[j-nsp] LX SFP Question

Shane Ronan sronan at fattoc.com
Fri Sep 25 11:15:32 EDT 2009

Along these lines, but slightly off topic, what kind of light meters  
do you guys use?


On Sep 25, 2009, at 10:50 AM, Richard A Steenbergen wrote:

> On Fri, Sep 25, 2009 at 10:15:16AM -0400, Stefan Fouant wrote:
>> It's expensive to put dB meters on every optical interface, and  
>> since these
>> are cheap commodity based switches those capabilities most likely  
>> do not
>> exist.  That most likely explains the reason you did not see any  
>> output in
>> the 9.2 release, which they finally decided to remove altogether  
>> from future
>> versions.  As Richard mentioned, you'll have DOM for 10GE  
>> interfaces, but
>> not the GE.  You get what you pay for... ;)
> Actually a lot of optics that have been manufactured over the last few
> years have DOM support built in. Sometimes the lower end optics don't
> support it (1GE SX and LX), but for the most part you'd be hard  
> pressed
> to find a long reach or DWDM optic for 1GE, or a LR/ER/ZR/DWDM optic  
> for
> 10GE, manufactured in the last 5 years that doesn't support it. All  
> the
> host board has to do is query the information from the optic using the
> low speed control interface, so it is a bit surprising that some older
> host boards didn't support this. For example, Cisco 6748-SFP doesn't,
> but the older generation 6716-GBIC does, go figure.
> I'm not saying that EX will never do DOM for 1GE, I don't know that  
> one
> way or another and given the newness of the product I would actually  
> be
> very surprised if the hardware doesn't support it. All I can tell  
> you is
> that 10.0 DOM on EX for 1GE LX doesn't work, and DOM for 10GE LR does.
> It's possible that this is just a limitation of the optics Juniper is
> shipping with the EX, I honestly don't do enough GE to have any better
> optics to test any more. :)
> Physical interface: ge-2/0/46
>    Optical diagnostics                       :  N/A
> FWIW this was high on our list of requirements for EX to implement.  
> Once
> you start using DOM for everything you just can't go back to trying to
> diagnose things with techs and light meters.
> -- 
> Richard A Steenbergen <ras at e-gerbil.net>       http://www.e-gerbil.net/ras
> GPG Key ID: 0xF8B12CBC (7535 7F59 8204 ED1F CC1C 53AF 4C41 5ECA F8B1  
> 2CBC)
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