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Extreme Networks Consolidated Hardware Guide 1-11

GBIC Type and Hardware/Software Support

• Distance is 20 km

• Fiber attenuation is 0.30 dB/km

• Loss penalties are 3 dB

Required Link Budget LB = (20 km * 0.30 dB/km) + 3 dB = 9 dB

When calculating the supported link distance, if the link distance is less than the

minimum length supported, external attenuators may be needed. To determine the

supported link distance, use the following formula:

Link distance supported = (system budget - loss penalties) / fiber attenuation

For example, Table 1-10 and Table 1-11 use the supported link distance formula to

determine the maximum link distances for two different GBICs: the ZX GBIC and the

LX70 GBIC.

Maximum Budget for Link Partners

Figure 1-2 displays the maximum budget for the following GBIC link partners:

• Older ZX GBIC and Older ZX GBIC

• LX70 GBIC and LX70 GBIC

• ZX GBIC and LX70 GBIC

Table 1-10: Cable Attenuation and Distances for the ZX GBIC

Cable Attenuation Minimum Distance Maximum Distance

0.30 dB/km 0 km (19.5-3)/0.30 = 55 km

0.25 dB/km 0 km (19.5-3)/0.25 = 66 km

0.23 dB/km 0 km (19.5-3)/0.23 = 71 km

Table 1-11: Cable Attenuation and Distances for the LX70 GBIC

Cable Attenuation Minimum Distance Maximum Distance

0.30 dB/km 27 km (22-3)/0.30 = 63 km

0.25 dB/km 33 km (22-3)/0.25 = 76 km

0.23 dB/km 36 km (22-3)/0.23 = 82 km

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