Network devices include hosted virtual machines and virtual machine applications. Hosted virtual machines and their applications implement additional functions and services in network devices. Network devices include data taps for directing network traffic to hosted virtual machines and allowing hosted virtual machines to inject network traffic. Network devices include unidirectional data flow specifications, referred to as hyperswitches. Each hyperswitch is associated with a hosted virtual machine and receives network traffic received by the network device from a single direction. Each hyperswitch processes network traffic according to rules and rule criteria. A hosted virtual machine can be associated with multiple hyperswitches, thereby independently specifying the data flow of network traffic to and from the hosted virtual machine from multiple networks. The network device architecture also enables the communication of additional information between the network device and one or more virtual machine applications using an extended non-standard network protocol.