JP2000278314A - Network system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a network system capable of dealing with the scale of a user even when an existent edge switch is used. SOLUTION: This network system is provided with an edge switch 20 for generating plural kinds of label information as a path identifier, plural WAN routers 30 and 30A for inserting the label information corresponding to the destination of relevant data generated by the edge switch 20 to data to be transmitted to the edge switch 20 and sending them out toward the edge switch 20 in order to determine the output route of data while referring to only the label information inserted to the data by the edge switch 20 and a line concentrating device capable of connecting the respective WAN routers 30 and 30A through a communication line for transmitting the data, in which the label information is inserted from the respective WAN routers 30 and 30A, through the communication line to the edge switch 20 when these data are received from the respective WM nodes 30 and 30A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a network system, and more particularly, to an MPLS (Multi Protocol Label Swap).
It relates to a label exchange network system using itching technology.

[0002]

2. Description of the Related Art In recent years, the spread of the Internet has progressed, and the number of Internet users has rapidly increased. Under these circumstances, there is a need for improved performance of the Internet backbone network. As one of the backbone networks that can realize high performance, there is a label switching network system (label switching system) using the MPLS technology, and application to a wide area network is being promoted.

The label switching system has two layers, a core network composed of label switches and an edge network (access network) below the core network, and an edge network composed of edge switches, and a user network exists below the access network. .

FIG. 6 is an explanatory diagram of a form of providing an MPLS service, showing an example of a label switching system and how to establish a link between a user, a wide area network, and a user for a circuit connection and a signaling connection.

In FIG. 6, a backbone switch (BBS)
W) corresponds to the core network, and edge switches (Edge SW) and WAN routers respectively housed on both sides of the backbone network
(WAN Router) corresponds to the access network.

[0006] Each edge switch is an OSPF (Open Shor
test Path First) and BGP4 (Border Gateway Protocol)
Obtain routing information in the core network according to existing routing protocols such as Version 4). Each edge switch generates a path identifier (referred to as “label information”) corresponding to the acquired routing information, and sends the routing information and the label information to the subordinate WAN router according to the label distribution protocol (LDP). .

Each WAN router receives the routing information and the label information from the upper edge switch according to the LDP, and creates and holds a lookup table in which the routing information and the label information are associated. Thereafter, when each WAN router receives the data from the user network, the WAN router refers to the look-up table, reads out the label information corresponding to the routing information corresponding to the destination of the data from the look-up table, and inserts the label information into the data;
Send to upper edge switch. Each edge switch
(Backbone switch), upon receiving the data with the label information inserted, determines the output route of the data only by referring to the label information inserted in the data, and determines the data output route from the relevant output route. Is sent. On the other hand, when each WAN router receives data from the edge switch, the WAN router removes the label information inserted in the data and transfers the data to the user network.

Thus, in the label switching system shown in FIG. 6, the edge switch and the backbone switch
A data output route is determined with reference to only the label information.
For this reason, data is transmitted at high speed in the core network (backbone network). FIG. 7 is a block diagram for realizing the function according to the configuration of FIG. 6 described above.

[0009]

SUMMARY OF THE INVENTION A label exchange system
When applying (MPLS technology) to a wide area network, it is necessary to flexibly cope with the variety of user scales,
It is desirable to keep the configuration of the existing access network as unchanged as possible.

However, in the conventional label switching system shown in FIGS. 6 and 7, since the WAN router is directly connected to the edge switch, the following problems have occurred. That is, when the number of users is large, it is necessary to increase the number of WAN routers. However, the number of connection ports (input line ports) of the WAN routers provided in the existing edge switch is limited. Even when it was desired to increase the number, there were cases where the number could not be increased. Further, if the number of WAN routers accommodated in the edge switch is increased, the cost of the edge switch may increase. In addition, WAN to edge switch
There was a case where the setting of the edge switch had to be changed according to the attachment / detachment of the router.

Also, since the edge switch must provide label information to all of the subordinate WAN routers,
When the number of WAN routers increases, the processing load on the edge switch increases, and the processing of acquiring routing information (route calculation) by OSPF or BGP4 may be delayed.
In view of this, there is a possibility that the cost of the edge switch will increase if the capability of the edge switch is to be enhanced.

[0012] The present invention has been made in view of the above problems, and has as its first object to provide a network system which can respond to the scale of a user even when an existing edge switch is used.

Another object of the present invention is to provide a network system capable of reducing the load on the edge switch.

