Understanding ATM Technology: Asynchronous Transfer Mode & Broadband in Telecom, Lecture notes of Computer Networks

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Introduction

To ATM

What we will cover

Module 1 : B-ISDN and ATM Module 2 : ATM Concepts Module 3 : ATM Protocol Reference Model Module 4 : ATM Physical Layer Module 5 : ATM Layer Module 6 : ATM Service Categories Module 7 : ATM Adaptation Layers Module 8 : ATM Traffic Management Module 9 : Signaling in ATM Module 10 : Related Areas and Developments

Jargon Used

AAL: ATM Adaptation Layer SAAL: Signaling AAL UNI: User-Network Interface PNNI: Private Network-Network Interface PMP: Point-to-Multipoint LIJ: Leaf Initiated Join

Module 1

B-ISDN and ATM

B-ISDN Services

 (^) Conversational (or Interactive) Services  Real time end to end information transfer  Can be bidirectional or Unidirectional.  Telephone, Tele-education, video conferencing etc.

B-ISDN Services

 (^) Messaging Services  Communication via storage units (mailbox etc)  Emails, Video Mails

B-ISDN Services

 (^) Distributed Services  Video and Audio transmission services.  Electronic Newspaper  Video Services:

• (^) TV Program Distribution
• (^) Digital Video Library

Types of Transfer Modes

Different techniques to transfer Data and Voice:  (^) Circuit Switching (Voice Transfer)  (^) Packet Switching (Data Transfer)

Circuit Switching

 (^) A channel is identified by position of its time slots within the frame  A channel is assigned a fixed number of slots within each frame Channel 1 Channel 2 Channel n Frame Time Slot Framing Bit

Circuit Switching

 (^) Low Switching Delay : Switching in Hardware  (^) Low Delay Variance  (^) No overheads of Packetization  No routing, No link level Error Control

Packet Switching

 (^) Packet = User Data + Header  Header for Routing, Error and Flow Control  (^) Variable Packet Length  Complex link - to - link protocol  Error and flow control  (^) Store and Forward Switching  (^) Statistical sharing of resources

Packet Switching

 (^) Best Effort transfer  Due to congestion in switches, packet loss might occur  Resources are not reserved for different applications

Which Switching Technique do we use for B-ISDN?

Combine best Packet and

Circuit Switching Features

 (^) Flexible Bandwidth and Statistical Multiplexing  Packet Switching : Virtual Circuit  (^) Low Delay Variation (Jitter)  Fixed Route for all packets of the connection