intelligent platform management bus (IPMI) (IPMB)
The Intelligent Platform Management Bus (IPMB) is based on the I2C bus and is used for the connection between different boards within a chassis. For example, for connecting an optional IPMB I/O board to other boards that support IPMB.
The IPMB interface can also connect to external chassis-to-chassis interfaces via a bridge chip. The bridge function can be performed by the baseboard management controller( BMC).
The management controllers( MC) communicate with the baseboard management controller (BMC) of an IPMI system via the IPMB bus. The IPMB bus is a serial three- wire bus, with one wire carrying the clock signal, Serial Clock Line (SCL), another wire carrying the data, Serial Data Line( SDL), and the third used for ground.
The IPMB connector is available in two versions, type A and type B. The only difference between them is the number of pins. These differ only in the number of contacts, with type B having the fourth contact unconnected. Contact 1 is assigned with the SDA signal for the data, contact 2 with ground and contact 3 with the SCL signal for the bus clock.