JP3974917B2 - Network system - Google Patents

Description

  The present invention relates to a network system, and more particularly to a line concentrator forming a network system.

  A basic structure in a conventional network system, for example, a LAN system such as Ethernet (registered trademark), is a shared medium. Shared media is a system in which terminal devices connected to the same LAN share a bandwidth. However, there is a problem that due to the sharing of the band, the band is insufficient and data communication or the like is not performed smoothly.

  As a countermeasure, there is a network system using a concentrator. Here, the line concentrator is, for example, in which a plurality of terminal devices and an address holding server are connected via a communication line, and the plurality of communication lines are divided into predetermined groups (broadcast domains) by setting, and this broadcast domain By turning on / off the transmission state of the communication line for each time (referred to as a port switching function), the band exclusive use for each broadcast domain is realized, and the decrease in throughput (communication capacity) due to insufficient bandwidth is prevented. .

  For example, as shown in FIG. 20, the network system using the line concentrator is formed by connecting a plurality of terminal devices 100a to 100n and an address holding server 110 to the line concentrator 10 via a communication line. .

  In this network system, a broadcast domain is formed by the terminal devices 100a to 100c and the address holding server 110 among the plurality of terminal devices 100a to 100n. Among the broadcast domains, the address holding server 110 holds a server address that is its own network address and the network addresses of the terminal devices 100a to 100c.

  Further, in each of the terminal devices 100a to 100c in such a network system, normally, when data transmission or the like is performed to other terminal devices 100 in the broadcast domain, the terminal device 100 that is the data transmission destination from the address holding server 110. The data can be transmitted to the data transmission destination terminal device 100 only after receiving the network address.

  In such a network system, for example, when data is transmitted from the terminal device 100a to the terminal device 100c, the following packet exchange is required.

  First, the terminal device 100 a transmits a broadcast (broadcast transmission) packet requesting the server address of the address holding server 110 to the address holding server 110.

  This broadcast packet is transmitted to all of the server address request broadcast domain, that is, the terminal devices 100b and 100c and the address holding server 110.

  Next, when the address holding server 110 receives this server address request, it broadcasts its own server address. As a result, the server address is transmitted to all in the broadcast domain.

  Next, when the terminal device 100a receives the broadcast server address, the terminal device 100a transmits a broadcast packet requesting the address holding server 110 to give the network address of the terminal device 100c.

  Next, when the address holding server 110 receives this network address assignment request, it broadcasts the network address of the terminal device 100c. Then, the terminal device 100a receives the network address of the terminal device 100c.

  In this manner, the terminal device 100a can receive data from the terminal device 100c that is the data transmission destination and transmit data to the terminal device 100c.

  When there are a plurality of network systems shown in FIG. 20, as shown in FIG. 21, in each network system, each of the line concentrators 10a and 10b is connected to a route relay apparatus 30 such as a router via a communication line. The network system as shown in FIG. 20 constitutes the network system as each segment.

  The route relay device 30 used here usually has a “relay agent function” for transmitting an input packet to another segment. In the line concentrator 10b shown in FIG. 21, the address holding server 110b, the terminal device 100d, and the terminal device 100e are in the broadcast domain. Further, the address holding server 110b has its own server address and the network addresses of the terminal devices 100d and 100e.

  In the network system shown in FIG. 21, for example, when data transmission is performed from the terminal device 100a to the terminal device 100d, the following packet exchange is required as a premise.

  First, the terminal device 100a transmits a broadcast packet requesting a server address. This broadcast packet is transmitted in the broadcast domain via the concentrator 10a, and is transmitted to the route relay apparatus 30 through the backbone communication line.

Next, the route relay device 30 terminates the broadcast packet.
By using the “relay agent function”, a broadcast packet is transmitted to the concentrator 10b side which is another segment.

  Next, when receiving the broadcast packet, the line concentrator 10b transmits the broadcast packet to the address holding server 110b and the terminal devices 100d and 100e, which are its own broadcast domains.

  Through such a path, the address holding server 110b receives the server address request broadcast packet transmitted from the terminal device 100a and broadcasts the server address in response thereto. Then, this server address is received by the terminal device 100a via the route through which the server address request is transmitted.

