Welcome to IM's homepage!
IM is a multicast communication package, that allows a small group of hosts to setup a multicast session and communicate with each other simultaneously and efficiently. The communication channel is established using UDP unicast or IP-multicast and spreads out as a spanning tree. The middleware package is currently written in C++ on Windows.
ABSTRACT: The Internet nowadays consists of multicast-capable domains or "islands" interconnected by multicast-incapable routers. In order to achieve efficient global multicast, we propose and study Island Multicast (IM) where overlay connections are used between islands while IP multicast is used within an island. IM may use any existing application-level multicast protocol to build island overlay. We describe how to elect a representative (or leader) in each island for such a purpose. We also present the mechanisms for electing the bridging nodes for overlay connections. Using Internet-like topologies, we show that IM achieves much higher bandwidth efficiency as compared to using application-level multicast alone, at the cost of a small increase in end-to-end delay.
ABSTRACT: Island Multicast (IM) has been recently proposed to achieve efficient global multicast, where IP multicast is used within multicast-capable domains (the so-called islands) while overlay connections are used to bridge islands. In the previously proposed scheme, the number of ping measurements to find good bridge-nodes is at least proportional to island size, and a leader needs to keep track of all its members in the island. In this paper, we improve the system scalability by presenting a bridge-node selection algorithm where both the numbers of ping measurements and members to keep track of are greatly reduced to some constants.We further propose a recovery scheme for packets lost across islands. Our scheme uses a number of recovery meshes formed by overlays of some randomly chosen nodes. Simulation results show that our bridge-node selection is efficient in terms of control overhead and achieves scalability with little cost in network stress and delay. As compared to traditional source and parent recoveries, our loss recovery scheme substantially reduces both the recovery delay and bandwidth overhead to achieve reliability.
With the availability and penetration of multicastcapable
routers, many local networks in today’s Internet are
multicast-capable. However, achieving global IP multicast is still
hindered by many management and technical difficulties. This
is because routers interconnecting these local multicast-capable
networks, or so-called “islands,” are often either multicastincapable
or multicast-disabled. Traditional application-level
multicast (ALM) only makes use of unicast connections to form
delivery trees and has not fully taken advantage of the local
multicast capability of an island. As a result, these protocols are
not very efficient.
In order to achieve efficient global multicast, we propose and study Island Multicast (IM) where unicast connections are used between islands while IP multicast is used within islands. We present the detailed mechanisms of the IM centralized approach. IM is simple to implement and is based on minimum spanning tree, and hence is applicable to many-to-many communication. We have implemented the protocol and done real measurements on PlanetLab. We show that our protocol significantly improves network performance (in terms of stress, delay and nodal degrees) as compared to using ALM alone.