Paper Review: IP Multicast Channels: EXPRESS Support for Large-scale Single-source Applications

Reviewer: Mark Meras (mm446)

Main Contribution

This paper by Holbrook and Cheriton proposes a new extension to the IP multicast model called EXPRESS. EXPRESS creates a channel model for delivering large amounts of data from one source to many subscribers.

Key Ideas

Critique of Contribution

The new EXPRESS model seems to be a very important contribution to the field of IP multicasting. It uses an existing infrastructure (IP multicasting over TCP or UDP), requiring only a small-bandwidth protocol to keep track of the subscribers. It addresses the world-wide uniqueness problem of group-based IP multicast, and closely mimics the dynamics of other broadcast mediums, such as radio and television.

Open Question

How will the pricing schemes work for the sending host if the number of subscribing hosts cannot be determined beforehand? Will it be a "possible viewer" scheme that is currently used for cable TV, or can something more intelligent be proposed using the Counting feature of EXPRESS?