A method and a system for transparently overlaying a logical transport network over an existing physical transport network is disclosed. The system designates a virtual channel located in a first transaction layer of a network conforming to a first network protocol. The system assembles a transaction layer packet in a second logical transaction layer of a second network protocol that is also recognizable by the first transaction layer. The system transfers the transaction layer packet from the second transaction layer to the virtual channel. The system transmits the transaction layer packet over the first transaction layer using the designated virtual channel over the network.

In a data processing device including two sets of circuit pairs which are respectively duplicated in two clock domains which are asynchronous to each other, an asynchronous transfer circuit that transfers a payload signal is provided between the two sets of circuit pairs. The asynchronous transfer circuit includes two sets of a pair of bridge circuits which are respectively connected to the two sets of circuit pairs, and asynchronously transfers the payload signal and a control signal indicating a timing at which the payload signal is stable on a reception side. The two sets of a pair of bridge circuits and the payload signals can be duplicated, but the control signal is not duplicated, and the received payload signal is used for timing control to supply an expected same time difference, to the pair of duplicated circuits. This enables asynchronous transfer between circuits duplicated in the asynchronous clock domains.

A method and a system for transparently overlaying a logical transport network over an existing physical transport network is disclosed. The system designates a virtual channel located in a first transaction layer of a network conforming to a first network protocol. The system assembles a transaction layer packet in a second logical transaction layer of a second network protocol that is also recognizable by the first transaction layer. The system transfers the transaction layer packet from the second transaction layer to the virtual channel. The system transmits the transaction layer packet over the first transaction layer using the designated virtual channel over the network.

In a data processing device including two sets of circuit pairs which are respectively duplicated in two clock domains which are asynchronous to each other, an asynchronous transfer circuit that transfers a payload signal is provided between the two sets of circuit pairs. The asynchronous transfer circuit includes two sets of a pair of bridge circuits which are respectively connected to the two sets of circuit pairs, and asynchronously transfers the payload signal and a control signal indicating a timing at which the payload signal is stable on a reception side. The two sets of a pair of bridge circuits and the payload signals can be duplicated, but the control signal is not duplicated, and the received payload signal is used for timing control to supply an expected same time difference, to the pair of duplicated circuits. This enables asynchronous transfer between circuits duplicated in the asynchronous clock domains.