Multicasting at the IP layer has not been widely adopted due to a combination of technical and non-technical
issues. End-system multicast (also called application-layer multicast) is an attractive alternative to IP layer
multicast for reasons of user management (set-up and control) and attack avoidance. Sessions can be established
on demand such that there are no static points of failure to target in advance.
In end-system multicast, an overlay network is built on top of available network services and packets are
multicasted at the application layer. The overlay is organized such that each end host participating in a multicast
communication re-sendsmulticasted messages to some of its peers, but not all of them. Thus end-system multicast
allows users to manage multicast sessions under varying network conditions without being dependent on specific
network conditions or specific network equipment maintaining multicast state information.
In this paper we describe a variety of proposed end-system multicast solutions and classify them according to
characteristics such as overlay building technique, management, and scalability. Comparing these characteristics
across different end-system multicast solutions is a step toward understanding which solutions are appropriate
for different battlespace requirements and where further research is needed.