I just purchased a MikroTik CRS310-8G+2S+IN from Baltic Networks and was wondering what type of DAC cable I should purchase to go from a SFP+ port on the switch to a Chelsio T6225-CR Two Port 1/10/25GbE NIC in my NAS? When I go to purchase DAC cables they ask for a manufacturer (CISCO, BROADCOM, etc. and there is not option for MikroTik or Chelsio. Also, the DAC spec says a passive DAC cable can be up to 7 meters long (which I need between the different servers) but whenever I look at a cable over 5 meters, the system (at multiple vendors) switches it to an AOC active DAC cable. I want the DAC cables to work with 25G so I assume I can get a SFP28 DAC cable and it will work with SFP+ (10G) without a problem but I am not sure give all the crazy DAC stories I have read. I have heard that they put firmware in the transceivers that can make DAC’s not work but I would think a passive DAC wouldn’t have any firmware or code so what’s going on? I never thought buying a cable would be so hard. I have heard rants the the switch manufactures want you to buy their cables and transcievers so they put code in the transcievers. But again this is a passive DAC. May because of all the hasseles with the active cables the vendors ask all these things for a DAC passive cable when they don’t need to??? Also what do you call the ends of a DAC cable as they aren’t really transcievers. … And what with not being able to buy a 7 meter DAC Cable if the spec allows it? . I just watched a few YouTube vides (Lawerence and others) and they did not go over the DAC dilema I am referring to. I sent an email to MikroTik last night and haven’t heard back… Thanks to all who are in the “KNOW” on this.
Some (all?) of the big names tend to do some fuckery with their (hugely overpriced) cables in order to display a scary prompt in software when you buy the same cable with a different sticker on it.
5 meters is about the longest I have seen for passive DACs.
Before going active-DAC, consider transceiver+fiber, depending on your retailers, it may end up cheaper.
SFP, SFP+ and SFP28 are the same physically.
I am running transceivers by FS (branded as FS) in my Intel E810 and Mikrotik devices, no problems anywhere.
SFP-Details from my CRS309 to CSS610 Link:
Thank you that was great info. I was afraid I would have to resort to fiber. Didn’t want to because of all the heat and power 4 transceivers will generate. Sincr the nic can run at 25g is there a way to split one 25g nic port into two spf+ ports and do aggregation on 2 switch 10g spf+ ports? I saw them doing that with dac cables and didn’t know how unless those were active dac cables?
No.
For a split as proposed, your “root”-switch would need to have a QSFP+port.