As I understand it, Cisco differentiates between an update (free, bug fixes only) and an upgrade (requires purchase, new features.) If I want to get the latest update (i.e. free) how do I know what versions I'm eligible for?
For example, I have a WS-C2960G-24TC-L running C2960-LANBASE-M, Ver. 12.2.35-SE5. When I sign in with my Cisco account and go to downloads, I'm presented with 20 versions of 12.2 going up to 12.2.58-SE2, as well as 10 versions of 15.0 going up to 15.0.2-SE6.
Which of these can I (legally) install without purchasing an upgrade license? How can I tell for other models I have?