Methods and apparatus are provided for virtualizing port adapter resources such as network interface cards (NICs) used to connect servers to packet based networks. Resources are offloaded from individual servers onto a resource virtualization switch. Servers connected to the resource virtualization switch using an I/O bus connection share access to NICs. Redundancy can be provided using multipathing mechanisms implemented at individual servers or high availability mechanisms implemented at the resource virtualization switch. Switchover can occur between ports on the same port adapter, between ports on separate adapters, or between ports on separate resource virtualization switches.