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A TECHNINCAL PAPER PRESENTATIONAT

S K P engineering college,

Tiruvannamalai-606611

TAMIL NADU

ON

ATM NETWORKS

PRESENTED BY:

ASHISH GUPTA (Third Year)DEPARTMENT OF COMPUTER ENGINEERING

Room no.-303, Old Boys Hostel,

S.S.T.s COET, P.O. BOX NO. 94,

Bambhori, Jalgaon, (M.S.) INDIA

E-mail id: [email protected]

Phone no: (0120) 277 2915

SUHAIL THUSU (Third Year)

DEPARTMENT OF COMPUTER ENGINEERING

Room no.-110, Old Boys Hostel,

S.S.T.s COET, P.O. BOX NO. 94,

Bambhori, Jalgaon, (M.S.) INDIA

E-mail id: [email protected]

Phone no: (0191) 2574 050

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mailto:[email protected]:[email protected]:[email protected]:[email protected]


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ABSTRACT

We have heard of the promises of ATM for years but we have not seen this

technology realise its potentials, thats because one crucial challenge has not been met

the challenge of delivering high quality service for voice, video, and data traffic while

maintaining efficiency and holding down costs, this report provides an analysis about

third generation ATM is finally meeting this challenge using sophisticated methods of

managing traffic flows as well as intelligent new approach for managing availability

as well as simplifying management needs integrating legacy traffic and enhancing

scalability, this is combination that unlocks the promises of ATM at NET we call this

methods and products as Intelligent ATM.ATM was developed because of developing trends in the networking field. In

this information age, customers are requesting an ever increasing number of new

services. The most famous communication services to appear in the future are HDTV

(high definition TV), video conferencing, high speed data transfer, video phony, video

library, home education and video on demand. This large span of requirements

introduces the need of one universal network which is flexible enough to provide all

these services and that led to the definition of asynchronous transfer mode (ATM)

principle.

ATM is a proposed communication standard for broadcasting ISDN. It is a

high performance cell oriented switching and multiplexing technology that utilizes

fixed-length packets to carry different types of traffics. ATM reduces infrastructure

costs through efficient bandwidth management operational simplicity and

consolidation of overlay networks. ATM technology will allow core network stability

while allowing service interfaces and other equipment to evolve rapidly thats why we

call it 3G CONVERGENCE INTELLIGENT ATM.

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INTRODUCTION TO ATM

(ATM) is an international telecommunication Union-Telecommunication

standards section (ITU-T) standard for cell relay wherein information for multiple

service types, such as voice, video, or data, is conveyed in small, fixed-size cells,

ATM networks are connection-oriented.ATM is an evolving technology designed for

high speed transfer of voice, video and data through public and private network in a

cost effective manner.

NEED AND ROLE OF ATM IN INTERNETWORKS

Today 90% of computing power resides on desktops, and that power is

growing exponentially. Distributed applications are increasingly bandwidth hungry. In

the LAN band width is free and connectivity is limited. In the WAN band width has

been the overriding cost and delay sensitive traffic such as voice, has remained

separate from data.ATM has emerged has one of the technologies for integrating

LANs and WANs. ATM can support any traffic type in separate or mixed streams,

delay or non-delay sensitive traffic .ATM can also scale from low to high speeds. It

has been adopted by the industry equipment vendors, from LAN to private branch

exchange (PBX) with ATM network designers can integrate LANs and WANs,

support emerging applications with economy in the enterprise, and support legacy

protocols with added efficiency.

ATM DEVICES AND THE NETWORK ENVIRONMENT

ATM is a cell-switching and multiplexing technology this combines the

benefits Of circuit switching (guaranteed capacity and constant transmission

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delay)with those of packet switching(flexibility and efficiency for intermittent traffic).

It provides scalable bandwidth from a new megabits per second (mbps) to many

gigabits per second (Gbps). Because of its asynchronous nature, ATM is more

efficient than synchronous technologies station has much data to send, it can send

only when its time slot comes up, even if all time slots are empty. However, if as

station has nothing to transmit when its time slot comes up. The time slot is sent

empty and is wasted. Because ATM is asynchronous, timeslots are available on

demand with information identifying the source of the transmission contained in the

header of each ATM cell.

