Ultra-highspeed packet transfer ring network

An optical add/drop multiplex type node apparatus for optical packets to be dropped from, added to or cut-through an optical fiber transmission path disposed in a ring network, comprising:

• a send packet terminating section for temporarily accumulating packets input from a user side, converting packets to optical packets and outputting, and preparing a label signal containing a n address of a destination node apparatus to correspond to a send-packet or routing information to the destination node apparatus;
• an optical circuit section for separating an optical signal input from the optical fiber transmission path to obtain a separated optical packet and an optical label signal, as well as for switching between a bar-state and a cross-state, so that, in the bar-state, two groups of optical packets consisting of said separated optical packet input from the optical fiber transmission path and an optical packet output from the send packet terminating section are received, and said separated optical packet is cut-through without any change to the optical fiber transmission path, while in the cross-state, said separated optical packet input from the optical fiber path side is dropped and output, and said send-optical packet from the send packet terminating section is added to the optical fiber transmission path, and further, an optical add-label signal received is wavelength multiplexed or polarization multiplexed with either an optical pass-packet or an optical add-packet, and sent through to the optical fiber transmission path;
• a packet send/receive control section for determining, according to an optical label signal retrieved by the optical circuit section, whether there is a corresponding optical packet, and controlling packet transmission in such a way that:
• (a) if an optical packet is addressed to its own node apparatus or a pass-packet is not present and packets are accumulated in the send packet terminating section, a drive signal is output to maintain the optical circuit section in the cross-state, and when packets are accumulated in the send packet terminating section, an optical packet send command signal is output to the send packet terminating section and, at the same time, an optical label signal for a corresponding optical packet to be added to or cut-through the optical fiber transmission path is output at given intervals to the optical circuit section;
• and (b) if an optical packet input from the optical fiber side is not addressed to its own node apparatus, a drive signal is output to the optical control section to maintain the bar-state, and an optical label signal relating to an optical pass-packet is output to the optical control section;
• and
• a receive packet terminating section for optical-electrical converting an optical packet separated from the optical fiber path side and addressed to its own node apparatus, and, by accessing a destination user address or routing information to a destination node apparatus included in the packet information obtained by conversion, restoring the optical packet to a state before editing and outputting the restored packet to a specific output port.

A method for operating an optical add/drop multiplex type node apparatus disposed in an optical fiber transmission path arranged in a ring for an optical packet to be added to, dropped from or cut-through the optical fiber transmission path, comprising:

• a step of separating and accessing an optical label signal from an optical signal input from the optical fiber transmission path to generate a separated optical label;
• a step of label discriminating for determining, according to the optical label signal separated in the separating step, whether there is a corresponding optical packet and its destination address;
• an optical packet sending step for converting a packet input from the user side to an optical packet and outputting the optical packet, when an optical packet in the optical fiber path side is addressed to its own node apparatus or when there is no optical pass-packet, according to a result of the label discriminating step;
• an optical switch driving step for outputting a drive signal to the optical fiber transmission path, after a standby interval, to switch the optical switch in such a way that routing through the optical fiber transmission path for packet adding, dropping and passed-through would be different, depending on, as a result of the label discriminating step, whether an optical packet on the optical fiber path side is addressed to its own node apparatus, or there is no optical pass-packet and packets addressed to its own node apparatus are accumulated, or when an optical packet on the optical fiber path side is not addressed to its own node apparatus;
• a label re-preparation step for preparing a new optical label when, as a result of the label discriminating step, the optical packet from the optical fiber transmission side is not addressed to its own node apparatus;
• an optical label sending step for sending the optical label re-prepared in the label re-preparation step to the optical fiber transmission path through the optical switch;
• a delaying step for delaying an optical packet arriving a specific time later than said separated optical label;
• and
• an emitting step for outputting without any changes the optical packet that arrives after the delaying step to the optical fiber transmission path through the optical switch.

A node apparatus for transferring optical packets to be dropped from, added to or cut-through a ring network comprised by connecting a plurality of said node apparatuses in a ring shaped optical fiber transmission path, wherein said node apparatus has a working path and a protection path;

