asynchronous transfer mode (atm)

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asynchronous transfer mode (atm)

  1. 1. Asynchronous Transfer Mode (ATM)
  2. 2. By. P. Victer Paul Dear, We planned to share our eBooks and project/seminar contents for free to all needed friends like u.. To get to know about more free computerscience ebooks and technology advancements in computer science. Please visit.... http://free-computerscience-ebooks.blogspot.com/ http://recent-computer-technology.blogspot.com/ http://computertechnologiesebooks.blogspot.com/ Please to keep provide many eBooks and technology news for FREE. Encourage us by Clicking on the advertisement in these Blog.
  3. 3. Agenda <ul><li>Definition </li></ul><ul><li>Basic characteristics </li></ul><ul><li>Why asynchronous </li></ul><ul><li>How to access the network </li></ul><ul><li>Service Categories </li></ul><ul><li>Connections </li></ul><ul><li>Protocol Architecture </li></ul><ul><li>pros & cons </li></ul><ul><li>Troubleshooting </li></ul>
  4. 4. ATM – definition <ul><li>&quot;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&quot;. </li></ul>
  5. 5. ATM Characteristics <ul><li>ATM uses packet switching with fixed length packet of 53 bytes – CELLs. Each cell has a 5-byte header and 48-byte payload </li></ul><ul><li>ATM uses Virtual Circuits </li></ul><ul><li>ATM can run over any physical layer. Often runs over fiber optics using the SONET standard at speeds of 155.52 Mbps, 622 Mbps and higher </li></ul>
  6. 6. ATM Characteristics <ul><li>A Cell network uses the cell as the basic unit of data exchange. A cell is defined as a small, fixed-sized block of information </li></ul><ul><li>ATM uses asynchronous TDM – to multiplex cells coming from different channels </li></ul><ul><li>Uses fixed slots (size of cells) </li></ul><ul><li>Fills a slot with a cell from any input channel that has a cell </li></ul><ul><li>– slot is empty if none of the channels has a cell to send </li></ul>
  7. 7. Asynchronous Transfer Mode (ATM) MUX Wasted bandwidth 4 3 2 1 4 3 2 1 4 3 2 1
  8. 8. ATM Access <ul><li>ATM is a cell-switched network. </li></ul><ul><li>The user access devices, called the endpoints, are connected through a user-to-network interface (UNI) to the switches inside the network. </li></ul><ul><li>The switches are connected through network-to-network interfaces (NNIs). </li></ul>
  9. 9. STDUCTURE X X X X X X X X X Private UNI Public UNI NNI Private NNI Private ATM network Public UNI B-ICI Public UNI Public ATM network A Public ATM network B
  10. 10. ATM Connections <ul><li>two levels of ATM connections: </li></ul><ul><li>virtual path connections </li></ul><ul><li>virtual channel connections </li></ul><ul><li>indicated by two fields in the cell header: </li></ul><ul><li>virtual path identifier VPI </li></ul><ul><li>virtual channel identifier VCI </li></ul>
  11. 11. Physical Link Virtual Paths Virtual Channels
  12. 13. ATM Service Categories <ul><li>Real-time services </li></ul><ul><ul><li>Constant bit rate – uncompressed audio/video info </li></ul></ul><ul><ul><ul><li>Videoconferencing, TV, pay-per-view, VOD, etc. </li></ul></ul></ul><ul><ul><li>rt-Variable bit rate </li></ul></ul><ul><li>Non-real-time services </li></ul><ul><ul><li>nrt-VBR – high end system QoS, critical response time </li></ul></ul><ul><ul><ul><li>Bank transactions, airline reservations, etc. </li></ul></ul></ul><ul><ul><li>Unspecified bit rate – best-effort service </li></ul></ul><ul><ul><ul><li>e.g. text/image messaging, telecommuting </li></ul></ul></ul><ul><ul><li>Available bit rate – bursty apps requiring reliable end-to-end connection </li></ul></ul><ul><ul><ul><li>e.g. LAN, router-to-router reliability </li></ul></ul></ul>
  13. 14. ATM Protocol Architecture Plane management Management plane Control plane User plane Physical layer ATM layer ATM adaptation layer Higher layers Higher layers Layer management
  14. 15. <ul><li>adaptation layer: only at edge of ATM network </li></ul><ul><ul><li>data segmentation/reassembly </li></ul></ul><ul><ul><li>roughly analogous to Internet transport layer </li></ul></ul><ul><li>ATM layer: “network” layer </li></ul><ul><ul><li>cell switching, routing </li></ul></ul><ul><li>physical layer </li></ul>Physical layer ATM layer AAL user
  15. 16. Pros & cons <ul><li>higher transmission speeds </li></ul><ul><li>quality of service </li></ul><ul><li>bandwidth-on-demand </li></ul><ul><li>application-independent </li></ul><ul><li>Cost </li></ul><ul><li>Complexity </li></ul><ul><li>Availability </li></ul>
  16. 17. Troubleshooting <ul><li>Performing Basic Interface Checks </li></ul><ul><li>Determining Network Connectivity </li></ul><ul><li>Performing Loopback Tests </li></ul><ul><li>Troubleshooting 155-Mbps and 622-Mbps Interfaces </li></ul><ul><li>Troubleshooting T1 and E1 Interfaces </li></ul><ul><li>Troubleshooting DS3 and E3 Interfaces </li></ul><ul><li>Troubleshooting CBR T1 and CBR E1 Interfaces </li></ul><ul><li>Troubleshooting 25-Mbps Interfaces </li></ul>
  17. 18. References: <ul><li>Asynchronous Transfer Mode (ATM) fundamentals, white paper from Internation Engineering Consortium </li></ul><ul><li>ATM tutorial-fnc educational services </li></ul><ul><li>Higher Layer Protocols:TCP/IP and ATM- Eytan Modiano,Massachusetts Institute of Technology </li></ul><ul><li>ATM Switch Troubleshooting Guide-Cisco </li></ul>

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