Page 94 - Optical Switching And Networking Handbook

04_200023_CH03/Batesx 1/17/01 9:42 AM Page 79

SONET 79

vivability in the event of a cable cut or a failure in a network node.
The multiplexers have sufficient intelligence to reroute or reverse
direction in the event of a failure. If more than one fiber link is
installed, the systems could use alternate paths, but they must
recover in milliseconds (which APS on SONET is designed to do).
Figure 3-22 shows the ring topology with dual fibers running (bidi-
rectional service) between the ADMs.

Figure 3-21 OC-1
Hub and spoke OC-1
in a SONET
multiplexer OC-3
network OC-1 OC-1

OC-1 OC-1

Figure 3-22
Ring architecture
of SONET
multiplexers ADM ADM