Maintain the Ethernet Link to the BMC in Server Power Actions
In most modern servers a baseboard management controller (BMC) is responsible for monitoring things such as temperature, voltages, and fans. The BMC can usually be configured to send out alerts (in the form of emails and/or SNMP alerts) when something in the system requires the attention of an administrator (such as the CPU starting to overheat).
The BMC usually has network connectivity via the sideband interface on some kind of LAN on motherboard (LOM). The most common sideband interface is Network Controller Sideband Interface (NC-SI) defined by the DMTF and available on many Intel as well as other vendor’s Ethernet Controllers. The NC-SI interface provides a mechanism by which the BMC can share Ethernet connectivity with the operating system.
The BMC can use this Ethernet connectivity to enable a remote management application to establish a connection. Over this connection a management application can do such things as view the temperature, voltage, and fan sensors along with a great many other tasks. One popular usage for this connection is Serial over LAN (SoL) by which one can reboot a server and do tasks such as BIOS configuration. A more advanced feature is Keyboard, Mouse & Video (KVM) redirection, which enables the BMC to provide a remote desktop type of capability independent of the operating system.
Read the full Maintain the Ethernet Link to the BMC in Server Power Actions Paper.