[0014]

According to the present invention, there is provided the above-described first embodiment.
In order to solve the above problem, the following configuration is adopted. That is,
The invention according to claim 1 is a network system, wherein an upper node that generates a plurality of pieces of label information as path identifiers, and the upper node determines a data output route only by referring to the label information inserted into the data. In order to insert the label information corresponding to the destination of the data generated by the upper node into the data transmitted to the upper node, a plurality of lower nodes to be transmitted to the upper node; And a concentrator for transmitting the data to the upper node via the communication line when the data with the label information inserted from each lower node is received from each lower node. It is characterized by having.

According to the first aspect of the present invention, since a plurality of lower nodes are connected to the upper node via the concentrator, the number of lower nodes accommodated in the upper node can be increased, and the size of the user can be reduced. It is possible to respond.

The present invention employs the following configuration in order to solve the above-mentioned second problem. In other words, the invention according to claim 2 is a network system, wherein an upper node that generates a plurality of label information as a path identifier, and a data output route by referring to only the label information inserted into the data. In order to determine, insert the label information corresponding to the destination of the data generated in the upper node in the data transmitted to the upper node, a plurality of lower nodes to send out to the upper node, A label information assigning server for holding the plurality of label information, and in response to a request from the lower node, providing the lower node with label information corresponding to a destination of data transmitted from the lower node to the upper node. It is characterized by the following.

According to a third aspect of the present invention, in the line concentrator according to the first aspect, the plurality of label information are held, and in response to a request from a lower node, a destination of data transmitted from the lower node to the upper node. Is specified by giving the label information corresponding to.

According to the second and third aspects of the present invention, since the label information providing server provides the label information to the lower node in place of the upper node, the load on the upper node can be reduced.

In the inventions of claims 1 to 3, the upper node is, for example, an edge switch, and the lower node is, for example, a WAN router. According to a fourth aspect of the present invention, the line concentrator of the third aspect requests the upper node to add the plurality of label information, and holds the plurality of label information sent from the upper node in response to the request. It is specified by doing.

According to a fifth aspect of the present invention, the line concentrator of the third aspect receives a label assignment request sent from the lower node to the upper node, and replaces the upper node with the higher node from the lower node instead of the upper node. It is specified by assigning label information corresponding to the destination of the data transmitted to the node to the lower order node.

According to a sixth aspect of the present invention, in the third aspect, a plurality of concentrators are connected to the upper node through a communication line, and the upper node generates a plurality of label information generated for giving to each concentrator. Is classified according to each concentrator, and each of the classified label information is given to each concentrator to specify the label.

According to a seventh aspect of the present invention, when the upper node of the second aspect newly generates label information, it specifies the label information by giving the label information to the server.
According to an eighth aspect of the present invention, when the higher-level node of the third aspect newly generates label information, it specifies the label information by giving the label information to the line concentrator.

According to a ninth aspect of the present invention, the higher-level node of the seventh or eighth aspect specifies a new label information when the configuration of a network existing on its own is changed.

According to a tenth aspect of the present invention, the upper node according to the seventh or eighth aspect specifies a new label information when a configuration of a network existing under the lower node is changed. is there.

The present invention employs the following configuration in order to solve the first problem. That is, the invention of claim 11 is a line concentrator, wherein an upper node that generates a plurality of label information as a path identifier is connected through a communication line, and the upper node refers to only the label information inserted into the data. A plurality of lower nodes that insert label information corresponding to the destination of the data generated by the upper node into the data transmitted to the upper node to determine a data output route can be connected through a communication line. Yes, when receiving data with label information inserted from each lower node, the data is transmitted to the upper node via a communication line.

The present invention employs the following configuration to solve the second problem. That is, a twelfth aspect of the present invention is a label information providing server, wherein an upper node that generates a plurality of label information as a path identifier is connected, holds the plurality of label information, and the upper node is inserted into data. Inserting label information corresponding to the destination of the data generated by the upper node into the data transmitted to the upper node in order to determine the output route of the data by referring to only the upper node, In response to a request from a lower node that sends data to the lower node, label information corresponding to the destination of data transmitted from the lower node to the upper node is provided to the lower node.

According to a thirteenth aspect of the present invention, in the line concentrator of the eleventh aspect, the plurality of label information are held, and in response to a request from a lower node, a destination of data transmitted from the lower node to the upper node. Is specified by giving the label information corresponding to.

According to a fourteenth aspect of the present invention, the line concentrator of the thirteenth aspect requests the upper node to provide the plurality of label information, and the plurality of labels transmitted from the upper node in response to the request. It is specified by holding information.

According to a fifteenth aspect of the present invention, the line concentrator of the thirteenth aspect receives a label assignment request sent from the lower node to the upper node, and replaces the upper node with the higher node from the lower node. It is specified by assigning label information corresponding to the destination of the data transmitted to the node to the lower order node.

