I have two servers that I wish to direct connect with 10GBE.

One server has an Oracle Sun 10GBE (Intel 82599) with dual SFP+ pluggable transceivers installed. The other has an HP 10GB MELLANOX CONNECTX-2 with no transceiver installed.

I'm planning to move one transceiver from the Sun to the Mellanox.

Can I direct connect the two interfaces with fibre, and if so what kind of fibre cable? If not, what kind of cable do I need?


You may be better off just using a copper DAC cable. But otherwise, you probably just need a multimode fiber LC-LC cable of the appropriate length.

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  • I'll just add to this that you'll need to "cross over" the fiber connections on one end, just as you used to have to do with 10/100 ethernet. – Mark Henderson Feb 25 '16 at 14:43
  • Could you please elaborate on why copper DAC might be better? Do you more likely to just work? – retrodev Feb 25 '16 at 15:30
  • LC-LC cables seem to listed as simplex, duplex, single mode and multi mode. Any suggestions there? – retrodev Feb 25 '16 at 15:32
  • DAC, because you don't know if your Sun transceiver will work on the HP card. – ewwhite Feb 25 '16 at 15:34

I'd recommend using Direct-Attach Cables: this is sort of semi-active equipment that consists of a cable and two strictly attached SFP+ transievers at it's ends. I doubt plugging Sun transiever into Mellanox adapter will do any good (but you can try, and I may be wrong), and DACs are cheap. The only thing to consider is the distance between these servers - unless they are around several meters one from another getting a DAC of this length may become impossible. Another thing to consider - flashing the transievers on the ends with a proper [vendor] firmware, but this is usually taken care of by the DAC vendors.

  • So are transceivers normally vendor specific then? – retrodev Feb 25 '16 at 15:30
  • Only by their firmware: there are only few companies if the world that manufacture SFP/SFP+ transievers, but every vendor tampers them with terir custom firmware, so people have to buy only so-called "original" transievers. Otherwise they would be detected as some "general" ones or even, in worst-case scenario, won't be supported at all. – drookie Feb 25 '16 at 15:50

DAC cables is perfect for your current situation. SFP+ DAC cables, as the name implies, use SFP+ MSA and the inexpensive copper twinax cable with SFP+ connectors on both sides, provides 10G Ethernet connectivity between devices with SFP+ interfaces, which make itself a cost-effective solution for 10G network application.


DAC SFP+ over copper works well. Have configured A B C Windows 10 -cable- Windows 2012 -cable- Windows 2012 Middle machine has 2 10G NICS, bridged. Others have 1 each. (All purchased on eBay for around $20 each).

All machines also have 1G NICs to access internet and serve HTTP. 10G NICs form a privatee network with IPs: (A), (B bridge), (C) Achived 500-700 MB/s between two machines directly connected, and 250MB/s between A and C (i.e., traffic had to route through software bridge in B).

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