We are looking to deploy a new data center build-out with Nexus 7ks and Nexus 2ks(FEX). I know the Nexus 2ks come bundled with the Fabric Extenders to be used to uplink to the Nexus 7ks. Our plan however is to put Gigamon fiber taps in-line of all of our uplinks back to our Nexus 7ks. Based off what I understand the FET needs to connect on one end to a FET on the other end. Would the SFP+ used on the in-line fiber taps cause a problem? Does anyone have experience with this? I'm considering just going with 10G SFP+ optics everywhere and not using the FETs.



  • As the FET is just a "USR" (ultra-short-reach) SFP+, it might work. Of course, you may not see what you expect to see on those links. Also, cisco may be checking the SFP in the FEX, so you may have to use the FET it comes with. (FETs are cheap on eBay anyway.)
    – Ricky
    Dec 3, 2013 at 21:27
  • Did any answer help you? if so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you could post and accept your own answer.
    – Ron Maupin
    Jan 3, 2021 at 19:43

2 Answers 2


Quote from Colby Beam (Cisco TAC) "FET-10G vs. SFP-10G-SR":

This shouldn't be an issue, as I've seen customers do it all the time and I've done it in the lab. There is some limitation on distance with the FET-10G vs 10-SR. Also the FET can ONLY be used to connect a N2K to either a N5K or N7K


FETs are not required to connect 2Ks, they are far cheaper than SFPs and for some odd reason (to me) you can only order them when you order 2ks. As Ricky said you are going to see a non standard Ethernet encapsulation but that is a matter of does wireshark support it. Cisco will be happy to take the extra $$s for SFP+

  • Hi Fred if I understand this question correctly it's about compatibility of the FET transceiver with his fiber tap. I don't see that concern addressed though Dec 4, 2013 at 1:50
  • As I commented, the FET is a lower power SR/SX SFP+. It should be able to talk to an SR SFP+ under ~100m.
    – Ricky
    Dec 4, 2013 at 3:03
  • First, like I said Fred did not mention FET optical compatibility with the tap in his answer; in fact he seems to suggest the OP just use more expensive optics. Second, are you speculating that there are not issues around over driving the FET optical inputs, or do you know this for a fact? Dec 4, 2013 at 4:11
  • As far as I know, it will not be an issue, but I don't have a box of FETs to test. Cisco's DS says they have the same receive power specs as the -SR. cisco.com/en/US/prod/collateral/modules/ps5455/… (table 2)
    – Ricky
    Dec 4, 2013 at 7:19

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