For RH2285 and X6000 devices, management IP is configured into DHCP automatic getting mode, but IP address is not assigned automatically.
RH2285 can get IP after complete power off (unplug power supply) and reboot, X6000 can get IP through pull and insert board.
The fundamental cause is management network port DHCP archiving policy. Management network port would not archive IP if previous archiving fails. Reboot BMC, network will try to archive again. If management port cable is not connected before device powered on, it cannot get IP.
1. Network cable failure
2. DHCP server failure
3. Device hardware failure
If management network port IP is in DHCP mode, before RH2285 and X6000 powered on, management network port must be already connected to make sure that IP can be assigned.