[c-nsp] SFP-10G-LRM in Nexus 5000

[Crist J. Clark]

So it took a while, but someone hit on it, and I wanted to emphasize
the point in case some other poor soul runs into this issue.

10Gbase-LRM modules are not supported on Nexus 5000 platforms.

The story I got is that the Nexus 5000s lack the Electronic Dispersion
Compensation (EDC) which is required to fully support LRM.

Since we'd been using these on our Nexus-to-Nexus links for the last
few years, I never thought to check the 10G module compatibility matrix,
but if you do, they are not listed for any Nexus 5000 models. We've
swapped them all out for SR optics on these new links. Those worked
without problems (except for some fiber pair rollovers).


On Thu, Sep 17, 2015 at 01:59:25AM +0200, Matthieu Michaud wrote:
> Hello,
> 
> Some LRM run on both SM and MM including Cisco's. At $JOB we do use
> 10G-LRM a lot.
> It's the predominent transciever because estate standards says "SM
> EVERYWHERE !@#!", we buy only Cisco brands and LR is 4 times the price
> of an LRM. It was removed from Nexus compatibility matrix in recent
> NX-OS release because of overheating issue as far as I was told by our
> SE.
> 
> Regards,
> 
> On Tue, Sep 15, 2015 at 7:09 PM, Mike Hale <eyeronic.design at gmail.com> wrote:
> > "No."
> >
> > I stand corrected.  ;)
> >
> > "What's on the opposite side of the 5548s?"
> >
> > They are up and running right now on a 3750X and a 2960S.  I have a
> > vague memory of having them in some servers in the past as well, but
> > I'm not seeing any of those right at this moment.
> >
> > On Tue, Sep 15, 2015 at 9:47 AM, Crist J. Clark
> > <cjc+cisco-nsp at pumpky.net> wrote:
> >> On Mon, Sep 14, 2015 at 03:21:27PM -0700, Mike Hale wrote:
> >>> Correct me if I'm wrong, but the LRM SFPs are designed to go over MMF,
> >>> not SMF.  Isn't that going to be a problem?
> >>
> >> No. As someone else already pointed out, Cisco says you can run LRM over
> >> SMF for 300m, which is actually longer than they say you can run it over
> >> MMF, 220m. You also don't need mode conditioning over SMF.
> >>
> >>> We're using some LRM SFPs between floors to a 5548, and they function
> >>> just fine.
> >>
> >> What's on the opposite side of the 5548s? It may be similar to what we're
> >> seeing. It looks like this works fine Nexus to Nexus, but it is flaky
> >> Nexus to Catalyst.
> >>
> >>> On Mon, Sep 14, 2015 at 3:15 PM, Crist J. Clark
> >>> <cjc+cisco-nsp at pumpky.net> wrote:
> >>> > On Mon, Sep 14, 2015 at 10:45:58PM +0100, Nick Hilliard wrote:
> >>> >> On 14/09/2015 22:39, Crist J. Clark wrote:
> >>> >> > We are running all of this over SMF.
> >>> >>
> >>> >> why are you using LRM transceivers then?
> >>> >
> >>> > I am not exactly sure of the design decisions behind the choice to use LRM over
> >>> > SMF to orginally connect the distro to the core when the campus was built. But
> >>> > given that it was working, and we already had almost enough spare LRMs on hand
> >>> > to complete the project, It Seemed Like a Good Idea at the Time.
> >>> >
> >>> > We also have OM3 MMF between the buildings so replacing this all with SR is
> >>> > the main plan right now, but whatever the problem is with the LRM modules
> >>> > looks more like software/firmware than a problem with the fiber paths (the links
> >>> > always do eventually come up with good light readings and no errors), and we
> >>> > were just curious if anyone had seen this issue with 5ks and LRM before and
> >>> > found a way to deal with it.
> >>> > --
> >>> > Crist J. Clark
> >>> > _______________________________________________
> >>> > cisco-nsp mailing list  cisco-nsp at puck.nether.net
> >>> > https://puck.nether.net/mailman/listinfo/cisco-nsp
> >>> > archive at http://puck.nether.net/pipermail/cisco-nsp/
> >>>
> >>>
> >>>
> >>> --
> >>> 09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0
> >>
> >> --
> >> Crist J. Clark
> >
> >
> >
> > --
> > 09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0
> > _______________________________________________
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> 
> 
> 
> -- 
> Matthieu MICHAUD

-- 
Crist J. Clark