Electrical Engineering
      and Computer Sciences

Electrical Engineering and Computer Sciences

COLLEGE OF ENGINEERING

UC Berkeley

Multi-Party Real-time Communication in Computer Networks

Amit Gupta

EECS Department
University of California, Berkeley
Technical Report No. UCB/CSD-96-896
February 1996

http://www.eecs.berkeley.edu/Pubs/TechRpts/1996/CSD-96-896.pdf

The Internet has traditionally concentrated on availability: maintaining end-to-end connectivity in the face of unreliable systems and network congestion. Many emerging applications, however, require predictable performance and support for multi-party communication from the network service; at the same time, advances in networking technology have led to development and deployment of high-speed networks. The combined consideration of the stringency of the requirements of real-time communication and the high bandwidth provided by the new network technologies raise an interesting set of scaling and efficiency problems. This dissertation investigates mechanisms for supporting multi-party real-time communication in packet-switching networks.

We first present the work done by the Tenet Group at Berkeley in designing and building network protocols for supporting unicast real-time communication. These protocols serve as the framework for our research; given the framework, we describe a few salient issues that arise in multi-party communication: managing multicast group membership, supporting dynamic changes in these groups, and supporting heterogeneity in receivers. We then introduce the ideas that form the basis of the research effort: exploiting the characteristics of multi-party communication to improve the efficiency in using network resources; providing the network managers with effective ability to control the network resources; and providing a more usable service to the network users.

The traditional approach to supporting real-time communication allocates network resources to individual connections; this approach provides well-defined performance guarantees that are independent of other network traffic. To improve network resource utilization without sacrificing well-defined guarantees, we present resource sharing, which exploits relationships among connections to share resource allocations among them; the applications maintain complete control over the sharing as they explicitly specify these relationships. With resource sharing, for large conferences with a bounded number of concurrent speakers, resource requirements do not increase with the number of potential speakers. Therefore, resource sharing is an important tool for economically providing real-time performance guarantees for large conferences.

For real-time communication services to achieve widespread usage, it is important that the protocols and schemes provide good capability for the network's management to control the allocation of resources. For this capability, we present resource partitioning, i.e., distributing the different resources available at any system among a number of partitions. Resource partitioning can then be used to form virtual private sub-networks. These sub-networks have many applications: the network management can keep a small fraction of resources for management and fault-handling traffic, or for non-real-time traffic; and better support for mobile computing and for advance reservation of real-time connections.

Conferencing and other important distributed multi-party multimedia applications would benefit from a network service that provides support for advance reservations. The network service clients who wish to set up multimedia multi-party meetings need to schedule those meetings in advance to make sure that the participants will be able to attend, and would like to obtain assurances that the network resources will be available for the entire duration of the meeting. We have devised mechanisms for reserving resources for real-time connections in advance.

We have devised mechanisms for resource sharing, resource partitioning, and advance reservations; it is critical that these mechanisms work well together, and with other components of our real-time communication system (e.g., routing). We have designed and implemented the Tenet Protocol Suite 2, which incorporates these mechanisms to provide network support for multi-partyreal-time communication. Simulation results show that these mechanisms interact well with one another; preliminary results from a measurement study show that the protocols are effective in supporting guaranteed performance multi-party applications in an internetworking environment.

Advisor: Domenico Ferrari


BibTeX citation:

@phdthesis{Gupta:CSD-96-896,
    Author = {Gupta, Amit},
    Title = {Multi-Party Real-time Communication in Computer Networks},
    School = {EECS Department, University of California, Berkeley},
    Year = {1996},
    Month = {Feb},
    URL = {http://www.eecs.berkeley.edu/Pubs/TechRpts/1996/5358.html},
    Number = {UCB/CSD-96-896},
    Abstract = {The Internet has traditionally concentrated on availability: maintaining end-to-end connectivity in the face of unreliable systems and network congestion. Many emerging applications, however, require predictable performance and support for multi-party communication from the network service; at the same time, advances in networking technology have led to development and deployment of high-speed networks. The combined consideration of the stringency of the requirements of real-time communication and the high bandwidth provided by the new network technologies raise an interesting set of scaling and efficiency problems. This dissertation investigates mechanisms for supporting multi-party real-time communication in packet-switching networks. <p>We first present the work done by the Tenet Group at Berkeley in designing and building network protocols for supporting unicast real-time communication. These protocols serve as the framework for our research; given the framework, we describe a few salient issues that arise in multi-party communication: managing multicast group membership, supporting dynamic changes in these groups, and supporting heterogeneity in receivers. We then introduce the ideas that form the basis of the research effort: exploiting the characteristics of multi-party communication to improve the efficiency in using network resources; providing the network managers with effective ability to control the network resources; and providing a more usable service to the network users. <p>The traditional approach to supporting real-time communication allocates network resources to individual connections; this approach provides well-defined performance guarantees that are independent of other network traffic. To improve network resource utilization without sacrificing well-defined guarantees, we present resource sharing, which exploits relationships among connections to share resource allocations among them; the applications maintain complete control over the sharing as they explicitly specify these relationships. With resource sharing, for large conferences with a bounded number of concurrent speakers, resource requirements do not increase with the number of potential speakers. Therefore, resource sharing is an important tool for economically providing real-time performance guarantees for large conferences. <p>For real-time communication services to achieve widespread usage, it is important that the protocols and schemes provide good capability for the network's management to control the allocation of resources. For this capability, we present resource partitioning, i.e., distributing the different resources available at any system among a number of partitions. Resource partitioning can then be used to form virtual private sub-networks. These sub-networks have many applications: the network management can keep a small fraction of resources for management and fault-handling traffic, or for non-real-time traffic; and better support for mobile computing and for advance reservation of real-time connections. <p>Conferencing and other important distributed multi-party multimedia applications would benefit from a network service that provides support for advance reservations. The network service clients who wish to set up multimedia multi-party meetings need to schedule those meetings in advance to make sure that the participants will be able to attend, and would like to obtain assurances that the network resources will be available for the entire duration of the meeting. We have devised mechanisms for reserving resources for real-time connections in advance. <p>We have devised mechanisms for resource sharing, resource partitioning, and advance reservations; it is critical that these mechanisms work well together, and with other components of our real-time communication system (e.g., routing). We have designed and implemented the Tenet Protocol Suite 2, which incorporates these mechanisms to provide network support for multi-partyreal-time communication. Simulation results show that these mechanisms interact well with one another; preliminary results from a measurement study show that the protocols are effective in supporting guaranteed performance multi-party applications in an internetworking environment.}
}

EndNote citation:

%0 Thesis
%A Gupta, Amit
%T Multi-Party Real-time Communication in Computer Networks
%I EECS Department, University of California, Berkeley
%D 1996
%@ UCB/CSD-96-896
%U http://www.eecs.berkeley.edu/Pubs/TechRpts/1996/5358.html
%F Gupta:CSD-96-896