Page 159 - Optical Switching And Networking Handbook

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144 Chapter 6

across the mirror to an output fiber carrying the full capacity
through the switch without conversion back to an electrical signal.
This is shown in Figure 6-12.

Scalable Solutions

These relatively small-port-count switches are useful, for example,
for network protection and restoration, to enable carriers to quickly
reroute data traffic around fault locations in the event of fiber breaks
or equipment failures. However, central offices often require larger
switches with hundreds and up to thousands of input-output ports.
To scale up channel counts beyond 32 32 ports, two solutions are
available depending on the specific requirements of the end system.
One solution is to use the smaller switch modules as building
blocks, cascading them to form a larger switch. A three-stage net-

Figure 6-12
The MEMS switch
in action (Lucent)