WO2006011225A1

WO2006011225A1 - Communication system, packet switch apparatus, and edge node apparatus

Info

Publication number: WO2006011225A1
Application number: PCT/JP2004/010922
Authority: WO
Inventors: Shoichiro Seno; Eiichi Horiuchi
Original assignee: Mitsubishi Denki Kabushiki Kaisha; Fujii, Teruko
Priority date: 2004-07-30
Filing date: 2004-07-30
Publication date: 2006-02-02
Also published as: JP4358232B2; JPWO2006011225A1

Abstract

A packet switch apparatus (201) transmits, to an OXC (101), a switch request for performing a communication path switching from an old path (301) to a new path (302); further converts packets to be transmitted to optical signals after the packets are stored for a storage period; and then transmits the optical signals to the OXC (101). The OXC (101) transfers the switch request to an OXC (102); duplicates the optical signals from the packet switch apparatus (201); and transmits the duplicated optical signals to the old and new paths (301,302). When receiving the switch request, the OXC (102) switches from the old path (301) to the new path (302), and transmits the optical signals received from the new path (302) to a packet switch apparatus (202).

Description

Specification

COMMUNICATION SYSTEM, PACKET SWITCH DEVICE, AND EDGE NODE DEVICE

Technical field

TECHNICAL FIELD [0001] 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. The present invention relates to a communication system that prevents troubles.

Background art

[0002] In recent years, in response to the rapid increase in data traffic due to the Internet and the increase in demand for high-quality multimedia communication, the network transmission path and switching node equipment have become wider, and the capacity has been increased. ing. Broadening the bandwidth of network transmission lines and switching node equipment 'To increase capacity, a layer that relays' exchanges data as it is, reducing optical signal' electric signal conversion on the communication path as much as possible. 1 Application of network is under consideration.

[0003] Layer 1 network is an open system interconnection (〇SI: Open Systems

Interconnection) Relay and exchange data at the physical layer located at the bottom of the model. In a layer 1 network, a node device that exchanges data with an optical signal called an optical cross connect is used.

[0004] The optical cross-connect has a plurality of input interfaces and output interfaces, and by setting the connection relationship of the optical switches in its own device, the data received at any input interface to any output interface Output.

[0005] A connection relationship from an input interface to an output interface is set for a plurality of node devices, and a node device to which a packet switch device having a layer 2 or layer 3 switching function is connected via a layer 1 network. Establish a communication path to transfer packets

[0006] In a layer 1 network, a communication path (new path) that goes through a different path or node device is changed from an active communication path (conventional path) due to the addition or change of transmission lines or node devices. It may be necessary to switch to.

[0007] 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 the redundant transmission line in the optical transmission network, the control information of each optical module is held in advance for all optical amplifiers affected by fluctuations in the input optical level due to the switching. The output level of the optical amplifier is raised in a short time by switching to the transmission mode after switching to the switching mode for operating each optical module based on the stored control information. The cut-off time of wavelength division multiplexed signals is greatly reduced.

Patent Document 1: Japanese Patent Application Laid-Open No. 2003-069455

Disclosure of the invention

Problems to be solved by the invention

[0008] 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 used to switch a plurality of communication paths composed of a plurality of node devices. I'll be taken into consideration.

[0009] In order to prevent the loss of a packet transmitted by a packet switch device when switching a communication path configured via a plurality of node devices, a packet switch device connected to the layer 1 network is connected to the packet switch device. Therefore, it is conceivable to switch the conventional path to the new path by terminating the conventional path and the new path, respectively.

[0010] For example, a conventional path and a new path are temporarily set between packet switch devices that perform mutual communication via a layer 1 network in which a plurality of communication paths are configured by a plurality of node devices, and packets are transmitted. The switch device changes the interface for transmitting packets from the conventional path to the new path, and receives packets 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 partner packet switch device, the conventional path is released. Since the packet switch device transmits data in units of packets, the packet destination interface can be easily changed. For packet reception, for example, the arrival of packets from the conventional path and the new path due to the difference between the transmission delay of the conventional path and the transmission delay of the new path. Even if there is a competition for arrivals, packet loss can be avoided by providing a sufficiently large packet buffer, and there is no data loss, and communication paths can be switched.

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 pairs of the conventional path and the new path in order to terminate both ends of the communication path.

[0012] The present invention has been made in view of the above, and can switch communication paths while preventing data loss at low cost without using a plurality of interfaces in the packet switch device. The purpose is to obtain a communication system.

Means for solving the problem

[0013] A 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 includes the plurality of packet switch devices. In a communication system in which mutual communication is performed using one of a plurality of communication paths configured by node devices, the packet switch device is connected to the own device and a communication partner from the first communication path that is currently performing communication. When it is necessary to switch the communication path to a second communication path that includes an edge node device to which the packet switch device is connected and is different from the first communication path, the second communication path is changed from the first communication path to the second communication path. A switch request for switching to the communication path is transmitted, and after the switch request is transmitted, the switch to the second communication path is completed. During this period, a path setting unit that outputs an accumulation start instruction for stopping packet output and a transfer resumption instruction for resuming packet output, and when an accumulation start instruction is received from this path setting unit, Stops output, accumulates packets, receives the transfer restart instruction, receives the accumulated packet, outputs the accumulated packet, converts the packet output from the receive buffer into an optical signal, and connects itself to the device. A packet switch circuit for transmitting to the edge node device, and when receiving 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. The path management unit that receives the switching request transmitted from the packet switch device and the packet switch device after receiving the switching request. A duplicating unit for duplicating the force optical signal remained optical signal, the phase When notified that the hand side edge node device power switching request has been received, the selection unit that switches the communication path to be selected from the first communication path to the second communication path and the duplication unit replicated An optical signal is transmitted to the first and second communication paths, and an optical signal input from the second communication path selected by the selection unit is transmitted to a packet switch device connected to the own device. And an optical switch. The invention's effect

