Cabletron Systems BRIM-A6 - page 46

Appendix B: ATM Overview

Page B-8 BRIM-A6 User’s Guide

Layer 3: The ATM Adaptation Layer vs. The Network Layer

Even though these two layers have the same “physical” location in their

perspective models, they are not alike. In the OSI model, the Network

Layer formats data to be sent out on a particular network (for example, IP,

or IPX). In the ATM model, since the Physical and ATM Layers take care

of all the information routing normally performed by the Networking

Layer, the ATM Adaptation Layer (AAL) acts as the ﬁrst link between the

ATM cell and the higher layer services.

In this role, the AAL provides the convergence sub-layer (CS) and the

segmentation and reassemble (SAR) sub-layer. When transmitting, the CS

prepares data from the higher layers to be converted into cells. The SAR

then segments the CS data into several 53 byte cells. Conversely, when

receiving ATM cells, the SAR recombines data received from the ATM

Layer and sends it to the higher layers.

book Page 8 Thursday, April 18, 1996 2:18 PM

Contents

Main BRIM-A6 Users Guide i NOTICE ii BRIM-A6 Users Guide VCCI NOTICE DOC NOTICE FCC NOTICE BRIM-A6 Users Guide iii EXCLUSION OF WARRANTY AND DISCLAIMER OF LIABILITY CABLETRON SOFTWARE PROGRAM LICENSE CABLETRON SYSTEMS, INC. PROGRAM LICENSE AGREEMENT Page BRIM-A6 Users Guide v DECLARATION OF CONFORMITY BRIM-A6 Users Guide vii CONTENTS Contents viii BRIM-A6 Users Guide CHAPTER 1 INTRODUCTION 1.1 USING THIS MANUAL 1.2 DOCUMENT CONVENTIONS 1.3 BRIM-A6 OVERVIEW 1.4 BRIM-A6 FEATURES 1.5 BRIM-A6 SPECIFICATIONS 1.6 RELATED MANUALS 1.7 GETTING HELP CHAPTER 2 INSTALLATION 2.1 UNPACKING THE BRIM 2.2 INSTALLING APIMS 2.3 INSTALLING BRIMS 2.3.1 Installing a BRIM in a MIM Chapter 2: Installation Page 2-4 BRIM-A6 Users Guide Figure 2-2 Removing the BRIM Coverplate Figure 2-3 Installing the BRIM 2.3.2 Installing a BRIM in a Hub Page CHAPTER 3 LOCAL MANAGEMENT Chapter 3: Local Management Page 3-2 BRIM-A6 Users Guide 3.1 LOCAL MANAGEMENT KEYBOARD CONVENTIONS 3.2 USING LIM TO CREATE PVCs 3.2.1 ATM Connection Tables Screen Fields 3.2.2 ATM Connection Tables Screen Commands 3.2.3 Using ATM Connection Tables Screen Commands 3.2.4 Adding PVCs to the Connection Tables Screen 3.2.5 Deleting PVCs from the Connection Tables Screen 3.3 USING LM TO CREATE PVCS 3.3.1 BRIM-A6 Setup Screen Fields 3.3.2 BRIM-A6 Setup Screen Commands 3.3.3 Using BRIM-A6 Setup Screen Commands 3.3.4 Accessing the BRIM-A6 Add/Delete Entry Screen 3.3.5 BRIM-A6 Add/Delete Entry Screen Fields 3.3.6 BRIM-A6 Add/Delete Entry Screen Commands 3.3.7 Adding a PVC 3.3.8 Modifying a PVC 3.3.9 Deleting a PVC BRIM-A6 Users Guide Page 4-1 CHAPTER 4 LANVIEW LEDs 4.1 BRIM-A6 LEDs Table 4-1 describes each of the BRIM-A6 LEDs. BRIM-A6 Chapter 4: LANVIEW LEDs 4.2 APIM LEDs Table 4-2 describes each of the APIM LEDs. APPENDIX A APIM SPECIFICATIONS A.1 APIM-11 SPECIFICATIONS A.2 APIM-21 SPECIFICATIONS A.3 APIM-22 SPECIFICATIONS A.4 APIM-29 SPECIFICATIONS A.5 APIM-67 SPECIFICATIONS APPENDIX B ATM OVERVIEW B.1 ATM BASICS B.2 THE ATM CELL Page B.3 THE ATM NETWORK B.3.1 VIRTUAL CHANNELS AND VIRTUAL PATHS B.3.2 PERMANENT AND SWITCHED VIRTUAL CHANNELS B.4 ATM PROTOCOL