  Similarly, packet exchange for acquiring the network address of the terminal device 100d is performed between the terminal device 100a and the address holding server 110b.

  Finally, data is transmitted from the terminal device 100a to the terminal device 100d.

  However, the above-described conventional network system has the following problems.

  For example, in the network system shown in FIG. 20, in the packet exchange for obtaining the server address and network address between each terminal device 100a and the address holding server 110, all the packets transmitted by both are transmitted by broadcast. The Accordingly, the broadcast packet is also transmitted to the terminal device 100b and the terminal device 100c that do not require the broadcast packet.

  At this time, for example, when data is transmitted / received between the terminal device 100b and the terminal device 100c, the bandwidth in the broadcast domain decreases, and the throughput decreases. Thus, there is a first problem that the smoothing of data communication is hindered. This is the same problem in the network system shown in FIG.

  In the network system shown in FIG. 21, each segment is connected by a route relay device 30 such as a router, but this route relay device 30 does not have a so-called port switching function. For this reason, a plurality of communication lines connected to the route relay apparatus 30 share a band.

  Therefore, for example, in the transmission / reception of data between the terminal device 100a and the terminal device 100d as described above, that is, in the so-called end-to-end data communication, the amount of data transmission through the route relay device 30 increases. Bandwidth decreases and throughput decreases.

  As described above, even if each of the line concentrators 10a and 10b has a function of occupying a band, if the route relay apparatus 30 does not have a function of occupying a band, data transmission / reception between segments is performed smoothly. There is a second problem that it is not broken.

  Furthermore, for example, in the network system shown in FIG. 21, the route relay device 30 may broadcast a packet for controlling its own internal control or the concentrator (referred to as an internal control packet). In this case, the internal control packet is transmitted in each broadcast domain via each concentrator 10a, 10b.

  However, this internal control packet is unnecessary for each of the terminal devices 100a to 100n and the address holding servers 110a and 110b. Further, the internal control packet may include basic network configuration data, and it is not preferable that the internal control packet be transmitted to each of the terminal devices 100a to 100n.

  Therefore, when this internal control packet is transmitted to each of the terminal devices 100a to 100n, etc., there is a third problem that not only the bandwidth in the broadcast domain is reduced but also the security of the network may be impaired. is there.

The present invention has been made in view of the above problems, to prevent a decrease in throughput due to a reduction in bandwidth, and purpose thereof is to provide a network system capable of transmitting and receiving smooth data.

The network system of the present invention is configured as follows to solve the above-described problems.

That includes a plurality of first concentrator for multiple terminal apparatuses are connected via a communication line, and a second concentrator which the plurality of first concentrator is connected via a communication line.

When each terminal device transmits data to a terminal device connected to a first concentrator different from the first concentrator to which it is connected, the address of the terminal device to which the data is transmitted A grant request can be sent. Each of the first line concentrators transmits an address assignment request for a terminal device that is a transmission destination of the data to the second line concentrator. When each first line concentrator receives an address assignment request packet for obtaining an address of a destination terminal as a data transmission destination of the terminal apparatus from a terminal apparatus connected to the first apparatus, the destination MAC of the address assignment request packet Conversion means for rewriting a broadcast address set as an address with the MAC address of the second concentrator and unicasting the address assignment request packet with the rewritten destination MAC address to the second concentrator.

The second concentrator includes an address storage table storing addresses of the plurality of terminal devices connected to the plurality of first concentrators, and the address assignment request unicast from any of the first concentrators. when a packet is received, the address from the storage table and detects the address of the destination terminal corresponding to the address assignment request packet, detects from the address storage table to the terminal apparatus which has transmitted the address assignment request packet Response means for transmitting the designated address.

  Hereinafter, the components will be described individually.

(Terminal device)
Each terminal device in the onset Ming, for example, in a case of transmitting the data to another terminal apparatus, if the data does not have the address of the destination to become another terminal device, the unknown addressing Broadcasts a request signal (address assignment request packet) .