[0014] Packet switch device power S, from the first communication path that is currently communicating, to the first communication path that includes the edge node device to which the own device and the packet switch device of the communication partner are connected After sending a switch request requesting switching to a different second communication path, transmission of input packets is paused and stored, and when switching from the first communication path to the second communication path is completed When the accumulated packet is converted into an optical signal and transmitted, and the edge node device receives the switching request transmitted from the packet switch device, it notifies the other edge node device that the switching request has been received, and The optical signal input from the packet switch device is copied as it is and transmitted to the first and second communication paths, and a switching request is received from the partner edge node device. Is selected, the second communication path is selected to switch from the first communication path to the second communication path, and the optical signal input from the second communication path is connected to the own device. Since transmission is made to the packet switch device, the communication path can be switched while preventing data loss at low cost without using a plurality of interfaces in the packet switch device.

Brief Description of Drawings

FIG. 1 is a diagram showing a configuration of a communication system according to a first embodiment that is useful for the present invention.

(Embodiment 1)

[FIG. 2] 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] FIG. 4 is a flowchart for explaining the operation of OXC on the transmission side. (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 of the first embodiment. (Embodiment 1)

7] FIG. 7 is a sequence diagram for explaining the operation of the communication system of the first embodiment. (Embodiment 1)

[FIG. 8] FIG. 8 is a flowchart for explaining the operation of OXC on the transmission side. (Embodiment 3)

[FIG. 9] FIG. 9 is a flowchart for explaining the operation of the OXC on the receiving side. (Embodiment 3)

FIG. 10 is a flowchart for explaining the operation of OXC on the transmission side. (Embodiment 4)

FIG. 11 is a flowchart for explaining the operation of the packet switch device on the transmission side. (Embodiment 4)

FIG. 12 is a sequence diagram for explaining the operation of the communication system of the fourth embodiment. (Embodiment 4)

13] FIG. 13 is a diagram showing a detailed configuration of the OXC and the packet switch device of the fifth embodiment. (Embodiment 5)

14 is a diagram showing a configuration of a pause frame insertion unit shown in FIG. (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 Nose Management Department

141 Replica 142 Selector

151, 152, 251, 252 Control communication section

171 Pause generator

181 Pause frame insert

201, 202 packet switch device

211 Packet switch circuit

221 Receive buffer

231 and 232 path setting section

301 Conventional path

302 New Pass

601 O / E converter

602 control circuit

603 buffer

604 Pause holding buffer

605 selector

606 E / O converter

BEST MODE FOR CARRYING OUT THE INVENTION

[0017] 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. Note that the present invention is not limited to the embodiments.

[0018] 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 a plurality of (in this case, five) node devices, which are optical cross-connects (hereinafter referred to as OXC) 101 and 105, and packet switch devices 201 and 202. It is equipped with.

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 OXC101. The packet switch device 202 is connected to the OXC102, and the redundant system is formed by the node 301 connected by XC101, 104, 105, 102 and the path 302 connected by OXC101, 103, 102. It is composed. In this way, the redundant system of communication paths with two different paths 301 and 302 between OXC101 and OXC102 is used as a means to make the communication path fault-tolerant and is called 1 + 1 protection . In the following, the path 301 will be referred to as the conventional path 301 used before switching the communication path (the first communication path in the claims), and the path 302 will be the new path 302 after switching the communication paths (the claims) This is called the second communication path). In addition, the conventional path 301 and the new path 302 are set by a signaling protocol.

[0020] The OXC 101 105 is a general optical cross-connect, and has a function of transferring an input optical signal as 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 the general optical cross-connect function, the OXCs 101 and 102 have the power of the packet switch devices 201 and 202. A function of switching between the conventional path 301 and the new path 302 based on a switching signal for requesting communication path switching is provided.

[0021] OXC 101 and 102 replicate layer 1 data as an optical signal when switching the communication path, transfer it to conventional path 301 and new path 302, and input from conventional path 301 and new path 302. One of the layer 1 data is selected and transferred to the packet switch devices 201 and 202 as the optical signal. After switching the communication path, the layer 1 data input from the packet switch devices 201 and 202 is left as the optical signal. In addition to transferring to the new path 302, the layer 1 data input from the new path 302 is transferred to the packet switch devices 201 and 202 as an optical signal.

[0022] When switching the communication path from the conventional path 301 to the new path 302, the packet switch devices 201 and 202 accumulate layer 1 data packets to be transmitted and switch the OXC 101 and 102 to request switching of the communication path. Send a request. The packet switch devices 201 and 202 stop accumulating packets 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 XCs 101 and 102.

FIG. 2 shows packet switch devices 201 and 202 and OXC1 of the communication system shown in FIG. 1 is a device configuration diagram including the configurations of 01 and 102. FIG. In FIG. 2, to facilitate the following explanation, 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. The bucket switch device 201 and OXC101 show only the components necessary for transmission processing, and the packet switch device 202 and OXC102 show only the components necessary for reception processing. Actually, the communication through the layer 1 network 100 is full-duplex communication and can be controlled independently. Therefore, the OXC101 and the OXC102 have the same function, and the packet switch device 201 and the packet switch device 202 Have the same function.

[0024] The OXC 101 is an optical switch 111 that exchanges layer 1 data as an optical signal, and a path management unit 131 that manages setting and releasing of a communication path of a layer 1 network that transfers layer 1 data without changing the optical signal. A duplication unit 141 that replicates 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, OXC102) according to the signaling protocol. Communication path setting 'A control communication unit 151 that exchanges messages related to release is provided.

