The problem might depend on how far the cable is from the device.
The problem might depend on how far the cable is from the device.
I purchased a SFP+ cable from 10Gtek, which has previously worked without problems. However, this particular 39-foot version isn’t functioning properly. I’ve tried using a shorter cable from the same brand and it also doesn’t connect. The main difference is the length. I’m using a Mellanox ConnectX-3 NIC card and an Ubiquiti USW-Aggregation 10G switch, and both 39-foot cables are failing while a shorter one works on the same ports. Could there be another factor affecting compatibility?
The P/N on the ~39 feet cables isn't listed clearly. You're likely using a Direct Attach Copper (DAC) cable or separate detachable SFP+ transceivers at each end. Your site only displays DAC cables up to 10 meters (~34 ft). Regarding the cables, CAT 5e doesn't meet the official standards for 10G due to its unshielded design and is rated for up to 2.5G; 10G might still function but over shorter distances. CAT 6 supports 10G operation.
The 39-foot cable features CAB-10GSFP-P12M 10G BASE CU with a passive DAC 12-M 24AWG, while the 14-foot version uses CAB10GSFP-P4M 10GBASE-CU with a passive DAC 4-M 26AWG. No Cat5e or 6 is involved; the PC connects straight to the switch.
A passive DAC won't function properly at 12 meters unless the components on either side are tailored for this range—typically found in SAN systems. Passive DACs lose reliability between 3 to 5 meters. Beyond that, you should use an AOC, essentially a permanently bonded fiber patch cable connected to two fiber optic modules, or opt for standard fiber optic modules with patch cables. There are also Active DACs available, though they consume more power and require matching devices at both ends.
They might be selling you because the product won’t function beyond a certain range, and you purchased it yourself instead of through their usual channels.
I mentioned there are systems built for these devices. In our workplace, we use many 10-meter cables from an outdated HP SAN setup, but they fail when connected to other equipment, mainly due to their length.
SFP offers a completely different experience. There are both passive and active cables available. Typically, DAC (direct attach copper) is suitable only for short ranges, generally up to about 10 meters. Beyond that, you can opt for an AOC (active optical cable) or pair transceivers connected by optical cable. Check your compatibility first. Certain manufacturers, such as Cisco, are known for not working well with other network equipment.
It depends on the specific model since some cables and fiber optics include firmware that can prevent compatibility with DAC cables longer than two meters years ago. Also, certain Intel cards won’t work with DAC cables that are too short.