JPWO2006011225A1 - Communication system, packet switch device, and edge node device - Google Patents

Abstract

The packet switch device (201) transmits a switching request for switching the communication path from the conventional path (301) to the new path (302) to the OXC (101), and stores the packet to be transmitted into the optical signal after accumulating during the accumulation period. Convert and send to OXC (101). The OXC (101) transfers the switching request to the OXC (102), and duplicates the optical signal from the packet switch device (201) and transmits it to the conventional path (301) and the new path (302). Upon receiving the switching request, the OXC (102) switches from the conventional path (301) to the new path (302) and transmits the optical signal received from the new path (302) to the packet switch device (202).

Description

  The present invention relates to a communication system in which a redundant system is configured by communication paths of different paths temporarily in a network, and the communication path of the redundant configuration is switched. Specifically, the network is prevented from being damaged due to loss of communication data. The present invention relates to a communication system.

  In recent years, in response to the rapid increase in data traffic due to the Internet and the like and the increase in demand for high-quality multimedia communication, the bandwidth and capacity of network transmission lines and switching node devices have been increased. Layer 1 that relays and exchanges data with optical signals as much as possible by reducing optical signal / electrical signal conversion on the communication path as much as possible in order to realize a wider bandwidth and larger capacity of network transmission lines and switching node devices. Network applications are being considered.

  The layer 1 network relays and exchanges data in a physical layer positioned at the lowest level of an open system interconnection (OSI) model. In a layer 1 network, a node device that exchanges data with an optical signal called an optical cross connect is used.

  The optical cross-connect has a plurality of input interfaces and output interfaces, and outputs data received at an arbitrary input interface to an arbitrary output interface by setting the connection relationship of the optical switches in the apparatus.

  A plurality of node devices have a connection relationship from an input interface to an output interface, and a node device to which a packet switch device having a layer 2 or layer 3 switching function is connected transfers a packet via a layer 1 network. Establish a communication path.

  In a layer 1 network, it may be necessary to switch an operating communication path (conventional path) to a communication path (new path) that passes through a different path or node device as the transmission path or node device is added or changed. is there.

Patent Document 1 discloses a technique related to a transmission path switching method in an optical transmission network that shortens a signal interruption time associated with transmission path switching. Specifically, before switching a redundant transmission line in an optical transmission network, control information of each optical module is held in advance for all optical amplifiers affected by fluctuations in the input light level due to the switching, and after switching Based on this stored control information, the optical path is switched after switching to the switching mode to operate each optical module, so that the output light level of the optical amplifier can be raised in a short time, and wavelength division associated with the switching of the transmission path The interruption time of the multiplexed signal is greatly shortened.
JP 2003-0669455 A

  However, the prior art described in Patent Document 1 switches between a working path and a backup path between the same node devices, and is considered for switching a plurality of communication paths configured by a plurality of node devices. Absent.

  In order to prevent loss of packets transmitted by the packet switch device when switching communication paths configured via a plurality of node devices, a conventional path and a new path are set in the packet switch device connected to the layer 1 network. It is conceivable to switch from the conventional path to the new path by terminating each of them.

  For example, a conventional path and a new path are temporarily set between packet switch apparatuses that perform mutual communication via a layer 1 network in which a plurality of communication paths are configured by a plurality of node apparatuses. The transmission interface is changed from the conventional path to the new path, and packets are received from both the interface connected to the conventional path and the interface connected to the new path. After the packet passing through the conventional path arrives at the counterpart packet switch device, the conventional path is released. Since the packet switch device transmits data in units of packets, the interface of the packet transmission destination can be easily changed. Also, for packet reception, for example, even if the arrival of packets from the conventional path and the new path competes due to the difference between the transmission delay of the conventional path and the transmission delay of the new path, a sufficiently large packet buffer is provided. Thus, packet loss can be avoided and communication path switching without data loss can be performed.

  However, in the communication path switching described above, the packet switch device must terminate the conventional path and the new path. The interface of the packet switch device is generally expensive, and there is a problem that it must be used for two sets of a conventional path and a new path in order to terminate both ends of the communication path.

  The present invention has been made in view of the above, and provides a communication system capable of switching communication paths while preventing data loss at low cost without using a plurality of interfaces in a packet switch device. It is an object.

  The communication system according to the present invention includes a packet switch device and a plurality of node devices including an edge node device to which the packet switch device is connected, and the packet switch device is configured by the plurality of node devices. In the communication system that performs mutual communication using one of a plurality of communication paths, the packet switch device is connected to the own device and the packet switch device of the communication partner from the first communication path that is currently communicating. When it is necessary to switch the communication path to a second communication path that includes the edge node device that is different from the first communication path, the switching from the first communication path to the second communication path is requested. Sending a switching request and after the switching request is sent until the switching to the second communication path is completed A path setting unit that outputs an accumulation start instruction for stopping the output of the packet and a transfer restart instruction for restarting the output of the packet, and when the accumulation start instruction is received from the path setting unit, the output of the input packet is stopped. The packet is accumulated, and when the transfer restart instruction is received, the reception buffer that outputs the accumulated packet, and the packet output from the reception buffer is converted into an optical signal and transmitted to the edge node device to which the device is connected A path management unit that, when receiving the switching request transmitted from the packet switch device, notifies the other edge node device that the switching request has been received, and Light input from the packet switch device after receiving the switching request transmitted from the packet switch device When a notification is received from the duplication unit that duplicates the optical signal as an optical signal and the switching request from the counterpart edge node device, the communication path to be selected is changed from the first communication path to the second communication path. The selection unit to be switched, and the optical signal duplicated by the duplication unit are transmitted to the first and second communication paths, and the optical signal input from the second communication path selected by the selection unit is automatically transmitted. And an optical switch for transmitting to a packet switch device connected to the device.

  The second communication path that is different from the first communication path, including the edge node device to which the packet switch device is connected to the packet switch device of its own device and the communication partner from the first communication path with which the packet switch device is currently communicating The transmission of the packet input after transmitting the switching request for requesting switching to is temporarily suspended and accumulated, and when the switching from the first communication path to the second communication path is completed, the accumulated packet is converted into an optical signal. When the edge node device receives the switching request transmitted from the packet switch device, the edge node device notifies the other edge node device that the switching request has been received, and the light input from the packet switch device. The signal is copied as an optical signal and transmitted to the first and second communication paths, and the switch request from the partner edge node device is received. Then, the second communication path is selected and switched from the first communication path to the second communication path, and the optical signal input from the second communication path is transmitted to the packet switch apparatus connected to the own apparatus. Therefore, the communication path can be switched while preventing data loss at low cost without using a plurality of interfaces in the packet switch device.

FIG. 1 is a diagram showing the configuration of the communication system according to the first embodiment of the present invention. (Embodiment 1) FIG. 2 is a device configuration diagram including the configuration of the packet switch device and the OXC of the communication system shown in FIG. (Embodiment 1) FIG. 3 is a flowchart for explaining the operation of the packet switch device on the transmission side. (Embodiment 1) FIG. 4 is a flowchart for explaining the operation of the transmission side OXC. (Embodiment 1) FIG. 5 is a flowchart for explaining the operation of the OXC on the receiving side. (Embodiment 1) FIG. 6 is a sequence diagram for explaining the operation of the communication system according to the first embodiment. (Embodiment 1) FIG. 7 is a sequence diagram for explaining the operation of the communication system according to the first embodiment. (Embodiment 1) FIG. 8 is a flowchart for explaining the operation of the transmission side OXC. (Embodiment 3) FIG. 9 is a flowchart for explaining the operation of the receiving side OXC. (Embodiment 3) FIG. 10 is a flowchart for explaining the operation of the transmission side OXC. (Embodiment 4) FIG. 11 is a flowchart for explaining the operation of the packet switch apparatus on the transmission side. (Embodiment 4) FIG. 12 is a sequence diagram for explaining the operation of the communication system according to the fourth embodiment. (Embodiment 4) FIG. 13 is a diagram illustrating a detailed configuration of the OXC and the packet switch device according to the fifth embodiment. (Embodiment 5) FIG. 14 is a diagram illustrating a configuration of the Pause frame insertion unit illustrated in FIG. 13. (Embodiment 5) FIG. 15 is a flowchart for explaining the operation of OXC. (Embodiment 5)

Explanation of symbols

100 Layer 1 network 101, 102, 103, 104, 105, 101a, 102a OXC
111, 112 Optical switch 131, 132 Path management unit 141 Replication unit 142 Selection unit 151, 152, 251, 252 Control communication unit 171 Pause generation unit 181 Pause frame insertion unit 201, 202 Packet switch device 211 Packet switch circuit 221 Reception buffer 231 , 232 Path setting unit 301 Conventional path 302 New path 601 O / E converter 602 Control circuit 603 Buffer 604 Pause holding buffer 605 Selector 606 E / O converter

  Hereinafter, embodiments of a communication system, a packet switch device, and an edge node device according to the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by this embodiment.