[0025] The OXC 102 is an optical switch 112 that exchanges layer 1 data as an optical signal, and a path management unit 132 that manages setting and releasing of a communication path of a layer 1 network that transfers layer 1 data without changing the optical signal. The switch includes a selection unit 142 for selecting either layer 1 data from the conventional path 301 or layer 1 data from the new path 302, and a control communication unit 152. The selection unit 142 is realized by the switching function of the optical switch 112.

[0026] The packet switch device 201 sets and releases a communication path in the packet switch circuit 211 for exchanging packets, a reception buffer 221 for storing packets located in the previous stage of the packet switch circuit 211, and the layer 1 network 100. Request / acceptance and control to exchange messages such as communication path requests with the path setting unit 231 that controls the accumulation of packets in the reception buffer 22 1 and the resumption of transfer of the accumulated packets, and the layer 1 network 100 A communication unit 251 is provided. Instead of the reception buffer 221, a transmission buffer that stores packets after the packet switch circuit 211 is provided, and the packets exchanged by the packet switch circuit 211 may be stored. ,. in this case, The transmission buffer is also provided with a function of converting accumulated packets into optical signals and transmitting them. 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 switch device 20 1 transmits the request for switching the communication path by manual setting or learning using the protocol with the OXC 101-105 in the layer 1 network 100, and then the OXC 101, 102 becomes the conventional path 301. Switching start time S required to start the operation to switch the communication path from the current path 302 to the new 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, The conventional path delay time D1 until the packet sent by the device reaches the OXC102 via the conventional path 301, and the new path delay time D2 until the packet sent by the local device reaches the OXC102 via the new path 302 Get the value of. 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.

[0028] Before starting switching from the conventional path 301 to the new path 302, if the forward margin for reliably storing packets in the reception buffer 221 is a, and the switching request transmission time at which the switching request is transmitted is Ts, accumulation starts The time is

Accumulation start time ≤ Ts + S_Dli (Equation 1)

It is necessary to satisfy.

[0029] In addition, if the backward margin to be inserted so that packet transfer can be resumed with sufficient margin after switching the communication path by absorbing clock jitter and synchronization error in the operation of OXC101-105, transfer is resumed. The time is

Transfer resume time ≥Ts + S + U— D2 + b (Equation 2)

It is necessary to satisfy.

[0030] The packet switch device 201 selects the accumulation start time and the transfer resumption time so that (Equation 1) and (Equation 2) are satisfied, and the packet switch device 201 receives a packet input between the accumulation start time and the transfer resumption time. Accumulate in the receive buffer 221. [0031] 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 亥卜 Accumulation start time ≥ U + a + b + Dl-D2 · · · (Equation 3). The optical switch switching time U currently implemented is about 10ms. In addition, the delay difference D1-D2 between the conventional path delay time D1 and the new path delay time D2 is a force that results in a path distance difference of 1000 km, but the delay difference D1-D2 is approximately 5 ms and depends on the error. However, it is not necessary to set the accumulation period so large.

[0032] The packet switch device 202 communicates with the packet switch circuit 212 for exchanging packets, the path setting unit 232 for requesting / accepting the setting and release of the communication path in the layer 1 network 100, and the layer 1 network 100. And a control communication unit 252 for exchanging messages such as communication path requests.

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

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.

[0035] The path setting unit 231 determines a switching request transmission time Ts for transmitting a switching request for switching a communication path from the conventional path 301 to the new path 302, and uses (Equation 1) and (Equation 2) described above. Then, the accumulation start time and transfer restart time are selected (step S100).

When the switching request transmission time Ts comes, the path setting unit 231 transmits a switching request for switching the communication path from the conventional path 301 to the new path 302 to the OXC 101 via the control communication unit 251 (step S 110).

[0037] 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 bucket switch circuit 211, and starts accumulation of the packet (steps S120 and S130). That is, the packet switch device 201 transfers the packet to the OXC 101. Stop sending.

[0038] 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 packet transfer to the OXC 101.

Next, the operation of the OXC 101 connected to the transmission side packet switch device 201 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.

[0040] When the switching request is received 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 that notifies 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 copy start instruction to the copy unit 141. Upon receiving the duplication start instruction, the duplication unit 141 duplicates the optical signal input from the packet switch device 201 as it is, 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 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 receiving the switching request from the OXC 101, 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).

[0045] The packet switch circuit 212 of the packet switch device 202 is input from the OXC 102. The optical signal packet is exchanged and output.

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.

[0047] At time 1 "T1, the control communication unit 251 of the packet switch device 201 transmits to the OXC 101 a switching request 430 for switching the communication path from the conventional path 301 to the new path 302.

When the control communication unit 151 of the OXC 101 receives the switching request 430, it outputs it to the path management unit 131. The path management unit 131 generates a switching request 431 for notifying 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 duplication start instruction to the duplication unit 141. As a result, when receiving an optical signal from the packet switch device 201, the duplicating unit 141 starts duplicating operation by duplicating the optical signal as it is and outputting it to the optical switch 111.

[0049] At time Τ3, 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 Τ4, 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, the transfer data may be disturbed due to physical movement of the optical switch components, etc. Switching to the new path 302 is complete.

[0050] On the other hand, the path setting unit 231 of the packet switch device 201 sets the time IJT1 for transmitting the switching request 403 before the control communication unit 251 transmits the switching request 430 at time ijTl (Expression 1) and ( Select the storage start time and transfer restart time as the switching request transmission time Ts in Equation 2). That is, the packet switch device 201

Accumulation start time ≤ T1 + S—D1— a

Transfer resume time ≥ Tl + S + U-D 2 + 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. [0051] When it is the accumulation start time In IJT2, the path setting unit 231 of the packet switch device 201 outputs an accumulation start instruction to the reception buffer 221, and the reception buffer 221 outputs the packet to the packet switch circuit 211. Output is stopped and packet accumulation is started.

