Abstract
Dynamic routing and congestion control are two major problems in software-defined hybrid satellite-terrestrial multicast networks research. Due to terrestrial users being allowed to join or leave the multicast group at any time and the differences between the satellite and the terrestrial networks, many multicast routing algorithms reroute rapidly and thus increase the rerouting overheads. Meanwhile, the congestion ratio is increased by some hot nodes of satellite-terrestrial link transmission paths. This paper focuses on rerouting overheads and congestion problems in satellite-terrestrial multicast networks. We present a satellite-terrestrial network architecture with the Software-Defined Networking (SDN) features to offer dynamic multicast services for terrestrial users. A Two-Layered Shared Tree Multicast (TSTM) routing algorithm is proposed to achieve efficient dynamic multicast group management, address the trade-off between bandwidth consumption and rerouting overheads. The algorithm also implements congestion control by using a load factor to reflect on the global network bandwidth usage in routing calculations. This algorithm balances the rerouting frequencies of satellite and terrestrial networks to decrease the rerouting overheads and also reduces the network congestion ratio. The simulation shows TSTM decreases rerouting cost, user time delay, and node congestion ratio compared with the locality-aware multicast approach (LAMA).
Highlights
Compared with terrestrial communication systems, satellite communication systems have a wider coverage area
Considering the differences between satellite and terrestrial links, as well as avoiding the large cost caused by frequent routing updates in the dynamic hybrid networks, we proposed a two-layered shared tree multicast routing algorithm for satellite-terrestrial networks based on Software-Defined Networking (SDN), in order to create a reliable satellite-terrestrial multicast transmission network where a large number of users join and leave the multicast group dynamically
The results indicate that the proposed algorithm Two-Layered Shared Tree Multicast (TSTM) can reduce the resource consumption of tree building and the link cost generated by link distance
Summary
Compared with terrestrial communication systems, satellite communication systems have a wider coverage area. Considering the congestions caused by some hot nodes of satellite-terrestrial link transmission paths, a load factor for each node is introduced in TSTM to reflect on the bandwidth usage in routing calculations to decrease the congestion ratio. Since PIM-SM is efficient applicable for large satellite-terrestrial hybrid networks, we build dynamic shared multicast trees based on PIM-SM protocol with Tabu search for Rendezvous Point (RP) selection to decrease the average delay of multicast users. When new terrestrial users request joining or leaving the multicast group, considering the long delay of satellite link transmission and the frequent topology changes in terrestrial networks, a cost-aware rerouting algorithm is proposed to determine the topological scope and timing of rerouting to decrease the rerouting overheads.
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