Optical Networking Best Practices Handbook

10.6. MULTISTAGE SWITCHING SYSTEM

The growth of broadband access networks, such as asynchronous digital subscriber line (ADSL) and wireless local area network (WLAN), is driving an increase in data traffic on the backbone network. As a result, the volume of data traffic is growing two to three times per year. Commercial switching systems for the backbone network now operate at hundreds of gigabits per second. This means that a terabit-per-second-class switching system for the backbone network will be required in the near future if data traffic continues to increase at the same pace [6].

For this purpose, a switch can be applied to an ATM/IP switch. Most high-speed packet switching systems, including IP routers, use a fixed-sized cell in the switch fabric. Variable-length packets are segmented into several fixed-sized cells when they arrive, switched through the switch fabric, and reassembled into packets before they depart. Therefore, an ATM switch and an IP switch can be considered in the same way [6].

Approaches to single- and multistage Clos switches are shown in Figure 10.19 [6]. Most switches today use several single-stage switching techniques [6]. Single-stage switches are relatively simple. They are usually implemented using electronic technologies. To increase the switch size, you need to enlarge the size of the basic switch element by using chips fabricated by deep submicron process technology and high-density packing technologies such as chip-scale packaging (CSP) and ...