[j-nsp] LX SFP Question

[Richard A Steenbergen]

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)