USITS 2001 Abstract
ALMI: An Application Level Multicast Infrastructure
Dimitrios Pendarakis, Tellium Optical Network Systems; Sherlia Shi, Washington University in St. Louis; Dinesh Verma, IBM T.J. Watson Research Center; and Marcel Waldvogel, Washington University in St. Louis
The IP multicast model allows scalable and efficient multi-party
communication, particularly for groups of large size. However,
deployment of IP multicast requires substantial infrastructure
modifications and is hampered by a host of unresolved open problems.
To circumvent this situation, we have designed and implemented ALMI,
an application level group communication middleware, which allows
accelerated application deployment and simplified network
configuration, without the need of network infrastructure support.
ALMI is tailored toward support of multicast groups of relatively
small size (several 10s of members) with many to many semantics.
Session participants are connected via a virtual multicast tree, which
consists of unicast connections between end hosts and is formed as a
minimum spanning tree (MST) using application-specific performance
metric. Using simulation, we show that the performance penalties,
introduced by this shift of multicast to end systems, is a relatively
small increase in traffic load and that ALMI multicast trees approach
the efficiency of IP multicast trees. We have also implemented ALMI as
a Java based middleware package and performed experiments over the
Internet. Experimental results show that ALMI is able to cope with
network dynamics and keep the multicast tree efficient.