26 iRMC S2/S3
IPMI - technical background
IPMI and “in band” and “out of band” management
In the field of system management, a distinction is made between “in-band” and
“out-of-band” management:
– The term “in-band” management is used when the operating system is
running on the managed server.
– The term “out-of-band” management is used when the operating system is
not running on the managed server, for instance if the hardware is faulty.
As different interfaces are available in an environment with IPMI compatible
systems, you can manage IPMI compatible systems either “in band” or “out of
band”.
IPMI-over-LAN
“IPMI-over-LAN” is the current name for the specification of the LAN interface in
the IPMI standard. This specification stipulates how IPMI messages can be sent
to or from the BMC of a managed system - encapsulated in RMCP (Remote
Management Control Protocol) data packets. These RMCP data packets are
transferred via an Ethernet LAN connection using the UDP (User Datagram
Protocol) under IPv4 (Internet Protocol Version 4).
The RMCP protocol has been specified to support the management of system
statuses in which the operating system is not running. The RMCP is a simple
inquiry/response protocol.
The interface for such a connection is provided on an onboard LAN controller
assigned to the BMC.
IThe interface can only be provided by an on-board LAN controller, not by
an inserted LAN card.