Asynchronous Transfer Mode (ATM) is a switching technique that uses fixed-sized cells to encode data for transmission over telecommunication networks. ATM can handle both traditional high-speed data traffic as well as real-time, low-latency content like voice and video. It provides services at the data link layer and has similarities to both circuit switching and packet switching. ATM is commonly used for wide area networks and some DSL implementations also use ATM technology.

1. Asynchronous Transfer Mode (ATM) By- Agreeta Sharma A1000810010 AMITY INSTITUTE OF INFORMATION TECHNOLOGY

2. Asynchronous Transfer Mode (ATM) is a switching technique for telecommunication networks. It uses asynchronous time-division multiplexing , [1] [2] and it encodes data into small, fixed-sized cells . ATM differs from networks such as the Internet or Ethernet LANs that use variable sized packets or frames . ATM provides data link layer services that run over OSI Layer 1 physical links. ATM has functional similarity with both circuit switched networking and small packet switched networking. This makes it a good choice for a network that must handle both traditional high-speed data traffic (e.g., file transfers), and real-time , low-latency content such as voice and video . Asynchronous Transfer Mode

3. ATM ATM standard (defined by CCITT) is widely accepted by common carriers as mode of operation for communication – particularly BISDN. ATM is a form of cell switching using small fixed-sized packets. Header Payload 5 Bytes 48 Bytes Figure 9.1 Basic ATM Cell Format Leon-Garcia & Widjaja: Communication Networks Copyright ©2000 The McGraw Hill Companies

4. Asynchronous Transfer Mode is a set of protocols used for computer networks . It is mostly used for Wide Area Networks . It splits the data, and encodes it into packets of a fixed size. Each packet can be routed differently, along virtual paths set up in the network. ATM has been very successful in WANs, as well as in LANs . Today, many ADSL implementations use ATM technology.

6. permanent virtual circuit , a virtual circuit that is permanently available. The only difference between a PVC and a switched virtual circuit (SVC) is that an SVC must be reestablished each time data is to be sent. Once the data has been sent, the SVC disappears. PVCs are more efficient for connections between hosts that communicate frequently switched virtual circuit , a temporary virtual circuit that is set up and used only as long as data is being transmitted. Once the communication between the two hosts is complete, the SVC disappears. In contrast, a permanent virtual circuit (PVC) remains available at all times.

8. ATM Virtual Connections Physical Link Virtual Paths Virtual Channels Leon-Garcia & Widjaja: Communication Networks Copyright ©2000 The McGraw Hill Companies

9. ATM is more complex, but this complexity allows to give guarantees as to data rate , maximum delay, and jitter . These are usually called Quality of Service . Quality of Service or QoS is a method of providing better service for selected traffic types over various types of packet-switched networks.

10. Advantages Universality Mixed traffic types, real-time and non-real-time Scalability LANs, MANs, WANs, WLANs Efficient use of network resources Bandwidth on demand concept Simplified network infrastructure

11. ATM challenges In-network mux/buffering can lead to cell delay or loss  QoS guarantees Many types of traffic Large geographic distribution Traffic modeling, control

12. THANKING YOU! Agreeta Sharma M.Sc Networking Management’12 Amity University