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US 2007/0166035 A1Published application
Optical transmission system
AssigneeFujitsu Limited
InventorYasuhiko Aoki
Life of this patent
Estimating the term…
Abstract
An optical transmission system capable of time difference correction without lengthening guard times, thereby improving optical packet transmission efficiency. A switching processor sets identical switching timing for all input ports thereof such that signals input from the input ports are switched at the same timing. When an optical dummy packet is received, the switching processor switches the optical dummy packet to be returned to the originating node. A time difference corrector detects synchroneity of the switched and looped-back optical dummy packet and, if asynchronism is detected, varies readout timing until synchroneity is attained, thereby correcting the time difference so that the optical dummy packet may fit in the switching time range and thus can be switched normally.
Claims5
An optical transmission system, comprising:
- an optical switch node including a switching processor, the switching processor setting identical switching timing for all 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 when an optical continuous signal is received, the switching processor samples the optical continuous signal at the set switching timing and returns an optical dummy packet sampled thereby to an originating node which originated the optical continuous signal;
- and
- a terminal node including a dummy packet memory for generating and storing 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 for transmitting the optical continuous signal to the optical switch node during the initial setting or, when the optical dummy packet is to be transmitted to the optical switch node during the initial setting, reading out the dummy packet at readout timing from the dummy packet memory, converting the read dummy packet to an optical signal to generate again the optical dummy packet, and transmitting the generated optical dummy packet to the switching processor, a dummy packet receiver for receiving the switched optical dummy packet and converting the received optical dummy packet to the dummy packet which is an electrical signal, and a time difference corrector for detecting synchroneity of the switched and looped-back optical dummy packet and, if asynchronism is detected, varying the readout timing until synchroneity is attained, thereby correcting a time difference such that the optical dummy packet is synchronized with the switching timing, wherein during in-service operation, the terminal node transmits optical packets to the switching processor by using the readout timing obtained after the time difference correction.
An optical transmission system, comprising:
- an optical switch node including an optical switch for switching an optical packet, a switch driver for receiving a port-to-port connection request, determining a switch connection route of the optical switch based on destination information, and controlling switching operation of the optical switch, and a timing adjustment signal generator, responsive to reception of a timing adjustment request signal, for generating and outputting a timing adjustment signal to a node which is transmitting an optical packet at such transmission timing as to cause timeslot displacement at an input port of the optical switch;
- and
- a plurality of terminal nodes each including a connection request transmitter for identifying a destination node to which an optical packet is to be transmitted, and transmitting, together with the destination information, the port-to-port connection request for connection with the optical switch, an optical packet transmitter for transmitting the optical packet affixed with a timestamp to the optical switch if port-to-port connection with the optical switch is permitted, a timestamp analyzer for receiving the switched optical packet, analyzing continuity of the timestamp and, on detection of timeslot displacement as a result of the analysis, transmitting the timing adjustment request signal, and a timing corrector for receiving the timing adjustment signal and correcting the transmission timing for the optical packet,
- wherein, provided that the terminal nodes include first and second terminal nodes and a destination terminal node and that first and second optical packets transmitted from the first and second terminal nodes, respectively, are addressed to the destination terminal node, the timestamp analyzer of the destination terminal node operates, in response to reception of the switched first and second optical packets, to analyze continuity of the timestamps affixed to the first and second optical packets and, if timeslot displacement has occurred, to output the timing adjustment request signal, the timing adjustment signal generator operates, in response to reception of the timing adjustment request signal, to output the timing adjustment signal for correcting transmission timing displacement, to the first or second terminal node whose optical packet transmission timing is displaced on a timeslot basis, and the timing corrector of the first or second terminal node corrects the optical packet transmission timing on a timeslot basis, in accordance with the received timing adjustment signal.
1 more element
Dependencies are inferred from the claim text.