According to a sixteenth aspect of the present invention, in the concentrator according to the thirteenth aspect, out of a plurality of label information generated by an upper node to which the plurality of concentrators are connected to give each concentrator, the own node holds the information. It is specified by the label information to be given from the upper node.

According to a seventeenth aspect of the present invention, in the label information providing server according to the twelfth aspect, when the upper node newly generates label information, the label information is specified by being given from the upper node. Things.

The invention of claim 18 is the concentrator of claim 13, wherein when the upper node newly generates label information, the label information is specified by being given from the upper node. is there.

According to a nineteenth aspect of the present invention, in the line concentrator according to the eighteenth aspect, a newly generated label information is given when a configuration of a network located above the upper node is changed. It is.

According to a twentieth aspect of the present invention, in the line concentrator according to the eighteenth aspect, when a configuration of a network located below the lower node is changed, label information newly generated by the upper node is provided. It is specified by that.

The invention of claim 21 is a label information assigning method for a network system, wherein an upper node generates a plurality of label information as a path identifier, is connected to the upper node via a communication line, and has a plurality of lower nodes. A concentrator connected to a node through a communication line holds the plurality of label information, and when a certain lower node transmits data to the upper node, assigns label information corresponding to a destination of the data. Request to the concentrator, the concentrator attaches the corresponding label information to the lower node in response to the request of the lower node, and the lower node inserts the label information assigned from the server into the data. And sends it to the upper node.

The invention according to claim 22 is a label information assigning method for a network system, wherein an upper node generates a plurality of label information as a path identifier, and a label information assigning server holds the plurality of label information. When the lower node transmits data to the upper node, the lower node requests the label information providing server to provide label information corresponding to the destination of the data, and the label information providing server responds to the request of the lower node. Accordingly, the corresponding label information is assigned to the lower node, and the lower node inserts the label information assigned from the label information assigning server into the data and transmits the data to the upper node. .

According to a twenty-third aspect of the present invention, in the method of the twenty-first aspect, when the upper node newly generates label information, the upper node specifies the label information by providing the label information to the label information providing server. .

According to a twenty-fourth aspect of the present invention, in the method of the twenty-second aspect, when the upper node newly generates label information, the upper node specifies the label information by giving the label information to the line concentrator.

The invention of claim 25 is the invention of claim 23 or 24.
In the method of (1), when the configuration of the network existing on the upper level of the own node is changed, the upper node specifies by newly generating label information.

The invention of claim 26 is the invention of claim 23 or 24.
In the above method, when the configuration of the network located below the lower node is changed, the upper node specifies the new node by generating new label information.

[0041]

Embodiments of the present invention will be described below with reference to the drawings. [Overall Configuration of Network System] FIG. 1 is an overall configuration diagram showing an example of a network system according to an embodiment of the present invention. In FIG. 1, the network system is:
Broadly, it comprises a plurality of LANs (Local Area Networks) and a WAN (Wide Area Network) accommodating the plurality of LANs.

The WAN includes access networks AN1 to AN1.
AN3 and a backbone network BN accommodating the access networks AN1 to AN3. The backbone network BN includes backbone switches 50 to 52 connected in a mesh or ring network configuration.

The backbone switch 50 accommodates each of the access networks AN1 and AN2, and the backbone switch 51 accommodates the access network AN3. Further, the backbone switch 53 accommodates a lower network (not shown).

The access network AN1 (corresponding to a network system according to the present invention) includes an edge switch 20 (corresponding to an upper node) connected to a backbone switch 50 through a communication line, and a concentrator (concentrator) connected to the edge switch 20. 10 and concentrator 1
0 and WAN routers 30 and 30A (corresponding to a plurality of lower nodes) connected by a ring or star (point-to-point) type network configuration.

As described above, in the network system according to the present embodiment, the edge switch 20 and the plurality of WANs
Each of the WAN routers 30, 30 is connected to the router 30, 30A.
A line concentrator 10 that accommodates A is provided.

The edge node 20 is connected to each WAN router 3
0, 30A, each WAN router 30,
Generate label information to be used in 30A. The concentrator 10 has a plurality of input line ports (not shown) and can accommodate a plurality of WAN routers. FIG.
Then, the line concentrator 10 accommodates each WAN router 30, 30A. In addition, the line concentrator 10 is connected to the edge node 2
0 holds the label information generated. Each of the WAN routers 30 and 30A inserts the label information received from the concentrator 10 into the data transmitted to the edge switch 20.

The LAN includes a plurality of user networks,
DSU for connecting user network to WAN
(Digital line terminator). For example, W
The DSU 40 accommodating the user network 60 is connected to the AN router 30, and the DSU 40A accommodating the user network 60A is connected to the WAN router 30A.

