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 OMUX-8, and the CWDM GBICs. The number of OADMs that can be supported is based on the loss budget calculations.

Figure 13 Hub and spoke network configuration

Transmission Distance

(GBIC to GBIC)

OADM

OADM

OADM

OADM

OADM

OADM

OADM

OADM

OMUX-8 GBIC B

AGBIC

Installation and Networking Guidelines for Optical Routing

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Nortel Networks 10396EA, 10292FA manual Hub and spoke transmission distance, Hub and spoke network configuration