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ASYNCHRONOUS TRANSFER

MODEATM

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AGENDA Overview Definition ATM cells Characteristics Protocol Architecture Pros & cons Applications Case study Research Bibliography

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OVERVIEW ATM is a packet-oriented transfer mode. It

allows multiple logical connections to be multiplexed over a single physical interface. The information flow on each logical connection is organized into fixed-size packets, called cells. As with frame relay, there is no link-by-link error control or flow control.

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ATM – DEFINITION"A transfer mode in which information is organized

into cells; it is asynchronous in the sense that the recurrence of cells containing information from an individual user is not necessarily periodic".

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ATM CELLSThe ATM cell has 53 bytes, containing 5 bytes of header and 48 bytes of information.

The advantages of this small and fixed cell size are: Cells can be switched more efficiently. Cell size is fixed. Queuing delay is reduced.

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ATM CHARACTERISTICS

ATM uses packet switching with fixed length packet of 53 bytes – CELLs.

ATM uses Virtual Circuits ATM can run over any physical layer. A Cell network uses the cell as the basic unit of data

exchange. ATM uses asynchronous TDM

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ATM PROTOCOL ARCHITECTURE

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Physical layer: Involves the specification of transmission medium and

the signal encoding scheme. Data rate specified in this layer 155.52Mbps and

622.08Mbps.ATM layer: Provide packet transfer capabilities. Defines transmission of data in fixed size cells. Define the use of the logical connection.

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ATM Adaptation Layer(AAL): Service dependent. Maps higher layer information into ATM cells to be

transported over an ATM network . Collects the information from ATM cells for deliver to

higher layers.It consists of three separate planes:1.User plane 2.Control plane3.Management plane

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User plane: provides user information transfer along with

associated controls.

Control plane: performs call control and connection control

function.

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MANAGEMENT PLANE:

1.Plane management • it performs management functions related to a system.• Provides coordination between all the planes.

2.Layer management • It performs management functions relating to resources

and parameters residing in its protocol entities.

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ATM LOGICAL CONNECTION

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ATM CONNECTIONS Two levels of ATM connections:

virtual path connectionsvirtual channel connections

Indicated by two fields in the cell header: virtual path identifier VPI virtual channel identifier VCI

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VIRTUAL CHANNEL:

Setup between two end users. through the network. Leads to control signaling and user-network exchange,

network-network exchange.Advantages: 1.Simplified network architecture

2.Increased network performance and reliability.3.Reduced processing and short connection setup4.Enhanced network services.

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CONTINUED…

A VCC can be established between end users, between end user and switch, or between two switches.

Between end users Between end user and switch Between two switches

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VIRTUAL PATH:

Helps to contain the control cost by grouping connections sharing common paths through the network into a single unit.

Network management actions can be applied to a small number of groups of connections instead of a large number of individual connection.

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PROS & CONS higher transmission speeds quality of service bandwidth-on-demand application-independent

Cost Complexity Availability

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ATM APPLICATIONSATM is used for applications such as audio/video

transmission in real time it is necessary that at the receiving end, the cells are received without variable delay. the cells should be received at a constant speed.

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APPLICATIONMEDICAL: Medical imaging applications include

storing and manipulating x-rays, CAT scans, and MRI images in digital form. Such images need to be accessed simultaneously by multiple physicians. Transporting them across a network to the physicians requires a great deal of bandwidth, which ATM technology can provide.

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CASE STUDY For several years now Milan's public transport

company’s policy has been to adopt a continuous evolution of its processes towards paperless

solutions. In 2005 the company decided to replace its old

document system since it had become obsolete, with a platform satisfying requirements of scalability, reliability and flexibility, thus allowing the optimization of management and digital storage procedures for the various types of documents “transiting” the business, from invoices to internal and external correspondence together with the management of contraventions

effected and legal documents of various kinds.

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FUTURE Multimedia will be one of the key applications to use ATM. In the near future ATM is intended to be used as a

backbone for other existing services like frame relay. improve LAN/Client-Server architectures and LAN

interconnection. ATM will provide the resources to ease the network

demands caused by the growing number of users that need to connect to a LAN, and with applications requiring more bandwidth.

The IETF was working on IP over ATM and routing over large clouds.

ATM is currently the focus of the communications industry ATM will likely be replaced by another technology such as Wavelength Division Multiplexing (WDM).

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BIBLIOGRAPHY http://www.ijsrp.org/research-paper-0413/ijsrp-p1611

8.pdf https://www.youtube.com/watch?v=3VAmcN8VmIU https://en.wikipedia.org/wiki/Asynchronous_Transfer_

Mode http://searchnetworking.techtarget.com/definition/AT

M

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