I have two Cisco Catalyst 4510R+E systems that I am interconnecting, using the interfaces on the sup's (both have dual Sup7-E's.) They are marked 1G/10G Uplinks (SFP/SFP+) on the sup above the interfaces. I have ordered 10G SFP+ modules, but in the meantime, I already have 1G SFP's available (GLC-SX-MM), and I have inserted one in one of the sup interfaces (Te5/1), and see the following:

Switch#sh int status mod 5

Port      Name               Status       Vlan       Duplex  Speed Type
Te5/1                        notconnect   1            full   auto 1000BaseSX
Te5/2                        notconnect   1            full   auto No XCVR
Te5/3                        inactive     1            full   auto No XCVR
Te5/4                        inactive     1            full   auto No XCVR

So, does this mean that the sup autosenses the module speed (in this case, 1G) and when I get the 10G modules, I can just replace the 1G mod's with the 10G mod's, and the links will come back up at 10G? (the infrastructure fiber as well as the patch cables are all OM-3 MM, so they're good to go for 10G...) Or, is there some command needed to set the interface to be 10G rather than 1G?

1 Answer 1


In a word: YES.

Unless you want to do something like force a 10G SFP+ to link at 1G, you don't have to do anything but plug it in.

  • 1
    This makes me curious and I don't have a lab 10G to play with at the moment. Can you actually force a 10G transceiver to operate at 1G? My first instinct would be to say no, but I have never tried.
    – YLearn
    Dec 19, 2013 at 0:42
  • 3
    @YLearn, depends on the SFP+ and device it's in. (finisar.com/products/optical-modules/sfp-plus for their modules)
    – Ricky
    Dec 19, 2013 at 3:09
  • Thanks for the pointer. Something new to play with to be added to my wish list...
    – YLearn
    Dec 19, 2013 at 21:30
  • 3
    confirmed autosensing works... Replaced the GLC-SX-MM module with the new SFP-10G-LRM= module I just rec'd, now the Type field shows 10GBase-LRM :) Dec 20, 2013 at 21:13

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