Quite often it is useful to put up a test stream or source with a new CDN configuration for testing purposes, this works with authenticated rtmp which is required when connected to Akamai or many Adobe/Flash Media Server servers.
ffmpeg -re -f lavfi -i testsrc=size=1920x1080 -c:v libx264 -b:v 500k -an -s 1920x1080 -x264opts keyint=50 -g 25 -pix_fmt yuv420p -f flv rtmp://<USERNAME>:<PASSWORD>@p.<CPCODE>.i.akamaientrypoint.net/EntryPoint/mystream_1_500@<STREAMID>
You need to get the username, password, entrypoint name and streamid from your Akamai account (Configure -> Live Media)
You can then play it back using the URLs you also see in your Akamai control panel.
Note that for the RTMP to be converted to HLS or HDS you need to make sure you have frequent enough keyframes which is what the keyint directive is for.