[0052] At the transfer restart time “l” T5, the path setting unit 231 of the packet switch device 201 outputs a transfer restart instruction to the reception buffer 221, and the reception buffer 221 sends the packet switch circuit 211 to the packet switch circuit 211. Start packet output. The reception buffer 221 outputs the packet accumulated in the accumulation period 441 from time IJT2 to time IJT5 to the packet switch circuit 211, and the packet switch circuit 211 transmits the packet 450 converted into the optical signal to the OXC101.

[0053] 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 a duplicating operation. Therefore, the duplicating unit 141 duplicates the optical signal of the packet 450 from the packet switch device 201 as an optical signal and outputs it to the optical switch 111.

[0054] The optical switch 111 of the OXC 101 transmits the optical signal of the packet 452, which is one of the optical signals of the packet 450 duplicated by the duplicating unit 141, to the conventional path 301, and the packet which is the optical signal of the other packet. 451 optical signals are transmitted to the new path 302.

[0055] Since the new path delay time D2 is larger than the conventional path delay time D1, at time Τ7, the optical signal of the packet 452 via the conventional path 301 arrives at ΟXC102. However, at time Τ6, the selection unit 142 of the OXC 102 does not select the optical signal of the packet 452 because the switching from the conventional path 301 to the new path 302 has been completed.

[0056] At time Τ8, the optical signal of packet 451 arrives at OXC102 via 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.

[0057] 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. Bucket switch device 201 sends switch request 431, and OXC 101 and 102 switch communication paths. The packet switching device 201 accumulates packets during the accumulation period 441 and resumes packet transfer at time T5, which is the transfer resumption time. The new path 302 shown in FIG. This is the same as when the new path delay time D2 with a longer path length is longer than the conventional path delay time D1, and therefore the description thereof is omitted here.

[0059] When it is the transfer resumption time In 1JT5, the optical signal of the packet 450 transmitted from the packet switch device 201 is copied as the optical signal by the OXC 101, and the optical signal of the packet 452 is transferred to the conventional path 301. 451 optical signals are transmitted to the new path 302.

[0060] Since the new path delay time D2 is smaller than the conventional path delay time D1, at time T7a, the optical signal of the packet 451 via the new path 302 arrives at XC102. At time T6, the selection unit 142 of the OXC 102 has completed switching from the conventional path 301 to the new path 302, so the selection unit 142 keeps the optical signal of the packet 451 received from the new path 302 as an optical signal. The packet switch device 202 transmits the packet 453 to the packet switch device 202, and the packet switch device 202 outputs the packet 453.

[0061] At time T8a, the optical signal of packet 452 that has passed through conventional path 301 arrives at OXC102. However, since switching from conventional path 301 to new path 302 has been completed, the optical signal of bucket 452 is selected. Part 142 is not selected.

[0062] As described above, in the first embodiment, 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 accumulates packets to be transmitted during the accumulation period. Later, it is converted to an optical signal and sent to the OXC101.

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. Upon receiving the switching request, the OX C 102 switches 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. This makes it possible to switch communication paths without losing packets.

[0063] In the first embodiment, the packet transmitted by the packet switch device 201 at the time of switching the communication path is transferred with the delay of the accumulation period at the maximum, but the accumulation period is relatively small as described above. Therefore, the impact on applications that send and receive packets is not significant. Embodiment 2

In the second embodiment, the switching request described in the first embodiment is defined by RFC 2471 in the communication path control protocol of the layer 1 network standardized as GMPLS (Generalized Multiprotocol Label Switching). An explanation will be given of the case where it is implemented using TE (Resource reSerVation Protocol-Traffic Engineering). RSVP-TE is a signaling protocol in the claims.

In the communication system according to 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. To the body white f, OXC101, 102. A function to create and process RSVP-TE messages in switch management units 31 and 132, and to control the optical switches 111 and 112 according to the contents of the messages and set the connection relationship of the optical switches that constitute the communication path And the control communication units 151 and 152 perform communication using RSVP-TE messages to dynamically set the conventional path 301 and the new path 302 between the XCs 101 and 102. Note that the path setting units 231 and 232 of the packet switch devices 201 and 202 have a function for supporting GMPLS protocol messages, communicate with the OXC101 and OXC102 using the control communication units 251 and 252, and perform the layer 1 network. A communication path passing through 100 may be set dynamically.

[0066] RSVP-TE implements procedures for setting and releasing communication paths by exchanging messages such as Path, Resv, ResvConf, PathTear, and PathErr between OXCs. In the communication system according to the third embodiment, which contributes to the present invention, the information mounted in these RSVP-TE messages is expanded, and a new path 302 is created while configuring a 1 + 1 protection relationship with the conventional path 301. to add. In addition, the relation between the 1 + 1 protection of 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 existing path 301, the path message of the RSVP-TE communication path setting sequence that sets the new path 302 includes the identifier of the existing path 301 and the relationship between the existing path 301 and the new path 302. Equipped with information indicating (1 + 1 protection). In addition, after switching the communication path from the conventional path 301 to the new path 302, in order to release the conventional path 301, a communication path that is not selected by the selection unit 142 in a message used for releasing the communication path such as PathTear. The information indicating that the communication path is released without changing the setting of the selected communication path. 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 set to the new path. Since the conventional path 301 is released after switching to 302, the communication path can be flexibly switched.

[0068] Embodiment 3

Embodiment 3 of the present invention will be described with reference to FIG. 8 and FIG. In the first embodiment, the packet switch device 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 request for switching the OXC 101 power is received, the packet switching device 202 on the reception side is connected. The communication path was switched by sending a switch request to the OXC102. That is, the switching operation of the communication path 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, since messages such as switching requests are generally generated and processed by software, it is difficult to set an upper limit of processing time between the packet switch devices 201, OXC 101, and 102. Therefore, when the packet switch device 201 shown in FIG. 6 transmits a switching request 430 to OXC 101, the time between IJT1 and time T4 when OXC102 starts switching the communication path, that is, (Equation 1) 1 (Equation 3 ) When the own device sends a communication path switch request, the error of the switch start time S required until XC101, 102 starts the operation to switch the communication path from the conventional path 301 to the new path 302 increases. A large margin must be expected for the accumulation period shown in (Equation 3). 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 request for switching between OXC101 and OXC102 is generated and processed by a hardware that does not use the control communication units 151 and 152, and is selected. Switching of unit 142 is also realized by hardware.

