I think this applies to various server hardware. My IBM here has 3 different ways of managing the system with IPMI and related technologies:
1) Standard IPMI connectors which I can connect to with lm-sensors and ipmitool, when logged in via ssh
2) The Baseboard Management Controller (BMC) which uses the same IPMI facilities to tell me about the system status, allow me to reboot. The only plus is that it can be connected on a separate IP address with its own small user management.
3) The Remote Supervisor adapter (RSAII) is like 2) but with the benefit that it is a separate small computer, with own Ethernet and CPU, with the sole purpose of managing the system it lives on.
I understand that each of these technologies represents different levels of "hardware sophistication", with each step up rendering lower steps redundant at times, BUT:
I see the benefit of 3) as it provides lights-out management, but why does 2) expose it's own IP inroad? When the system is ON, I can access IMPI via shell, when it's OFF I can't access BMC and shell. Is the extra IP address and user/login stuff a gimmick??