1. ATM-Asynchronous Transfer Mode
Chapter 19
ATM-Asynchronous Transfer Mode

2. ATM
ATM is the cell relay protocol designed by the ATM Forum and adopted by ITU-T.
The combination of ATM and B-ISDN will allow high speed interconnection of all the world’s networks.
ATM is the “highway” of the information superhighway.

3. History of ATM
Developed in the early 80’s as a switching technology for Broadband Integrated Services Digital Network
Anchorage Accord in 1996 declares availability of specs required to implement a multi-service ATM network

4. ATM Fast Packet Standards and Services
Handles traffic through fast – packet switching technique
Must be able to handle both circuit and packet switching
Must also be able to accommodate the different bit rates – variable (packet switching) and constant (circuit switching)
Uses Cell relay technology

5. Multiplexing Using Different Packet Sizes
Figure 19-1
Multiplexing Using Different Packet Sizes

6. Multiplexing Using Cells
Figure 19-2
Multiplexing Using Cells

7. Figure 19-3
ATM Multiplexing

8. Architecture of an ATM Network
Figure 19-4
Architecture of an ATM Network
UNI – user-to-network interface
NNI – network-to-network interface

9. Figure 19-5
TP, VPs, and VCs

10. Figure 19-6
Example of VPs and VCs

11. Connection Identifiers
Figure 19-7
Connection Identifiers
VCI – Virtual Circuit Identifier
VPI – Virtual Path Identifier

12. Virtual Connection Identifiers
Figure 19-8
Virtual Connection Identifiers
in UNIs and NNIs

13. Figure 19-9
An ATM Cell

14. ATM Connection types (pvc & svc)

15. PVC (Permanent Virtual Circuit)
VPIs and VCIs are defined for the permanents connections and the values are entered for the tables of each switch.

16. SVC (Switched Virtual Circuit)
Figure 19-10
SVC (Switched Virtual Circuit)
Setup

17. Switching in atm

18. Routing with a VP Switch
Figure 19-11
Routing with a VP Switch

19. A Conceptual View of a VP Switch
Figure 19-12
A Conceptual View of a VP Switch

20. Routing with a VPC Switch
Figure 19-13
Routing with a VPC Switch

21. A Conceptual View of a VPC Switch
Figure 19-14
A Conceptual View of a VPC Switch

22. Switch fabrics

23. Figure 19-15
Crossbar Switch

24. Figure 19-16
Knockout Switch

25. Figure 19-17
A Banyan Switch

26. Example of Routing in a Banyan Switch (a)
Figure Part I
Example of Routing in a Banyan Switch (a)

27. Example of Routing in a Banyan Switch (b)
Figure Part II
Example of Routing in a Banyan Switch (b)

28. Features and Benefits of ATM
Convergence of Voice , Video and Data on one network
High speed switching at hardware level
Bandwidth on demand
Predefined and guaranteed QoS
Superior Management features
Scalability in network size and speed
Ease of integration with other technologies