JP2000232483A - Communication network system and communication node - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a network by which an optimum optical part and nodes are dynamically set in accordance with the fluctuation of a communication band. SOLUTION: A network system is provided with a plurality of nodes and a network management part. Each node is provided with an optical cross connect OXC and a packet switch PSW, and besides, it stores plural terminals. Each node measures the traffic amount of a flow in the packet switch PSW in one's own node, the activation/end of an application in each terminal or an inter-node delay time. Then, the node announces the monitoring result to a network managing part. The network managing part sets an inter-node optical path in order to optimize the through-put of a network.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a network system. It also relates to a communication node arranged in such a network system.

[0002]

2. Description of the Related Art A communication network system includes a plurality of nodes and links connecting the nodes. Typically, the node includes, for example, an electronic exchange EX or a router. Nodes further include cross-connects. In recent years, with the increase in communication data, the development of optical cross-connects for handling optical signals has been promoted. FIG. 2 shows a typical configuration of a communication network system using an optical cross-connect.

FIG. 2 shows a network in which a plurality of nodes from node A to node D are interconnected by optical fibers. In each node, the electronic exchange EX is connected to the optical cross-connect OXC.
Each electronic exchange EX accommodates a plurality of terminals as users.

[0004] The electronic exchange EX has a switch SW and a switch control unit. The electronic exchange EX switches information provided from the terminal and performs optical cross-connect OX.
Give to C. At this time, when a plurality of terminals are trying to transmit information to the same destination node, the information is multiplexed and given to the optical cross-connect OXC.

[0005] The optical cross connect OXC is an electronic exchange E
It has a function of inserting a signal given from X into the network and a function of extracting a signal transmitted in the network and giving it to the electronic exchange EX. The optical cross connect OXC further has a function of inputting a signal transmitted in the network and relaying the signal to another adjacent optical cross connect.

As a result, an optical signal connection is set between two adjacent nodes or between two non-adjacent nodes. This connection of the optical signal is called an optical path. In FIG. 1, one optical path is set between the node A and the node B. Another optical path is set between the node A and the node C. Further, an additional optical path is set between a node (not shown) and the node D.

In the network system shown in FIG. 2, each optical cross-connect OXC transmits a plurality of optical signals through one optical fiber using an optical wavelength multiplexing technique. As a result, the communication capacity can be increased. In FIG. 2, wavelength multiplex transmission is realized using an optical multiplexer / demultiplexer and an optical space switch OSW.

That is, each optical cross-connect OXC
Is an interface IF, an optical multiplexer / demultiplexer (Optical MUX /
DEMUX) OMD, and an optical space switch OSW. The information signal given to the optical cross connect OXC from the electronic exchange EX is converted into an optical signal in the interface IF. The optical signal thus generated is provided to the optical space switch OSW. The optical space switch OSW inputs a given optical signal to an optical fiber directed to a desired optical cross connect.

Next, the operation of the network system will be described. When starting communication, each terminal specifies a partner terminal to the electronic exchange EX. The terminal is simultaneously
A band required for communication is declared to the electronic exchange EX.

[0010] Upon receiving a call from a user, the electronic exchange EX first specifies a partner terminal. Next, the electronic exchange EX determines whether or not the band declared by the user can be secured between the calling terminal and the partner terminal. As a result of this determination, if it is determined that the band declared by the user can be secured, the electronic exchange EX accepts the call and starts the call processing. Therefore, the electronic exchange EX knows in advance the bandwidth of the optical path from one node to another node. Further, each of the electronic exchanges EX stores information on the currently accepted call in a network management center (network ma).
nagement center) sent to NMC.

[0011] Ordinary telephone and N-ISDN (Narrow-ban
ST such as d Integrated Services Digital Network)
The M (Synchronous Transport Module) service is a service in which the band required for communication is fixed. Therefore,
By declaring the required bandwidth before the start of communication, the required bandwidth is guaranteed.

[0012]

However, in recent years, an ABR (Available Bit Ratio) service by an ATM exchange and an IP (Internet Protocol) by an IP packet exchange have been proposed.
l) Services that basically do not guarantee bandwidth, such as communication services, have begun to be provided. That is, these services are based on the premise that a user does not declare or reserve a band to the network before starting communication. In addition, these services have much greater traffic fluctuations than conventional voice communications.

[0013] Therefore, in such a service, an optimal optical path is dynamically set in accordance with a fluctuation of a communication band, instead of setting an optical path fixedly as in a conventional network. There is a strong demand.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a network system for dynamically setting an optimal optical path so that a maximum throughput can be achieved in response to a change in a communication band. Another object is to provide a communication node suitable for such a network system.

[0015]

According to a first aspect of the present invention, a network system has a plurality of nodes and a network management unit. The plurality of nodes and the node and the network management unit are connected by an optical transmission line. Each node arranged on the network includes an optical cross connect and a packet switch. Each node accommodates a plurality of terminals.

At each node, the optical cross-connect
An optical path for transmitting and receiving an optical signal between the own node and another node,
And / or set an optical path for relaying an optical signal between other nodes. Each node monitors the amount of traffic flowing in the packet switch in the own node.

The network management unit detects a change in the communication band based on the packet flow monitored by each node. And
Based on the fluctuation of the communication band, an optical path between the nodes is set so that the throughput of the network is optimized.

In the second invention, the network system has a plurality of nodes and a network management unit. The plurality of nodes and the node and the network management unit are connected by an optical transmission line. Each node arranged on the network includes an optical cross connect and a packet switch. Each node accommodates a plurality of terminals.

Each node monitors the start / end of an application in each terminal accommodated in the own node. Each node reports the start / end of the application to the network management unit.

The network management unit detects a change in the communication band based on the status of activation / termination of the application in each terminal. Then, based on the fluctuation of the communication band, the optical path between the nodes is set so that the throughput of the network is optimized.

In a third aspect, a network system has a plurality of nodes and a network management unit. The plurality of nodes and the node and the network management unit are connected by an optical transmission line. Each node arranged on the network includes an optical cross connect and a packet switch. Each node accommodates a plurality of terminals.

Each node attaches a time stamp to the management packet and transmits the packet to another node. When a management packet with a time stamp is returned from another node, each node measures the delay time from the time stamp.

