I have a ISR 4451 router with a SM-X-6X1G module with only one port on the 6X-1G module in use (using a GLC-GE-100FX SFP) currently. Even though I have configured the interface with the Media-type SFP command, every time I reload the router this interface reverts to the RJ45 interface on that port and I lose connectivity.
I have saved the config (copy run start) and when I do a show run on the interface in question it doesn't show the media-type SFP is set, yet it is working with the SFP and the RJ45 port is inactive, that is until a reload happens. This only happens to the interfaces on the SM-X-6X1G module, the four on-board interfaces correctly show the media-type SFP setting and do not behave in this fashion.
I am at home writing this and do not have access to the router so I can't provide the IOS version.
I have seen the following Bug reports:
CSCus77336
CSCur01886
CSCus77336 is actually identical to my issue, however they report "No known workaround for this problem" but list IOS's that are known to be affected (15.5(2)S) and known fixed IOS's 15.5(1)S0.7,15.5(1)S1,15.5(1)SN1,15.5(2.1)S.
Is the actual fix for this to upgrade to one of these IOS 15.5(1)S0.7,15.5(1)S1,15.5(1)SN1,15.5(2.1)S? What is actually causing this? Why only ports on the SM-X-6X1G module and not the onboard ports?