Embodiment 1
Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 is a diagram showing the configuration of the communication system according to the first embodiment of the present invention. The communication system shown in FIG. 1 includes a layer 1 network 100 having optical cross-connects (hereinafter referred to as OXC) 101 to 105, which are a plurality of (in this case, five) node devices, packet switch devices 201 and 202, and It has.

  The packet switch device 201 and the packet switch device 202 communicate with each other via the layer 1 network 100. In FIG. 1, the packet switch device 201 is connected to the OXC 101, the packet switch device 202 is connected to the OXC 102, and the path 301 connected by the OXCs 101, 104, 105, and 102 is connected by the OXCs 101, 103, and 102. The path 302 forms a redundant system. As described above, the redundant system of the communication path including the two different paths 301 and 302 between the OXC 101 and the OXC 102 is used as a means for giving the communication path fault tolerance, and is called 1 + 1 protection. Hereinafter, the path 301 will be referred to as the conventional path 301 (first communication path as used in the claims) used before switching the communication path, and the path 302 will be referred to as the new path 302 (referred to in the claims) after switching the communication path. However, this is called a second communication path). Further, the conventional path 301 and the new path 302 are set by a signaling protocol.

  The OXCs 101 to 105 are general optical cross-connects and have a function of transferring an input optical signal that is layer 1 data as an optical signal. The OXCs 101 and 102 connected to the packet switch devices 201 and 202 are edge node devices of the layer 1 network 100. In addition to a general optical cross-connect function, communication paths from the packet switch devices 201 and 202 are provided. A function of switching between the conventional path 301 and the new path 302 based on a switching signal for requesting switching is provided.

  The OXCs 101 and 102 copy the layer 1 data as an optical signal at the time of switching the communication path, transfer it to the conventional path 301 and the new path 302, and the layer 1 data input from the conventional path 301 and the new path 302. One is selected and transferred to the packet switch devices 201 and 202 as an optical signal, and after switching the communication path, the layer 1 data input from the packet switch devices 201 and 202 is transferred to the new path 302 as an optical signal. At the same time, the layer 1 data input from the new path 302 is transferred to the packet switch devices 201 and 202 as an optical signal.

  When switching the communication path from the conventional path 301 to the new path 302, the packet switch apparatuses 201 and 202 accumulate Layer 1 data packets to be transmitted and transmit a switching request for requesting the OXCs 101 and 102 to switch the communication path. To do. The packet switch devices 201 and 202 stop accumulating packets at the timing when the OXCs 101 and 102 are switched from the conventional path 301 to the new path 302 by the switching request, and transfer the accumulated packets to the OXCs 101 and 102.

  FIG. 2 is a device configuration diagram including the configuration of the packet switch apparatuses 201 and 202 and the OXCs 101 and 102 of the communication system shown in FIG. In FIG. 2, in order to facilitate the following description, it is assumed that when the layer 1 data is transferred from the packet switch device 201 to the packet switch device 202, the conventional path 301 is switched to the new path 302. Only the components necessary for the transmission process are shown in the switch device 201 and the OXC 101, and only the components necessary for the reception process are shown in the packet switch device 202 and the OXC 102. Actually, the communication through the layer 1 network 100 is full-duplex communication and can be controlled independently. Therefore, the OXC 101 and the OXC 102 have the same function, and the packet switch device 201 and the packet switch device 202 are It has the same function.

  The OXC 101 includes an optical switch 111 that exchanges layer 1 data as an optical signal, and a path management unit 131 that manages setting / release of a communication path of a layer 1 network that transfers layer 1 data as an optical signal, such as an optical coupler. Communication path setting / release by the signaling protocol between the duplicating unit 141 that replicates the layer 1 data from the packet switch device 201 to the conventional path 301 and the new path 302 and the other edge node device (in this case, the OXC 102) The control communication part 151 which exchanges the message regarding is provided.

  The OXC 102 includes an optical switch 112 that exchanges layer 1 data as an optical signal, and a path management unit 132 that controls setting and release of a communication path of a layer 1 network that transfers layer 1 data as an optical signal, such as an optical switch. A selection unit 142 that selects either layer 1 data from the conventional path 301 or layer 1 data from the new path 302 and a control communication unit 152 are provided. Note that the selection unit 142 is realized by an exchange function of the optical switch 112.

  The packet switch device 201 requests / accepts a packet switch circuit 211 for exchanging packets, a reception buffer 221 that is located in the previous stage of the packet switch circuit 211 and stores and sets and releases a communication path in the layer 1 network 100. In addition, a path setting unit 231 that controls accumulation of packets in the reception buffer 221 and resumption of transfer of the accumulated packets, and a control communication unit 251 that exchanges messages such as communication path requests with the layer 1 network 100 are provided. Yes. Instead of the reception buffer 221, a transmission buffer that accumulates buckets may be provided in the subsequent stage of the packet switch circuit 211, and the packets that have been exchanged by the packet switch circuit 211 may be accumulated. In this case, the transmission buffer has a function of converting the accumulated packet into an optical signal and transmitting the optical signal. That is, the accumulation of packets may be before the packet switch circuit 211 exchanges packets or after exchange of packets.

  Here, a method for determining the accumulation start time for accumulating packets in the reception buffer 221 and the transfer resumption time for resuming packet transfer will be described. The packet switching device 201 transmits the request for switching the communication path by manual setting or learning using the protocol with the OXCs 101 to 105 in the layer 1 network 100, so that the OXCs 101 and 102 are new from the conventional path 301. Switching start time S required for starting the operation of switching the communication path to the path 302, switching time U required for the selection unit 142 of the OXC 102 to switch the communication path from the conventional path 301 to the new path 302, and a packet transmitted by the own apparatus Obtains the value of the conventional path delay time D1 until the packet reaches the OXC 102 via the conventional path 301 and the new path delay time D2 until the packet transmitted by the own device reaches the OXC 102 via the new path 302 . The packet switch device 201 measures these values in advance. Note that the conventional path delay time D1 and the new path delay time D2 may be calculated in advance from the path length of the communication path.

If the forward margin for reliably accumulating packets in the reception buffer 221 before starting switching from the conventional path 301 to the new path 302 is a, and the switching request transmission time at which the switching request is transmitted is Ts, the accumulation start time is
Accumulation start time ≦ Ts + S−D1−a (Expression 1)
It is necessary to satisfy.

Further, assuming that the backward margin to be inserted so that the transfer of the packet can be resumed with a margin after switching the communication path by absorbing the clock jitter and synchronization error in the operation of the OXCs 101 to 105, the transfer restart time is
Transfer restart time ≧ Ts + S + U−D2 + b (Expression 2)
It is necessary to satisfy.

  The packet switch device 201 selects the accumulation start time and the transfer resumption time so that (Equation 1) and (Equation 2) hold, and the packet input between the accumulation start time and the transfer resumption time is stored in the reception buffer 221. accumulate.

The capacity of the reception buffer 221 needs to be set so that packets input during the accumulation period from the accumulation start time to the transfer resume time can be accumulated. The accumulation period is calculated from (Equation 1) and (Equation 2): accumulation period = transfer restart time−accumulation start time ≧ U + a + b + D1−D2 (Equation 3)
It becomes. The switching time U of the optical switch currently realized is about 10 ms. In addition, the delay difference D1-D2 between the conventional path delay time D1 and the new path delay time D2 results in a path distance difference. Even if the distance difference is 1000 km, the delay difference D1-D2 is approximately 5 ms, which is an error. Although it depends, the accumulation period need not be set too large.

