Paper review : IP Multicast Channels: EXPRESS Support for Large-scale Single-source Applications (HC99)

• Goal
  To provide an IP multicast model based on the conventional model and solve the problems on accounting, security, and scalability, etc.

• Contribution
  This paper specifies the single-source multicast as an extension of IP multicast, demostrates its advantages for large-scale multicast applications, and adds the accounting support.

• Main ideas
  • The EXPRESS channel model is a straightforward extension to the conventional IP multicast model, and can be implemented using a simple protocol that requires no change to the current mechanisms in routers.

  • The EXPRESS channel model has many advantages w.r.t. the old group model, e.g., it provides a basis for charging, provides easier access control, and it's easier to scale.

• Evaluation
  • Significance rating: 3
    This paper proposes several drawbacks of the traditional group model for IP multicast, and presents the new channel model, which is based on the single-source multicast model. This is a promising try on the modification of the IP multicast model, but it does not solve all the problems.

  • Convincing rating
    The authors compare the new model and the protocol with the existing ones; hence analysis the cost and scalability with some calculations; they also simulate the counting overhead and the proactive counting. Now that the authors claim they care about the scalabilty problem most, and examplify the sports-tv.net several times in the paper, why don't they provide an experiment in the scale as large as the sports-tv.net application?

  • Limitation
    Although the channel model seems like better than the original IP multicast group model, I still doubt the scalability of the EXPRESS multicast, especially for the case of multi-source applications. Hence, I do not know whether it's easy to be deployed by the Internet in the near future.

• Conclusion
  How to provide a scalable multicast model is a challenging topic, all the other problems on multicast, such as accounting, safety, efficiency, etc., are all facing the scalability problem.

  11/14/01