In general, techniques for secure communicating over a virtual IPMB of a mainframe computing system are described herein. More specifically, the mainframe computing system comprises a plurality of independent computing cells communicatively coupled together by a network interconnect and that form a plurality of partitions. Each partition is a logical association of one or more of the cells to define a single execution environment. Each cell further executes a virtual intelligent platform management interface (IPMI) protocol to define and configure a respective logical intelligent platform management bus (IPMB) for each of the partitions. Each of the IPMBs logically interconnects with each of the other cells included within the same partition, and each is defined for communication of IMPI messages over the network interconnect. The cells securely communicate the IPMI messages between each of the one or more other cells of each partition via the respective logical IPMB of each partition.