[0070] Embodiments 1 and 2 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 technology that provides fault tolerance for communication paths. In the node equipment that terminates the path redundancy system, the communication path is selected so that data is received from the redundant communication path that has not failed.

As described in Embodiment 1 above, OXC 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 OXC 101 and 102 have a mechanism for detecting layer 1 optical signals 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 or not. Note that the optical signal of layer 1 data is modulated to carry the bit string constituting the upper layer data by the optical signal, and continues to be transferred regardless of the presence or absence of packet data transfer in the upper layer. Therefore, the OXC 101 artificially interrupts the optical signal with respect to the conventional path 301 while setting the conventional path 301 and the new path 302 to have a 1 + 1 protection relationship and stopping the packet data transmission in the packet switch device 201. By generating a failure in the state, the path management unit 132 of the OXC 102 can detect the failure of the conventional path 301 and use the 1 + 1 protection function to switch to the new path 302 where no failure has occurred. The 1 + 1 protection function is implemented by hardware to enable high-speed switching.

[0072] Next, the operation of the OXCs 101 and 102 of the communication system according to the third embodiment that is useful for the present invention will be described with reference to the flowcharts of Figs. The operations of the packet switch devices 2 01 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 to obtain an optical signal to the conventional path 301. The optical signal to the new 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 duplicating unit 141 of the optical switch 111 (step S410). Hikari Switch 111 is a new The optical signal is transferred using the network 302 (step S420).

[0075] 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 level of the optical signal is decreased by the 1 + 1 protection function. A selection instruction for selecting a new path 302 that has not been detected 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 the optical signal from the new path 302 to the packet switch device 202 (step S520).

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

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

[0079] Upon detecting a decrease in the optical signal level in the conventional path 301, the OXC102 selects the new path 302 in which the decrease in the optical signal level is not detected by the 1 + 1 protection function, and selects the selected new path. The optical signal from 302 is transmitted to the packet switch device 202.

As described above, in this third embodiment, since the OXC 101 interrupts the optical signal of the conventional path 301 and uses the 1 + 1 protection function, the OXC 102 selects the communication path. Compared to a case where a communication path switching request is made using a message by software processing without adding hardware, the switching request is transmitted at a higher speed and variation in transmission delay is suppressed. It is possible to reduce an error in the time from when the switching request is transmitted until the switching is started, and to reduce the capacity of the reception buffer 221.

[0081] Embodiment 4

Embodiment 4 of the present invention will be described with reference to FIG. 10 to FIG. In Embodiments 1 to 3, the packet switch device 201 transmits a switching request and starts switching operation of the communication path. did. 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.

Using the control communication unit 151, the path management unit 131 of the OXC 101 according to the fourth embodiment notifies the packet switch device 201 of a transmission stop request for requesting stop of packet transmission, and communicates with the OXC 102. It has a function to notify a switching request that requests path switching.

[0083] The path management unit 131 of the OXC 101 sends a request for stopping transmission to the packet switch device 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 〇X C102. Time required for packet switch device 201 to start storing packets Q to send to 201 Q, Time required for OXC102 to start switching communication path after sending own device switch request to OXC102 P , Switching time U required for the selection unit 142 to switch the communication path from the conventional path 301 to the new path 302, the conventional path until the packet transmitted by the packet switch device 201 reaches the XC102 via the conventional path 301 The delay time Dl and the value of the new path delay time D2 until the packet data transmitted by the packet switch device 201 reaches the OXC102 via the new path 302 are obtained. The The bus management unit 131 measures and stores these values in advance. For the conventional path delay time D1 and the new path delay time D2, values calculated from the path length of the communication path may be used.

[0084] If the transmission stop request transmission time at which OXC101 transmits a transmission stop request is Ta and the switching request transmission time at which OXC101 transmits a switching request is Tb, the accumulation start time and transfer resumption time are

Accumulation start time = Ta + Q Tb + P_D1 (Equation 4)

Transfer restart time> Tb + P + U— D2 (Equation 5)

It is necessary to satisfy.

[0085] The path management unit 131 of the OXC 101 sets the transmission stop request transmission time Ta, the switch request transmission time Tb, and the stop request time R as the accumulation time so as to satisfy the conditions of (Equation 4) and (Equation 5). select. Specifically, packet transfer via the conventional path 301 is a communication path disconnection. The margin to insert so that it can be surely stopped before the switching operation starts is c, and the time required for the OXC102 to start switching the communication path after the local device sends a switching request to the OXC102 during the operation P Time required for the own device to send a transmission stop request to the packet switch device 201 and the packet switch device 201 to start accumulating packets Q, error in conventional path delay time D1, new path delay time D2, or packet OXC101 path management, where d is the margin to be inserted to absorb the clock jitter and synchronization error in the operation of switch device 201 and OXC101, 102 and resume the transfer with sufficient margin after switching the communication path Unit 131 transmits transmission stop request transmission time Ta, switching request transmission time Tb, and stop request time R.

Ta + Q + Dl = Tb + P + c… (Formula 6)

R = U + Dl-D2 + c + d… (Formula 7)

Choose to meet.

