To make the calculations simple, we will assume that all ADMs and
PADMs are an equal 10 miles apart from one another. Using these two figures and the
formulas presented above yields the following results.
Total Cost for Fiber in Hub and Spoke Configuration = $384,000
Total Cost for Fiber in Ring Configuration = $240,000 = 100%
Savings with RPR Ring = $144,000 = 62.5%
The point-to-point approach represented by the hub and spoke architecture results in
62.5% higher fiber cost for the equivalent connectivity.
Optical Port and Equipment Savings
The Hub and Spoke architecture requires the use of both a transport device, in this
case, an ADM and a L2/L3 switch as shown in Figure 12.23. The RPR ring collapses
the functions of these two devices into one. This reduces equipment requirements and
costs for optical ports and rack space in CO facilities.
Table 12.5 above compares the optical ports required for the two architectures. More
equipment involves higher costs for buying, installing, configuring, maintaining, and
troubleshooting. The hub and spoke design requires 28 optical ports verses only 14
needed for the RPR ring design.
Separately managing L2/L3 switching and SONET/SDH devices at each location
presents more challenges as well.
Pages:
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823