understanding atm networks

Asynchronous Transfer Mode

Presented ByMr. Anirban Roy

4/4 B.Tech ECERoll No. - 04404

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Overview Introduction Why ATM? ATM Implementation example. Business & Profits ATM Switch Conclusions Questions and Suggestions

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Introduction ATM – Asynchronous Transfer Mode Past Situation

Emerged in 1990s but could not take off immediately because of cost of implementation

High cost mainly due to lack of technology to make fast ATM switches

Inability of organizations to use high bandwidth provided by ATM

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Introduction Present situation

Emergence of VLSI Technology to make fast transistor switching possible.

Increase in demand for fast networks. Lowering of prices for ATM switches and

Interface cards.

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What is ATM? A packet switching network. Connection oriented network. Simple concept

Data is broken down into cells ATM frame consists of 53 such cells

5 cells are used as header Remaining 48 cells are the payload

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Physical LayersLargely ‘physical layer’

independentE1, E3, DS3, OC3, OC12, etcMegabits rather than kilobits

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Why ATM? Incorporates variety of information

Voice, video, data, multimedia Applications in the field of:

Business Manufacturing Health Care Government Software Legal

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Why ATM? Lowers network costs because of a

common network. Higher Bandwidth Flexible Bandwidth QOS Standardization of equipment

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Implementation Example Sprint ATM Network Consists of ATM network with a

range of ATM switches and an Integrated Services HUB.

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Integrated Services

Hub (ISH)

LAN

Dedicated IP

VideoPBX systems

Managed Network Service

Fax Voice

Workstation

Cell Structure

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ATM Reference Model

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ATM AAL’sTraffic Class

Class A Class B Class C Class D

Adaptation Layer

AAL-1 AAL-2 AAL-3/4AAL-5 (SEAL)

AAL-3/4

Mode Connection Oriented

Connection Oriented

Connection Oriented

Connectionless

End-to-End Timing?

Yes Yes No No

Bit Rate Constant Variable Variable VariableExamples PCM voice,

constant bit-rate video

Variable bit-rate voice and video

Frame relay, SNA, TCP-IP, E-mail

SMDS

ATM Services

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Permanent Virtual Circuits (PVC’s)

Manual setup/static connectivity

Switched Virtual Circuits (SVSC’s)

Flexibility but establishment overhead.

Connectionless ServiceMost wireless devices.

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ATM Growth Results for backbone

technologies adopted obtained from studies by Infonetics Research.

IP and ATM are prevalent networks

MPLS Growing Fast Suggests Multi-service

networks.

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ATM QOS Results obtained

from Infonetics Research.

ATM dominant. MPLS growing fast.

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QOS.• QOS. traffic contract

Peak Bandwidth. Average sustained bandwidth. Burst size.

• traffic shaping Constrain data bursts. Limit peak data rate. Smooth jitters.

• and traffic policing Measures the actual traffic flow. Based on it set CLP of the offending cell to 1.

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Cisco BPX 8600 Series Switches Standards-based ATM

switch with advanced IP and ATM capabilities.

Designed to meet the demanding, high-traffic needs

Delivers high-performance ATM switching, multi-service adaptation and aggregation

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Cisco BPX 8600 Series Switches Up to 20 Gbps of high-

throughput switching Supports a wide range of

interfaces, from Frame Relay to full broadband subscriber interfaces

Also supports multi-protocol label switching (MPLS)

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Cisco BPX 8600 Series Switches Multi-shelf architecture

Allows users to incrementally expand the capacity of the system as needed and fully utilize the switch fabric

Advanced switching capabilities Intelligent call processing for

Frame Relay and ATM switched virtual circuits (SVCs)

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Cisco BPX 8600 Series Switches Reliability

Automatic Routing Management reroutes virtual circuits if a trunk fails

Scalability High service availability and

performance Robust, redundant

architecture

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Conclusions ATM network supports constant bit

rate and variable bit rate applications.

Organizations are able to run different applications using a common network.

Lower cost of implementation because of a single network.

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Conclusions ATM provides good QOS. Organizations using ATM networks

are earning profits. ATM is a network for the future. Compatible for implementing

MPLS.

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Conclusion

ATM Backbone Network of British Airways

Questions ?

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Q What is the purpose of the adaptation layer?Q What is the difference between UNI and NNI?Q Which adaptation layer is most frequently adapted and why?Q What is the one line advantage of ATM ?Q Main function of PNNI?

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References http://www.sprintbiz.com/bizpark/

products_services/network http://www.cisco.com/univercd/cc/

td/doc/pcat/bp8600.htm#ov http://telephonyonline.com/ar/

telecom_tough_crowd_sprint/ http://news.earthweb.com/xSP/

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