A Framework for Integrated Services Over Shared and Switched Ieee 802 Lan Technologies

By Ghanwani, A.

Book Id: WPLBN0000659567
Format Type: PDF eBook:
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Reproduction Date: 2005

Title:	A Framework for Integrated Services Over Shared and Switched Ieee 802 Lan Technologies
Author:	Ghanwani, A.
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Language:	English
Subject:	Topology, Math, Technology
Collections:	Technical eBooks and Manuals Collection, Technical eBooks Collection
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Citation APA MLA Chicago Ghanwani, B. A. (n.d.). A Framework for Integrated Services Over Shared and Switched Ieee 802 Lan Technologies. Retrieved from http://gutenberg.cc/

Description
Technical Reference Publication

Excerpt
Introduction: The Internet has traditionally provided support for best effort traffic only. However, with the recent advances in link layer technology, and with numerous emerging real time applications such as video conferencing and Internet telephony, there has been much interest for developing mechanisms which enable real time services over the Internet. A framework for meeting these new requirements was set out in RFC 1633 [8] and this has driven the specification of various classes of network service by the Integrated Services working group of the IETF, such as Controlled Load and Guaranteed Service [6,7]. Each of these service classes is designed to provide certain Quality of Service (QoS) to traffic conforming to a specified set of parameters. Applications are expected to choose one of these classes according to their QoS requirements. One mechanism for end stations to utilize such services in an IP network is provided by a QoS signaling protocol, the Resource Reservation Protocol (RSVP) [5] developed by the RSVP working group of the IETF. The IEEE under its Project 802 has defined standards for many different local area network technologies. These all typically offer the same MAC layer datagram service [1] to higher layer protocols such as IP although they often provide different dynamic behavior characteristics -- it is these that are important when considering their ability to support real time services. Later in this memo we describe some of the relevant characteristics of the different MAC layer LAN technologies. In addition, IEEE 802 has defined standards for bridging multiple LAN segments together using devices known as MAC Bridges or Switches [2]. Recent work has also defined traffic classes, multicast filtering, and virtual LAN capabilities for these devices [3,4]. Such LAN technologies often constitute the last hop(s) between users and the Internet as well as being a primary building block for entire campus networks. It is therefore necessary to provide standardized mechanisms for using these technologies to support end-to-end real time services. In order to do this, there must be some mechanism for resource management at the data link layer. Resource management in this context encompasses the functions of admission control, scheduling, traffic policing, etc.

Table of Contents
Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . 3 2. Document Outline . . . . . . . . . . . . . . . . . . . . . 4 3. Definitions . . . . . . . . . . . . . . . . . . . . . . . 4 4. Frame Forwarding in IEEE 802 Networks . . . . . . . . . . 5 4.1. General IEEE 802 Service Model . . . . . . . . . . . 5 4.2. Ethernet/IEEE 802.3 . . . . . . . . . . . . . . . . . 7 4.3. Token Ring/IEEE 802.5 . . . . . . . . . . . . . . . . 8 4.4. Fiber Distributed Data Interface . . . . . . . . . . 10 4.5. Demand Priority/IEEE 802.12 . . . . . . . . . . . . . 10 5. Requirements and Goals . . . . . . . . . . . . . . . . . . 11 5.1. Requirements . . . . . . . . . . . . . . . . . . . . 11 5.2. Goals . . . . . . . . . . . . . . . . . . . . . . . . 13 5.3. Non-goals . . . . . . . . . . . . . . . . . . . . . . 14 5.4. Assumptions . . . . . . . . . . . . . . . . . . . . . 14 6. Basic Architecture . . . . . . . . . . . . . . . . . . . . 15 6.1. Components . . . . . . . . . . . . . . . . . . . . . 15 6.1.1. Requester Module . . . . . . . . . . . . . . 15 6.1.2. Bandwidth Allocator . . . . . . . . . . . . . 16 6.1.3. Communication Protocols . . . . . . . . . . . 16 6.2. Centralized vs. Distributed Implementations . . . . 17 7. Model of the Bandwidth Manager in a Network . . . . . . . 18 7.1. End Station Model . . . . . . . . . . . . . . . . . . 19 7.1.1. Layer 3 Client Model . . . . . . . . . . . . 19 7.1.2. Requests to Layer 2 ISSLL . . . . . . . . . . 19 7.1.3. At the Layer 3 Sender . . . . . . . . . . . . 20 7.1.4. At the Layer 3 Receiver . . . . . . . . . . . 21 7.2. Switch Model . . . . . . . . . . . . . . . . . . . . 22 7.2.1. Centralized Bandwidth Allocator . . . . . . . 22 7.2.2. Distributed Bandwidth Allocator . . . . . . . 23 7.3. Admission Control . . . . . . . . . . . . . . . . . . 25 7.4. QoS Signaling . . . . . . . . . . . . . . . . . . . . 26 7.4.1. Client Service Definitions . . . . . . . . . 26 7.4.2. Switch Service Definitions . . . . . . . . . 27 8. Implementation Issues . . . . . . . . . . . . . . . . . . 28 8.1. Switch Characteristics . . . . . . . . . . . . . . . 29 8.2. Queuing . . . . . . . . . . . . . . . . . . . . . . . 30 8.3. Mapping of Services to Link Level Priority . . . . . 31 8.4. Re-mapping of Non-conforming Aggregated Flows . . . . 31 8.5. Override of Incoming User Priority . . . . . . . . . 32 8.6. Different Reservation Styles . . . . . . . . . . . . 32 8.7. Receiver Heterogeneity . . . . . . . . . . . . . . . 33 9. Network Topology Scenarios . . . . . . . . . . . . . . . 35 9.1. Full Duplex Switched Networks . . . . . . . . . . . . 36 9.2. Shared Media Ethernet Networks . . . . . . . . . . . 37 9.3. Half Duplex Switched Ethernet Networks . . . . . . . 38 9.4. Half Duplex Switched and Shared Token Ring Networks . 39