The network management unit sets an optical path between the nodes based on the delay time between the nodes so that the throughput of the network is optimized.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a first embodiment of the present invention will be described. FIG. 1 is a block diagram illustrating a configuration of a communication node installed in the network according to the first embodiment. In FIG. 1, the node is a packet switch PE
X and an optical cross-connect OXC.

The packet switch PEX includes a packet switch PSW, a call processing unit (call processing unit) CPU,
It has a bandwidth manager (BM) BM and a data communication unit (DCU).
A plurality of terminals are accommodated in the packet switch PSW. Each terminal specifies a partner terminal to the packet switch when starting communication.

In this case, the packet exchange PEX starts communication in a predetermined fixed band even if there is no declaration of the band from the terminal. Of course, if a terminal reports a band, communication may be started in that band. However, it should be noted that the bandwidth at the start of communication fluctuates adaptively at any time according to traffic fluctuations.

The packet switch PEX gives a user packet input from the terminal to the packet switch PSW. Alternatively, the packet switch PEX gives the user packet input from the optical cross connect OXC to the packet switch PSW. Packet switch PSW
According to the destination of the input user packet,
Switch the user packet. Thus, the user packet is provided to the input terminal of the optical cross connect OXC or the terminal.

The packet switch PSW has a packet flow monitor PFM. The packet flow monitoring means PFM includes a packet switch PSW.
It monitors how much traffic is flowing from which input terminal to which output terminal. Information communication means DCU
Is connected to a network management center NMC via an information communication network (not shown). The amount of traffic monitored by the packet flow monitoring means PFM is sent to the network management center NMC via the information communication means DCU.

As the packet switch PSW, for example, an ATM switch can be used. In this case, by providing a call processing unit and a band management unit in the packet switch PEX, a band reservation is received prior to the start of communication, such as a CBR service, as well as a service that does not perform a band reservation such as an IP packet switching service. Services can also be provided at the same time. Also, an IP packet router can be used as the packet switch PSW.

On the other hand, the optical cross connect OXC has an interface IF with the packet switch PEX and an optical space switch OSW. That is, the optical space switch OS
W is the packet switch P via the interface IF.
Connected to EX. The interface IF is E /
It has an O (electric / light) converter and an O / E (light / electric) converter (neither is shown). Therefore, an electric signal provided from the packet switch PEX to the interface IF is converted into an optical signal in an E / O converter (not shown). The converted optical signal is used as an optical space switch OS.
W.

On the other hand, the optical signal supplied from the network to the optical cross-connect OXC is supplied to the interface IF via the optical space switch OSW. Then, the signal is converted into an electric signal by an O / E conversion unit (not shown), and is supplied to the packet switch PEX.

The optical cross connect OXC further has an optical multiplexer / demultiplexer OMD. The optical multiplexer / demultiplexer OMD demultiplexes the optical wavelength multiplexed signal input from the optical fiber and supplies the demultiplexed signal to the optical space switch OSW. Optical space switch OS
A plurality of optical signals given from W are wavelength-multiplexed and input to an optical fiber. The optical space switch OSW guides an optical signal input from the optical multiplexer / demultiplexer OMD or an optical signal input from the interface IF to a desired output. As a result, the optical signal guided to the desired output is provided to the desired optical multiplexer / demultiplexer OMD or the interface IF.

In FIG. 1, it will be understood that two communication paths are provided from the packet switch PSW to the interface IF. The information transmitted by these communication paths is subjected to electrical / optical conversion at the interface IF, and is converted to an optical cross connect OX as an optical path.
Connected to C. In FIG. 1, it will be understood that the two optical paths output from the interface IF are input to the same optical fiber via the optical cross connect OXC. In this case, an optical wavelength division multiplexing transmission technique is used. Therefore, one of the two optical paths input to the same optical fiber has, for example, a wavelength λ1
Is set using. The other optical path is set using, for example, the wavelength λ2.

It is to be noted that the optical space switch OSW is not necessarily required to optically connect one arbitrary optical multiplexer / demultiplexer OMD or interface IF to any arbitrary optical multiplexer / demultiplexer OMD or interface IF. There is no. Alternatively, the optical space switch OSW is an optical ADM (Ad
d / Drop Multiplexer). Light AD
In the optical switch composed of M, an optical signal input from a certain optical multiplexer / demultiplexer OMD is guided to a specific optical multiplexer / demultiplexer OMD.

The optical cross connect OXC further has an information communication unit DCU. This information communication means DCU,
The network management center N also through the information communication network
Connected to MC.

When a plurality of nodes shown in FIG. 1 are arranged and connected to each other by optical fibers, a network as shown in FIG. 3 is formed. That is, FIG. 3 shows a network in which four nodes shown in FIG. 2 are arranged. In FIG. 3, node A is a packet switch PEX.
-A and the optical cross connect OXC-A. Similarly, the node B, the node C and the node D are respectively connected to the packet switch PEX-B and the optical cross-connect OXC.
-B, a packet switch PEX-C and an optical cross-connect OXC-C, and a packet switch PEX-D and an optical cross-connect OXC-D. In the following description, an optical path set between the node A and the node C is referred to as an optical path A. Next, an optical path set between the node A and the node B is referred to as an optical path B. Further, an optical path set between the node B and the node D is referred to as an optical path C.

Each node accommodates several terminals. As described above, these terminals are accommodated in the packet switch PEX in each node. In the following description, one of the terminals accommodated in node A will be referred to as terminal A. Similarly, one of the terminals accommodated in the node C is referred to as a terminal B. further,
One of the terminals accommodated in the node D is referred to as a terminal C.

Next, the operation of the network system according to the first embodiment will be described with reference to FIG. As an example, a case where information is sent from terminal A to terminal B will be described.

The terminal A sends a user packet to the packet switch PEX-A. In this user packet, information indicating the terminal A which is the source user and information indicating the terminal B which is the destination user are stored as user information.

