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[10GMMF] Fibre vs. Cable specs in LRM



Title: Fibre vs. Cable specs in LRM

Piers,
Happy New Year - hope you had a good holiday and some time to rest up for an exciting 2005.
I have to respectfully disagree with your observation that you don't think we have to specify cable - applications run on cable, 11801 specifies cable and the cable and fibre specifications are different. Generally, fibre specifications are more stringent (e.g., attenuation and the environmental specifications) than cable specifications. Our power budget must be based on a 3.5dB/km value of cable, not the 2.5 dB/km value typically specified on fibre. This has caused confusion in the past in the marketplace and the only real reason we did not fix it previously is that we had no cable specifications to specify - now we do and we should reference them. It really doesn 't change any functional requirements and I believe that the 60794 series does not disenfranchise any of the installed base (unless it did not meet 11801 in the first place, which in my mind does not meet our requirements).

Regarding your other questions:
1. The 60794 series specifies both optical and environmental requirements; the optical requirements reference OM-1, OM-2 and OM-3 fibre specifications so they are identical with the exception of attenuation. The only environmental requirement specified in the 60794 series is temperature cycling which is specified at -20 to 60 consistent with the requirement in 11801 for indoor cable. There are specifications for duplex, multi-fibre and ribbon cables in the -2 series. The -3 series specifies outdoor cable and we could add those as references also.

2. "PAS" means "Publicly Available Standard" and is a new process used by IEC to get standards to the market quickly (or quicker). Basically, it allows the committee to make the standard "available" after the completion of a successful CDV (Committee Draft for Vote) ballot. The PAS is then replaced by the "official" published standard once it completes FDIS (Final Draft International Standard) ballot.

3. Regarding the question on fibre types, 60793-2-10 specifies all multimode fibre types and 60793-2-50 specifies all single-mode fibre types. The cable specifications specify both fibre types in a single document, i.e., 60794-2-11 covers duplex cable for premises applications for BOTH multimode and single-mode fibres and references the multimode fibres in 60793-2-10 and the single-mode fibres in 60793-2-50. 60794-3-12 covers duct and directly buried cable (read outdoor) for premises applications for BOTH multimode and single-mode fibres and references the multimode fibres in 60793-2-10 and the single-mode fibres in 60793-2-50.

Hope that helps; let me know if further clarification is needed.
Cheers,
Steve