ATM NETWORKING

ATM DEVICES

An ATM network is made up of an ATM switch and ATM endpoints. An

ATM switch is well defined. It accepts the incoming cell from an ATM endpoint or

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another ATM switch. It then reads and updates the cell header information and

quickly switches the cell to an output interface toward its destination. An ATM

endpoint (or end system) contains an ATM network interface adapter. Examples of

ATM endpoints are workstations, routers, digital service units (DSU), LAN switches,

and video coder-decoder (CODEC)

STRUCTURE OF ATM NETWORK

ATM is based the concept of two end-points devices communicating by means

of intermediate switches. An ATM network is made up of series of switches and end-

points devices. The end point devices can be ATN- attached end stations, ATM-

attached end points, ATM attached servers, or ATM-attached routers.

User-to-User interface (UNI)

Network-to-Network interface (NNI)

Fig. Structure of ATM

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The UNI connection is made up of an end-point device and a private or public ATM

switch. The NNI is the connection between two ATM switches. The UNI and NNI

connections can be carried by different physical conditions. In addition to the UNI

and NNI protocols, the ATM forum has defined a set of LAN Emulation (LANE)

standards and a private Network to Network interface (PNNI) phase 0 protocols.

LANE is a technology network designers can use to integrate legacy LAN such as

Ethernet and Token Ring with ATM attached devices. Most LANE networks consist

of multiple ATM switches and typically the PNNI protocol.

GENERAL OPERATION OF AN ATM NETWORK

Because ATM is connection oriented, a connection must be established

.Between two end points before any data transfer can occur. This connection is

accomplished through a signaling protocol as shown in figure.

As figure shows, for router A to connect to Router B the following must occur.

Router A sends a signaling request packet to its directly connected ATM switch

(ATM switch 1)

Fig . Working of ATM

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1. ATM switch 1 resembles the signaling packet from Router A, and then

examines it.

2. If ATM switch 1 has an entry for Router B ATM address in its switch table

and it can accommodate the QoS requested for the connection, it set up the

connection and forwards the request to the next switch(ATN switch along path

2)

3. Every switch along the path to router B reassembles and examines the

signaling packet, and then forwards it to the next switch if the QoS parameter

can be supported. Each switch also sets up the virtual connection as the

signaling packet is forwarded.

If any switch along the path cannot accommodate the requested QoS parameters,

the request is rejected and a rejection message is sent back to Router A.

4. When the signaling packet arrives at Router B, router B reassembles it and

evaluates the packet. If Router B can support the requested QoS, it responds

with an accept message. As the accept message is propagated back to Router

A, the switches set up a virtual circuit.

5. Router A receives accept message from its directly connected ATM switch

(ATM switch 1) as well as the virtual path identifier (VPI) and virtual channel

identifier (VCI) others that it should use for cells sent to Router B.

ATM FUNCTIONAL LAYER

Just as an Open System Interconnection (OSI) reference model describes how

to computers communicate over a network, the ATM protocol model describes

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how to end systems communicate through ATM switches. The ATM protocol

model consists of the following three functional layers

ATM Physical layer

ATM layer

ATM adaptation layer

ATM SWITCHING OPERATION

The basic operation of an ATM switch is straightforward. The cell is received

across a link on known VCI or VPI value. The switch looks up the connection value

in a local translation table to determine the outgoing port (or ports) of the connection

and the new VPI/VCI value of the connection on that link. The switch then

retransmits the cell on that outgoing link with the appropriate connection identifiers.

Because all VCI and VPI have only local significance across a particular link, these

values are remapped, as necessary, at each switch.

DIFFERENT TYPES OF ATM SWITCHES

Even though all ATM switches perform cell relay, ATM switches differ

manually in the following ways:

1. Variety of interfaces and services that are supported

2. Redundancy

3. Depth of ATM internetworking software

4. Sophistication of traffic management mechanism

Just as there are routers and LAN switches available at various

price/performance points with different levels of functionality, ATM switches can be

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segmented into the following four distinct types that reflect the needs of particular

applications and markets.

