: Support for Virtual Switching System (VSS), which allows two physical switches to operate as a single logical entity.
boot system flash bootflash:cat4500e-universalk9.spa.03.11.04.e.152-7.e4.bin and save the configuration. OSPF Considerations
This is where it gets confusing for new engineers. IOS XE versions map to "Classic" IOS 15 versions for feature parity tracking.
is a specific release of the Cisco IOS XE software, which is based on IOS 15.2(7)E4.
Features like Non-Stop Forwarding (NSF) and Stateful Switchover (SSO) ensure that if a Supervisor engine fails, the network stays up.
: Indicates this is a "Universal" image containing all feature sets (IP Base, Enterprise Services, etc.). The "k9" signifies that it supports strong payload encryption (triple DES/AES).