[Internal Configuration of Network System] FIG.
2 is an internal configuration diagram of the network system shown in FIG. FIG. 2 shows a line concentrator 10, an edge switch 20, and each WAN router 3 forming an access network AN1.
0, 30A, and a backbone switch 5 connected to an access network AN1.
0 and the internal configuration of each DSU 40, 40A. However, FIG. 2 shows a backbone router in a LAN as an example of each DSU 40, 40A.

Each component shown in FIG. 2 can be roughly divided into a configuration related to generation and distribution of label information as a path identifier and a configuration related to data transmission. Hereinafter, a configuration relating to generation / distribution of label information and a configuration relating to data transmission will be described.

[Configuration Related to Generation / Distribution of Label Information] The components related to generation / distribution of label information will be described in order from the lowest. <DSU> Each DSU (backbone router) 40, 40A
Have the same configuration, and have a RIP (Route Information
Protocol) processor 41.

The RIP processor 41 stores the DSU 4 as user network information in accordance with the RIP protocol.
IP address of a PC (terminal device) connected to a user network (workgroup: WG) located below 0
Information (including a PPP (point-to-point) address) is collected, and a routing table storing IP address information is created.

After that, the RIP processor 41
The IP address information stored in the routing table is transmitted to the WAN router 30 in response to a request from the RIP processor 31 of the router 31.

<WAN Router> Each WAN router 30, 3
0A have the same configuration, and the RIP processor 31
And an LDP (Label Distribution Protocol) client 32. Hereinafter, the WAN router 30 will be described as an example.

The RIP processor 31 is connected to the WAN router 3
Each DSU 40, 40 subordinate to 0 (connected to itself)
The IP address information is collected from the RIP processor 41 of A, and a routing table storing the collected IP address information is created.

The RIP processor 31 converts the IP address information stored in the routing table into L in response to a request from the route processor 22 of the edge switch 20.
DP client 32, LDP proxy server 11 of line concentrator 10, and LDP server 21 of edge switch 20
Through the route processor 22.

The LDP client 32 sends the IP packet
When sending (including a PPP packet) to the edge switch 20, it requests the LDP proxy server 11 of the line concentrator 10 to add label information according to the destination IP address of the IP packet.

After that, the LDP client 32 returns to the LT
It controls an R (Label Translation) 34 and inserts the label information received from the LDP proxy server 11 into the IP packet.

The LDP client 32 receives and manages the label information referred to in the process of determining the outgoing route of the IP packet by the label matrix 35 from the LDP server 21.

<Concentrator> The concentrator 10 has an LDP proxy server 11 (corresponding to a label information providing server). The LDP proxy server 11 receives, from the LDP server 21 of the edge switch 20, label information on the networks (WAN routers 30 and 30A) under its control. After that, the LDP proxy server 11 creates a label table storing the received label information.

As a configuration for this purpose, in the present embodiment,
For example, the LDP proxy server 11
1, a label table transfer request message similar to that generated by the LDP client 32 is generated, and the
Transmitted to the P server 21, and
The label table transmitted from the DP server 21 to the LDP client 32 is acquired. By this, LDP
The server 21 does not need to be aware of the existence of the LDP proxy server 11.

After that, in response to the request from the LDP client 32 of each of the WAN routers 40 and 40A, the LDP proxy server 11 changes the label information corresponding to this request to L.
The data is transmitted to the DP client 32.

As a configuration for this, in this embodiment,
As an example, the LDP proxy server 11 extracts and terminates the label information addition request message sent by the LDP client 32 to the LDP server 21, and terminates the LDP server 2
In place of 1, processing according to this grant request message is performed. With this configuration, each WAN router 3
0, 30A does not need to be aware of the existence of the concentrator 10.

However, the LDP client 32 sends the LDP
Regarding the IP address information transferred to the server 21,
The LDP proxy server 11 is through.

<Edge Switch> Edge Switch 20
Is an LDP server 21, a route processor 22,
And an SPF (Open Shortest Path First protocol) processor 23.

The LDP server 21 has the route processor 2
2 receives and holds the label table transferred from the server. The LDP server 21 reads out the corresponding label information from the label table and transmits it to the LDP proxy server 11 in response to a request from the LDP proxy server 11 or voluntarily.

The route processor 22 stores a routing table storing routing information in the backbone network BN corresponding to the upper network of the edge switch 20 and the RI of each of the WAN routers 40 and 40A.
With reference to the routing table storing the IP address information received from the P processor 31, label information that associates the IP address information with the routing information of the backbone network BN is calculated (generated).

