Range using single-mode SFPs across multi-mode fiber

Chuck Anderson cra at WPI.EDU
Thu Dec 15 03:33:01 UTC 2011

On Wed, Dec 14, 2011 at 10:02:58PM -0500, oliver rothschild wrote:
> 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. We
> successfully established a 1G ethernet connection. Testing to date has
> been meager, but shows that the link is viable. Under significant load
> there is some minor packet loss. Since the link far exceeds the amount
> of data it required, we have decided to continue using it.
> Interestingly neither interface showed any physical errors.

Technically you should be using offset-launch "mode conditioning"
patch cords at each end when running LX over multimode fiber.  I had
been lucky with not using them for many years on 62.5/125 (OM1)
multimode (and just started doing so again, albiet only for
OOB/non-production traffic use).  I believe my longest link was/is
around 1 km.


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