Fiber Channel Insertion Loss Budget

Unanswered Question
Feb 14th, 2007

I'm trying to find a credible source for link loss budget in a 4Gb short wave fiber channel. I'm looking for the total budget. I can find lots of data on insertion loss over specific components and attenuation over any myriad types of fiber. However, I cannot find anything more specific than 4.2-6.0db total loss across a system. 50% variability seems too high for a scientific answer. Does anyone know a definitive document that could help? Specifically I'm using Cisco 9513 switches with 4Gb shortwave Gbics, Corning Universal Plug-n-Play fiber and on the other end, HP SAN hardware with the same 4Gb short wave Gbics. Thanks,

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inch Wed, 02/14/2007 - 20:24

G'day,

It will depend on how many connections in total there are and the type of connections they are.

Single mode or multi mode can/will have different loss ratios as will different manufacturers.

So in short, there really is no generic answer to your question. You will need to get the specifications from your cable and patch panel (if any) manufacturer and add them all up long the way.

Cheers

Andrew

bushellrr Thu, 02/15/2007 - 04:27

Thank you for answering. I'm really hoping there is some physics behind insertion loss. If there is, then when we strip away all the connectors of various quality and remove the media itself all that is left is a raw loss budget. I bet you are right that the budget is modified by wavelength and wether single-mode or mulit-mode signals are being used. If the answer isn't a number, but an equation, I'm fine with that. I'm pretty sure I cannot be the first person to ever ask this question. I'm hoping it's been answered thousands of times in hundreds of labs and someone is willing to share. Thanks,

inch Thu, 02/15/2007 - 04:51

G'day,

I'm sure there is a generic loss rate on types of cables (50micron vs 62.5 vs 9). But I'm tipping that even different manufacturers will have differing quality cables which will then intern give different loss rates.

The same would go with the manufacturers of the various connectors....

I would be super keen to find out if there is a generic loss rate tho :-)

So if anyone knows, speak up! :-)

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