The packet switch PEX-A analyzes the user information in the received user packet. Then, it is determined that the node accommodating the terminal B as the destination user is the node C. Next, the packet switch PEX-A
Determines whether an optical path has already been set up between the node A and the node C. In the network shown in FIG. 3, the optical path A is already set between the nodes A and C. Therefore, the packet switch PEX-A
Transmits this user packet to the optical cross-connect OXC-
Send to A. Then, the optical cross connect OXC-A inputs the user packet to the optical path A.

The user packet thus inserted into the network reaches the optical cross-connect OXC-B via the optical path A. This user packet is cut through the optical cross-connect OXC-B, and further reaches the optical cross-connect OXC-C via the optical path A. In this specification, the term “cut-through” refers to a state where a certain optical path is relayed as an optical signal in an optical cross-connect OXC in an intermediate node.

The information transmitted in the optical path A is connected to the interface IF in the optical cross connect OXC-C. Here, the signal in the optical path A is optically / electrically converted and connected to the packet switch PEX-C. The packet switch PEX-C analyzes the user information in the received user packet and determines that the destination user is the terminal B. Therefore, the packet switch PEX-C sends the user packet to the terminal B.

As another example, a case where information is sent from terminal A to terminal C will be described below. In this case, no optical path is set between the nodes A and D. Therefore, the user packet is once sent from the node A to the node B, and the user packet is transferred from the node B to the node D.

That is, the terminal A receives the packet switch PEX
Send a user packet to A. The packet switch PEX-A analyzes the header of the received user packet, and determines that the node accommodating the terminal B as the destination user is the node D. Therefore, the packet switch PEX-A sends the user packet to the node B once using the optical path B. The optical path B is connected to the packet switch PEX-B in the optical cross connect OXC-B. Packet switch PEX-
B determines that the destination user of the user packet is the terminal C, and that the terminal C is accommodated in the node D. Therefore, the packet switch PEX-B inputs this user packet to the optical path C via the optical cross-connect OCX-B. Thus, information is sent from terminal A to terminal C.

The network management center NMC inquires each packet exchange PEX at predetermined time intervals about the traffic volume. This inquiry is given from the information communication unit DCU of the packet exchange PEX to the packet flow monitoring unit PFM. Packet flow monitoring means PFM
Calculates the traffic volume input to each optical path, for example, from the monitored traffic volume. Alternatively, the packet flow monitoring means PFM calculates the traffic volume transmitted to a specific node regardless of the optical path. Alternatively, the packet flow monitoring unit PFM calculates the amount of traffic input to the optical fiber connecting between adjacent nodes regardless of the optical path.

The inquiry from the network management center NMC to each of the packet switches PEX may be made, for example, by polling. Then, the packet flow monitoring means PFM receiving this inquiry responds to the network management center NMC with the information on the calculated traffic. According to the result, the network management center NMC sets a new optical path in a section with a lot of traffic. Conversely, in a section where the traffic is small, the optical path set in that section is deleted. For this reason, the network management center NMC sets / sets the optical path for the optical cross-connect OXC related to the optical path.
Give instructions for deletion. The network management center NMC further transmits information to that effect to the packet switch PEX.

For example, in the network shown in FIG. 3, a case is considered where the traffic between node A and node B is extremely large. The network management center NMC issues an instruction to the nodes A and C to delete the optical path A. As a result, the band used by the optical path A becomes empty. Therefore, a new optical path is set between the node A and the node B using the band. As a result, the number of optical paths between the nodes A and B is increased to two, and more user packets can be transmitted. However, as a result, there is no optical path between the nodes A and C. Therefore, it is necessary to set up a new communication path such that the user packet to be transmitted between these nodes is once sent to the node B using the optical path B and then sent to the node C via the node D. There is.
As a result, the packet switch PEX-
The load on B will increase. Therefore, the network management center N
The MC needs to set / delete an optical path after judging whether or not to improve the throughput of the entire network.

Hereinafter, a procedure for setting an optical path will be described with reference to FIG. FIG. 4 shows only the network management center NMC and any one packet switch and optical cross-connect device for simplicity of explanation. Hereinafter, the user packet is simply referred to as a packet.

In FIG. 4, the network management center NMC has information communication means DC. This information communication means DCU,
Data is exchanged between the DCU in each packet switch and the DCU in each optical cross-connect. The network management center NMC also has a path allocation algorithm. This path allocation algorithm defines a processing procedure for setting an optical path between each node. Network management center NM
C performs setting / deletion of an optical path based on this path arrangement algorithm. In the following description, not only the processing procedure for setting the optical path itself but also the processing procedure and the processing means for executing this processing procedure may be referred to as a “path arrangement algorithm”.

The network management center NMC further has a traffic information table and an optical path arrangement table. These are stored, for example, in a semiconductor memory. The traffic information table records and updates the flow rate of packets input to / output from each packet switch and the traffic of each optical path. The optical path arrangement table is a table in which the number and path of optical paths set in the network at the present time, the occupied bandwidth of each optical path, and the like are recorded.

The network management center NMC firstly collects traffic information through the information communication means DCU.
Inquires the packet exchange PEX (SP10
1, SP102). Information communication means D in the packet switch
Upon receiving the inquiry, the CU refers to the traffic information of the packet flow monitoring means PFM (SP10).
3, SP104). Then, the information communication unit DCU in the packet switch returns the referred traffic information to the network management center NMC (SP105).

Information communication means DCU of network management center NMC
Receives the traffic information returned from the packet switch PEX, and records the information in the traffic information table. Information communication means DC of network management center NMC
U further notifies the path allocation algorithm that the traffic information table has been updated (SP106).

In response to this notification, the path allocation algorithm refers to the optical path allocation table and the traffic information table (SP107 to SP110), for example, to newly set an optical path for a path with a large traffic, It is determined that a path with a small traffic is deleted. Subsequently, the path allocation algorithm notifies the optical cross-connect OXC of the determined optical path, and causes a new optical path to be set (SP111).

After setting a new optical path, the path allocation algorithm updates information in the optical path allocation table. At the same time, it instructs each packet exchange PEX to rewrite the optical path table in the packet exchange PEX (SP112).

As described above, in the first embodiment, communication is started when a user does not particularly declare a band required for communication when starting communication. Then, the band at the start of the communication then fluctuates as needed in response to traffic fluctuations. Therefore, in a packet network system having means for providing an optical path, such as an optical cross-connect or an optical ADM, an optimal optical path is dynamically set so that the maximum throughput can be achieved with resources held by the network. You.

