They're pretty fragile assemblies too, I ruined about 30 of them lacing them in, they need fish-paper around each cable so you don't crush the conductors when lacing.
-----Original Message----- From: NANOG [mailto:nanog-boun...@nanog.org] On Behalf Of Brant Ian Stevens Sent: Thursday, September 14, 2017 2:05 PM To: Tyler Conrad Cc: NANOG Subject: Re: 100G QSFP28 DAC cables - experience +1 on this... I'd go so far as to say skip the copper, and just go with active-optical for short-run interconnects. > Tyler Conrad <mailto:ty...@tgconrad.com> > September 14, 2017 at 2:12 PM > We're using a mix as well, some QSFP28 AOC, others DAC. One thing that you > need to keep in mind about the DACs is going to be the bend radius. These > things are girthy af, so make sure to either overestimate your runs > slightly, or buy one to test first. > > Hugo Slabbert <mailto:h...@slabnet.com> > September 14, 2017 at 12:54 PM > > On Wed 2017-Sep-06 09:17:39 +0200, Jiri Prochazka <j...@cdn77.com> wrote: > > > We're deploying a decent chunk of 100G QSFP28 at the moment, but it's > a mix of: > > - a handful of 100G QSFP28 copper DACs for some switch peerlinks > - a bit >100x 100G QSFP28 AOC for interswitch links > - a lot more 100G QSFP28 -> 4x25G SFP28 copper breakouts > > We're only a few weeks in at this point, so mileage may vary in the > long run etc. > > The copper peerlinks are mostly 1M with some 3M. We've had no issues > with them so far. > > The AOC interswitch links vary more in length, but some of those are > >10M (hence AOC rather than copper). We've faced no issues with > those. Granted, there is BGP with BFD running across those, so those > should help in terms of liveness checks and such. > > I mention that because where we _have_ had issues are on the 100G -> > 4x25G copper breakouts. Those are for 25G edge connectivity. It's a > decent sample size with a bit north of 600x 25G ports. The trouble > we've had there have been with some links showing link up on the > switch and server side but actually failing to pass any traffic, so we > need to stuff some >L1 liveness checks on there to ensure those links > are good while we sort out the root issue. It is not yet clear if > this is a cable fault, driver issue, or something firmware-ish on the > NICs. > > Also, fun fact: 25G only made its way into the 802.3ad bonding mode > driver in the Linux kernel in March this year[1]. > > Jiri Prochazka <mailto:j...@cdn77.com> > September 6, 2017 at 3:17 AM > Hi folks, > > I'm wondering if anyone have (either positive or negative) experience > with 100G QSFP28 DAC cables? > > Is there anyone who is using 100G DAC in large scale and would > recommend it (which means there are no issues compared to SR4 links)? > > I'm thinking about cables with lenght up to 1m, not more. > > We have had quite bad experience with 10G DAC in the past - but I do > not want to be slave of the past. > > > > > Thank you for your thoughts! > > > > Jiri > -- -- Regards, -- Brant I. Stevens, Principal & Consulting Architect bra...@argentiumsolutions.com d:212.931.8566, x101. m:917.673.6536. f:917.525.4759. http://argentiumsolutions.com