• and said working path is provided with:
• an optical label extraction circuit section for extracting a label signal that contains at least address information relating to an optical packet in the optical fiber transmission path;
• an optical label attaching circuit section for attaching a pass-label signal for an optical packet to be passed through its own node and attaching an add-label signal for an optical packet to be added from its own node to the optical fiber transmission path;
• an optical switch for switching optical packets so as to drop an optical packet arriving in the optical fiber path side when the optical packet is addressed to its own node, or to add an optical packet from its own node to the optical fiber transmission path, or to cut-through an optical packet arriving in the optical fiber transmission path side that is not addressed to its own node;
• a label receiving circuit section for receiving label signals extracted by the optical label extraction circuit section;
• a monitor for monitoring a transmission code included in a received label signal, and issuing a trigger signal to report an abnormal state when detected;
• a control circuit section for issuing a packet send command signal to add an optical packet to the optical fiber transmission path by matching timing according to a label signal received, and receiving trigger signals issued by the monitor;
• not less than one terminating section for packetizing data input from the user side according to a relevant interface;
• a packet editing sending circuit section for editing a plurality of packets addressed to node apparatuses having a common destination address into one packet and accumulating edited packets, and outputting a label signal containing at least node information on a destination node of a packet or routing information to the control circuit section;
• not less than one packet sending circuit section for adding a packet sent from the packet editing sending circuit section to the optical fiber transmission path according to a packet send command issued from the control circuit section;
• not less than one packet receiving circuit section for receiving optical packets addressed to its own node and dropped from the optical fiber transmission path;
• a packet editing receiving circuit section for editing a packet received from the packet receiving circuit section into original pre-edited packets and accumulating original packets and transferring to user destinations;
• according to user side interface, and said protection path is provided with:
• an optical label extraction section for extracting a label signal;
• an optical switch for switching optical packets so as to drop an optical packet arriving in the optical fiber transmission path side when the optical packet is addressed to its own node, or to cut-through an optical packet arriving in the optical fiber transmission path side that is not addressed to its own node;
• an optical label receiving section for receiving label signals extracted by the optical label extraction circuit section;
• a monitor for monitoring a transmission code included in a received label signal, and issuing a trigger signal to report an abnormal state when detected;
• a control circuit section for receiving information contained in received label signals and trigger signals issued by the monitor;
• not less than one packet receiving circuit section for receiving optical packets addressed to its own node apparatus and dropped from the optical fiber transmission path;
• a packet editing receiving circuit section for separating a packet received from the packet receiving circuit section into original pre-edited packets and accumulating original packets and transferring to user destinations;
• and the node apparatus is further provided with:
• a second optical switch controlled by the control circuit section to pass a packet through without any change to the working path of the optical fiber transmission path or to switch to the protection path of the optical fiber transmission path by reversing the direction of transmission;
• and
• an input buffer provided in front of an input section of the second optical switch for connecting to the protection path of the optical fiber transmission path.

A node apparatus, for transferring optical packets to be dropped from, added to or cut-through a ring network comprised by connecting a plurality of said node apparatuses in a ring shaped optical fiber transmission path, wherein said node apparatus has a working path and a protection path;

• and each of said working path and said protection path is provided with:
• an optical label extraction circuit section for extracting a label signal that contains at least address information relating to said optical packet in the optical fiber transmission path;
• a monitor for monitoring extracted label signals and, if an abnormal state is found by monitoring, generating a trigger signal to notify that abnormality exists;
• a control circuit section for discriminating whether an optical packet relating to an extracted label signal is to be dropped or passed through its own node apparatus according to the extracted label signal;
• an optical label attaching circuit section for sending to the optical fiber transmission path a pass-label signal for an optical packet to be cut-through its own node, according to a result of discrimination by the control circuit section;
• an optical switch for switching a path for optical packets according to a result of discrimination by the control circuit section;
• a packet receiving circuit section for receiving optical packets dropped into its own node apparatus by way of the optical switch;
• and further, in the working path, a sending circuit section is provided to send an optical packet input from the user side to the optical fiber transmission path through the optical switch, and the control circuit section switches the optical switch at same intervals as the optical packets sent through the sending circuit section;
• and
• the control circuit section switches between the working path and the protection path according to a trigger signal issued by a monitor circuit section.

An optical packet compression circuit comprising:

• an optical pulse generation section for generating optical pulses at ΔT intervals;
• an optical divider for separating optical pulses output from the optical pulse generation section into N pieces of signal lines, where N is a natural number;
• a buffering circuit for temporarily storing serially input data and outputting N parallel trains;
• N pieces of modulators, one modulator for each of N signal lines, for modulating optical signals output from the optical divider individually according to N pieces of data output from the buffering circuit;
• an optical delay line provided in a back stage of the modulator in each signal line for delaying output signals of the modulator by an amount equal to a whole multiple of Δt;
• and
• an optical coupler for outputting modulated optical pulses so that each optical pulse is shifted by an interval Δt by means of the optical delay line.

An optical packet decompression circuit comprising:

• an optical serial/parallel conversion circuit for converting continual input optical pulse signals into N parallel trains of optical pulses, where N is a natural number;
• N pieces of photo detectors for optical/electrical conversion of respective optical pulse signals produced by the serial/parallel conversion circuit;
• not less than one start-bit detection circuit for detecting a start-bit of electrical signals output from the N pieces of photo detectors;
• N pieces of switches for directing electrical signals output from the N pieces of photo detectors to respective buffers;
• N2 pieces of memories for temporarily storing each bit of N pieces of electrical signals directed to N pieces of switches;
• a read circuit for generating a read-signal, when a start-bit is detected by a start-bit detection circuit-1, for each bit of the N2 pieces of memories so that N2 pieces of signals are successively read out from the memories, beginning with a memory corresponding to said start-bit detection circuit-1;
• and
• N pieces of multiplexing circuit sections for multiplexing each group of N data read from the N2 pieces of memories according to a read-signal, and outputting resulting groups of multiplexed signals to output signal lines.