Maximum Length for 1000Base-SX
Bookmark this page:
 Yahoo!
 Google
 Windows Live
 del.icio.us
 digg
 Netscape
|
|
||||||||||||||||
|
Posted by Wrolf on September 15, 2006, 2:25 pm
Please log in for more thread options Can I calculate the maximum run length for 1000Base-SX based on: Max dB Loss (7.5dB) > # patch panels * loss per mated pair + distance
attenuation
Where loss per mated pair is nominally < .75 dB, but we test for < .3 dB; and distance attenuation is 3 db / km And thus exceed 220 m over 62.5/125 =B5m? Do I count the switch to patch cable as a mated pair, or is that included within the optical budget? How about modal dispersion? Is there a calculation for that? Or should I run replacement 50 =B5m fiber? TIA Wrolf (P.S. Sorry about cross-posting, but I realise that this is a better forum than comp.dcom.lans.ethernet for this question.) | ||||||||||||||||
|
Posted by Dmitri(Cabling-Design.com on September 15, 2006, 4:34 pm
Please log in for more thread options Wrolf wrote: > Can I calculate the maximum run length for 1000Base-SX based on:
> Max dB Loss (7.5dB) > # patch panels * loss per mated pair +
> distance > attenuation > Where loss per mated pair is nominally < .75 dB, but we test for
> < .3 > dB; > and distance attenuation is 3 db / km
You actually have to be more conservative with your margins. 3.75dB/km is more realistic for a standard 62.5/125 mkm fiber. Also, I would still stick with 0.75 dB per connector even if the measured value is 0.3 dB per mated pair. This is simply because if you test the same connector pair again, you will get another value (usually worse, but not necessarily). Test it in a year after couple re-connections and you'll see it drop to 0.75 dB if lucky or even beyond that. > And thus exceed 220 m over 62.5/125 =B5m?
> Do I count the switch to patch cable as a mated pair, or is that
> included within the optical budget? No the connectors on equipment don't count > How about modal dispersion? Is there a calculation for that?
The degrading effect of modal dispersion is figured into the maximum loss figure. > Or should I run replacement 50 =B5m fiber?
Or you can use 1000BASE-LX on the same fiber and get 550 meters. That may be much cheaper, depending on how difficult it is to re-pull the fiber. -- Best Regards, Dmitri Abaimov, RCDD http://www.cabling-design.com/ Home Cabling Guide, Cabling Forum, color codes, pinouts and other useful resources for premises cabling users and pros -- +----------------------------------------------------------+ | http://forums.cabling-design.com/ | | *** a better way to USENET *** | | no-spam Web and RSS interface to your favorite newsgroup | | comp.dcom.cabling - 2919 messages and counting! | +----------------------------------------------------------+ | ||||||||||||||||
| Similar Threads | Posted |
| Maximum Length for 1000Base-SX | September 15, 2006, 2:25 pm |
| Cabling length | December 1, 2005, 4:47 am |
| Cable length | July 18, 2006, 9:43 pm |
| Average Length of Cat5 Run | August 25, 2004, 10:21 am |
| Minimum 10Base100 Cable Length | July 16, 2004, 9:32 am |
| Program to Estimate Cat 5 Cable Length | October 1, 2004, 4:52 pm |
| Looking for 2 MM LC-LC fiber cables 30m to 50m in length-surplus/cheap | October 6, 2004, 1:48 am |
| Power + DSL signal in same 700ft cable length | October 12, 2006, 6:35 pm |
| OTDR: Launch Cable Length for Singlemode | April 10, 2008, 2:50 pm |
| Re: Ethernet connection sensitive to cable length | May 3, 2008, 12:37 pm |