Cabletron Systems manual B-6 BRIM-A6 User’s Guide

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Appendix B: ATM Overview

When a message is sent out by a user:

It passes from the highest layer in the model, the Applications Layer, down to the lowest layer, the Physical Layer.

The Physical Layer physically transmits the message over a particular media.

When this message reaches its destination:

It passes upward, in the reverse order, from the Physical Layer to the Applications Layer.

Each layer strips off the information that was added by its counterpart on the transmitting end. What you inevitably end up with is the same thing you started out with -- the original message. See the arrow flow in Figure B-4.

Both the ATM model and the OSI model are comprised of seven layers. Fortunately, only the first three layers in each model differ. The following diagram illustrates the comparison between the ATM and the OSI models.

7

6

5

4

3

2

1

Application

Presentation

Session

Transport

ATM Adaptation

ATM

Physical

ATM Model

Application

Presentation

Session

Transport

Network

Data Link

Physical

OSI Model

7

6

5

4

3

2

1

Figure B-4 ATM Model vs. OSI Model

All of the upper layers (that is, Transport and higher) generally follow the same rules. The bottom three layers of the ATM model, however, replace the bottom three layers of the OSI model.

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BRIM-A6 User’s Guide

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Contents BRIM-A6 USER’S Guide BRIM-A6 User’s Guide Vcci Notice FCC NoticeDOC Notice Cabletron Software Program License Exclusion of Warranty and Disclaimer of LiabilityCabletron SYSTEMS, INC. Program License Agreement United States Government Restricted Rights Declaration of Conformity Contents Viii BRIM-A6 User’s Guide Using this Manual Chapter IntroductionDocument Conventions Following conventions are used throughout this documentBRIM-A6 Features BRIM-A6 OverviewBRIM-A6 Specifications Related ManualsEMI EMCGetting Help Chapter Installation Unpacking the BrimInstalling Apims Installing an ApimInstalling Brims Installing a Brim in a MIMRemoving the Brim Coverplate Installing a Brim in a Hub BRIM-A6 User’s Guide Chapter Local Management Local Management Keyboard Conventions Keyboard Conventions FunctionUsing LIM to Create PVCs ATM Connection Tables ScreenATM Connection Tables Screen Fields ATM Connection Tables Screen Commands Using ATM Connection Tables Screen CommandsAdding PVCs to the Connection Tables Screen Deleting PVCs from the Connection Tables ScreenUsing LM to Create Pvcs BRIM-A6 Setup ScreenVCI BRIM-A6 Setup Screen FieldsVPI BRIM-A6 Setup Screen Commands Using BRIM-A6 Setup Screen Commands Accessing the BRIM-A6 Add/Delete Entry ScreenBRIM-A6 Add/Delete Entry Screen Fields BRIM-A6 Add/Delete Entry Screen Commands Adding a PVCModifying a PVC Deleting a PVC Chapter BRIM-A6 LEDsApim LEDs Describes each of the Apim LEDsAPIM-21 Specifications Appendix a Apim SpecificationsAPIM-11 Specifications APIM-22 Specifications APIM-29 SpecificationsAPIM-67 Specifications BNCAppendix B ATM Overview ATM BasicsATM Cell Figure B-1 ATM CellsBRIM-A6 User’s Guide B-3 ATM Network Virtual Channels and Virtual PathsPermanent and Switched Virtual Channels ATM ProtocolB-6 BRIM-A6 User’s Guide BRIM-A6 User’s Guide B-7 B-8 BRIM-A6 User’s Guide