ATM Shweta

raichura

shweta raichura

What is ATM?????•ATM is a high-speed networking standard designed to support voice,image,video and data communications. 

Why ATM is used?????

• ATM provide larger bandwidth, high speed data transfer rate, quality of service and grade of service.• ATM transmits all information in small, fixed-size

packets called cells.• In ATM cell switching is used because it is highly

flexible and can handle both constant rate traffic (audio, video) and variable rate traffic (data) easily.

How ATM is used???

• ATM is a transmission technique: • A company can implement its own ATM

network. Network operators provide fixed ATM connections for subscribers on a permanent contract basis

Advantages of ATM….

•High-speed communication.• Provides the best multiple service support • A single network connection that can easly mix voice, video, and data.• efficient allocation of network bandwidth.

Disadvantages of ATM…

•New customer premises hardware and software are required.• ATM used fix size cell.• ATM is a complex standard,complexity makes the implementation expensive - lots of parts required.

Protocol Architecture

Physical Layer: •The lowest layer in the ATM protocol. •It describes the physical transmission media. We can use coaxial cable, and fiber-optic cable. ATM Layer: •It performs all functions relating to the routing and multiplexing.•It generates a header to the segment streams generated by the AAL. Similarly, on receipt of a cell streams, it removes the header from the cell and pass the cell contents to the AAL protocol. •To perform all these functions, the ATM layer maintains a table which contains a list of VCIs

ATM Adaptation Layer: •Top layer in the ATM protocol Model. It converts the submitted information into streams of fixedsize segments and transports these in the payload field of multiple ATM cells. •This layer is used for in order to support information transfer protocols•Examples of services that need adaptations are Gigabit Ethernet, IP, Frame Relay.

ATM Services1- Constant Bit Rate (CBR):• CBR is used by a connections that requires a static amount of bandwidth that

is continuously available during the connection time.• It appropriates for such applications as telephone traffic, video

conferencing, interactive Audio, TV

2- Rate-Non-Real Time Variable Bit (nrt-VBR)• Allows users to send traffic at a rate that varies with time depending on the

availability of user information.• Application: email.

3- Available Bit Rate (ABR)•Available Bit Rate (ABR) is a service used in ATM networks when source and destination don't need to be synchronized•Depending on the state of congestion in the network, the source is required to control its rate.Allows users to declare a minimum cell rate guaranteed to the connection by the network.Aimed at data traffic such as file transfer and e-mail.

4- Unspecified Bit Rate (UBR)Intended for non-real time application which do not require tightly constrained delay and delay variation.Widely used today for TCP/IP

5- Rate-Real Time Variable Bit Rate (rt-VBR):Intended for those application which requires tightly constrained delay and delay variation. Application: voice with speech activity detection (SAD) and interactive compressed video.

Conclusion

• ATM is a flexible and powerful technology which integrates the cell-switching and multiplexing functions, and enables transmissions over a variety of carrier system.

• ATM technology is a powerful common platform for LAN and WAN to increase productivity, to reduce costs and to implement new applications and service.

Thank you….