Recent researches consecrate their efforts to overcome multicast network problems by moving all the multicast functions and responsibilities from network layer (routers) to application layer ( terminal nodes (Users)).
Most of Application-Level Multi
cast (ALM)protocols rely on the idea that when a parent node leaves the overlay tree, all itspredecessors should re-join the tree again,which cause several re-organization operations in addition to the interruption of communication frequently. Membership Duration Aware ALM (MDA-ALM) protocol was suggested to solve this problem, it depends on the announcement of the expected membership duration for each new user in order to build a stable and efficient tree.
Although the performance of MD-ALM protocol is good, but it is based on membership duration parameter and this makes it more sensitive for the cheating and non-cooperative nodes. The main goal for the cheating nodes is to improve its position in the tree by trying to get the nearest position to the source node and to avoid having any children’s in order to relieve its load by manipulating the membership duration information.
Our research aims to find the best solution to detect the cheating nodes and cancel its affects in order to improve the performance of MDA against cheating. The simulation results improve that the proposed method detects effectively the cheating nodes.
Overlay multicast (Application-Level Multicast (ALM)) constructs a multicast delivery tree among end hosts. Unlike traditional IP multicast where the internal tree nodes are dedicated routers which are relatively stable and do not leave the multicast
tree voluntarily, the non-leaf nodes in the overlay tree are free end hosts which can join/leave the overlay at will, or even crash without notification. So, the leaving node can leave suddenly and cannot give its descendants (and the Rendez-vous Point (RP)) the time to prepare the recovering (the reconnection) of the overlay tree, and so there is a need to trigger a rearrangement process in which each one of its descendants should rejoin the overlay tree. In this case, all of its downstream nodes are partitioned from the overlay tree and cannot get the multicast data any more. These dynamic characteristics cause the instability of the overlay tree, which can significantly impact the user.
A key challenge in constructing an efficient and resilient ALM protocol is to provide fast data recovery when overlay node failures partition the data delivery paths. In this paper, we analyze the performance of the ALM tree recovery solutions using different metrics.
Application-Level Multicast (ALM) has been proposed as an alternative solution to
overcome the lack of deployment of the IP Multicast group communication model. It
builds an overlay tree consisting of end-to-end unicast connections between end-host
s
based on the collaboration of group members with each other. The efficiency of the
constructed overlay tree depends entirely on the honesty and on the cooperation of all
participating members. However such behaviour can not be guaranteed and some selfish
and non-cooperative nodes may take profit from the honesty of other members in the
overlay.
Recently, many researchers have been investigating the impact of selfishness of
nodes in the overlay multicast. Our contribution in this paper is to describe in detail the
basic algorithms used to construct the overlay tree, and evaluate the impact of cheating
nodes on the stability and on the performance of constructed overlay tree using these
algorithms.
Multi hop wireless networks face many challenges basically the
limitation of bandwidth, loss of packets because of many problems
in wireless medium also loss of paths because of the random and
unpredictable movement of wireless nodes, which reduce
the
performance of these networks. Recently, Network coding has been
used as promising technology that achieves the reliable transfer of
data in wireless networks with high throughput. Considering the
efficiency of this technology and with benefiting from both the
same cost paths and the broadcasting property of wireless medium,
a multi transmission mechanism for random linear network coding
has been proposed in multi hop wireless networks, which depends
on multicasting of coded packets on the same cost paths.