Next, referring to the flowcharts of FIG. 10 and FIG. 11 and the sequence diagram of FIG. 12, when layer 1 data is transmitted from the packet switch device 201 to the packet switch device 202, a new one is introduced from the conventional path 301. The operation of switching the communication path to the path 302 will be described as an example, and the communication path switching operation of the communication system that is useful for this invention will be described. Note that the operations of the OXC 102 and the packet switch device 202 are the same as those in the first embodiment, and thus 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 device 201 via the control communication unit 151. Send (step S600).

[0088] When the switching request transmission time Tb selected by (Equation 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 duplication start instruction to the duplication unit 141.

Upon receiving the duplication start instruction, duplication unit 141 duplicates the optical signal input from packet switch device 201 as an optical signal, and transmits the optical signal to conventional path 301 and the optical signal to new path 302. And outputs the two generated optical signals to the optical switch 111. The light switch 111 The two input optical signals are transmitted 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 the transmission stop request is received from the OXC 101 via the control communication unit 251, the path setting unit 231 receives 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. Select the storage start time and transfer restart time (steps S700, 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 is received from the OXC 101 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. Then, packet accumulation is started (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 the input packet, converts the exchanged packet into an optical signal, and transfers it. That is, the packet switch device 201 resumes the packet transfer to the OXC 101.

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

At time T11, the control communication unit 151 of the OXC 101 transmits to the packet switch device 201 a transmission stop request 501 for stopping packet transfer in order to switch the communication path from the conventional path 301 to the new path 302. The transmission stop request 501 includes the time T11 as the transmission stop request transmission time ijTa selected by (Equation 6) and (Equation 7), the time T14 as the switching request transmission time Tb, and the stop request time R. It is included.

At time T12, the path setting unit 231 of the packet switch device 201 receives the transmission stop request 501 via the control communication unit 251. The path setting unit 231 sends a transmission stop request 501 Based on this, the storage start time and transfer restart time are selected. In FIG. 12, the path setting unit 23 1 selects the time IJT13 immediately after receiving the transmission stop request 501 as the accumulation start time, and at least the stop request time R has elapsed from the time T13 which is the accumulation start time as the transfer restart time. When 1JT17 is selected.

[0096] 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 duplication start instruction to the duplication unit 141. As a result, when receiving the optical signal from the packet switch device 201, the duplicating unit 141 starts duplicating operation for duplicating the optical signal as it is and outputting it to the optical switch 111.

[0097] 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 T16, 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, the transfer data may be disturbed due to physical movement of the optical switch components. Switching to 302 is complete.

On the other hand, the path setting unit 231 of the packet switch device 201 outputs a storage start instruction to the reception buffer 221 at time T13, which is the storage start time, and sends the storage buffer 221 to the bucket switch circuit 211. Stop outputting packets and start accumulating packets.

[0099] When it is the transfer resumption time In IJT17, the path setting unit 231 of the packet switch device 201 outputs a transfer resumption instruction to the reception buffer 221, and the reception buffer 221 outputs the packet to the packet switch circuit 211. Start output. The reception buffer 221 outputs the packet accumulated in the accumulation period 441 from time T13 to time ijTl 7 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 into the packet signal. Send to OXC101.

[0100] The replication unit 141 of the OXC 101 receives the replication instruction from the path management unit 131 after transmitting the switching request 431 to the OXC 102, and is set to perform the replication operation. Gatsutsu Then, 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.

[0101] The optical switch 111 of the OXC 101 is the optical signal of the packet duplicated by the duplication unit 141.

The optical signal of one packet 452 is transmitted to the conventional path 301, and the optical signal of packet 451, which is the optical signal of the other packet, is transmitted to the new path 302.

[0102] Since the new path delay time D2 is larger than the conventional path delay time D1, at time T19,

The optical signal of the packet 452 arrives at the OXC 102 via the conventional path 301. But time

At T18, the selection unit 142 of the OXC 102 does not select the optical signal of the packet 452 because the switching from the conventional path 301 to the new path 302 has been completed.

[0103] At time T20, the optical signal of packet 451 arrives at OXC102 via 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.

[0104] The packet switch circuit 212 of the packet switch device 202 outputs the received packet 453.

As described above, in the fourth embodiment, the node device OX C101 in the layer 1 network 100 notifies the packet switch device 201 of the transmission stop request, transmits the switch request to the OXC 102, and the packet switch device 201. The optical signal from is copied as it is 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 into 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 the optical signal from the new path 302 to the packet switch device 202. This makes it possible to switch communication paths without losing packets.

[0106] Note that the Pause operation in Annex 31B of IEEE Standard 802.3 (2002 edition) includes the packet switch device 201 of the fourth embodiment that sends a transmission stop request 501 for a device having an Ethernet (registered trademark) interface. An operation similar to the operation of receiving and temporarily stopping packet transmission is specified. Specifically, in the Pause operation, a specific frame called a Pause frame is defined, and a device having an Ethernet (registered trademark) interface that receives the Pause frame is included in the Pause frame. Stop sending Ethernet frames to that interface during the encoded pause period.

[0107] As the packet switch device 201 of the fourth embodiment, a packet switch device that supports the pause operation as defined in the pause operation in IEEE standard 802.3 (2002 version) (Z) Annex 31B is used. When the control communication unit 251 receives the transmission stop request 501 and adds a control function to the path setting unit 231 to stop the transmission of the Ethernet frame to the OXC101 connection interface, as in the case of receiving the Pause frame, the packet is set. Packet transmission, and accumulation in the reception buffer 221 and resumption of packet transfer after the lapse of the requested stop time R can be realized with a minimum of additional functions.

[0108] Embodiment 5

In the fifth embodiment, a description will be given only when the Pause operation in Annex 31B of IEEE Standard 802.3 (2002 edition) is used.

The communication system according to the fifth embodiment of the present invention includes OXClOla, 102a instead of OXC101, 102 of the communication system shown in FIG.