1. Workgroup ATM switches

2. Campus ATM switches

3. Enterprise ATM switches

4. Multiservice access switches

ATM SIGNALING AND CONNECTION ESTABLISHMENT

When an ATM device wants to establish a connection with another ATM

device, it sends a signaling-request packet to it is directly connected ATM switch.

This request contains the ATM address of the desired ATN endpoint, as well as any

QoS parameters required for the connection. ATM signaling protocols vary by the

type of ATM link, which can be either UNI signals or NNI signals. UNI is used

between an ATM end system across ATM UNI, and NNI across NNI links.

Fig . ATM Signaling and Connection

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THE ATM CONNECTION-ESTABLISHMENT PROCESS

ATM signaling uses the one-pass method of connection setup that is used in

all modern telecommunication networks, such as the telephone network. An ATM

connection setup proceeds in the following manner. First, the source endpoints send, a

connection-signaling request. The connection request is prorogated through the

network. As a result, connections are set up through the network. The connection

request reaches the final destination, which either or rejects the connection request.

Fig. ATM Establishment

LAN EMULATION

LAN Emulation (LANE) is a standard defined by the ATM forum that gives to

station attached via ATM the same capabilities that they normally obtain from legacy

LAN, such as Ethernet and Token ring. As the name suggests, the function of the

LANE protocol is to emulate a LAN on top of ATM network. The LANE protocol

defines a service interface for higher-layer (that is. Network layer) protocols that is

identical to that of existing LAN. Data sent across the ATM network is encapsulated

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in the appropriate LAN MAC packet format. Simply put. The LANE protocols make

an ATM network look and behave like an ETHERNET LAN.

BENEFITS OF ATM

Distributed Architecture of ATM

Intelligent ATM minimizes the effect of failure with distributed architecture

when there is no single point of failure faults can be localized and have little or no

effect on overall network performance intelligent routing supports this approach by

instantly redirecting traffic around problem areas.

Fault Handling

Every network management platform should include intelligent features that

include the time it takes to identify and resolve network problems and keep downtime

to a minimum .For example alarm correlation provides a quick way to provide

meaningful information about the root causes and automated responses solve problem

faster.

In Service Upgrade

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Network availability should not be interrupted by hardware and a software

replacement in-service upgrade enables the network to continue operating throughout

making this activity.

Redundancy

Redundancy is important for preventing downtime but it must be provided cost

effectively that means matching the level of redundancy with the equipment role in

the network one to one redundancy is the system closest to the core for lesser the one

to n redundancy may be more cost effective this balance approach provides optimum

availability for the price.

LEGACY ACCESS TO ATM

Adaptation

Network interworking adopts flows to ATM carries across ATM network

adapts it back in its original format this provides the benefit of consolidated ATM

back pond while allowing non ATM services to be provisioned to end to end bases

service interworking adopts non ATM services to ATM and allowing and delivers it

in an ATM format for carrier this provision non ATM sites to communicate with an

ATM hub site.

Efficiency

Intelligent ATM makes efficient use of network resources with traffic

consideration of ATM switch port traffic aggregation and physical port

Leverage.

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CONCLUSION

3g Convergence Intelligent ATM is one of the evolving technology which

provides high quality service for voice, video and data traffic using sophisticated

methods of managing traffic flows as well as intelligent new approach for managing

availability as well as simplifying management needs integrating legacy traffic and

enhancing scalability, NET we called these methods and products as INTELLIGENT

ATM.

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REFRENCES

1) COMPUTER NETWORKS BY TANENBAUM

2) INTRODUCTION TO ATMBY GORALSKI

3) ATM NETWORK ADDISON- WELSLEY PUBLICATION.

WEB SITES

http://www.atmforum.com

http://www.ietf.com

http://cisco.com

http://itu.com

14 Intelligent ATM
http://www.atmforum.com/http://www.atmforum.com/http://www.ietf.com/http://cisco.com/http://itu.com/http://www.atmforum.com/http://www.ietf.com/http://cisco.com/http://itu.com/

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