Inside plant 10G fiber specs?

Jeff Kell jeff-kell at
Sun Mar 14 13:16:53 CDT 2010

I am working up network specs for a new building, and trying to
accomodate a 10G distribution from the start.  The safe bet of running
singlemode everywhere doesn't quite fit due to cost of the optics and
the need for multimode for some other (non-network) devices anyway.

We have a legacy 62.5u/MM campus, inside and out.  The 100M to 1G
transition led to some outside plant singlemode additions due to length
restrictions on MM (even with conditioned LH optics), but the inside
plant gig was fine with multimode (typically SH optics).

10G appears to break the inside 62.5u/MM fit, with the addition that
there is no option of "LH over MM" for the little extra push beyond the
SH limit that worked with 1G optics.  Cisco's references give 10G SH
over 62.5u/MM at 26m or 33m, depending on the "modal bandwidth" of the
fiber.  At those distances it is of little benefit except some limited
vertical risers.

10G over 50u/MM looks better, depending on the "modal bandwidth" of the
fiber (66m, 82m, 300m).

So, a couple of questions...

(1) Do you have a good vendor specification (or sample cables) for
multistrand 50u/MM suitable for the 2000Mhz/km (300m) advertised reach?

(2) Inter-operability issues with legacy equipment where we have always
used 62.5?  We have at least two alarm half-duplex loops over 62.5 that
will have to "mate" with devices in this building... if I can avoid
running both types MM that would be great.

(3) Any other considerations or words of advice would be welcomed.

Thanks in advance.


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