(First concentrator)
When each of the first line concentrators receives an address assignment request for a terminal apparatus that is the data transmission destination, the first line concentrator transmits an address assignment request for the terminal apparatus that is the data transmission destination only to the second line concentrator. That is, when an address assignment request packet for obtaining an address of a destination terminal as a data transmission destination of the terminal device is received from a terminal device connected to the own device, it is set as a destination MAC address of the address assignment request packet. The broadcast address is rewritten to the MAC address of the second concentrator, and conversion means for unicasting the address assignment request packet with the rewritten destination MAC address to the second concentrator is provided.

  This is preferable in that the address assignment request can be prevented from being transmitted to a terminal device that does not require the address assignment request. This conversion means transmits the signal received by the first concentrator to only the second concentrator.

Thus, when received signal is an address granted request by broadcast, conversion means transmits the broadcast address assignment request is converted into address assignment request by unicast to the second concentrator.

  When the first concentrator is provided with conversion means, the first concentrator may be provided with analysis means for analyzing the content of the received signal. For example, the analyzing means analyzes whether or not the received signal is an address assignment request of a terminal device connected to another first concentrator, and the conversion means operates when it is determined as an address assignment request. Like that.

(Second concentrator)
The second line concentrator in the present invention has an address storage table and response means. For the address request received by the second line concentrator, the response means detects an address corresponding to the address request from the address storage table, generates a response signal including the detected address, and transmits the address request. Is transmitted to the terminal device.

Forming a network system which is present onset bright and the first concentrator and the second concentrator, it is also possible to configure as follows. That is, the address storage table of the second line concentrator further stores information on each first line concentrator corresponding to the address, and the second line concentrator receives the reception means instead of the response means. In response to the received address assignment request, information on the corresponding first line concentrator is detected from the information on each first line concentrator stored in the address storage table, and the address assignment request is sent to the corresponding first line concentrator. The conversion means of the first concentrator is connected to a predetermined communication line when the address assignment request is received from the second concentrator. You may make it transmit to these terminal devices. For example, each of the first line concentrators includes a plurality of communication interface units for transmitting and receiving packets to and from the terminal apparatus and the second line concentrator connected to the own apparatus, and a terminal apparatus connected to the own apparatus. When an address assignment request packet for obtaining an address of a destination terminal serving as a data transmission destination is received, the broadcast address set as the destination MAC address of the address assignment request packet is rewritten to the MAC address of the second line concentrator, Conversion means for unicasting the address assignment request packet in which the destination MAC address is rewritten to the second line concentrator, wherein the second line concentrator includes a table storing the MAC addresses of the first line concentrators, , The address assignment request packet unicast from any of the first concentrators. Is received from the table, the destination MAC address of the first concentrator accommodating the destination terminal having the address requested by the address assignment request packet is detected from the table. Rewriting the MAC address of the first concentrator that has been rewritten, and second conversion means for unicasting the address assignment request packet with the rewritten destination MAC address to the first concentrator having the destination MAC address, In order to broadcast the address assignment request packet to a broadcast domain including the destination terminal when the address grant request packet unicasted from the second line concentrator is received, the conversion unit of the first line concentrator Destination MAC address of the address assignment request packet The rewritten to broadcast address.

  Note that the second line concentrator can also be composed of a conventional line concentrator and an address resolution server. In this case, an address storage table and response means are provided in the address resolution server. Alternatively, an address storage table and second conversion means are provided in the address resolution server. Thereby, the configuration and operation of the concentrator can be simplified, and the operation burden of the concentrator itself can be reduced.

  As described above, according to the present invention, it is possible to prevent a decrease in throughput due to a decrease in bandwidth and perform smooth data transmission / reception.

<First Embodiment>
Hereinafter, a network system according to a preferred embodiment of the present invention will be further described with reference to the drawings. FIG. 2 shows a first embodiment of the network system of the present invention.

  The network system in the first embodiment is a LAN system and includes a plurality of terminal devices 100a to 100n, two address holding servers 110a and 110b, line concentrators 10a and 10b, and a route relay device 30.

  FIG. 2 shows a plurality of terminal devices 100a to 100n. Among the plurality of terminal devices 100a to 100n, the terminal devices 100a to 100m and the address holding server 110a are respectively connected to the line concentrator 10a via a communication line.