  The packet switch device 202 includes a packet switch circuit 212 for exchanging packets, a path setting unit 232 for requesting / accepting setting and release of a communication path in the layer 1 network 100, a communication path request with the layer 1 network 100, etc. A control communication unit 252 for exchanging messages.

  Next, referring to the flowcharts of FIGS. 3 to 5 and the sequence diagrams of FIGS. 6 and 7, when layer 1 data is transmitted from the packet switch apparatus 201 to the packet switch apparatus 202, the conventional path 301 is changed to the new path 302. The communication path switching operation of the communication system according to the present invention will be described by taking the operation of switching the communication path as an example.

  First, the operation of the packet switch apparatus 201 on the transmission side when switching the communication path from the conventional path 301 to the new path 302 will be described with reference to the flowchart of FIG.

  The path setting unit 231 determines a switching request transmission time Ts for transmitting a switching request for switching the communication path from the conventional path 301 to the new path 302, and starts accumulation using the above-described (Expression 1) and (Expression 2). A time and a transfer restart time are selected (step S100).

  When the switching request transmission time Ts comes, the path setting unit 231 transmits a switching request to switch the communication path from the conventional path 301 to the new path 302 to the OXC 101 via the control communication unit 251 (step S110).

  When the accumulation start time comes, the path setting unit 231 outputs an accumulation start instruction to the reception buffer 221. When receiving the accumulation start instruction, the reception buffer 221 stops the operation of outputting the input packet to the packet switch circuit 211, and starts accumulation of the packet (steps S120 and S130). That is, the packet switch device 201 stops transferring the packet to the OXC 101.

  When the transfer restart time is reached, the path setting unit 231 outputs a transfer restart instruction to the reception buffer 221. When receiving the transfer restart instruction, the reception buffer 221 outputs the accumulated packets to the packet switch circuit 211 (steps S140 and S150). The packet switch circuit 211 exchanges input packets, converts the exchanged packets into optical signals, and transfers them. That is, the packet switch device 201 resumes the transfer of the packet to the OXC 101.

  Next, the operation of the OXC 101 connected to the packet switch apparatus 201 on the transmission side when switching the communication path from the conventional path 301 to the new path 302 will be described with reference to the flowchart of FIG.

  When receiving the switching request from the packet switch device 201 (step S200), the control communication unit 151 outputs the received switching request to the path management unit 131. The path management unit 131 generates a switching request for notifying the OXC 102 that the switching request from the packet switch device 201 has been received, and outputs the switching request to the control communication unit 151. The control communication unit 151 transmits the switching request generated by the path management unit 131 to the OXC 102 (S210).

  The path management unit 131 outputs a replication start instruction to the replication unit 141. Upon receiving the duplication start instruction, the duplication unit 141 duplicates the optical signal input from the packet switch device 201 as the optical signal, generates an optical signal to the conventional path 301 and an optical signal to the new path 302, The two generated optical signals are output to the optical switch 111. The optical switch 111 transmits the two input optical signals to the conventional path 301 and the new path 302 (step S220).

  Next, the operation of the OXC 102 connected to the packet switch apparatus 202 on the receiving side when switching the communication path from the conventional path 301 to the new path 302 will be described with reference to the flowchart of FIG.

  When the switching request from the OXC 101 is received, the control communication unit 152 notifies the path management unit 132 that the switching request from the OXC 101 has been received. The path management unit 132 outputs a selection instruction indicating that the new path 302 is selected to the selection unit 142 (steps S300 and S310).

  The selection unit 142 selects the new path 302 based on the selection instruction, and outputs the optical signal from the new path 302 to the packet switch device 202 (step S320).

  The packet switch circuit 212 of the packet switch apparatus 202 exchanges and outputs the optical signal packet input from the OXC 102.

  FIG. 6 is a sequence diagram at the time of switching communication paths when the new path 302 has a longer path length than the conventional path 301 and the new path delay time D2 is greater than the conventional path delay time D1.

  At time T1, the control communication unit 251 of the packet switch apparatus 201 transmits a switching request 430 for switching the communication path from the conventional path 301 to the new path 302 to the OXC 101.

  When receiving the switching request 430, the control communication unit 151 of the OXC 101 outputs the switching request 430 to the path management unit 131. The path management unit 131 generates a switching request 431 that notifies the OXC 102 that the switching request 430 has been received, and transmits the switching request 431 to the OXC 102 via the control communication unit 151. Further, the path management unit 131 outputs a replication start instruction to the replication unit 141. Thereby, when receiving the optical signal from the packet switch device 201, the duplicating unit 141 duplicates the optical signal as it is and starts a duplicating operation to output to the optical switch 111.

  At time T3, the control communication unit 152 of the OXC 102 receives the switching request 431. The control communication unit 152 notifies the path management unit 132 that the switching request 431 has been received, and the path management unit 132 outputs a selection signal indicating that the new path 302 is selected to the selection unit 142. Thereby, at time T4, the selection unit 142 starts switching the communication path from the conventional path 301 to the new path 302. When the selection unit 142 switches the communication path, at the time T6 when the protection period 442 that may cause a problem in the transfer data due to physical movement of the optical switch component, the new path 302 is changed from the conventional path 301. Switching to is completed.

On the other hand, the path setting unit 231 of the packet switch apparatus 201 switches the time T1 at which the switching request 403 is transmitted before the control communication unit 251 transmits the switching request 430 at the time T1 between the (expression 1) and the (expression 2). As the request transmission time Ts, an accumulation start time and a transfer resumption time are selected. That is, the packet switch device 201
Accumulation start time ≦ T1 + S−D1-a
Transfer restart time ≧ T1 + S + U−D2 + b
The accumulation start time and transfer restart time are selected so as to satisfy In FIG. 6, the path setting unit 231 selects time T2 as the accumulation start time and selects time T5 as the transfer restart time.

  At time T2, which is the accumulation start time, the path setting unit 231 of the packet switch apparatus 201 outputs an accumulation start instruction to the reception buffer 221, stops the reception buffer 221 from outputting packets to the packet switch circuit 211, and Start accumulating.

  At time T5, which is the transfer restart time, the path setting unit 231 of the packet switch device 201 outputs a transfer restart instruction to the reception buffer 221, and causes the reception buffer 221 to start outputting packets to the packet switch circuit 211. The reception buffer 221 outputs the packet accumulated in the accumulation period 441 from time T2 to time T5 to the packet switch circuit 211, and the packet switch circuit 211 transmits the packet 450 converted into the optical signal to the OXC 101.

  When receiving the switching request 430 from the packet switch device 201, the duplicating unit 141 of the OXC 101 receives a duplication instruction from the path management unit 131 and is set to perform duplication operation. Therefore, the duplicating unit 141 duplicates the optical signal of the packet 450 from the packet switch device 201 as it is, and outputs it to the optical switch 111.

  The optical switch 111 of the OXC 101 transmits the optical signal of the packet 452 that is one of the optical signals of the packet 450 duplicated by the duplicating unit 141 to the conventional path 301, and the optical signal of the packet 451 that is the optical signal of the other packet. A signal is transmitted to the new path 302.

  Since the new path delay time D2 is larger than the conventional path delay time D1, the optical signal of the packet 452 that has passed through the conventional path 301 arrives at the OXC 102 at time T7. However, at time T6, the selection unit 142 of the OXC 102 has not switched the conventional path 301 to the new path 302, and therefore does not select the optical signal of the packet 452.

  At time T8, the optical signal of the packet 451 arrives at the OXC 102 via the new path 302. The selection unit 142 of the OXC 102 selects the optical signal of the packet 451, and transmits the optical signal as the packet 453 to the packet switch device 202 as it is.

  The packet switch circuit 212 of the packet switch device 202 outputs the received packet 453.

  FIG. 7 is a sequence diagram at the time of switching communication paths when the new path 302 has a shorter path length than the conventional path 301 and the new path delay time D2 is smaller than the conventional path delay time D1. The packet switch device 201 transmits a switching request 431, the OXCs 101 and 102 switch the communication path, and the packet switch device 201 accumulates the packet during the accumulation period 441, and at time T5, which is the transfer restart time, The operation for resuming the transfer is the same as when the new path 302 shown in FIG. 6 has a longer path length than the conventional path 301 and the new path delay time D2 is larger than the conventional path delay time D1, and the description thereof will be given here. Omitted.

