Dynamic RP relocation schemes considering networks centrality and bandwidth

Abstract

Among multicast routing methods, a Protocol Independent Multicast - Sparse Mode (PIM-SM), especially used in IPTV services, is based on core-based tree protocol. The core node of PIM-SM is called Rendezvous Point (RP). The PIM-SM can reduce resource usage such as bandwidth rather than the source-based tree protocol. The group members can join/leave with a multicast group by only sending JOIN/PRUNE messages to a RP. So, this property can help to be scalable easily. These benefits are known as considerable gain in the real networks. In the PIM-SM, the RP is very important node, because it handles all of traffic from sources and manages members`` join or leave. A centrality measurements is used to judge a important node. According to cretation of importance, there are various methods in centrality measurements like as degree, closeness, betweenness, and eigenvector. To reduce delay of traffic transmission, in this paper, the closeness centrality which minimizes average distance between other nodes is more proper to proposed schemes. This centrality can consider states of networks; and it help to arrive traffic fast to receivers. Also, the optimalized location of RP should be changed according to traffic states of networks. Because of a characteristic of PIM-SM, sources should send data to receivers first. In this time, it can use the unicast protocol. After that, the RP replicates data and transmits it to receivers in that multicast group. Like this, because all of traffic is centralized to the RP, it causes congestion at the RP. Therefore, users suffer delay and can``t have guaranteed QoS. Also, the PIM-SM doesn``t reflect states of networks so that it doesn``t place at an appropriate location. In the networks, links flowing traffic changes continuasely as changes of sources and receivers; and there are effectiveness of unwanted traffic flowing through paths except traffic from sources. Therefore, the RP should reflect traffic states of networks to distribut...