For example, in a typical IP network, it is difficult to contract a band, provide various service classes, or maximize throughput in cooperation with a physical layer. However, according to the present invention, these functions can be easily provided.

The general procedure for setting an optical path described here is merely an example, and the scope of the present invention is as follows.
It is not limited to such a procedure or the components shown in FIGS.

Next, a second embodiment of the present invention will be described. In the second embodiment, the operation when a packet is sent from one terminal to another terminal is basically the same as that in the first embodiment. However, the second embodiment differs from the first embodiment in the procedure for the network management center NMC to grasp the flow rate of packets flowing in the optical path.

FIG. 5 is a block diagram showing the configuration of a communication node installed in the network according to the second embodiment. When a plurality of nodes shown in FIG. 5 are arranged and connected to each other by optical fibers, a network similar to that of the first embodiment is formed. That is, the network of the second embodiment is basically the same as the network shown in FIG. Therefore, with regard to the network of the second embodiment, a specific illustration is omitted, and the nodes will be described below.

In FIG. 5, the node has a packet switch PEX and an optical cross-connect OXC. In the second embodiment, the packet switch PEX has a threshold monitoring unit TM1 in addition to the packet flow monitoring unit PFM. This threshold monitoring means TM1 is connected to the packet flow monitoring means PFM.

The packet flow monitoring means PFM calculates the amount of traffic input to each optical path. This traffic amount may be a traffic amount transmitted to a specific node regardless of the optical path. Or,
This traffic volume may be a traffic volume input to an optical fiber connecting between adjacent nodes regardless of the optical path.

The threshold monitoring means TM1 holds a predetermined traffic volume threshold for each optical path. Alternatively, it holds a threshold value of the traffic amount transmitted to a specific node regardless of the optical path. Alternatively, the threshold value of the traffic amount input to the optical fiber connected to the adjacent node is held regardless of the optical path.

The threshold monitoring means TM compares the measured traffic value with the predetermined threshold. This threshold is determined by the network management center NMC when a new path is set. It is useful to determine not only the maximum value of the packet flow rate but also the minimum value of the packet flow rate as the threshold value. Hereinafter, a case where the traffic amount input to the optical path is monitored will be described.

The packet flow monitoring means PFM monitors packets flowing in the packet switch PSW. Then, it is determined which path the packet should be input to. As a result, the packet flow monitoring means PFM
Calculate traffic for each path. Then, the packet flow monitor PFM gives the measured traffic value to the threshold monitor TM1 for each path.

The threshold monitoring means TM1 compares the measured traffic value with a predetermined threshold for each path. This threshold is set when a new path is set.
It is determined by the network management center NMC. It is useful to determine not only the maximum value of the packet flow rate but also the minimum value of the packet flow rate as the threshold value.

When the traffic of a certain optical path exceeds the maximum value of the packet flow rate, the threshold monitoring means TM1 notifies the network management center NMC of the fact. At the same time, the network management center NMC is notified of a request that, for example, a new optical path needs to be set because the traffic is large. Conversely, when the traffic of a certain optical path falls below the minimum value of the packet flow rate, the threshold monitoring means TM1 notifies the network management center NMC of the fact. At the same time, a request is sent to the network management center NMC, for example, a request that "either one of the two optical paths may be deleted because the traffic is below a certain threshold".

Alternatively, when the traffic of a certain optical path deviates from the threshold value of the packet flow rate, the threshold value monitoring means TM1 notifies the network management center NMC of the measured value of the packet flow rate itself.

That is, each node of the second embodiment autonomously monitors the flow rate of packets. Then, when the traffic deviates from the threshold value, this is autonomously notified to the network management center NMC.

The network management center NMC sets a new optical path in the section in response to such a request. Alternatively, the optical path that has already been set is deleted. This operation is performed in the same manner as described in the first embodiment.

Of course, even if a request for setting a new optical path occurs, if there is no band for the request, the network management center NMC does not set a new path. Conversely, even if a request to delete the optical path occurs, if there is sufficient room in the available bandwidth, the network management center NMC keeps the optical path without deleting it. In some cases.

Hereinafter, a procedure for setting an optical path in the second embodiment will be described with reference to FIG. FIG. 6
1 shows only the network management center NMC and any one packet switch and optical cross-connect device for simplicity of explanation.

In FIG. 6, in the packet exchange PEX, the threshold monitoring means TM1 detects that the packet flow exceeds the threshold. Then, the threshold monitoring unit TM1 notifies the information communication unit DCU of the fact (SP201). Upon receiving this notification, the information communication unit DCU notifies the information communication unit DCU of the network management center NMC of the information (S
P202).

In the network management center NMC, the information communication unit DCU that has received the notification from the packet switch PEX updates the contents of the traffic information table (SP20).
3). The information communication unit DCU of the network management center NMC further notifies the path allocation algorithm that the traffic information table has been updated (SP204).

When the traffic information table is updated, the path allocation algorithm determines a new optical path while referring to the optical path allocation table and the updated traffic information table (SP205 to SP208). Next, the path allocation algorithm refers to the optical path allocation table and the traffic information table (S
P205 to SP208), for example, a new optical path is set for a path with a large traffic, or a path with a small traffic is deleted.

The path allocation algorithm notifies the optical cross connect OXC of the determined optical path and causes a new optical path to be set (SP209). Then, after setting a new optical path, the path allocation algorithm updates the information in the optical path allocation table. At the same time, it instructs each packet exchange PEX to rewrite the optical path table in the packet exchange PEX (SP210).

As described above, also in the network of the second embodiment, the optimum optical path is dynamically set according to the fluctuation of the traffic so that the maximum throughput can be achieved with the resources held by the network. I do. This is the first
This is the same as the embodiment.

