Chapter 2 Calculating transmission distance 33
Hub and spoke transmission distance
Hub and Spoke topologies are the most complex. The characteristics of all components designed into the network must be considered in calculating transmission distance. The following factors determine maximum transmission distance for the hub and spoke configuration in Figure 13:
•CWDM OADM insertion add loss
•CWDM OADM insertion drop loss
•Passthrough insertion loss for intermediate nodes
•Fiber attenuation of 0.25 per kilometer
The Ethernet switch host does not have to be near the CWDM OADM, and the CWDM OADM does not regenerate signal. Therefore, maximum transmission distance is from GBIC to GBIC.
As the signal in Figure 13 passes from point A to point B (the most remote points in the hub and spoke), it is expected to lose strength in the fiber optic cable, and in each connection between the individual CWDM OADMs, the CWDM
Figure 13 Hub and spoke network configuration
Transmission Distance
(GBIC to GBIC)
OADM
OADM
OADM
OADM
OADM
OADM
OADM
OADM
AGBIC