  At time T5, which is the transfer resumption time, the optical signal of the packet 450 transmitted from the packet switch device 201 is duplicated as it is by the OXC 101, the optical signal of the packet 452 is transmitted to the conventional path 301, and the optical signal of the packet 451 is transmitted. It is transmitted to the new path 302.

  Since the new path delay time D2 is smaller than the conventional path delay time D1, the optical signal of the packet 451 that has passed through the new path 302 arrives at the OXC 102 at time T7a. At time T6, since the selection unit 142 of the OXC 102 has completed switching from the conventional path 301 to the new path 302, the selection unit 142 uses the optical signal of the packet 451 received from the new path 302 as an optical signal. 453 is transmitted to the packet switch apparatus 202, and the packet switch apparatus 202 outputs the packet 453.

  At time T8a, the optical signal of the packet 452 that has passed through the conventional path 301 arrives at the OXC 102. However, since the switching from the conventional path 301 to the new path 302 has been completed, the optical signal of the packet 452 is selected by the selection unit 142. It will never be done.

  As described above, in the first embodiment, the packet switching apparatus 201 transmits a switching request for switching the communication path from the conventional path 301 to the new path 302 to the OXC 101, and stores the packet to be transmitted after accumulating during the accumulation period. And is transmitted to the OXC 101. The OXC 101 transfers the switching request to the OXC 102 and copies the optical signal from the packet switch device 201 as the optical signal and transmits it to the conventional path 301 and the new path 302. When receiving the switching request, the OXC 102 switches from the conventional path 301 to the new path 302 and transmits the optical signal received from the new path 302 to the packet switch apparatus 202. This makes it possible to switch communication paths without losing packets.

  In the first embodiment, the packet transmitted by the packet switch device 201 at the time of switching the communication path is transferred with a delay of the accumulation period at the maximum, but the accumulation period is relatively small as described above. The impact on applications that send and receive is not significant.

Embodiment 2
In the second embodiment, the switching request described in the first embodiment is RSVP-TE (ResourceVP) defined by RFC 2471 in the communication path control protocol of the layer 1 network standardized as GMPLS (Generalized MultiProtocol Label Switching). The case where it implement | achieves using reSerVation Protocol-Traffic Engineering) is demonstrated. Note that RSVP-TE is a signaling protocol in the claims.

  In the communication system of the first embodiment shown in FIG. 1 or FIG. 2, the conventional path 301 and the new path 302 between the OXCs 101 and 102 can be dynamically set using RSVP-TE. Specifically, RSVP-TE messages are generated and processed in the path management units 131 and 132 of the OXCs 101 and 102, and the optical switches 111 and 112 are controlled according to the contents of the messages to configure the optical path. The switch communication relationship is provided, and the control communication units 151 and 152 dynamically set the conventional path 301 and the new path 302 between the OXCs 101 and 102 by performing communication using RSVP-TE messages. Note that the path setting units 231 and 232 of the packet switch apparatuses 201 and 202 have a function for supporting GMPLS protocol messages, communicate with the OXC 101 and OXC 102 using the control communication units 251 and 252, and pass through the layer 1 network 100. The communication path to be set may be set dynamically.

  RSVP-TE implements a communication path setting and communication path release procedure by exchanging messages such as Path, Resv, ResvConf, PathTear, and PathErr between OXCs. In the communication system according to the third embodiment of the present invention, information mounted on these RSVP-TE messages is expanded, and a new path 302 is added while configuring a 1 + 1 protection relationship with respect to the conventional path 301. Also, the 1 + 1 protection relationship between the new path 302 and the conventional path 301 is canceled, and only the conventional path 301 is released. That is, in order to add the new path 302 to the conventional path 301, the identifier of the conventional path 301 and the relationship between the conventional path 301 and the new path 302 (in the Path message of the RSVP-TE communication path setting sequence for setting the new path 302 ( 1 + 1 protection) is installed. In addition, after switching the communication path from the conventional path 301 to the new path 302, a communication path not selected by the selection unit 142 is selected in a message used to release the communication path, such as PathTear, in order to release the conventional path 301. The information indicating that the communication path is released without changing the communication path setting is installed.

  As described above, in the second embodiment, the RSVP-TE of the communication path control protocol standardized as GMPLS is expanded to set a new path 302 for the conventional path 301 and the communication path is switched to the new path 302. Since the conventional path 301 is released, the communication path can be flexibly switched.

Embodiment 3
A third embodiment of the present invention will be described with reference to FIGS. In the first embodiment, the packet switch apparatus 201 on the transmission side transmits a switching request for switching the communication path of the layer 1 network 100 to the OXC 101. When the OXC 101 receives the switching request, the packet switch apparatus 202 on the reception side is connected. The communication path is switched by transmitting a switching request to the OXC 102. That is, the communication path switching operation is performed by transmitting the switching request message by the control communication units 251, 151, and 152 of the packet switch device 201 and OXC 101 and 102.

  However, generally, since a message such as a switching request is generated and processed by software, it is difficult to set an upper limit of the processing time between the packet switch device 201 and the OXCs 101 and 102. Therefore, the time between the time T1 when the packet switch apparatus 201 shown in FIG. 6 transmits the switching request 430 to the OXC 101 and the time T4 when the OXC 102 starts switching the communication path, that is, (Expression 1) to (Expression 3) The error of the switching start time S required until the OXC 101, 102 starts the operation of switching the communication path from the conventional path 301 to the new path 302 after the own apparatus transmits the communication path switching request increases (Equation 3). A large margin must be expected for the accumulation period shown in. The fact that a large margin must be allowed for the accumulation period causes a problem that the buffer capacity of the reception buffer 221 increases. In the third embodiment, in order to improve such a problem, a switching request between the OXC 101 and the OXC 102 is generated and processed by hardware instead of using the control communication units 151 and 152, and is selected. Switching of the unit 142 is also realized by hardware.

  The first and second embodiments described above are based on the premise that the conventional path 301 and the new path 302 are set in a 1 + 1 protection relationship prior to switching of communication paths. 1 + 1 protection is a technique for providing fault tolerance to a communication path, and receives data from a redundant two communication paths that do not fail in a node device that terminates a redundant system of communication paths. The communication path is selected.

  As described in the first embodiment, the OXCs 101 and 102 shown in FIG. 2 are node devices that exchange layer 1 data as optical signals. The path management units 131 and 132 of the OXCs 101 and 102 include a mechanism for detecting a layer 1 optical signal as means for determining the presence or absence of a communication path failure, and whether or not a communication path failure has occurred depending on the light reception level of the optical signal. Determine whether. The optical signal of the layer 1 data is a signal obtained by modulating the bit string constituting the data of the upper layer so as to be carried by the optical signal, and is continuously transferred regardless of whether or not the packet data is transferred in the upper layer. Therefore, a failure in a state in which the optical path is artificially interrupted by the OXC 101 with respect to the conventional path 301 while the packet path switching apparatus 201 stops the transmission of packet data by setting the conventional path 301 and the new path 302 to have a 1 + 1 protection relationship. , The path management unit 132 of the OXC 102 can detect a failure in the conventional path 301 and switch to the new path 302 in which no failure has occurred using the 1 + 1 protection function. The 1 + 1 protection function is implemented by hardware in order to enable a high-speed switching operation.

  Next, operations of the OXCs 101 and 102 of the communication system according to the third embodiment of the present invention will be described with reference to the flowcharts of FIGS. The operations of the packet switch devices 201 and 202 are the same as those in the first embodiment.

  First, the operation of the OXC 101 will be described with reference to the flowchart of FIG. When receiving the switching request from the packet switch device 201, the control communication unit 151 notifies the path management unit 131 that the switching request has been received (step S400). The path management unit 131 outputs a duplication start instruction to the duplication unit 141, and the duplication unit 141 duplicates the optical signal input from the packet switch device 201 as an optical signal, and the new optical signal to the conventional path 301 and the new one. The optical signal to the path 302 is generated, and the two generated optical signals are output to the optical switch 111.