In addition, in the second embodiment, each node autonomously monitors traffic. Therefore, each node autonomously notifies the network management center NMC without waiting for an inquiry from the network management center NMC. Therefore, the burden on the network management center NMC is reduced. Further, the network management center NMC can start an optical path changing process at a moment when traffic exceeds a predetermined threshold value at a certain node. Therefore, quicker response is possible. However, when the load on the entire network increases rapidly, there is a possibility that a plurality of packet switches PEX may simultaneously issue requests to the network management center NMC. For this reason, the network management center NMC needs to have processing performance capable of responding to these multiple requests.

Next, a third embodiment of the present invention will be described. FIG. 7 is a diagram illustrating a configuration of a network according to the third embodiment. FIG. 7 shows a network having four nodes from node A to node D. A center terminal CT1 is arranged in this network. The center terminal CT1 is connected to the network management center N
Connected to MC.

The center terminal CT1 communicates with all terminals in the network. For this reason, the center terminal CT1 is connected to each node on the network. In FIG. 7, the center terminal CT1 is illustrated as being connected to only the node C. But actually,
The center terminal CT1 can communicate with all of the nodes A to D. Specifically, for example, the center terminal CT1 transmits the packet switch PEX in each node.
Can communicate with The packet switch PEX performs packet forwarding so as to connect the center terminal CT1 to the terminal.

Further, in the third embodiment, each terminal is provided with an application monitor AM.
Is provided. In FIG. 7, the application monitoring means AM is shown only in the terminal A, but the other terminals also
Application monitoring means is provided.

Next, the operation of the third embodiment will be described with reference to FIGS. In the third embodiment, each terminal generally executes a plurality of applications in a time-division manner. Some of the applications have a function of transmitting data from the own terminal to another terminal. The application monitoring means AM monitors that such an application starts transmitting data to another terminal. The application monitoring means AM also monitors that such an application has finished sending data.

Therefore, when a certain application starts transmitting data to another terminal, the application monitoring means AM provided in the source terminal uses
This is notified to the center terminal CT1. Also, when data transmission by the application ends,
The application monitoring means AM notifies the center terminal CT1 of the fact. The center terminal CT1 receives the notification from each terminal and sends it to the network management center NMC. The network management center NMC rearranges optical paths as necessary. That is, a new optical path is set or an existing optical path is deleted.

Information that the optical path is to be relocated is notified to each node. In response to the notification, the packet switch PEX and the optical cross-connect OXC in the node implement a new optical path that has been reset.

Hereinafter, a procedure for setting an optical path in the third embodiment will be described with reference to FIG. FIG. 8
1 shows only the network management center NMC and any one packet switch and optical cross-connect device for simplicity of explanation.

In FIG. 8, the application monitoring means AM provided in each terminal monitors the start / end of the application in the terminal itself. When the activation / termination of the application is detected, the fact is notified to the center terminal CT1 (SP301). The center terminal CT1 transfers this notification to the network management center NMC (SP302).

In the network management center NMC, the center terminal CT
The information communication unit DCU having received the notification from 1 updates the contents of the traffic information table (SP303). The information communication unit DCU of the network management center NMC further notifies the path allocation algorithm that the traffic information table has been updated (SP304).

When the traffic information table is updated, the path allocation algorithm determines a new optical path while referring to the optical path allocation table and the updated traffic information table (SP305 to SP308).

The path allocation algorithm notifies the determined optical path to the optical cross-connect OXC, and sets a new optical path (SP309). Then, after setting a new optical path, the path allocation algorithm updates the information in the optical path allocation table. At the same time, it instructs each packet switch PEX to rewrite the optical path table in the packet switch PEX (SP310).

In the above description of the procedure, the terminal has been described as exchanging information with the network management center NMC via the center terminal CT1. This is because typically, there are few networks in which a management device such as the network management center NMC directly communicates with a terminal. That is, data transmission and reception between a terminal and a management device such as the network management center NMC are typically performed by providing a dedicated terminal. However, the present invention is not necessarily limited to such a network configuration. That is,
Instead of providing the center terminal CT1, the network management center NMC may directly exchange information with the terminal.

The above description is based on the application monitoring means A.
M has been described as being provided in the terminal.
However, the application monitoring means AM may be provided at another place. For example, the application monitoring means AM may be provided in the packet switch PEX.

In this case, the application monitoring means AM
By analyzing the TCP / IP header input from the terminal, the application can detect the start / end of the application. For example, by analyzing the destination of the header, if a packet for a new destination not seen before that time appears, it can be determined that a new application has been started in the terminal. Further, the destination of the header is analyzed, and if a packet to the destination that has been flowing until then cannot be seen for a certain period of time or more, it can be determined that the application has ended.

As described above, according to the third embodiment, even if the user does not particularly declare the band required at the start of communication, the optical path can be set such that the maximum throughput can be achieved with the resources held by the network. Network optimization is achieved. Further, when the application monitoring means is provided in each terminal, even if the packet switch PEX does not have the application monitoring means, it is possible to detect the start / end of the application. That is, each packet switch PEX can use a conventional one.

Also in the third embodiment, since each node autonomously monitors the traffic, the load on the network management center NMC is also reduced. Furthermore, since each node autonomously notifies, quicker response is possible.

Needless to say, the resetting of the optical path is performed so that the traffic in the network flows optimally. Therefore, the network management center N
The MC does not need to reset the optical path according to the start / end of all data communication in the terminal. For example, the optical path may be reset only when an application for performing large-capacity data communication such as moving image communication is started / terminated. Further, the application monitoring means AM may notify the network management center NMC only when an application for performing large-capacity data communication is started / terminated.

As described above, in the third embodiment, a case has been described in which a new application is activated and a new optical path is set accordingly. However, this new light path
It is not occupied by the new application.
For example, when a new application is activated on the terminal A and a new optical path is set accordingly, a packet transmitted by the application activated on the terminal D may be multiplexed on this optical path. .

Next, a fourth embodiment of the present invention will be described. FIG. 9 is a diagram illustrating a configuration of a network according to the fourth embodiment. The network according to the fourth embodiment has the same configuration as the network according to the third embodiment. That is, this network has four nodes from node A to node D. The network further includes a center terminal CT1 and a network management center N
Has MC.

In the fourth embodiment, at least one of the terminals connected to each node is provided with a delay detector DD. In FIG.
Delay measurement means D is provided only to terminal A accommodated in node A.
Although D is illustrated, all other nodes are also provided with at least one delay measuring means DD.

