Extreme Networks WM-4T1i Especificações descarregar pdf (Página 36)

1-10 Extreme Networks Consolidated Hardware Guide

Summary of Common Switch Features

If a ZX GBIC is used on the same link with an LX70 GBIC, the available link budget is

reduced to a total of 18 dB. Additionally, a minimum attenuation of 6 dB is required to

ensure correct operation of the ZX GBIC receiver.

*The transmitter output power level for the 1000BASE-LX70 is +4 dBm. The maximum allowable receiver input power level is

-3 dBm. Therefore, there is a minimum of 7 dB loss required for the link to operate without errors. This minimum required loss

can be achieved using a fiber length of 32 km (0.25 dB/km provides 8 dB loss), or by adding 10 dB of fixed optical attenuator

at the receiver end.

Determining Budget and Distance Calculations

When calculating the distance that is attainable by using optical cable with a specified

loss per kilometer, Extreme Networks recommends that 3 dB of the total budget be

reserved for losses that are induced by cable splices, cable connectors, and operating

margin. These are referred to as loss penalties.

To determine the required link budget for a specific distance of fiber, use the following

formula:

Required Link Budget LB = [(Distance d) * (Fiber Attn)] + all other Loss Penalties

• Distance is the distance between the links

• Fiber attenuation is the fiber or cable attenuation

• loss penalties are the amounts reserved for losses that are induced by cable splices,

cable connectors, and operating margin.

The following example determines a required link budget of 9 dB where the following

is true:

Table 1-9: 1000BASE-LX70 Specifications

Parameter Minimum Typical Maximum

Transceiver

Optical output power 0 dBm 3 dBm 4 dBm*

Center wavelength 1540 nm 1550 nm 1560 nm

Receiver

Optical input power sensitivity -24 dBm

Optical input power maximum -3 dBm

Operating wavelength 1200 nm 1560 nm

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Extreme Networks WM-4T1i Especificações Página 36