  The path management unit 131 outputs an instruction to cancel the connection relationship of the conventional path 301 to the optical switch 111. The optical switch 111 releases the connection relationship between the conventional path 301, that is, the connection relationship between the input interface and the output interface of the optical signal to the conventional path 301 replicated by the duplication unit 141 of the optical switch 111 (step S410). The optical switch 111 transfers the optical signal using the new path 302 (step S420).

  Next, the operation of the OXC 102 will be described with reference to the flowchart of FIG. When the path management unit 132 monitors the level of the optical signal input to the optical switch 112 and detects a decrease in the level of the optical signal from the conventional path 301, the decrease in the level of the optical signal is detected by the function of 1 + 1 protection. A selection instruction for selecting a new path 302 that has not been output is output to the selection unit 142 (steps S500 and S510).

  The selection unit 142 selects the new path 302 based on the selection instruction, and outputs an optical signal from the new path 302 to the packet switch device 202 (step S520).

  Next, the communication path switching operation of the communication system according to the third embodiment will be described. Note that the operation of the packet switch apparatus 201 outputting the switching request and accumulating the packet is the same as in the first embodiment. Therefore, the description thereof is omitted here, and the OXC 101 receives the switching request from the packet switch apparatus 201. In response, the OXC 102 is notified and only the operation of the OXC 102 switching to the new path 302 will be described.

  When receiving the switching request from the packet switch device 201, the OXC 101 cancels the connection relationship to the conventional path 301 so that the optical signal does not flow to the conventional path 301.

  When detecting the decrease in the optical signal level of the conventional path 301, the OXC 102 selects the new path 302 in which the decrease in the optical signal level is not detected by the 1 + 1 protection function, and the optical signal from the selected new path 302 is selected. Transmit to the packet switch device 202.

  As described above, in the third embodiment, since the OXC 101 interrupts the optical signal of the conventional path 301 and the OXC 102 selects the communication path using the 1 + 1 protection function, new hardware is added. Compared with the case where a communication path switching request is made using a message by software processing, the switching request is transmitted at a higher speed and variation in transmission delay is suppressed, and the packet switch device 201 transmits the switching request. The error in the time from the start to the start of switching can be reduced, and the capacity of the reception buffer 221 can be reduced.

Embodiment 4
A fourth embodiment of the present invention will be described with reference to FIGS. In the first to third embodiments, the packet switch device 201 transmits a switching request and starts a communication path switching operation. In the fourth embodiment, a switching procedure in which the OXC 101 that is connected to the packet switch device 201 on the transmission side and becomes a node device at the near end of the communication path in the layer 1 network 100 starts the switching operation will be described.

  The path management unit 131 of the OXC 101 according to the fourth embodiment uses the control communication unit 151 to notify the packet switch device 201 of a transmission stop request for requesting stop of packet transmission, and to switch the communication path to the OXC 102. It has a function to notify the requested switching request.

  The path management unit 131 of the OXC 101 transmits a transmission stop request to the packet switch device 201 by manual setting or learning using a protocol with a device in the layer 1 network 100 such as the packet switch device 201 or the OXC 102. Q required for the packet switch device 201 to start storing packets from time to time P, the time P required for the OXC 102 to start switching the communication path after the own device transmits a switching request to the OXC 102, and the selection unit 142 is conventionally Switching time U required for switching the communication path from the path 301 to the new path 302, the conventional path delay time D1 until the packet transmitted by the packet switch device 201 reaches the OXC 102 via the conventional path 301, and the packet switch device Packet data sent by 201 There is obtained the value of the new path delay time D2 to reach the OXC102 via new path 302. The bus management unit 131 measures and stores these values in advance. Note that values calculated from the path length of the communication path may be used for the conventional path delay time D1 and the new path delay time D2.

Assuming that the transmission stop request transmission time at which the OXC 101 transmits a transmission stop request is Ta and the switching request transmission time at which the OXC 101 transmits a switching request is Tb, the accumulation start time and the transfer resumption time are:
Accumulation start time = Ta + Q <Tb + P−D1 (Formula 4)
Transfer restart time> Tb + P + U−D2 (Formula 5)
It is necessary to satisfy.

The path management unit 131 of the OXC 101 selects the transmission stop request transmission time Ta, the switching request transmission time Tb, and the stop request time R as the accumulation time so as to satisfy the conditions of (Expression 4) and (Expression 5). Specifically, a margin for insertion so that packet transfer via the conventional path 301 is surely stopped before the start of the switching operation of the communication path is set to c, and the own device at the time of operation transmits a switching request to the OXC 102. The time P required for the OXC 102 to start switching the communication path from the first time, the time Q required for the packet switch device 201 to start storing packets after the device transmits a transmission stop request to the packet switch device 201, The error of the conventional path delay time D1, the new path delay time D2, or the clock jitter and synchronization error in the operation of the packet switch device 201 and the OXC 101, 102 is absorbed, and the transfer is resumed with a margin after switching the communication path. For this reason, if the margin to be inserted is d, the path management unit 131 of the OXC 101 needs to stop transmission. Transmission time Ta, the switching request transmission time Tb, and the stop request time R Ta + Q + D1 = Tb + P + c ··· (Equation 6)
R = U + D1-D2 + c + d (Expression 7)
Choose to meet.

  Next, referring to the flowcharts of FIGS. 10 and 11 and the sequence diagram of FIG. 12, when transmitting layer 1 data from the packet switch apparatus 201 to the packet switch apparatus 202, the communication path from the conventional path 301 to the new path 302 is shown. The operation of switching communication paths of the communication system according to the present invention will be described by taking the operation of switching between the two as an example. Since the operations of the OXC 102 and the packet switch device 202 are the same as those in the first embodiment, the description thereof is omitted here.

  First, the operation of the OXC 101 will be described with reference to the flowchart of FIG. The path management unit 131 sends a transmission stop request including the transmission stop request transmission time Ta, the switching request transmission time Tb, and the stop request time R selected by (Equation 7) to the packet switch apparatus 201 via the control communication unit 151. Transmit (step S600).

  When the switching request transmission time Tb selected by (Expression 6) is reached, the path management unit 131 transmits a switching request to the OXC 102 via the control communication unit 151 (steps S610 and S620). Further, the path management unit 131 outputs a replication start instruction to the replication unit 141.

  Upon receiving the duplication start instruction, the duplication unit 141 duplicates the optical signal input from the packet switch device 201 as the optical signal, and generates an optical signal to the conventional path 301 and an optical signal to the new path 302. The two generated optical signals are output to the optical switch 111. The optical switch 111 transmits the two input optical signals to the conventional path 301 and the new path 302 (step S630).

  Next, the operation of the packet switch device 201 will be described with reference to the flowchart of FIG. When receiving a transmission stop request from the OXC 101 via the control communication unit 251, the path setting unit 231 starts accumulation from the transmission stop request transmission time Ta, the switching request transmission time Tb, and the stop request time R included in the transmission stop request. A time and a transfer restart time are selected (steps S700 and S710). The path setting unit 231 selects a time when at least the stop request time R has elapsed from the accumulation start time as the transfer restart time. Further, the path setting unit 231 selects the time when the transmission stop request from the OXC 101 is received via the control communication unit 251 as the accumulation start time.

  When the accumulation start time comes, the path setting unit 231 outputs an accumulation start instruction to the reception buffer 221, and the reception buffer 221 stops the operation of outputting the input packet to the packet switch circuit 211, and accumulates the packet. Start (steps S720 and S730). That is, the packet switch device 201 stops transferring the optical signal of the packet to the OXC 101.

  When the transfer resumption time is reached, the path setting unit 231 outputs a transfer resumption instruction to the reception buffer 221, and the reception buffer 221 outputs the accumulated packets to the packet switch circuit 211 (steps S740 and S750). The packet switch circuit 211 exchanges input packets, converts the exchanged packets into optical signals, and transfers them. That is, the packet switch device 201 resumes the transfer of the packet to the OXC 101.

  FIG. 12 is a sequence diagram at the time of switching communication paths when the new path 302 has a longer path length than the conventional path 301 and the new path delay time D2 is greater than the conventional path delay time D1.

