out of band management - OOBM

• The simplest definition is that OOBM provides access and control of IT assets outside of the production network

As the name would imply, the primary use of OOBM is access and control of IT infrastructure when the production network is unavailable, such as cases involving unplanned downtime. OOBM networks can be 100% dedicated or leveraged hybrid models. The type of assets that require OOBM can include the mission critical routers, switches, KVMs, servers, storage, and appliances that serve as the backbone of the IT infrastructure.
https://www.lantronix.com/blog/out-of-band-management-what-why-where-and-when/