In-band communication interface power management fencing

An apparatus and method for providing efficient power management for data transfer protocols between components. A source generates requests and a destination services the requests. The source and destination support a communication protocol that includes both a transfer channel and one or more transaction channels for each type of request. The source and destination rely on a valid signal and a ready signal of the transfer channels to autonomously manage power consumption. The source and destination remove any dependencies on an external power manager and make it unnecessary to add signal extensions to the communication protocol to support power management.