  At time T <b> 11, the control communication unit 151 of the OXC 101 transmits a transmission stop request 501 for stopping packet transfer to switch the communication path from the conventional path 301 to the new path 302 to the packet switch apparatus 201. The transmission stop request 501 includes time T11 as the transmission stop request transmission time Ta selected by (Expression 6) and (Expression 7), time T14 as the switching request transmission time Tb, and stop request time R.

  At time T12, the path setting unit 231 of the packet switch apparatus 201 receives the transmission stop request 501 via the control communication unit 251. The path setting unit 231 selects an accumulation start time and a transfer restart time based on the transmission stop request 501. In FIG. 12, the path setting unit 231 selects the time T13 immediately after receiving the transmission stop request 501 as the accumulation start time, and the time when at least the stop request time R has elapsed from the time T13 that is the accumulation start time as the transfer restart time. T17 is selected.

  At time T14, when the switching request transmission time selected by the path management unit 131 of the OXC 101 is reached, the path management unit 131 transmits the switching request 431 to the OXC 102 via the control communication unit 151. The path management unit 131 outputs a replication start instruction to the replication unit 141. Thereby, when receiving the optical signal from the packet switch device 201, the duplicating unit 141 duplicates the optical signal as it is and starts a duplicating operation to output to the optical switch 111.

  At time T15, the control communication unit 152 of the OXC 102 receives the switching request 431. The control communication unit 152 notifies the path management unit 132 that the switching request 431 has been received, and the path management unit 132 outputs a selection signal indicating that the new path 302 is selected to the selection unit 142. Thereby, at time T <b> 16, the selection unit 142 starts switching the communication path from the conventional path 301 to the new path 302. When the selection unit 142 switches the communication path, at the time T18 when the protection period 442 that may cause a problem in the transfer data due to physical movement of the optical switch components, the new path 302 is changed from the conventional path 301. Switching to is completed.

  On the other hand, the path setting unit 231 of the packet switch device 201 outputs an accumulation start instruction to the reception buffer 221 and stops outputting packets to the packet switch circuit 211 at the reception buffer 221 at time T13 which is an accumulation start time. To start accumulating packets.

  At time T17, which is the transfer restart time, the path setting unit 231 of the packet switch device 201 outputs a transfer restart instruction to the reception buffer 221, and causes the reception buffer 221 to start outputting packets to the packet switch circuit 211. The reception buffer 221 outputs the packet accumulated in the accumulation period 441 from time T13 to time T17 to the packet switch circuit 211. The packet switch circuit 211 converts the packet into an optical signal and converts the optical signal of the packet 450 to the OXC 101. Send.

  The duplication unit 141 of the OXC 101 receives the duplication instruction from the path management unit 131 after transmitting the switching request 431 to the OXC 102, and is set to perform the duplication operation. Therefore, the duplicating unit 141 duplicates the optical signal of the packet 450 from the packet switch device 201 as it is, and outputs it to the optical switch 111.

  The optical switch 111 of the OXC 101 transmits the optical signal of the packet 452 that is one of the optical signals of the packet duplicated by the duplicating unit 141 to the conventional path 301, and the optical signal of the packet 451 that is the optical signal of the other packet. To the new path 302.

  Since the new path delay time D2 is larger than the conventional path delay time D1, the optical signal of the packet 452 that has passed through the conventional path 301 arrives at the OXC 102 at time T19. However, at time T18, the selection unit 142 of the OXC 102 has not switched the conventional path 301 to the new path 302, and therefore does not select the optical signal of the packet 452.

  At time T20, the optical signal of the packet 451 arrives at the OXC 102 via the new path 302. The selection unit 142 of the OXC 102 selects the optical signal of the packet 451 and transmits it as the packet 453 to the packet switch device 202.

  The packet switch circuit 212 of the packet switch device 202 outputs the received packet 453.

  As described above, in the fourth embodiment, the OXC 101 that is the node device in the layer 1 network 100 notifies the packet switch device 201 of the transmission stop request, transmits the switching request to the OXC 102, and receives the optical signal from the packet switch device 201. Is copied as an optical signal and transmitted to the conventional path 301 and the new path 302. Upon receiving the transmission stop request, the packet switch device 201 accumulates the packets during the accumulation period, converts the accumulated packets to an optical signal after the accumulation period has elapsed, and transmits the optical signal. Upon receiving the switching request, the OXC 102 switches from the conventional path 301 to the new path 302 and transmits an optical signal from the new path 302 to the packet switch device 202. This makes it possible to switch communication paths without losing packets.

  Note that in the Pause operation in Annex 31B of IEEE Standard 802.3 (2002 edition), the packet switch apparatus 201 of the fourth embodiment receives a transmission stop request 501 for a device having an Ethernet (registered trademark) interface. An operation similar to the operation of temporarily stopping packet transmission is defined. Specifically, in Pause operation, a specific frame called a Pause frame is defined, and a device having an Ethernet (registered trademark) interface that has received a Pause frame is in a pause period encoded in the Pause frame. The transmission of the Ethernet frame to the interface is stopped.

  As the packet switch device 201 of the fourth embodiment, a packet switch device that supports Pause operation specified in Pause operation in Annex 31B of IEEE Standard 802.3 (2002 version) is used, and a transmission stop request is made by the control communication unit 251 If a control function for stopping the transmission of the Ethernet frame to the OXC101 connection interface is added to the path setting unit 231 when the Pause frame is received when the 501 is received, the packet transmission is temporarily stopped and stored in the reception buffer 221. In addition, resumption of packet transfer after the stop request time R elapses can be realized with a minimum additional function.

Embodiment 5
In the fifth embodiment, a case where Pause operation in Annex 31B of IEEE standard 802.3 (2002 edition) is used will be described.

  The communication system according to the fifth embodiment of the present invention includes OXCs 101a and 102a instead of the OXCs 101 and 102 of the communication system shown in FIG.

  The OXCs 101a and 102a have the same function. FIG. 13 shows detailed configurations of the OXC 101a and the packet switch device 201. Note that the packet switch device 201 illustrated in FIG. 13 illustrates a configuration part related to transmission processing of the packet switch device 201 illustrated in FIG. 2 and a part related to reception processing of the packet switch device 202. In addition, regarding the OXC 101a, the configuration part related to the transmission process shown in the OXC 101 shown in FIG. 2 and the configuration part related to the reception process shown in the OXC 102 are shown. Have been added. Components having the same functions as those in FIG. 2 are denoted by the same reference numerals, and description thereof is omitted.

  The Pause generation unit 171 generates a Pause frame including a stop time obtained by encoding the stop request time R selected by the path management unit 131 using (Expression 6) and (Expression 7).

  The Pause frame insertion unit 181 inserts the Pause frame generated by the Pause generation unit 171 into the data flow to the packet switch device 201.

  FIG. 14 is a block diagram showing a configuration of the Pause frame insertion unit 181. As shown in FIG. The Pause frame insertion unit 181 includes an optical signal / electrical signal conversion unit (hereinafter referred to as an O / E conversion unit) 601 that converts optical signal data input from the optical switch 111 into an electrical signal, and an O / E conversion unit. A control circuit 602 for observing an electrical signal output from 601 and controlling a Pause frame insertion operation, and a buffer 603 for storing an Ethernet (registered trademark) frame in the electrical signal output by the O / E converter 601 during Pause frame insertion. A Pause holding buffer 604 that holds the Pause frame generated by the Pause generation unit 171 until it is inserted, and an electric signal input from the O / E conversion unit 601 under the control of the control circuit 602 and input from the buffer 603 An electrical signal or Pause frame input from Pause holding buffer 604 A selector 605 for selecting a signal and an electric signal / optical signal conversion unit (hereinafter referred to as an E / O conversion unit) 606 for converting an electric signal selected by the selector 605 into an optical signal.

  Next, the operation of the OXC 101a will be described with reference to the flowchart of FIG. Before switching the communication path, the optical signal packet input from the conventional path 301 is selected by the selection unit 142 and input to the O / E conversion unit 601. The control circuit 602 controls the selector 605 so as to select the electrical signal input from the O / E conversion unit 601. As a result, the selector 605 selects the electrical signal input from the O / E converter 601, and the E / O converter 606 converts the electrical signal from the O / E converter 601 into an optical signal to convert the packet signal to the packet switch device. 201 is transmitted.