After that, the route processor 22 creates a label table storing the generated label information. Further, the route processor 22 copies the label table and transfers it to the LDP server 21. The route protocol 22 controls the label matrix 25 based on the contents of the label table.

The route processor 22 controls the LTR 24 on the user side to replace the label information on the backbone network BN inserted in the IP packet transmitted toward the user network with the label information on the user side. .

On the other hand, the route processor 22 controls the LTR 26 on the backbone network BN side to transmit the ITR transmitted to the backbone network BN.
The label information on the user side inserted in the P packet is replaced with the label information on the backbone network BN side.

When the plurality of concentrators 10 are connected to the edge switch 20, the route processor 22
A plurality of pieces of label information to be held by the LDP proxy server 11 of each concentrator 10 are generated, and the plurality of pieces of label information are separately stored according to each concentrator 10. That is, a plurality of pieces of label information are segmented for each line concentrator. After that, the route processor 22 gives the corresponding segment of the label information to the corresponding concentrator 10 in response to a request from each concentrator 10.

The OSPF processor 23 communicates with the backbone switch 50 (backbone network BN) in accordance with the OSPF protocol in response to a request from the route processor 22, and obtains routing information in the backbone network BN. Then OSP
The F processor 23 creates a routing table holding routing information in the backbone network BN.

<Backbone Switch> The backbone switch 50 has an OSPF processor 53 and a route processor 55. OSPF processor 53
Collects the routing information of the backbone network BN periodically according to the OSPF protocol, and creates a routing table in which the routing information is stored.

The route processor 55 controls the label ATR 54 and the label matrix 56 using the routing table. [Configuration Related to Data Transmission] Each DSU (backbone router) 40, 40A has a routing matrix 42. The routing matrix 42 determines the outgoing route of the IP packet input to itself by the RIP processor 41.
Is determined with reference to the routing table created in step (1), and transmitted from the corresponding outgoing route.

Each of the WAN routers 30 and 30 A has a label insertion section 33, an LTR 34, and a label matrix 35. The label insertion part 33 and the LTR 34
The label information corresponding to the IP address is inserted into the IP packet received from the SU 40. On the other hand, the label insertion unit 33 and the LTR 34
Remove the label information from the packet, insert the destination IP address corresponding to this label information into the IP packet, and
Send to SU40 or DSU40A. The label matrix 35 refers to the label information of the IP packet received from the LTR 34 or the line concentrator 20, and transmits the IP packet from an output path corresponding to the label information.

The concentrator 10 has a demultiplexer 12. The demultiplexing unit 12 is connected to each of the WAN nodes 30, 30A.
And multiplexes the IP packet received from the multiplexed packet and sends the multiplexed packet to the edge switch 20. On the other hand, the demultiplexing unit 12 separates the multiplexed packet received from the edge switch 20 and converts each of the separated IP packets into the WAN router 30 or the WAN router 30A corresponding to the destination.
Send to.

The edge switch 20 has an LTR 24, a label matrix 25, and an LTR 26.
After changing the label information of the IP packet received from the label matrix 25, the LTR 24 sends the IP packet to the line concentrator corresponding to the label information. The label matrix 25 converts the IP packet received from the LTR 24 or the LTR 26 into the LTR 24 according to the label information.
Alternatively, the data is transmitted to the LTR 26. The LTR 26 changes the label information of the IP packet received from the label matrix 25, and transmits the IP packet to the backbone switch 50.

The backbone switch 50 has the label AT
R54 and a label matrix 56. The label ATR 54 sends out the IP packet received from the label matrix 56 to the lower network (the access network AN1 or the access network AN2) corresponding to the label information.

[Operation Example in Network System]
Next, an operation example (an operation example of the line concentrator 10) in the network system shown in FIGS. 1 and 2 will be described. The operation example roughly includes operation examples of pre-processing, data transmission processing, and label information updating processing. Hereinafter, each operation example will be described in detail.

<Preprocessing> FIG. 3 is a sequence diagram showing an operation example of the preprocessing. In FIG. 3, in the network, each DSU (backbone router) 40, 40A
According to the IP protocol, each user network (W
G: Workgroup) The user network information (IP address information of the terminal device (PC) connected to each user network 60, 60A) in the user network 60, 60A is acquired (S0).
1) Create a routing table storing the acquired IP address information (S02).

Thereafter, the backbone switch 50
According to the SPF protocol, in order to obtain the routing information of the backbone network BN, communication is performed with each of the backbone switches 51 and 52 and the edge switch 20 corresponding to its own adjacent node to exchange routing information (S03 to S03). S05).

By the processing of S03 to S05, each of the backbone switches 51 to 53 and the edge switch 20
The routing information of the backbone network BN is acquired, and a routing table storing the routing information is created (S06 to S08).

