Optical Network Design and Implementation

SONET/SDH

SONET/SDH networks are typically built in a hierarchical topology. The campus network could be GE or even an OC-3/STM-1 or OC-12/STM-4 SONET/SDH ring. Campus-to-central office (CO) traffic is normally carried over the metro access ring. CO-to-CO traffic is commonly carried over metro core rings and, finally, if the traffic is required to leave the metro core, long-haul traffic is typically carried over DWDM circuits.

As shown in Figure 1-1, customer rings are known as access rings and typically span a campus. The access rings converge and interconnect at major network traffic collection points. These collection points are referred to as points of presence (POPs) by carriers or as headends in the cable industry. The collector rings aggregate ...