1. An apparatus comprising: a network connection module comprising one or more network interfaces; a virtual host interface configured to communicate with a plurality of host servers; a transmit and receive module comprising multiple instances of transmit and receive resources configured to pass data from the virtual host interface to the network connection module; and an input/output (IO) controller configured to connect each of the host servers to at least one of the network interfaces such that the connections between each host server and corresponding one or more network interfaces are operationally isolated and independent from connections between other host servers and their corresponding network interfaces, wherein the IO controller includes a processor to receive Peripheral Component Interconnect Express (PCIe) configuration transactions from a particular host server, build a virtual topology for the particular host server, and map the virtual topology to instances of the transmit and receive resources.