To help differentiate the different designations of code, i.e., MD, ED, GD, take a look here.To help you decide which version of code is right for you, there’s the cisco IOS feature navigator found here.
Cisco has been nice enough to include a 1Gb USB flash drive with their new ISRs, making the software upgrade process a cinch. Here are the steps involved to install a new version of IOS-XE via USB drive. Just got in a new Cisco ISR 4431 and needed to upgrade IOS-XE out of the box.