  When switching communication paths, the Pause generation unit 171 generates a Pause frame including a stop time obtained by encoding the stop request time R selected by the path management unit 131 using (Expression 6) and (Expression 7) ( Step S800). The pause generating unit 171 outputs the generated pause frame to the pause holding buffer 604.

  When the switching request transmission time is reached, the path management unit 131 notifies the control circuit 602 that the communication path is switched, and the control circuit 602 observes an electrical signal of the O / E conversion unit 601 and detects Ethernet (registered trademark). An idle signal between frames is detected (steps S810 and S820).

  When detecting the idle signal, the control circuit 602 causes the buffer 603 to start accumulating Ethernet (registered trademark) frames converted into electric signals by the O / E conversion unit 601 (step S830). Further, the control circuit 602 outputs a pause frame held in the pause holding buffer 604 and controls the selector 605 to select an input from the pause holding buffer 604, and sends a pause to the E / O conversion unit 606. The Pause frame held in the holding buffer 604 is output (step S840). The E / O converter 606 converts the input pause frame from an electric signal to an optical signal and outputs the converted signal to the packet switch device 201.

  After outputting the Pause frame, the control circuit 602 controls the selector 605 to select an electrical signal input from the buffer 603. As a result, the selection circuit 602 outputs the electrical signal input from the buffer 603 to the E / O conversion unit 606, and the E / O conversion unit 606 converts the Ethernet (registered trademark) frame stored in the buffer 603 into the electrical signal. The signal is converted into an optical signal and transmitted to the packet switch device 201 (steps S850 and S860).

  After outputting the Ethernet (registered trademark) frame stored in the buffer 603, the control circuit 602 controls the selector 605 to select the electrical signal input from the O / E conversion unit 601. As a result, the selection circuit 602 outputs the electrical signal input from the O / E conversion unit 601 to the E / O conversion unit 606, and the E / O conversion unit 606 receives the Ethernet input from the O / E conversion unit 601. The (registered trademark) frame is converted from an electrical signal to an optical signal and transmitted to the packet switch device 201 (steps S870 and S880).

  As described above, the operation of the communication system after the OXC 101a stops packet transmission to the packet switch device 201 by the Pause frame is the same as that described in the fourth embodiment. Omitted.

  As described above, in the fifth embodiment, the OXC 101 notifies that the Pause frame is inserted and the communication path is switched during the idle time between Ethernet (registered trademark) frames transmitted to the packet switch device 201. Therefore, it is possible to realize accumulation start of packet transmission and resumption of packet transfer after the stop request time R elapses without adding a new function to the packet switch device 201 that supports the IEEE standard 803.2 Pause operation. Communication path can be switched without packet loss.

  As described above, the communication system according to the present invention is useful for a network using an optical transmission line, and in particular, communication in which a redundant system is configured by communication paths of different paths temporarily to switch communication paths in the network. Suitable for the system.

Claims (18)

