One of my colleagues asked me if I knew what he could use to test Cisco twinax cables – specifically the SFP-H10GB-CUxM passive cables, and the SFP-H10GB-ACUxM active cables. These cables are identified in the industry as SFP+ direct-attach copper cables, and can be used to interconnect Nexus switches and other devices at 10GE. He has recently connected a bunch of them in his data center.
I looked into it a bit – these cables use the Etherent Alliance’s SFF-8431 and SFF-8461 standards. Specifically, SFF-8431 for the Passive Twinax cables, and SFF-8461 for the Active Twinax cables.
Based on my reseach, I think the practical answer is no – there is just not a simple ” yes, good cable / no, bad cable” hand-held tool for Cisco twinax cables. For example, I spoke with Cisco, they do not have a test tool. I spoke with Fluke, they don’t have an module that accepts the Cisco twinax cables. I spoke with CableandKits – they don’t have a tester either. I also talked to CDW, who looked internally, and called around their associates. They don’t have a hand-held tester, or know of anyone who does.
I did see that Tektronix gear was previously used for testing the SFF-8431 standard in Etherent Alliance’s SFP+ Direct Copper Attach Interoperability paper, so I asked them as well. Tektronix said you could use a DSA8300 sampling oscilloscope with a 80E04 TDR module and 80SSPAR software to test the cable. They said that there is some learning curve to it, but that a local account manager could demonstrate how to use it properly. However, this is probably more advanced then most end users will want. These tools would give you a frequency response graph and impedance and reflections, but not a simple Pass or Fail test. fwiw, these components have a list price of about $64,000, so while technically possible, it appears to be too expensive to be a practical solution for most end users.
Workaround: I recommended to my colleague that since all the twinax cables are 1m – 10m, he should probably reserve two ports on adjacent Nexus gear, configure them to be up, and just hook a suspect cable up between the two “active” ports and see if it works.