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dB loss in Avaya Structure cabling


We have completed the Large MAN Cabling project at one of the oldest University in India. Following components are used:

1. Avaya SMF 9micro Cables.

2. Avaya SMF LC Connectors.

3. Avaya LC Coupler.

and other Avaya Fiber structured cabling products.

According to Avaya site we have taken following Equation for Acceptance test of this cabling.

Link Attenuation = Cable Attn + Connector Attn + Splice Attn WHERE

Cable Attn (dB) = Attn Coefficient (dB/km) * Length (Km)

Connecter Attn (dB, for LC) = (number of connector pairs * 0.14) + 0.24

Attn Coefficient (dB/km) = 0.4 at 1310 nm and 0.3 at 1550 nm

We are facing following problem:

1. Large variation in dB loss readings for different cores. (Reading varies by 1 to 1.5 dB every time u measure)

2. 40% readings are overshooting the expected reading (As per above formula)

Help Required:

1. Confirmation that weather these formulees are valid?

2. Sample Readings for SMF LC connectorization.

3. General allowed variation in the LC / SMF reading.

Help will be greatly appreciated.

regards....Prakash Somani


Re: dB loss in Avaya Structure cabling

Often times complex troubleshooting issues are best addressed in an interactive session with one of our trained technical assistance engineers. While other forum users may be able to help, it’s often difficult to do so for this type of issue.

To utilize the resources at our Technical Assistance Center, please visit and to open a case with one of our TAC engineers, visit

If anyone else in the forum has some advice, please reply to this thread.

Thank you for posting.

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