Black Box TS250A, Manual, Page: 31 / 64

Attenuation
Chapter 3 Optical TAPs
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analyzer for details. If auto-negotiation is not disabled, the
analyzer will not be able to receive the stream from the TAP until
it is.
As an alternative, you can split your own duplex cable (or use two
simplex cables) to connect each side of the Analyzer ports on the
TAP to the receive ports on each of the NICs in the analyzer.
Attenuation
Network administrators who manage optical links have the added
challenge of dealing with signal attenuation—the rate at which light
dissipates over a network. Attenuation is caused by a number of
factors and can affect both network performance and the ability to
analyze the network.
Excessive signal attenuation can cause link failure. Understanding
signal levels, selecting the right split ratio on TAPs, and carefully
managing the location of repeaters can prevent problems. This section
defines attenuation, explains how it is affected by fiber and other
optical elements on a network, and how it can be efficiently managed.
Attenuation is the reduction of signal strength during transmission
caused by the absorption of light from the materials through which it
travels. Greater signal loss equals higher attenuation. A signal can lose
intensity or experience increased attenuation with each surface or
medium it traverses. Many factors contribute to the attenuation rate
of signals including devices such as TAPs and transmission through
optical cables.
Optical signal strength is measured in decibels (dB) and is based on a
logarithmic scale. If a signal attenuates too much, the destination
device cannot identify it, or worse, the signal may not even reach the
destination. This is why some optical links depend on repeaters, which
amplify the signal.
Attenuation and TAPs
TAPs are used to provide access to the data streams passing through a
high-speed, full-duplex network link. TAPs deliver a complete copy of
data to a monitoring device for accurate analysis. An Optical TAP
optically splits the light power of the full-duplex signal into two