Then, each WAN router 30, 30A
According to the RIP protocol, the DSU (D
SU40 or DSU40A) obtained in S01
P address information is acquired (S09), and a routing table storing the acquired IP address information is created (S09).
10).

After that, according to the LDP protocol, the edge switch 20 sends a message from each WAN node 30, 30A to
The IP address information obtained in S09 is obtained via the line concentrator 20 (S11), and a routing table storing the obtained IP address information is created (S12).

Subsequently, the edge switch 20 uses the contents of the routing table created in S08 (routing information of the backbone network) and the contents of the routing table created in S12 (IP address information) to generate a plurality of labels. Information is generated, and a label table storing the generated label information is created (S13).

After that, the edge switch 20 divides the label table for each concentrator (S14), and transfers the divided label table to each concentrator under its own control.
(S15, S16). However, in the present embodiment, since the edge switch 20 has only the line concentrator 10 under its control,
There is no processing in S14 and S16, and in S15, S1
The label table created in 3 is transferred to the line concentrator 10.

After that, the concentrator 10 creates a label table using the label table (label information) given from the edge switch 20 (S17). When the pre-processing is completed as described above, each of the WAN routers 30, 30
A becomes ready to insert label information into the data (IP packet) transmitted to the edge switch 20.

In FIG. 3, the order of the processes of S01 and S03 may be reversed. Also, S03 to S0
The order of the processing of S5 and the processing of S06 to S08 may be any order.

<Data Transmission Processing> FIG. 4 is a sequence diagram showing an operation example of the data transmission processing. As shown in FIG. 4, it is assumed that an IP packet (IP diagram) is transmitted from a terminal device (PC) connected to the user network (WG) 60 to a terminal device located below the backbone switch 51 as a destination (S101). . This IP packet is received by the WAN router 30 via the user network (WG) 60 and the DSU (backbone router) 40 (S102, S103).

Then, the WAN router 30 requests the LDP proxy server 11 of the line concentrator 10 to add label information corresponding to the destination IP address of the IP packet (S104).

LDP proxy server 11 of concentrator 10
Reads the corresponding label information from the label table in response to a request from the WAN router 30,
(S105).

Then, the WAN router 30 inserts the label information given from the concentrator 10 into the IP packet (S106) and transmits it to the concentrator 10 (S107). The line concentrator 10 transfers the IP packet received from the WAN router 30 to the edge node 20 (S108).

Thereafter, the edge node 20 and the backbone switch 50 perform an outgoing route determination process (label exchange) of the IP packet with reference to only the label information inserted into the IP packet. (S109, 110).

Thereafter, the IP packet is transmitted to the terminal corresponding to the destination via the access network AN3. <Label Information Update Processing> FIG. 5 is a sequence diagram showing an operation example of the label information update processing. In FIG. 5, after the end of the preprocessing, the edge switch 20 periodically or sporadically acquires the routing information of the backbone network BN according to the OSPF protocol (S20).
1).

Next, the edge switch 20 updates the routing table storing the routing information of the backbone network BN (S203). Subsequently, the edge switch 20 updates the label table according to the update of the routing table (S204), divides the label table as necessary (S205), and transfers the updated new label table to the line concentrator 10. Yes (S206).

Then, the LDP proxy server 11 of the line concentrator 10 updates its own label table with the label table received from the edge switch 20 (S207).

Although not shown, the edge switch 2
0 performs the processing of S11 shown in FIG. 3 periodically or sporadically after the end of the pre-processing, and the WAN routers 30, 30A
To obtain IP address information. Then, the edge switch 20 updates the routing table holding the IP address information, generates new label information according to the update, updates the label table, and transmits the label table to the LDP proxy server 11, The LDP proxy server 11 updates its own label table.

As described above, when the edge switch 20 updates each routing table held by itself, the edge switch 20 and the LDP proxy server 11
Are updated.

[Operation of Embodiment] According to the network system of the embodiment of the present invention, each WAN router 3
0, 30A and the edge switch 20, a plurality of WAs
Since the concentrator 10 capable of accommodating N routers is provided, if the concentrator is accommodated in each input line port held by the edge switch, and each concentrator accommodates a plurality of WAN routers, The number of WAN routers equal to or larger than the number that can be accommodated by the edge switch 20 (the number of input line ports prepared in the edge switch 20) is set to the edge switch 2
0 can be accommodated. Further, when attaching / detaching the WAN router, there is no need to set the edge switch 20 in accordance with the attachment / detachment. Therefore, the operation of the network system can be efficiently performed, and the consistency with the existing wide area network (backbone network BN or the like) can be improved.