  Among these, the communication lines connected to the terminal devices 100a to 100c, the address holding server 110a, and the route relay device 30 are gathered to form a so-called broadcast domain.

  On the other hand, the terminal device 100n and the address holding server 110b are connected to the line concentrator 10b via a communication line. The line concentrators 10a and 10b are connected to the route relay apparatus 30 via communication lines.

<Terminal device>
Each of the terminal devices 100a to 100n is a client in the client-server system, and it is necessary to set a network address as a premise when transmitting owned data to other terminal devices.

  Therefore, each of the terminal devices 100a to 100n receives a server address that is the network address of the address holding servers 110a and 110b from any one of the address holding servers 110a and 110b, and any one of the network addresses of the terminal devices 100a to 100n. It is necessary to receive grant of.

When any one of the terminal devices 100a to 100n requests to give a network address, first, when searching for the address holding servers 110a and 110b, a message signal for requesting the server address to be given to both is “address holding server” _DISCOVER (discovery) request “packet” (hereinafter referred to as “DISCOVER (discovery) request” packet)) is broadcast.

  Further, when any one of the terminal devices 100a to 100n receives a server address from each of the address holding servers 110a and 110b, a signal indicating that the server address has been acquired is “address holding server_REQUEST (request ) Signal “packet” (hereinafter referred to as “REQUEST (request) signal” packet) is broadcast.

  Further, when any of the terminal devices 100a to 100n receives a plurality of server addresses, an appropriate server address is selected from the plurality of server addresses, and a “REQUEST (request) signal” indicating that it has been acquired. Packets are broadcast.

  Further, when the packet exchange for obtaining the network address between each of the terminal devices 100a to 100n and each of the address holding servers 110a and 110b is forcibly stopped, the signal is an instruction to forcibly end the packet exchange. An address holding server_RELEASE (release) request “packet” (hereinafter referred to as a “RELEASE (release) request” packet)) is transmitted.

  Each of the terminal devices 100a to 100n has the same configuration.

<Address holding server>
Each of the address holding servers 110a and 110b has a server address that is its own network address and a network address of the terminal device 100 in each broadcast domain.

When each address holding server 110a, 110b receives a "DISCOVER (discovery) request" packet transmitted from any of the terminal devices 100a to 100n, a "address holding server_OFFER (presentation) response that is a response signal including the server address" “Packets” (hereinafter referred to as “OFFER (presentation) response” packets)) are broadcast.

Further, when each of the address holding servers 110a and 110b receives the “REQUEST (request) signal” packet transmitted from each of the terminal devices 100a to 100n, the “address holding server_ACK signal” packet ( Hereinafter, it is called "" ACK signal "packet").

  The address holding servers 110a and 110b have the same configuration.

<Hardware configuration of concentrator>
Next, the hardware configuration of the line concentrator 10a configuring the network system will be described with reference to FIG. Since the concentrator 10b has the same configuration as the concentrator 10a, description thereof is omitted.

  In terms of hardware, the line concentrator 10 a includes a CPU 12, an interface unit 13, a buffer memory 14, a switch control unit 15, a timer 16, and a storage device 20.

  Here, the CPU 12 executes an application program stored in the storage device 20. The buffer memory 14 temporarily stores packets received from the terminal devices 100a to 100n or the address holding servers 110a and 110b.

  The interface unit 13 is a so-called port and is provided in each of the line concentrators 10a and 10b, and accommodates each communication line connected to each of the terminal devices 100a to 100n and the address holding servers 110a and 110b.

  Each interface unit 13 is provided with a switch (not shown) for turning on / off the transmission state of the accommodated communication line. Each interface unit 13 has a unique number.

<Switch control section>
The switch control unit 15 controls on / off of the switches provided in each of the interface units 13 described above.

  The broadcast domain described above includes, for example, a switch of each interface unit 13 in which communication lines connecting the line concentrator 10a, the terminal apparatuses 100a to 100c, the address holding server 110a, and the route relay apparatus 30 are accommodated. The controller 15 is formed so as to be turned on / off all at once.

  However, the combination of ON / OFF control of the interface unit 13 by the switch control unit 15 is arbitrary, and any combination may be used as long as the address holding server is included in the broadcast domain.

