Computer communications

Congestion control mechanisms for ATM networks as selected by the ATM Forum traffic management group are described. Reasons behind these selections are explained. In particular, selection criterion for selection between rate-based and credit-based approach and the key points of the debate between these two approaches are presented. The approach that was finally selected and several other schemes that were considered are described.

https://www.cse.wustl.edu/~jain/papers/ftp/cnis0.pdf

Congestion control and traffic management in ATM networks: recent advances and a survey

In this work, transcoding of pre-encoded MPEG-1, 2 video into lower bit rates is realized through altering the coding algorithm into H.261/H.263 standards with lower spatio-temporal resolutions. For this heterogeneous transcoding, we extract and compose a set of candidate motion vectors, from the incoming bit stream, to comply with the encoding format of the output bit stream. For the spatial resolution reduction we generate one motion vector out of a set of input motion vectors operating on the higher spatial resolution image. Finally, for the temporal resolution reduction we compose new motion vectors from the dropped frames motion vectors. Throughout the paper, we discuss the impact of motion estimation refinement on the new motion vectors and show that for all cases a simple half-pixel refinement is sufficient for near-optimum results.

/pdf/heterogeneous-video-transcoding-to-lower-spatio-temporal-1u4dkydd3e.pdf

Heterogeneous video transcoding to lower spatio-temporal resolutions and different encoding formats

Communication Networks--The center of the information revolution High performance networks are revolutionizing our lives in ways we cannot yet fully perceive. Meet your evolving needs with this in-depth presentation of emerging technologies used to build high speed, high performance communication networks. Authoritatively written, it explains how the converging telephone, data, and CATV technologies are combined into high performance networks, and how to plan, manage, and control these networks. An essential guide for networking professionals This book is well suited for a variety of networking needs. It enables network specialists and system administrators to make informed decisions for implementing and maintaining their companies' networks. It supplies network hardware and software developers with the tools to develop networking solutions, and it provides students in electrical engineering, computer science, operations research, and industry courses with a substantial introduction to networking principles. Features Explains the principles of network design and operation, and their implementation in state-of-the-art technologies such as Internet, high speed LANs and WANs, ISDN, ATM, BISDN, and SONET. Combines the perspectives of the communications engineer, the computer scientist and the economist to provide a system-level understanding of the core networking principles and technologies. Presents essential tools for analyzing, designing, and managing high performance networks. Provides unique coverage of economic issues including cost recovery and pricing schemes. Includes up-to-date coverage of delays, losses, admission control, routing, flow control, switching, networkplanning, pricing, and billing.

High-Performance Communication Networks

The authors examine the transport and storage of video compressed with a variable bit rate (VBR). They focus primarily on networked video, although they also briefly consider other applications of VBR video, including satellite transmission (channel sharing), playback of stored video, and wireless transport. Packet video research requires careful integration between the network and the video systems; however, a major stumbling block has resulted because commonly used terms are often interpreted differently by the video and networking communities. The paper then, has two main goals: (i) to clarify the definitions of terms that are often used with different meaning by networking and video-coding researchers and (ii) to explore the tradeoffs entailed by each of the various modalities of VBR transmission (unconstrained, shaped, constrained, and feedback). In particular, they evaluate the tradeoff among the advantages (better video quality, less delay, and more calls) that were identified by early proponents of VBR video transmission. An underlying theme of this paper is that increased interaction between the video and network design has potential for improving overall decoded video quality without changing the network capacity.

/pdf/vbr-video-tradeoffs-and-potentials-5bzxm0darr.pdf

VBR video: tradeoffs and potentials

The available bit rate (ABR) service has been developed to support data applications over asynchronous transfer mode (ATM) networks. The network continuously monitors its traffic and provides feedback to the source end systems. This article explains the rules that the sources have to follow to achieve a fair and efficient allocation of network resources.

Source behavior for ATM ABR traffic management: an explanation

ATM-UBR service responds to congestion by dropping cells when switch buffers become full. TCP connections running over UBR experience low throughput and high unfairness. For 100% TCP throughput, each switch needs buffers equal to the sum of the window sizes of all the TCP connections. Intelligent drop policies can improve the performance of TCP over UBR with limited buffers. The UBR+ service proposes enhancements to UBR for intelligent drop. The early packet discard scheme improves throughput but does not attempt to improve fairness. The selective packet drop scheme based on per-connection buffer occupancy improves fairness. The fair buffer allocation scheme further improves both throughput and fairness.

https://www.cse.wustl.edu/~jain/papers/ftp/icc97/icc_ubrp.pdf

UBR+: improving performance of TCP over ATM-UBR service

Erica+: extensions to the erica switch algorithm

We give a general definition of weighted fairness and discuss how a pricing policy can be mapped to general weighted (GW) fairness. The GW fairness can be achieved by calculating the excess fairshare (weighted fairshare of the left over bandwidth) for each VC. We show how a switch algorithm can be modified to support the GW fairness by using the excess fairshare term. We use ERICA+ as an example switch algorithm and show how it can be modified to achieve the general fairness. Simulations results are presented to demonstrate that, the modified switch algorithm achieves GW fairness. An analytical proof for convergence of the modified ERICA+ algorithm is given in the appendix.

https://www.cse.wustl.edu/~jain/papers/ftp/icnp98_bv.pdf

Rohit Goyal

Papers

Source behavior for ATM ABR traffic management: an explanation

UBR+: improving performance of TCP over ATM-UBR service

Erica+: extensions to the erica switch algorithm

A definition of general weighted fairness and its support in explicit rate switch algorithms

The erica switch algorithm for abr traffic management in atm networks: Part ii: Requirements and per