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Network, IEEE

Issue 5 • Date Sept.-Oct. 2003

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Displaying Results 1 - 5 of 5
  • An evolution to crossbar switches with virtual output queuing and buffered cross points

    Page(s): 48 - 56
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (749 KB) |  | HTML iconHTML  

    Input queued (IQ) switch architectures with virtual output queues (VOQ) scale up to very high speeds and have been a subject of intense research in the past decade. VOQ IQ switches require switch matrix scheduling algorithms to match input ports to out ports. In this tutorial article, we present an overview of switch matrix scheduling for VOQ IQ switches with crossbar switch fabrics. We then describe what we believe will be the next generation of high-speed crossbar switches: the evolution of IQ switches to combined input and crossbar queued (CICQ) switches. With the continued increase in density of VLSI, sufficient buffering at crossbar cross points for one cell or packet has become feasible to implement. We show how CICQ switches have simple schedulers and result in lower delay than IQ switches. Both IQ and CICQ switches have unstable regions. We show how a threshold and bursting technique can feasibly achieve stability. We also show how CICQ switches are better suited (than IQ switches) for switching of variable-length packets such as IP packets. Many challenges remain in IQ and CICQ switches. In particular, the inclusion of QoS scheduling methods that are currently only suitable for output queued switches is a major open problem. View full abstract»

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  • Evaluation of transport protocols for the session initiation protocol

    Page(s): 40 - 46
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (736 KB) |  | HTML iconHTML  

    SCTP is a newly developed transport protocol tailored for signaling transport. Whereas in theory SCTP is supposed to achieve a much better performance than TCP and UDP, at present there are no experimental results showing SCTP's real benefits. This article analyzes SCTP's strengths and weaknesses and provides simulation results. We implemented SIP on top of UDP, TCP, and SCTP in the network simulator and compared the three transport protocols under different network conditions. View full abstract»

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  • Transport of TCP/IP traffic over assured forwarding IP-differentiated services

    Page(s): 18 - 28
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1435 KB) |  | HTML iconHTML  

    The Internet is facing a twofold challenge: to increase network capacity in order to accommodate a steadily increasing number of users; to guarantee the quality of service for existing applications and for new multimedia applications requiring real-time network response. In order to meet these requirements, IETF is currently defining the differentiated service (DiffServ) architecture, which should offer a simple and scalable platform to guarantee differentiated QoS in the Internet. In the DiffServ domain, the assured forwarding service is designed to provide data applications with acceptable performance, overcoming the limits of the Internet's current best-effort service. Since data applications mostly rely on the TCP transport protocol, it is important to examine the interaction between the congestion avoidance and control mechanisms of TCP and assured forwarding. Our main purpose is to shed light on this interaction, and to show that, in the current DiffServ framework, poor performance of TCP traffic flows can result from the existing mismatch between the assured forwarding traffic conditioning procedures and the TCP congestion management. We propose a new adaptive packet marking policy to deal with congestion situations that may occur. We show that, with this policy, the provisioned rate for TCP flows can be achieved. View full abstract»

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  • Key management approaches to offer data confidentiality for secure multicast

    Page(s): 30 - 39
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1261 KB) |  | HTML iconHTML  

    Multicasting is an efficient way to deliver data to a large group of users in applications such as Internet stock quotes, audio and music delivery, file and video distribution, etc. Many of these applications require the security feature of data confidentiality, which is not readily offered by the "open" nature of multicast. In order to offer such confidentiality, the encryption and decryption keys must be constantly changed upon a membership change. In this article, after discussing some performance criteria to offer secure multicast, we present a number of the proposed key management schemes for data confidentiality. We categorize these schemes into four groups: key tree-based approaches, contributory key agreement schemes supported by the Diffie-Hellman algorithm, computational number theoretic approaches, and secure multicast framework approaches. Through examples, we describe the operation of the schemes and compare their performances. View full abstract»

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  • Mobile number portability

    Page(s): 8 - 16
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (728 KB) |  | HTML iconHTML  

    Mobile number portability allows a mobile subscriber to switch operators without changing his/her telephone number. This article describes and analyzes mobile number portability routing mechanisms and their implementation costs. We first describe the signaling relay function (SRF)-based solution for call related and noncall related routing. Then we describe the intelligent network (IN)-based solution for call related routing. Cost recovery issues for number portability are discussed in this article from a technical perspective. We note that rules for cost recovery also depend on business and regulatory factors that vary from country to country. View full abstract»

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Aims & Scope

IEEE Network covers topics which include: network protocols and architecture; protocol design and validation; communications software; network control, signaling and management; network implementation (LAN, MAN, WAN); and micro-to-host communications.

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Meet Our Editors

Editor-in-Chief
Xuemin (Sherman) Shen, PhD
Engineering University of Waterloo