Patent ID: 7751708

Claim:
An optical transmission system, comprising: an optical switch node including a switching processor to set identical switching timing for input ports thereof such that signals input from the input ports are switched at the identical switching timing, wherein when an optical dummy packet is received, the switching processor switches the optical dummy packet at the set switching timing to be returned to an originating node which originated the optical dummy packet; and a terminal node to transmit, during in-service operation, optical packets to the switching processor, the terminal node including: a dummy packet memory to generate and store a dummy packet, which is an electrical signal, during initial setting executed on connection of the terminal node with the optical switch node, an optical dummy packet transmitter to read out the dummy packet at readout timing from the dummy packet memory, convert the read dummy packet to an optical signal to generate an optical dummy packet, and transmit the generated optical dummy packet to the switching processor during the initial setting, a dummy packet receiver to receive the switched optical dummy packet and convert the received optical dummy packet to the dummy packet which is an electrical signal, and a time difference corrector to detect synchroneity of the switched and looped-back optical dummy packet and, upon detection of asynchronism, vary the readout timing until synchroneity is attained, thereby correcting a time difference such that the optical dummy packet is synchronized with the switching timing, and permitting the terminal node to transmit the optical packets to the switching processor by using the readout timing obtained after the time difference correction.