A packet switch device, and a plurality of node devices including an edge node device to which the packet switch device is connected, wherein the packet switch device uses one of a plurality of communication paths configured by the plurality of node devices. In a communication system that performs mutual communication,
The packet switch device
The communication path is switched from the first communication path that is currently communicating to the second communication path that includes the edge node device to which the own device and the packet switch device of the communication partner are connected, and is different from the first communication path. When the necessity arises, a switching request for requesting switching from the first communication path to the second communication path is transmitted, and switching to the second communication path is performed after the switching request is transmitted. A path setting unit that outputs a storage start instruction for stopping output of a packet and a transfer restart instruction for restarting output of the packet until completion,
When receiving an accumulation start instruction from this path setting unit, the output of the input packet is stopped and the packet is accumulated, and when receiving the transfer restart instruction, a reception buffer that outputs the accumulated packet;
A packet switch circuit that converts a packet output from the reception buffer into an optical signal and transmits the optical signal to an edge node device to which the device is connected;
With
The edge node device is:
When a switching request transmitted from the packet switch device is received, a path management unit that notifies the partner edge node device that the switching request has been received;
A replication unit that replicates the optical signal input from the packet switch device as it is after receiving the switching request transmitted from the packet switch device;
A selector that switches a communication path to be selected from the first communication path to the second communication path when notified of a switching request from the counterpart edge node device;
The optical signal duplicated by the duplicating unit is transmitted to the first and second communication paths, and the optical signal inputted from the second communication path selected by the selecting unit is connected to the own apparatus. An optical switch that transmits to the packet switch device;
A communication system comprising: The path management unit of the edge node device is
The communication system according to claim 1, wherein the first communication path and the second communication path are set by a signaling protocol. The path management unit of the edge node device is
When the selection unit switches from the first communication path to the second communication path, a message for releasing the first communication path by the signaling protocol is transmitted to the partner edge node device, and the partner side The communication system according to claim 2, wherein the first communication path is released when a message for releasing the first communication path is received from the edge node device. The path management unit of the edge node device is
The communication system according to claim 1, wherein a notification of receiving the switching request is notified by a message. The path management unit of the edge node device is
When notifying that the switching request has been received by generating a failure in the first communication path to the counterpart edge node device, and detecting that a failure has occurred in the first communication path, The communication system according to claim 1, wherein it is determined that the switching request is received from the counterpart edge node device. The path setting unit of the packet switch device includes:
A delay time for a packet to arrive via the first and second communication paths, and a second edge node device from the first communication path to the second time after the packet switch device transmits the switching request. 2. The communication system according to claim 1, wherein a time for outputting the accumulation start instruction and the transfer resumption instruction is selected based on a switching time required for switching to a communication path. A packet switch device, and a plurality of node devices including an edge node device to which the packet switch device is connected, wherein the packet switch device uses one of a plurality of communication paths configured by the plurality of node devices. In a communication system that performs mutual communication,
The edge node device is:
When it is necessary to switch the communication path from the first communication path that is currently communicating to the second communication path that includes the own apparatus and the partner edge node apparatus and is different from the first communication path, A path for notifying a packet switch apparatus connected to the packet transmission apparatus for a transmission stop request for requesting a packet transmission stop, and notifying the other edge node apparatus of a switching request for switching from the first communication path to the second communication path. The management department,
A replication unit that replicates an optical signal input from the packet switch device as an optical signal after notifying a transmission stop request by the path management unit;
A selector that switches a communication path to be selected from the first communication path to the second communication path upon receiving a notification of a switching request from the counterpart edge node device;
The optical signal duplicated by the duplicating unit is transmitted to the first and second communication paths, and the optical signal inputted from the second communication path selected by the selecting unit is connected to the own apparatus. An optical switch that transmits to the packet switch device;
With
The packet switch device
Path setting for outputting a storage start instruction for stopping the output of the packet and a transfer restart instruction for restarting the output of the packet between the reception of the transmission stop request and the completion of switching to the second communication path And
When receiving an accumulation start instruction from this path setting unit, the output of the input packet is stopped and the packet is accumulated, and when receiving the transfer restart instruction, a reception buffer that outputs the accumulated packet;
A packet switch circuit that converts a packet output from the reception buffer into an optical signal and transmits the optical signal to an edge node device to which the device is connected;
A communication system comprising: The transmission stop request is
The path setting unit of the packet switch device includes a transmission stop time for selecting the accumulation start instruction and the transfer resumption instruction, and the accumulation period in which the reception buffer stops outputting the packet and accumulates the packet is at least the The communication system according to claim 7, wherein the communication stop time is longer than the transmission stop time. The transmission stop request is
8. The communication system according to claim 7, wherein a Pause frame defined by the IEEE standard 802.3 is used. The path setting unit of the packet switch device includes:
Delay time when a packet arrives via the first and second communication paths, and the other edge node device from the first communication path to the second communication after the edge node device notifies the switching request The communication system according to claim 7, wherein selection is made according to a switching time required for switching to a path. A packet switch device, and a plurality of node devices including an edge node device to which the packet switch device is connected, wherein the packet switch device uses one of a plurality of communication paths configured by the plurality of node devices. In a communication system that performs mutual communication,
The packet switch device
A packet switch circuit that distributes and outputs input packets to the edge node device to which the device is connected; and
The communication path is switched from the first communication path that is currently communicating to the second communication path that includes the edge node device to which the own device and the packet switch device of the communication partner are connected, and is different from the first communication path. When the necessity arises, a switching request for requesting switching from the first communication path to the second communication path is transmitted, and switching to the second communication path is performed after the switching request is transmitted. A path setting unit that outputs a storage start instruction for stopping output of a packet and a transfer restart instruction for restarting output of the packet until completion,
When the storage start instruction is received from the path setting unit, the output of the packet input from the packet switch circuit is stopped and the packet is stored, and when the transfer restart instruction is received, the stored packet is converted into an optical signal and automatically transmitted. A transmission buffer that outputs to the edge node device to which the device is connected;
With
The edge node device is:
When a switching request transmitted from the packet switch device is received, a path management unit that notifies the partner edge node device that the switching request has been received;
A replication unit that replicates the optical signal input from the packet switch device as it is after receiving the switching request transmitted from the packet switch device;
A selector that switches a communication path to be selected from the first communication path to the second communication path when notified of a switching request from the counterpart edge node device;
The optical signal duplicated by the duplicating unit is transmitted to the first and second communication paths, and the optical signal inputted from the second communication path selected by the selecting unit is connected to the own apparatus. An optical switch that transmits to the packet switch device;
A communication system comprising: A packet switch device, and a plurality of node devices including an edge node device to which the packet switch device is connected, wherein the packet switch device uses one of a plurality of communication paths configured by the plurality of node devices. In a communication system that performs mutual communication,
The edge node device is:
When it is necessary to switch the communication path from the first communication path that is currently communicating to the second communication path that includes the own apparatus and the partner edge node apparatus and is different from the first communication path, A packet switching apparatus connected to the packet switching apparatus is notified of a transmission stop request for requesting the transmission stop of the optical signal of the packet, and a switching request for switching from the first communication path to the second communication path is sent to the counterpart edge node apparatus. A path management unit to notify,
A replication unit that replicates the optical signal input from the packet switch device after notifying the transmission stop request by the path management unit;
A selector that switches a communication path to be selected from the first communication path to the second communication path upon receiving a notification of a switching request from the counterpart edge node device;
The optical signal duplicated by the duplicating unit is transmitted to the first and second communication paths, and the optical signal inputted from the second communication path selected by the selecting unit is connected to the own apparatus. An optical switch that transmits to the packet switch device;
With
The packet switch device
A packet switch circuit that distributes input packets to the edge node device to which the device is connected;
Path setting for outputting a storage start instruction for stopping the output of the packet and a transfer restart instruction for restarting the output of the packet between the reception of the transmission stop request and the completion of switching to the second communication path And
When the storage start instruction is received from the path setting unit, the output of the packet input from the packet switch circuit is stopped and the packet is stored, and when the transfer restart instruction is received, the stored packet is converted into an optical signal and automatically transmitted. A transmission buffer that outputs to the edge node device to which the device is connected;
A communication system comprising: In a packet switch device that is connected to an edge node device and performs mutual communication using one of a plurality of communication paths configured by a plurality of node devices including the edge node device.
The communication path is switched from the first communication path that is currently communicating to the second communication path that includes the edge node device to which the own device and the packet switch device of the communication partner are connected, and is different from the first communication path. When the necessity arises, a switching request for requesting switching from the first communication path to the second communication path is transmitted, and switching to the second communication path is performed after the switching request is transmitted. A path setting unit that outputs a storage start instruction for stopping output of a packet and a transfer restart instruction for restarting output of the packet until completion,
When receiving an accumulation start instruction from this path setting unit, the output of the input packet is stopped and the packet is accumulated, and when receiving the transfer restart instruction, a reception buffer that outputs the accumulated packet;
A packet switch circuit that converts a packet output from the reception buffer into an optical signal and transmits the optical signal to an edge node device to which the device is connected;
A packet switch device comprising: In a packet switch device that is connected to an edge node device and performs mutual communication using one of a plurality of communication paths configured by a plurality of node devices including the edge node device.
A packet switch circuit that distributes and outputs input packets to the edge node device to which the device is connected; and
The communication path is switched from the first communication path that is currently communicating to the second communication path that includes the edge node device to which the own device and the packet switch device of the communication partner are connected, and is different from the first communication path. When the necessity arises, a switching request for requesting switching from the first communication path to the second communication path is transmitted, and switching to the second communication path is performed after the switching request is transmitted. A path setting unit that outputs a storage start instruction for stopping output of a packet and a transfer restart instruction for restarting output of the packet until completion,
When the storage start instruction is received from the path setting unit, the output of the packet input from the path switch circuit is stopped and the packet is stored. When the transfer restart instruction is received, the stored packet is converted into an optical signal and is automatically transmitted. A transmission buffer that outputs to the edge node device to which the device is connected;
A packet switch device comprising: In a packet switch device that is connected to an edge node device and performs mutual communication using one of a plurality of communication paths configured by a plurality of node devices including the edge node device.
An accumulation start instruction for stopping the output of the packet and a transfer restart for restarting the output of the packet between the reception of the transmission stop request transmitted by the edge node device and the completion of switching to the second communication path A path setting unit for outputting instructions;
When receiving an accumulation start instruction from this path setting unit, the output of the input packet is stopped and the packet is accumulated, and when receiving the transfer restart instruction, a reception buffer that outputs the accumulated packet;
A packet switch circuit for transmitting a packet output from the reception buffer to an edge node device to which the own device is connected;
A packet switch device comprising: In a packet switch device that is connected to an edge node device and performs mutual communication using one of a plurality of communication paths configured by a plurality of node devices including the edge node device.
A packet switch circuit that distributes and outputs input packets to the edge node device to which the device is connected; and
The communication path is switched from the first communication path that is currently communicating to the second communication path that includes the edge node device to which the own device and the packet switch device of the communication partner are connected, and is different from the first communication path. When the necessity arises, a switching request for requesting switching from the first communication path to the second communication path is transmitted, and switching to the second communication path is performed after the switching request is transmitted. A path setting unit that outputs a storage start instruction for stopping output of a packet and a transfer restart instruction for restarting output of the packet until completion,
When the storage start instruction is received from this path setting unit, the output of the packet input from the packet switch circuit is stopped and the packet is stored. When the transfer restart instruction is received, the own apparatus connects the stored packet. A transmission buffer to be output to the edge node device;
A packet switch device comprising: In an edge node device connected to a packet switch device that performs mutual communication using one of a plurality of communication paths constituted by a plurality of node devices,
When a switching request for requesting switching to a second communication path different from the first communication path is received from the first communication path that is currently performing communication, including the local device and the partner-side edge node device, A path management unit for notifying the other edge node device that the switching request has been received;
A replication unit that replicates the optical signal input from the packet switch device after receiving the switching request as an optical signal;
A selector that switches a communication path to be selected from the first communication path to the second communication path when notified from the counterpart edge node device that a switching request has been received;
The optical signal duplicated by the duplicating unit is transmitted to the first and second communication paths, and the optical signal inputted from the second communication path selected by the selecting unit is connected to the own apparatus. An optical switch that transmits to the packet switch device;
An edge node device comprising: In an edge node device connected to a packet switch device that performs mutual communication using one of a plurality of communication paths constituted by a plurality of node devices,
When it is necessary to switch the communication path from the first communication path that is currently communicating to the second communication path that includes the own apparatus and the partner edge node apparatus and is different from the first communication path, A path for notifying a packet switch apparatus connected to the packet transmission apparatus for a transmission stop request for requesting a packet transmission stop, and notifying the other edge node apparatus of a switching request for switching from the first communication path to the second communication path. The management department,
A replication unit that replicates an optical signal input from the packet switch device as an optical signal after notifying a transmission stop request by the path management unit;
A selector that switches a communication path to be selected from the first communication path to the second communication path upon receiving a notification of a switching request from the counterpart edge node device;
The optical signal duplicated by the duplicating unit is transmitted to the first and second communication paths, and the optical signal inputted from the second communication path selected by the selecting unit is connected to the own apparatus. An optical switch that transmits to the packet switch device;
An edge node device comprising:

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