Further, according to the network system of the present invention, the LDP proxy server 11 is provided in the line concentrator 10, and each WAN router 30, 30A obtains the label information to be inserted into the IP packet from the LDP proxy server 11. , Each WAN router 30, 30A,
Since it is not necessary to perform the process of determining the corresponding label information from the destination IP address of the IP packet, the addition of each WAN router 30, 30A can be reduced.

On the other hand, the edge switch 20 has a plurality of WANs.
Since it is not necessary to perform the process of assigning the label information to the router, the processing load on the edge switch 20 is reduced. As a result, C which has been used for the label information adding process
Since the PU time can be allocated to the route calculation based on the OSPF, the time required for the route calculation can be reduced.

Further, the configuration relating to the processing performed by the LDP proxy server 11 on behalf of the edge switch 20 can be omitted from the edge switch 20, and the number of accommodated WAN routers (input line ports) can be reduced. Therefore, the number of components of the edge switch 20 can be reduced, and the cost of the edge switch 20 can be reduced.

Further, since the WAN routers 30 and 30A and the edge switch 20 do not need to be aware of the existence of the LDP proxy server 11, when the LDP proxy server 11 is implemented, the WAN routers 30 and 30A and the edge switch 20 No configuration changes are required.

Also, when there is a change in the routing information of the backbone network BN (when the configuration of the backbone network BN is changed), or
When there is a change in the P address information (WAN router 3
If there is a configuration change under 0.30A), LDP
The label information of the proxy server 11 is always updated to the latest one. This prevents the LDP proxy server 11 from giving erroneous label information to the WAN router 30 or the WAN router 30A.

With the effects described above, the load on the edge switch can be reduced, and the size of the user can be adjusted. Therefore, in particular, even when an existing edge switch is used, it is possible to easily apply the MPLS technology to a wide area network.

[Modifications of Embodiment] The following modifications can be made to the embodiment. That is, LDP proxy server 1
1 may request the LDP server 21 to transfer the label table.

The label table may be updated as a whole, or only the label information related to the change of the routing information or the IP address information may be updated.

The line concentrator 10 may be provided with a label rewriting function so that the label information can be effectively used. In the present embodiment, the access network AN1 and the backbone network BN are IP
The case of transmitting a packet has been described, but the access network AN1 and the backbone network BN
The present invention can also be applied to a case in which is for transmitting an ATM cell.

[0108]

According to the network system of the present invention, even when an existing edge switch is used, it is possible to cope with the scale of the user.

According to the network system of the present invention, the load on the edge switch can be reduced.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a network system according to an embodiment of the present invention;

FIG. 2 is an internal configuration diagram of the network system shown in FIG. 1;

FIG. 3 is a sequence diagram showing an operation example of preprocessing.

FIG. 4 is a sequence diagram showing an operation example of a data transmission process.

FIG. 5 is a sequence diagram showing an operation example of a label information update process;

FIG. 6 is a system configuration diagram of a label exchange network using MPLS.

FIG. 7 is an internal configuration diagram of a conventional network system.

[Explanation of symbols]

 AN1 to AN3 Access network BN backbone network 10 Concentrator 11 LDP proxy server 12 Demultiplexer 20 Edge switch 21 LDP server 22 Route processor 23 OSPF processor 24, 26, 34 LTR 25 Label matrix 30 WAN router 31 RIP processor 32 LDP client 33 Label insertion unit 35 Label matrix 40 DSU (backbone router) 41 RIP processor 42 Routing matrix 50-52 Backbone switch 53 OSPF processor 54 Label ATR 55 Label matrix

Claims (26)