[0110] OXCl Ola, 102a has the same function. FIG. 13 shows the detailed configuration of the OXClOla and the packet switch device 201. The packet switch device 201 shown in FIG. 13 shows the components related to the transmission processing of the packet switch device 201 shown in FIG. 2 and the portions related to the reception processing of the packet switch device 202. Also for OXClOla, the components related to transmission processing shown in OXC101 shown in FIG. 2 and the components related to reception processing shown in OXC102 are shown. A Pause generation unit 171 and a Pause frame insertion unit 181 include 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.

[0111] The Pause generation unit 171 generates a Pause frame including a stop time in which the stop request time R selected by the path management unit 131 using (Expression 6) and (Expression 7) is encoded.

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. The Pause frame insertion unit 181 converts the optical signal data input from the optical switch 111 into an electrical signal. Optical signal / electrical signal conversion unit (hereinafter referred to as “O / E conversion unit”) 601, a control circuit 602 for controlling the Pause frame insertion operation by observing the electric signal output from the O / E conversion unit 601, and the Pause During frame insertion, buffer 603 that stores Ethernet (registered trademark) frames in the electrical signal output by O / E converter 601 and Pause holding that holds the Pause frame generated by Pause generator 171 A selector that selects a Pause frame that is controlled by the buffer 604 and the control circuit 602 and that is input from the OZE converter 601, the electrical signal input from the buffer 603, or the Pause holding buffer 604. 605 and an electric signal / optical signal conversion unit (hereinafter referred to as an E / O conversion unit) 606 that converts the electric signal selected by the selector 605 into an optical signal.

Next, the operation of OXClOla will be described with reference to the flowchart of FIG. Before the switching of the communication path, the optical signal packet input from the conventional path 301 is selected by the selection unit 142 and input to the OZE conversion unit 601. The control circuit 602 controls the selector 605 so as to select the electrical signal input from the ○ / E converter 601. As a result, the selector 6 05 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 and converts it into a packet switch. Transmitting to device 201.

[0115] When the communication path is switched, the Pause generation unit 171 has the path management unit 131 (Equation 6) and

A pause frame including a stop time encoded with the stop request time R selected using (Equation 7) is generated (step S800). The pause generation unit 171 outputs the generated pause frame to the pause holding buffer 604.

[0116] When the switching request transmission time comes, the path management unit 131 notifies the control circuit 602 that the communication path is switched, and the control circuit 602 observes the electrical signal of the ZE conversion unit 601 and An idle signal between (registered trademark) frames is detected (steps S810 and S820).

[0117] When the idle signal is detected, the control circuit 602 causes the buffer 603 to start accumulating the Ethernet (registered trademark) frame converted into the electrical signal by the OZE conversion unit 601 (step S830). In addition, the control circuit 602 outputs the pause frame held in the pause holding buffer 604 and controls the selector 605 to select the input from the pause holding buffer 604 to the E / O conversion unit 606. Held in holding buffer 604 A pause Pause frame is output (step S840). The E / O converter 606 converts the input pause frame from an electrical signal to an optical signal and outputs the converted signal to the packet switch device 201.

[0118] After outputting the Pause frame, the control circuit 602 controls the selector 605 to select the 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 EZ 0 conversion unit 606, and the EZ 0 conversion unit 606 converts the Ethernet (registered trademark) frame stored in the buffer 603 into the electrical signal. Is converted to an optical signal and transmitted to the packet switch device 201 (steps S850 and S860).

[0119] After outputting the Ethernet (registered trademark) frame stored in the buffer 603, the control circuit

602 controls the selector 605 to select an electrical signal input from the OZE converter 601. As a result, the selection circuit 602 outputs the electrical signal input from the OZE converter 601 to the EZ converter 606, and the EZ converter 606 receives the Ethernet (registered trademark) frame input from the OZE converter 601. The electrical signal is converted into an optical signal and transmitted to the packet switch device 201 (steps S870 and S880).

[0120] As described above, the operation of the communication system after OXClOla stops packet transmission to the packet switch device 201 by the Pause frame is the same as that described in the fourth embodiment. The description is omitted here.

[0121] As described above, in the fifth embodiment, the communication path is switched by inserting the Pause frame during the idle time between the Ethernet (registered trademark) frames transmitted to the packet switch device 201 and the OXC101 power S. Since the packet switch device 201 that supports the IEEE 802.3 Pa use operation is added to the packet switch device 201 without adding a new function, the packet transmission accumulation start and stop request time R elapses. Packet transfer restart can be realized, and the communication path can be switched without packet loss.

Industrial applicability

[0122] As described above, the communication system according to the present invention is useful for a network using an optical transmission line, and in particular, communicates by configuring a redundant system with communication paths of different paths temporarily in the network. Suitable for communication systems that switch paths.

Claims

The scope of the claims

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 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 changed from the first communication path that is currently communicating to the second communication path that is different from the first communication path, including the edge node device to which the own device and the packet switch device of the communication partner are connected. When it becomes necessary to switch, 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 transmitting the switching request. A path setting unit that outputs a storage start instruction for stopping packet output and a transfer restart instruction for resuming packet output.

Receiving a storage start instruction from the path setting unit, stops outputting the input packet, stores the packet, and receives the transfer resumption instruction, a reception buffer that outputs the stored packet;

A packet switch circuit for converting the packet output from the reception buffer into an optical signal and transmitting it to the edge node device to which the device is connected;

With

The edge node device is:

A path management unit that, when receiving a switching request transmitted from the packet switch device, notifies the other edge node device that the switching request has been received;

A duplicating unit that duplicates the input optical signal as an optical signal after receiving the switching request transmitted from the packet switch device;

When notified from the counterpart edge node device that a switching request has been received, the selection unit that switches the communication path to be selected from the first communication path to the second communication path, and the replication unit that has been replicated An optical signal is transmitted to the first and second communication paths, and an optical signal input from the second communication path selected by the selection unit. An optical switch that transmits a signal to a packet switch device connected to the device itself.

