ATM-Asynchronous Transfer Mode Chapter 19 ATM-Asynchronous Transfer Mode

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.

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

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

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

Multiplexing Using Cells Figure 19-2 Multiplexing Using Cells

Figure 19-3 ATM Multiplexing

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

Figure 19-5 TP, VPs, and VCs

Figure 19-6 Example of VPs and VCs

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

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

Figure 19-9 An ATM Cell

ATM Connection types (pvc & svc)

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

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

Switching in atm

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

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

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

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

Switch fabrics

Figure 19-15 Crossbar Switch

Figure 19-16 Knockout Switch

Figure 19-17 A Banyan Switch

Example of Routing in a Banyan Switch (a) Figure 19-18-Part I Example of Routing in a Banyan Switch (a)

Example of Routing in a Banyan Switch (b) Figure 19-18-Part II Example of Routing in a Banyan Switch (b)

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