on minimum propagation delay paths. As an extension to this algorithm, a minimum overhead multicasting algorithm is described for the same environment, which carries multicast packets on source-based trees. The next routing algorithm introduced is designed for multi-layered satellite IP networks. The multi-layered satellite network proposed consists of several layers of satellites orbiting at different altitudes. The routing tables on-board the satellites are created and updated in a distributed manner following a hierarchical organization. Lastly, a protocol to accomplish the network layer integration of terrestrial and satellite IP networks is presented. With this protocol, the routes over satellite networks are discovered automatically and propagated to the rest of the routers in the Internet.