Capacity limit of queueing timing channel in shared FCFS schedulers

The capacity of a queueing timing channel in which a user modulates messages to another user via his pattern of access to a shared resource scheduled in an FCFS manner is calculated. One example of such a channel is the cross-Virtual Network (VN) covert channel in data center networks. In data center networks, software-defined-networks generate logically isolated virtual networks, across which direct data exchange is impossible. However, since packet flows belonging to different VNs inevitably share underlying network infrastructure, it is possible to transfer data across VNs through timing channels resulting from the queueing effects of the shared resource.