[j-nsp] EX3400 or EX4600, and HPE FlexFabric-20/40, QSFP+ DAC's

[Michael Loftis]

My experience with DACs in the wild is they're not worth the trouble. Even
if they "work" once you look closer you'll spot that they're not working
well. Lots of errors/corrections at higher rates etc. better luck with say
1m or truely active DACs but thing is (Q)SFP(+) was never meant to be more
than an interconnect between points on the same board and the signal timing
constraints, drive levels and basically every other design decision and
constraints reflect that. It's got a very short maximum distance.

On Fri, Dec 1, 2017 at 13:18 Emille Blanc <emille at abccommunications.com>
wrote:

> To close this thread, DAC's appear to have been a wash.
> Using like-vendor branded optics on both sides, and we have a functioning
> 40Gbps link.
>
> Thanks for the feedback on, and off-list. :]
>
> -----Original Message-----
> From: juniper-nsp [mailto:juniper-nsp-bounces at puck.nether.net] On Behalf
> Of Chuck Anderson
> Sent: November-21-17 7:10 AM
> To: juniper-nsp at puck.nether.net
> Subject: Re: [j-nsp] EX3400 or EX4600, and HPE FlexFabric-20/40, QSFP+
> DAC's
>
> On Tue, Nov 21, 2017 at 06:28:07AM -0800, Emille Blanc wrote:
> > Hello folks,
> >
> > Trudging through the woes that are cross-vendor compatibility issues,
> and failing completely at getting a link between an EX3400 or EX4600, and
> an HPE FlexFabric-20/40 F8 card in our c7000 enclosure using an HPE branded
> QSFP+ 3mtr DAC.  That is to say, Juniper on one side, HPE on the other.
> > As an added bonus, the HPE module seems to be allergic to Juniper's QSFP
> completely.
> >
> > After the inevitable "It's not us, it's them" back-and-forth between
> JTAC and HPE Support, I'm looking for any success (or failure) stories from
> the community.
> >
> > We've been testing with a pair of HPE DACs, and they each work fine when
> we loop it to two QSFP+ slots in the same chassis/module.
> >
> > Has anyone been successful in making such a connection in the wild?
>
> Buy cheap QSFP+ optics and use fiber?
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