[120149] in North American Network Operators' Group
Re: Optical fiber question
daemon@ATHENA.MIT.EDU (Anton Kapela)
Thu Dec 10 17:52:51 2009
In-Reply-To: <4B216849.3040804@craigslist.org>
Date: Thu, 10 Dec 2009 17:52:02 -0500
From: Anton Kapela <tkapela@gmail.com>
To: Leslie <leslie@craigslist.org>
Cc: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
Wanted to add something to this and clarify/correct a few points:
> Plus, while I'm sure someone in a lab has done it, you really don't run D=
WDM
> over multimode fiber - I'd second the opinion of it's cheap enough, go fo=
r
> the single mode and get the most flexibility in your options possible.
In fact, already being done - this is how 10GB-LX4 operates. The point
here is that each of the four channels operates at less than 10
gigabits/sec, and that MMF didn't prevent it, in fact, it was done
entirely to make 10 gig work over MMF. Caveats include mode-adapter
cables and other funk to interface LX4 to mmf.
Long-reach single-carrier (ie. single optical channel/frequency) 10
gig over MMF salso has a 'spec' (10G-LRM), but I'm not personally
familiar enough with vendors to offer anything useful or practical.
> One minor consideration is usually SM optics are stronger, so don't forge=
t
> attenuation if it's a short distance or you might burn out your pricey ne=
w
> optics!
I would invite folks to examine the various gradations of gig and 10
gig LR/ER/ZR devices. Pulled from a handy table at
http://www.andovercg.com/datasheets/juniper-ethernet-pics.pdf, I
submit for your consideration a summary of the powers across the
various flavors of xenpak. Note the modest increases in launch power,
while there are considerable and huge increases in sensitivity.
10-Gbps Gigabit Ethernet XENPAK, 1-port
=95 XENPAK pluggable optics (SR, LR, ER, ZR types)
=95 SR optical interface (IEEE 802.3ae compliant)
=96 Average launch power: -4.5 through -1 dBm
=96 Receiver saturation: -1.0 dBm
=96 Receiver sensitivity: -7.5 dBm
=95 LR optical interface (IEEE 802.3ae compliant)
=96 Average launch power: -4 through 0.5 dBm
=96 Receiver saturation: 0.5 dBm
=96 Receiver sensitivity: -10.3 dBm
=95 ER optical interface (IEEE 802.3ae compliant)
=96 Average launch power: -4.7 through 4 dBm
=96 Receiver saturation: 1 dBm
=96 Receiver sensitivity: -11.3 dBm
=95 ZR optical interface (IEEE 802.3ae compliant)
=96 Average launch power: 0 through 4 dBm
=96 Receiver saturation: -7 dBm
=96 Receiver sensitivity: -24 dBm
-tk