[Claims] An upper node for generating a plurality of pieces of label information as a path identifier; and the upper node for the upper node to determine a data output route only by referring to the label information inserted into the data. A plurality of lower nodes that insert label information corresponding to the destination of the data generated by the upper node into the data transmitted to the upper node, and transmit the lower nodes through the communication line. And a concentrator that is connectable and, when receiving data with label information inserted from each lower node from each lower node, transmitting the data to the upper node via a communication line. Network system. 2. An upper node for generating a plurality of pieces of label information as path identifiers, and said upper node for determining the output route of data by referring to only the label information inserted into the data. Insert the label information corresponding to the destination of the data generated by the upper node in the data transmitted to, a plurality of lower nodes to be sent out to the upper node, holding the plurality of label information, A network system, comprising: a label information providing server that provides, to a lower node, label information corresponding to a destination of data transmitted from the lower node to the upper node in response to a request from the lower node. 3. The line concentrator holds the plurality of label information and, in response to a request from a lower node, stores the label information corresponding to the destination of data transmitted from the lower node to the upper node. 2. The network system according to claim 1, wherein the network system is provided to a node. 4. The line concentrator requests the upper node to add the plurality of label information to the upper node, and retains the plurality of label information sent from the upper node in response to the request. The network system according to claim 3, wherein 5. The line concentrator receives a label assignment request sent from the lower node to the upper node, and receives a destination of data transmitted from the lower node to the upper node on behalf of the upper node. 4. The network system according to claim 3, wherein label information corresponding to the sub-node is assigned to the lower node. 6. A plurality of concentrators are connected to the upper node via a communication line, and the upper node classifies a plurality of label information generated for giving to each concentrator according to each concentrator. 4. The network system according to claim 3, wherein each of the classified label information is provided to each of the line concentrators. 7. The network system according to claim 2, wherein when the upper node newly generates label information, the upper node gives the label information to the server. 8. The network system according to claim 3, wherein the upper node gives the label information to the line concentrator when newly generating label information. 9. The network system according to claim 7, wherein said higher-level node newly generates label information when the configuration of a network existing on its own is changed. 10. The network system according to claim 7, wherein the upper node newly generates label information when a configuration of a network located below the lower node is changed. 11. An upper node that generates a plurality of pieces of label information as path identifiers is connected via a communication line, and the upper node determines a data output route only by referring to the label information inserted into the data. A plurality of lower nodes that insert label information corresponding to the destination of the data generated by the upper node into data transmitted to the upper node can be connected through a communication line, and the label information is transmitted from each lower node. A line concentrator, wherein when the inserted data is received, the data is transmitted to the upper node via a communication line. 12. An upper node that generates a plurality of label information as a path identifier is connected, holds the plurality of label information, and outputs data by referring to only the label information inserted into the data. In response to a request from a lower node that inserts label information corresponding to the destination of the data generated by the upper node into data transmitted to the upper node to determine a route and sends the data to the upper node. And a label information assigning server that assigns label information corresponding to a destination of data transmitted from the lower node to the upper node to the lower node. 13. A method according to claim 13, wherein said plurality of label information are held, and in response to a request from a lower node, label information corresponding to a destination of data transmitted from said lower node to said upper node is given to said lower node. Claim 11
Concentrator as described. 14. The system according to claim 13, wherein said upper node is requested to add said plurality of label information, and said plurality of label information sent from said upper node in response to said request is held. Concentrator. 15. A label information corresponding to a destination of data transmitted from the lower node to the upper node on behalf of the upper node in response to a label assignment request sent from the lower node to the upper node. 14. The line concentrator according to claim 13, wherein is added to the lower node. 16. A plurality of label information generated by an upper node to which a plurality of concentrators are connected to provide each concentrator, label information to be held by itself is provided from the upper node. 14. The concentrator according to claim 13, wherein: 17. The server according to claim 12, wherein when the upper node newly generates label information, the label information is given from the upper node. 18. The line concentrator according to claim 13, wherein when the upper node newly generates label information, the label information is given from the upper node. 19. The line concentrator according to claim 18, wherein newly generated label information is given when the configuration of a network existing above the upper node is changed. 20. The line concentrator according to claim 18, wherein when a configuration of a network existing under the lower node is changed, label information newly generated by the upper node is provided. 21. A concentrator, wherein an upper node generates a plurality of pieces of label information as a path identifier, and wherein the concentrator connected to the upper node through a communication line and connected to a plurality of lower nodes through a communication line, Holding a label information, when a certain lower node transmits data to the upper node, requests the concentrator to add label information corresponding to the destination of the data; The corresponding label information is assigned to the lower node in response to the request, and the lower node inserts the label information assigned from the server into the data and sends the data to the upper node. Labeling method for network system. 22. When the upper node generates a plurality of label information as a path identifier, the label information assigning server holds the plurality of label information, and the lower node transmits data to the upper node. Requesting the label information providing server to provide label information corresponding to the destination of the data, wherein the label information providing server provides corresponding label information to the lower node in response to a request from the lower node, A label information assigning method for a network system, wherein a lower node inserts label information assigned from the label information assigning server into the data and sends the data to the upper node. 23. The method according to claim 21, wherein when the upper node newly generates the label information, the upper node supplies the label information to the label information providing server. 24. The method according to claim 22, wherein when the upper node newly generates label information, the upper node gives the label information to the line concentrator. 25. The network system according to claim 23, wherein said higher-level node newly generates label information when the configuration of a network existing on its own is changed. Method. 26. The apparatus according to claim 23, wherein the upper node newly generates label information when a configuration of a network located below the lower node is changed.
Or the label information assigning method for a network system according to 24.