(Georgia Institute of Technology, 1998)
Ammar, Mostafa H.; Zegura, Ellen W.; Donahoo, Michael J.
A key technique for allowing a server to handle a large volume of
requests for file transfers is to multicast the data to the set
of requesting clients. Typically, the paths from the server to the
clients will be heterogeneous in bandwidth
availability. Multiple-Channel Multicast (MCM) is an approach that can
be used to handle this heterogeneity. In this approach the data is
multicast over multiple channels, each addressed as a separate
multicast group. Each receiver subscribes to a set of channels (i.e.,
joins the corresponding multicast groups) commensurate with its own
rate capabilities. Of particular interest in the design of MCM
schemes is the scheduling of data transmission across the multiple
channels to accomodate asynchronous requests from clients. In this
paper, we present and analyze a new multiple-channel multicast
approach called Partition Organization (PO) scheduling. The scheme is
designed to result in good reception efficiency when compared to
existing proposals while improving on their performance when other
measures of interest (which we introduce) are considered.
(Georgia Institute of Technology, 1995)
Donahoo, Michael J.; Zegura, Ellen W.
Efficient multicast communication provides one of the best avenues for
scaling bandwidth intensive applications. Current multicast
routing mechanisms perform well for multicast groups which reach a
long-term, steady-state distribution of membership. However, when
the membership migrates throughout the network, current routing
techniques may perform poorly. One type of multicast routing
technique involves selection of a "core" router through which all multicast
communication is routed. We propose to adapt this routing scheme
to efficiently support dynamic groups, by allowing the core to migrate.
As part of our work we provide solutions to several problems that are
more general, including estimating multicast bandwidth using unicast
information and soliciting responses from a limited number of participants
to avoid message implosion.
(Georgia Institute of Technology, 1995)
Calvert, Kenneth L.; Zegura, Ellen W.; Donahoo, Michael J.
Multicast routing is an important topic of both theoretical and practical
interest. Some recently-proposed multicast routing algorithms involve the
designation of one or more network nodes as the "center" of the routing
tree for each multicast group address. The choice of this designated router
(which we refer to as the "core") influences the shape of the multicast
routing tree, and thus influences performance of the routing scheme. In this
paper we investigate the relationship between the choice of core and three
performance measures. Specifically, we compare various methods of selecting
a core with respect to their effect on bandwidth, delay, and traffic
concentration. We conclude that simple methods are adequate for widely
distributed groups, but that the addition of group information can be
leveraged to improve performance especially when the group is small or
exhibits a high degree of locality. We also conclude that core choice has
a significant impact on traffic concentration, in fact traffic concentration
effects can be ameliorated by appropriate core choice policies.