The center terminal CT1 performs communication with all terminals in the network. For this reason, the center terminal CT1 is connected to each node on the network. In FIG. 7, the center terminal CT1 is illustrated as being connected to only the node C. But actually,
The center terminal CT1 can communicate with all of the nodes A to D. Specifically, for example, the center terminal CT1 transmits the packet switch PEX in each node.
Can communicate with The packet switch PEX performs packet forwarding so as to connect the center terminal CT1 to the terminal.

All the delay measuring means DD existing on the network are operated by clocks synchronized with each other. Then, it has a function of transmitting a management packet to the delay measuring means DD accommodated in another node. Further, it has a function of returning a management packet sent from another delay measuring means DD to the delay measuring means DD of the transmission source. When transmitting a management packet or returning a management packet received from another, each delay measuring means DD writes a transmission time (time stamp) in the management packet.

Therefore, the delay measuring means DD of the transmission source reads the time stamp in the management packet when the management packet transmitted by itself returns, and determines the time at which the management packet was transmitted and the delay of the destination. It is possible to recognize three kinds of times, that is, the time at which the measuring means DD returns the management packet and the time at which the management packet returns.

From these times, the delay measuring means DD at the transmission source can obtain the delay time of the forward path, the delay time of the return path, and the delay time required for the round trip. Such a function can be realized by using a function similar to a “Ping” command or a “Trace Route” command in inter-computer communication, for example.

Next, the operation of the fourth embodiment will be described with reference to FIGS. 9 and 10. In the fourth embodiment, each delay measuring means DD sends a management packet to another delay measuring means DD at a certain time interval. Another delay measuring means DD which has received the management packet transmits the management packet to the delay measuring means D of the transmission source.
Return to D.

The delay measuring means DD at the transmission source can determine the delay time required for the round trip of the management packet from the transmission time written in the management packet. That is,
The delay time required for the management packet to reciprocate between the own node and another node can be obtained.

Each delay measuring means DD obtains a delay time for each path set in the network.
Then, the value is stored for each pass. Then, when there is an instruction from the network management center NMC, the stored delay time is reported to the network management center NMC according to the instruction.

In general, a packet switch PEX-A or a packet switch P arranged on a network
If congestion occurs in EX-D, the delay time should be large. Conversely, if the network is free, the delay time should be small.

At predetermined time intervals, the network management center NMC inquires each delay measuring means DD on the network about the delay time measured by the delay measuring means DD. This inquiry is made, for example, by polling. Each of the delay measuring means DD transmits the stored delay time in response to the inquiry. The network management center NMC relocates the optical path based on the delay time reported from each delay measuring means DD.

The procedure for setting an optical path according to the fourth embodiment will be described below with reference to FIG. In FIG. 10, for simplicity of explanation, the network management center NMC,
Only one optional packet switch and optical cross-connect device is shown.

In FIG. 10, delay time measuring means DD
Calculates the delay time for each path (SP401, S
P402). The network management center NMC includes information communication means DC
U and the delay measuring means DD via the center terminal CT1.
To the delay time (SP403, SP404,
SP405).

The delay time measuring means DD is connected to the network management center N.
In response to the inquiry from the MC, the held delay time is reported to the network management center NMC via the center terminal CT1 (SP406) (SP407).

Information communication means DCU of network management center NMC
Is the delay time reported from the delay time measuring means DD,
The information is recorded in the traffic information table (SP408).
The information communication means DCU of the network management center NMC further comprises:
The path allocation algorithm is notified that the traffic information table has been updated (SP409).

In response to this notification, the path allocation algorithm determines a new optical path while referring to the optical path allocation table and the traffic information table (SP410 to SP413). The path placement algorithm further:
The optical path is notified to the optical cross-connect OXC, and a new optical path is set (SP414). At the same time, the information of the optical path arrangement table is updated (SP415).

In the fourth embodiment, the network management center NMC may directly exchange information with the terminal without providing the center terminal CT1.

Further, the delay time measuring means DD may be provided in another place instead of in the terminal. For example, the delay time measuring means DD may be provided in the packet switch PEX. In this case, for example, (a) the terminal generates a management packet and sends the management packet to another terminal. At this time, the delay time measuring means DD provided in the packet exchange PEX monitors the management packet passing through the packet switch, and may attach a time stamp to the management packet. Alternatively, (b) the delay time measuring means provided in the packet exchange PEX may generate a management packet and send the management packet to the delay time measuring means DD provided in the packet exchange PEX in another node. Can be

As described above, according to the fourth embodiment, even if the user does not particularly declare the band required at the start of communication, the optical path network can be achieved so that the maximum throughput can be achieved with the resources held by the network. Is optimized. When the delay time measuring means is provided in each terminal, the conventional packet switch PEX can be used.

In the fourth embodiment, when a delay monitoring unit is provided in a terminal, it is sufficient that at least one terminal has a delay monitoring unit for one node. Therefore, it is very easy to construct a network. Here, the terminal provided with the delay monitoring means is prepared by a node manager (for example, a communication carrier). Alternatively, a delay monitoring unit may be provided in a user terminal accommodated in the node.

Next, a fifth embodiment of the present invention will be described. FIG. 11 is a diagram illustrating a configuration of a network according to the fifth embodiment. The network according to the fifth embodiment has the same configuration as the networks according to the third and fourth embodiments. That is, this network has four nodes from node A to node D. This network further has a center terminal CT1 and a network management center NMC.

In the fifth embodiment, at least one of the terminals connected to each node is provided with the delay measuring means DD and the threshold monitoring means TM2.
In FIG. 11, the delay measuring means DD and the threshold monitoring means TM are shown only for the terminal A accommodated in the node A, but at least one delay measuring means DD and the threshold monitoring means are also provided for all other nodes. A TM is provided.

The center terminal CT1 communicates with all terminals in the network. For this reason, the center terminal CT1 is connected to each node on the network. In FIG. 7, the center terminal CT1 is illustrated as being connected to only the node C. But actually,
The center terminal CT1 can communicate with all of the nodes A to D. Specifically, for example, the center terminal CT1 transmits the packet switch PEX in each node.
Can communicate with The packet switch PEX performs packet forwarding so as to connect the center terminal CT1 to the terminal.

Also in the fifth embodiment, each delay measuring means DD sends a management packet to another delay measuring means DD at a certain time interval. Another delay measuring means DD which has received this management packet returns the management packet to the delay measuring means DD of the transmission source. The delay measuring means DD of the transmission source obtains the delay time required for the round trip of the management packet from the transmission time written in the management packet.

Each delay measuring means DD obtains a delay time for each path set in the network.
Then, the value is given to the threshold monitoring means TM2 for each path.

The threshold monitor TM2 basically operates in the same manner as in the second embodiment. That is, the threshold monitor TM2
Compares a given delay time value with a threshold value given in advance for each path. This threshold is determined by the network management center NMC when a new path is set. It is useful to determine not only the maximum value of the delay time but also the minimum value as the threshold value.

When the delay time of a certain optical path exceeds the maximum value, the threshold monitor TM2 informs the network management center NM of the fact.
Notify C. At the same time, the threshold monitoring means TM2 sends, for example, a report to the network management center NMC that "congestion has occurred on the optical path". At the same time as this report, the network management center NMC may be requested to relocate the optical path. Conversely, when the delay time of a certain optical path is shorter than the minimum value, the threshold monitor TM notifies the network management center NMC of the fact. At the same time, the threshold monitoring means TM2 notifies the network management center NMC, for example, of a request that "some traffic may be deleted because the traffic in the optical path seems to be small."

Alternatively, if the delay time of a certain optical path deviates from a predetermined threshold value,
The measured threshold value itself is notified to the network management center NMC.

That is, in the fifth embodiment, the terminal provided with the delay measuring means DD and the threshold monitoring means TM2 is
It monitors the delay time autonomously. Then, when the delay time deviates from the threshold, the fact is autonomously notified to the network management center NMC.

The network management center NMC sets a new optical path in the section in response to such a request. Alternatively, the optical path that has already been set is deleted. This operation is performed in the same manner as described in the first embodiment.

Hereinafter, a procedure for setting an optical path in the fifth embodiment will be described with reference to FIG. In FIG. 12, for simplicity of explanation, the network management center NMC,
Only one optional packet switch and optical cross-connect device is shown.

In FIG. 12, delay time measuring means DD
Calculates the delay time for each path (SP501, SP5
02). This delay time is given to the threshold monitor TM (SP503).

When the threshold monitor TM2 determines that the given delay time exceeds the threshold, it sends a notification to that effect to the center terminal CT1 (SP504). The center terminal CT1 transfers this notification to the network management center NMC (SP505).

Information communication means DCU of network management center NMC
Records the delay time notified from the threshold monitor TM2 in the traffic information table (SP506). The information communication unit DCU of the network management center NMC further notifies the path allocation algorithm that the traffic information table has been updated (SP507).

Upon receiving this notification, the path allocation algorithm determines a new optical path while referring to the optical path allocation table and the traffic information table (SP508 to SP511). The path placement algorithm further:
The optical path is notified to the optical cross-connect OXC, and a new optical path is set (SP512). At the same time, the information of the optical path arrangement table is updated (SP513).

In the fifth embodiment, the network management center NMC may directly exchange information with the terminal without providing the center terminal CT1. In addition, the fourth
Similarly to the embodiment, the delay time measuring means and the threshold monitoring means may be provided not in the terminal but in the packet switch PEX, for example.

As described above, according to the fifth embodiment, even if the user does not particularly declare the bandwidth required at the start of communication, the optical path network can be realized so that the maximum throughput can be achieved with the resources held by the network. Can be optimized. In addition to this, in the fifth embodiment, the status of the network
, The optical path is rearranged earlier.

In each of the above-described embodiments, the network management center NMC is illustrated as existing at a location independent of each node. Further, the information communication network connecting the network management center NMC and each node is illustrated as a separate line from the optical path through which the user packet flows. However, any node of the network management center NMC may have the function. The information communication network may be constructed using an optical path through which a user packet flows.

The present invention can also be applied to a network in which each terminal declares a necessary band at the start of communication. Even in such a network, each node can calculate the total value of the bandwidth values declared from each terminal. Each node notifies the network management center in response to an inquiry from the network management center or autonomously when the band exceeds a predetermined threshold. The network management center may dynamically arrange optical paths in response to this notification.

[0135]

As described above in detail, according to the present invention, there is provided a network system for dynamically setting an optimal optical path so that a maximum throughput can be achieved in response to a change in a communication band. Can be provided. Also, a communication node suitable for such a network system can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a communication node installed in a network according to a first embodiment.

FIG. 2 is a diagram showing a typical configuration of a network system using an optical cross connect.

FIG. 3 is a diagram illustrating a network according to the first embodiment.

FIG. 4 is an explanatory diagram showing a procedure for setting an optical path in the first embodiment.

FIG. 5 is a block diagram illustrating a configuration of a communication node installed in a network according to a second embodiment.

FIG. 6 is an explanatory diagram showing a procedure for setting an optical path in the second embodiment.

FIG. 7 is a diagram illustrating a network according to a third embodiment.

FIG. 8 is an explanatory diagram showing a procedure for setting an optical path in the third embodiment.

FIG. 9 is a diagram illustrating a network according to a fourth embodiment.

FIG. 10 is an explanatory diagram showing a procedure for setting an optical path in a fourth embodiment.

FIG. 11 is a diagram illustrating a network according to a fifth embodiment.

FIG. 12 is an explanatory diagram showing a procedure for setting an optical path in the fifth embodiment.