[2] The path management unit of the edge node device

2. The communication system according to claim 1, wherein the first communication path and the second communication path are set by a signaling protocol.

[3] The path management unit of the edge node device

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 counterpart edge node device, and 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 counterpart edge node device.

[4] The path management unit of the edge node device includes:

The communication system according to claim 1, wherein the notification of the switching request is notified by a message.

[5] The path management unit of the edge node device includes:

When notifying the other edge node device that the switching request has been received by causing a failure in the first communication path and detecting that a failure has occurred in the first communication path, 2. The communication system according to claim 1, wherein it is determined that the partner-side edge node device power has been notified that the switching request has been received.

[6] 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 the second edge node device from the first communication path to the second 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 the communication path.

[7] 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 one of a plurality of communication paths configured by the plurality of node devices. A communication system for mutual communication using Leave

The edge node device is:

If it is necessary to switch the communication path from the first communication path that is currently communicating to a second communication path that includes the own device and the partner edge node device and is different from the first communication path, Notifying the packet switch device connected to the device of the transmission stop request for requesting the packet transmission stop, and notifying the counterpart edge node device of the switching request for switching from the first communication path to the second communication path A path management unit, 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 duplication unit is transmitted to the first and second communication paths, and the optical signal input from the second communication path selected by the selection unit is connected to the own apparatus. An optical switch for transmitting to the packet switch device,

With

The packet switch device

A path 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. A setting section;

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 restart instruction, and the reception buffer outputs a packet 8. The communication system according to claim 7, wherein an accumulation period for stopping packets and accumulating packets is at least the transmission stop time or longer.

[9] The transmission stop request is

The communication system according to claim 7, wherein a Pause frame defined by IEEE standard 802.3 is used.

[10] The path setting unit of the packet switch device includes:

The delay time for the packet to arrive via the first and second communication paths, and the other edge node device from the first communication path to the second time after the edge node device notifies the switching request. The communication system according to claim 7, wherein the communication system is selected according to a switching time required for switching to the communication path.

[11] 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 is one of a plurality of communication paths configured by the plurality of node devices. In a communication system that performs mutual communication using

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

When receiving an instruction to start accumulation from the path setting unit, the packet switch circuit force stops outputting the input packet and accumulates the packet. When receiving the transfer restart instruction, the accumulated packet is converted into an optical signal. A transmission buffer for output to the edge node device to which the device is connected; With

The edge node device is:

When notified from the counterpart edge node device that a switching request has been received, the selection unit that switches the communication path to be selected from the first communication path to the second communication path, and the replication unit that has been replicated An optical signal is transmitted to the first and second communication paths, and an optical signal input from the second communication path selected by the selection unit is transmitted to a packet switch device connected to the own device. With a light switch,

A communication system comprising:

The edge node device is:

If it is necessary to switch the communication path from the first communication path that is currently communicating to a second communication path that includes the own device and the partner edge node device and is different from the first communication path, Notifying the packet switch device connected to the device of a transmission stop request for requesting to stop the transmission of the optical signal of the packet, and switching to switch the first communication path from the first communication path to the other edge node device A path management unit that notifies the request;

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;

The optical signal replicated by the replication unit is sent to the first and second communication paths. An optical switch that transmits an optical signal input from the second communication path selected by the selection unit to a packet switch device connected to the own 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;

When receiving an instruction to start accumulation from the path setting unit, the packet switch circuit force stops outputting the input packet and accumulates the packet. When receiving the transfer restart instruction, the accumulated packet is converted into an optical signal. A transmission buffer for output to the edge node device to which the device is connected;

A communication system comprising:

In a packet switch device connected to an edge node device and performing mutual communication using one of a plurality of communication paths configured by a plurality of node devices including the edge node device.

Packets output from this reception buffer are converted into optical signals and the device is connected A packet switch circuit for transmitting to the edge node device;

A packet switch device comprising:

[14] In a packet switch device connected to an edge node device and performing mutual communication using one of a plurality of communication paths configured by a plurality of node devices including the edge node device.

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 Sending node output to the edge node device connected to the

A packet switch device comprising:

[15] In a packet switch device connected to an edge node device and performing mutual communication using one of a plurality of communication paths configured by a plurality of node devices including the edge node device.

The storage start instruction for stopping the output of the packet and the transfer 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 the switching to the second communication path. A path setting unit for outputting a restart instruction;

Receiving a storage start instruction from the path setting unit, stops outputting the input packet, stores the packet, and receives the transfer resumption instruction, a reception buffer that outputs the stored packet; A packet switch circuit for transmitting packets output from the reception buffer to the edge node device to which the device is connected;

A packet switch device comprising:

[16] In a packet switch device connected to an edge node device and performing mutual communication using one of a plurality of communication paths configured by a plurality of node devices including the edge node device.

When receiving a storage start instruction from the path setting unit, the packet switch circuit power stops outputting the input packet and stores the packet. When receiving the transfer restart instruction, the self-device connects the stored packet. And a transmission buffer that outputs to the edge node device.

[17] 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,

A switching request has been received from the first communication path that is currently communicating to request switching to a second communication path that is different from the first communication path, including the local device and the partner edge node device. A path management unit that notifies the other edge node device that the switching request has been received, and

A duplicating unit that duplicates an optical signal input from the packet switch device after receiving the switching request as an optical signal; When notified from the partner edge node device that the switching request has been received, the selection unit that switches the communication path to be selected from the first communication path to the second communication path, and the replication unit replicated An optical signal is transmitted to the first and second communication paths, and an optical signal input from the second communication path selected by the selection unit is transmitted to a packet switch device connected to the own device. With a light switch,

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,

An edge node device comprising: