Downgrading SD-WAN Image to Classic IOS-XE on Cisco Routers

Recently I was working on an engagement that involved 100+ Cisco C1111 Routers, the only problem was that the routers all shipped with Cisco’s IOS-XE-based SD-WAN image instead of the “classic” IOS-XE image.

The documentation on Cisco’s website on the downgrade process is rather slim, so I’ve listed the steps below:

Delete all files from flash:

delete /force /recursive flash:/*

Insert a USB drive containing the image into the USB port and copy the IOS-XE image onto the routers flash (I used the latest star release at the time, 16.09.04:

copy usb0:c1100-universalk9_ias.16.09.04.SPA.bin flash:

Stop the SD-WAN process that tries to re-download the SD-WAN image:

pnpa service discovery stop

Reload the router:

reload

I had some issues where I couldn’t copy the image from the USB port on several routers due to read errors that don’t appear to be flash drive related. If so, the process to avoid this is booting into RMON, booting the IOS-XE image from the flash drive (surprisingly works despite USB read errors on copying), and then TFTP’ing the image off a TFTP server.

From RMON:

boot usb0:c1100-universalk9_ias.16.09.04.SPA.bin

Once the image boots from your USB drive, configure a TFTP server and copy the image across.

en
conf t
interface vlan 1
ip address <IP Address> <Subnet>
exit
ip tftp blocksize 8192
exit
copy tftp:c1100-universalk9_ias.16.09.04.SPA.bin flash:

And you’re done. Hopefully this helps someone in need.