[Explanation of symbols]

 PEX: Packet switch PSW: Packet switch CPU: Call processing unit BM: Bandwidth management unit DCU: Information communication means PFM: Packet flow monitoring means OXC ··· Optical cross-connect IF · · · Interface NMC · · · Network management center TM1, TM2 · · · Threshold monitoring means AM · · · Application monitoring means DD · · · Delay measurement means CT1, CT2 · · · ..Center terminals

Claims (25)

[Claims] 1. A network system, comprising: a plurality of nodes; and at least one network management unit, wherein an optical path is set between any two of the plurality of nodes. Having monitoring means for monitoring the data packet flow rate in the, based on the packet flow rate monitored by the monitoring means,
An optical path between the nodes is set,
Network system. 2. The network system according to claim 1, wherein the network system includes a threshold monitoring unit that retains a predetermined packet flow threshold for each path, and determines that the packet flow has exceeded the threshold. Wherein the optical path between the nodes is set when the operation is performed. 3. The network system according to claim 1, wherein the network system includes a threshold monitoring unit that holds a threshold value of a traffic amount transmitted to a specific node, wherein the traffic amount is smaller than the threshold value. A network system wherein an optical path between the nodes is set when it is determined that the number of nodes exceeds the limit. 4. The network system according to claim 1, wherein the network system includes a threshold monitoring unit that holds a threshold value of a traffic amount flowing through a communication path between the node and the adjacent node, wherein the traffic amount is the threshold value. A network system, wherein an optical path between the nodes is set when it is determined that the threshold value is exceeded. 5. A network system, comprising: a plurality of nodes; and at least one network management unit, wherein an optical path is set between any two of the plurality of nodes. A network system, comprising: an application monitoring unit configured to monitor activation / termination of an application, wherein an optical path between the nodes is set based on an activation status of the application. 6. A network system, comprising: a plurality of nodes; and at least one network management unit, wherein an optical path is set between any two of the plurality of nodes. It has means for measuring a delay time generated between any one of the nodes and one of the other nodes, and an optical path between each node is set based on the delay time. , Network system. 7. The network system according to claim 6, wherein the network system includes a threshold monitoring unit that holds a delay time threshold predetermined for each path, and determines that the delay time exceeds the threshold. If done,
An optical path between the nodes is set,
Network system. 8. The network system according to claim 6, wherein the network system includes a threshold monitoring unit that holds a delay time threshold predetermined for each of the nodes; If it is determined to exceed,
An optical path between the nodes is set,
Network system. 9. A network system having a plurality of nodes and at least one network management unit, wherein an optical path is set between any two of the plurality of nodes, wherein the node has a plurality of terminals. A packet switch for accommodating, an optical cross-connect, and monitoring means for monitoring a data packet flow rate in the optical path, wherein the network system inter-nodes the nodes based on the packet flow rate monitored by the monitoring means. A network system, wherein an optical path is set. 10. The network system according to claim 9, wherein said network management unit has means for inquiring said monitoring means about a data packet flow rate in said optical path, and said monitoring means responds to said inquiry. Means for responding to the network management unit with the data packet flow rate in the optical path, wherein the network management unit sets an optical path between the nodes based on the packet flow rate, Network system. 11. The network system according to claim 9, wherein the node has a threshold monitoring unit that holds a predetermined packet flow threshold for each path, and the network management unit determines that the packet flow is A network system, wherein, when it is determined that a threshold value has been exceeded, an optical path between the nodes is set. 12. The network system according to claim 9, wherein the node includes a threshold monitoring unit that holds a threshold of a traffic amount transmitted to a specific node, and the network management unit includes A network system, wherein, when it is determined that the amount exceeds the threshold, an optical path between the nodes is set. 13. The network system according to claim 9, wherein the node has a threshold monitoring unit that holds a threshold value of a traffic amount flowing through a communication path between the node and the adjacent node. A network system configured to set an optical path between the nodes when it is determined that the traffic volume exceeds the threshold. 14. The network system according to claim 11, wherein the threshold monitoring unit notifies the network management unit when it determines that the packet flow rate or the traffic volume exceeds the threshold value. A network system configured to set an optical path between the nodes based on a notification from the threshold monitoring unit. 15. A network system, comprising: a plurality of nodes; and at least one network management unit, wherein an optical path is set between any two of the plurality of nodes, wherein the nodes include a plurality of terminals. The network system includes a packet switch to accommodate, an optical cross-connect, and an application monitoring unit that monitors an application status in the terminal, and the network system sets an optical path between the nodes based on an activation status of the application. A network system, characterized in that: 16. The network system according to claim 15, wherein said application monitoring means is provided in said terminal. 17. The network system according to claim 15, wherein the application monitoring unit notifies the network management unit of an activation status of the application, and the network management unit transmits a notification from the application monitoring unit. A network system, wherein an optical path between the nodes is set based on the setting. 18. A network system comprising: a plurality of nodes; and at least one network management unit, wherein an optical path is set between any two of the plurality of nodes. A packet switch, an optical cross-connect, and delay monitoring means for measuring a delay time between the nodes, wherein the network system sets an optical path between the nodes based on the delay time. Characterized by a network system. 19. The network system according to claim 18, wherein the delay monitoring unit measures the delay time by transmitting / receiving a management packet storing time information to / from another node. And a network system. 20. The network system according to claim 19, wherein said network management unit has means for inquiring said delay monitoring means about said delay time, and said delay monitoring means responds to said inquiry by said delay monitoring means. A network system, comprising: means for responding to the network manager with the delay time, wherein the network manager sets an optical path between the nodes based on the delay time. 21. The network system according to claim 18, wherein the node has a threshold monitoring unit that holds a predetermined delay time threshold for each path; A network system, wherein when it is determined that a threshold value has been exceeded, an optical path between the nodes is set. 22. The network system according to claim 18, wherein the node includes a threshold monitoring unit that holds a threshold of a delay time of traffic transmitted to a specific node, wherein the network management unit includes: A network system, wherein, when it is determined that the delay time exceeds the threshold, an optical path between the nodes is set. 23. The network system according to claim 18, wherein the node has a threshold monitoring unit that holds a threshold value of a delay time of traffic flowing on a communication path between the node and the adjacent node, and the network management unit. Wherein the optical path is set between the nodes when it is determined that the delay time exceeds the threshold. 24. The network system according to claim 21, wherein the delay monitoring unit transmits / receives a management packet storing time information to / from another node so as to reduce the delay time. A network system characterized by measuring 25. The network system according to claim 21, wherein the threshold monitoring unit has a unit that notifies the network management unit when it is determined that the delay time exceeds the threshold. The network system, wherein the network management unit sets an optical path between the nodes based on a notification from the threshold monitoring unit.