Range using single-mode SFPs across multi-mode fiber

Mark Foster blakjak at blakjak.net
Wed Dec 14 21:46:13 CST 2011


On 15/12/11 16:38, Keegan Holley wrote:
> 2011/12/14 oliver rothschild <orothschild at gmail.com>
>
>> Thanks to all who responded to my clumsy first question (both on
>> matters of etiquette and technology). The group I work with (we are a
>> small project acting as a last mile provider) was in the midst of
>> deploying this solution when I posed the question. We put the single
>> mode Juniper SFPs (LX) on to a run of approximately 1670 meters.
>>
> How did you end up with a MM run this long?  SX optics are only rated at
> 500 meters at best.  Even with mode conditioning jumpers more the 1km is a
> risk.  I'm glad it held up during testing though.  Just out of curiosity
> did you purchase dark from a provider?  Is it inside of a building?

Um.. check that.

https://en.wikipedia.org/wiki/Multi-mode_optical_fiber

"Typical transmission speed and distance limits are 100 Mbit/s for
distances up to 2 km (100BASE-FX
<https://en.wikipedia.org/wiki/100BASE-FX>), 1 Gbit/s to 220--550 m
(1000BASE-SX <https://en.wikipedia.org/wiki/1000BASE-SX>), and 10 Gbit/s
to 300 m (10GBASE-SR
<https://en.wikipedia.org/wiki/10_Gigabit_Ethernet#10GBASE-SR>)."

The old OM1 installations I used to work on started out as 10Mbit hubbed
ethernet links and on the odd occasion would run out to close to 2km
within a campus.  They were progressively upgraded with the flow of:

10FX on 3Com Linkbuilder Kit
100FX on 3Com Corebuilder Kit and Allied Telesyn 100FX Media converters
1000SX on a variety of 3Com, Nortel and Cisco kit out to ~220m
1000LX via Mode-Conditioning out to ~900-1000m.

The OM1 only got retired when the distance was >900m or there was budget
to put new fibre on the run, in which case we ran SMF and rigged LX drivers.

Mark.






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