atm

ATM

PRADEEP THOMAS THUNDIYIL

Introduction

• Circuit Switched.• Cell Based.• Statistical Multiplexed.• Sophisticated QoS.• Virtual Path.• Virtual Connections.

ATM Service Categories

• The ATM layer supports five service categories:

• Real-time Services1. Constant Bit Rate (CBR)2. real-time Variable Bit Rate (rt-VBR)

• Non-real-time Services3. Non-real-time Variable Bit Rate (nrt-VBR)4. Unspecified Bit Rate (UBR)5. Available Bit Rate (ABR).

ATM Capacity Allocation

ATM Layer Diagram

AAL Layer Service Category

Network Priority Cell Loss

AAL 1 CBR, connection oriented, Circuit Emulation

CBR -1 Low

AAL 2 RT VBR , conn oriented, synchronous (doesn ve SAR)

RT VBR - 2 Med

AAL ¾ NRT ,async, connectless

NRT VBR - 3 Med

AAL 5 Similar to AAL ¾, simplified header

VBR , connection oriented async

ATM Cell Formation

Sublayers of AAL

Cell Header

Transmission Media

Virtual Path Switching

Receiver Modes

References

• http://www.techfest.com/networking/atm/atmaal.html• campus.murraystate.edu/tsm/tsm241/ATM.ppt• http://www3.rad.com/networks/2005/atmapp/applet.htm