<Storage device>
Next, the storage device 20 of the concentrator 10a will be described with reference to FIG. The storage device 20 includes, as application programs, a packet determination unit 21 that is a signal analysis unit, a line information storage unit 50 that is a line information storage unit, a communication line control unit 60 that is a communication line control unit, and a traffic amount. A traffic volume measuring unit (traffic monitoring unit) 25 that is a measurement unit and a procedure cancellation unit 31 that is a procedure cancellation unit are stored.

  These application programs are functions that are loaded into a main memory included in the storage device 20 and executed by the CPU 12. The concentrator 10a employs a store-and-forward method in which the received packet is temporarily stored in the buffer memory 14 and the contents of the data portion included in the packet are analyzed. However, other methods may be used. .

  Hereinafter, each part of the storage device 20 will be described individually.

<Packet discrimination unit>
The packet discriminating unit 21 discriminates the type of the packet stored in the buffer memory 14 of the line concentrator 10a and analyzes the contents thereof.

  For example, a “DISCOVER (discovery) request” packet or the like, that is, each of the terminal devices 100a to 100n transmits a server's own data, or a server address assignment request or a data transmission destination. It is determined whether or not the packet relates to a network address assignment request of any of the terminal devices 100a to 100n. When it is determined that the packet is related to the address assignment request, the content of the packet is sent to the communication line control means 60.

In the case of other packets, the contents of the packet are not sent to the communication line control means 60. Further, for example, it is also determined whether the packet received from the route relay device 30 is a packet (internal control packet) for controlling the route relay device 30 and / or each of the line concentrators 10a and 10b, and is an internal control packet. If it is discriminated, an instruction is sent to the effect that the packet stored in the communication line control means 60 is an internal control packet.

<Line information storage unit>
The line information storage unit 50 includes an address request unit 22 and a line information storage table (line information storage table) 24.

<Address request section>
The address request unit 22 broadcasts a “DISCOVER (discovery request)” packet by itself.

<Line information storage table>
In the line information storage table 24, when the “OFFER (presentation) response” packet for the “DISCOVER (discovery) request” packet transmitted from the address holding server 110a, 110b is received by the line concentrator 10a, the “OFFER ( Presentation) Response "A unique number of the interface unit 13 that has received the packet is stored.

  Further, when the concentrator receives a "DISCOVER (discovery) request" packet transmitted from any of the terminal devices 100a to 100n, the unique number of the interface unit 13 that has received the "DISCOVER (discovery) request" packet is It is also stored.

<Communication line control unit>
For example, when the concentrator 10 a receives a “DISCOVER (discovery) request” packet or the like transmitted from any of the terminal devices 100 a to 100 n, the communication line controller 60 stores the interface unit 13 stored in the line information storage table 24. And a control amount for turning on the switch of the interface unit 13 corresponding to the unique number is given to the switch control unit 15.

<Procedure Cancellation Department>
The procedure canceling unit 31 compulsorily obtains a server address between each of the terminal devices 100a to 100n and the address holding servers 110a and 110b or an address of the terminal device 100a to 100n that is a data transmission destination. The “RELEASE (release) request” packet, which is a signal to be terminated at the beginning, is transmitted to the address holding servers 110a and 110b by itself.

<Traffic volume measurement unit>
The traffic volume measuring unit 25 has a counter (not shown), and detects the communication traffic volume by measuring the number of packets stored per unit time for packets temporarily stored in the buffer memory 14. ing.

  However, it is also possible to configure the traffic volume measuring unit 25 so as to detect the communication traffic volume by measuring the number of packets received by each interface unit 13.

  The traffic volume measuring unit 25 has a storage table 26 for a predetermined reference traffic volume. When the measured traffic volume falls below the reference traffic volume, a “DISCOVER (discovery request)” packet is transmitted to the address request module 22. An instruction to do so is issued. The traffic amount measuring unit 25 is controlled by the timer 16 so as to operate every certain time.

<Route relay device>
The route relay device 30 is connected to each of the line concentrators 10a and 10b via a communication line. The route relay device 30 has a so-called relay agent function that, when receiving a packet from either the concentrator 10a or the concentrator 10b, transmits the packet to either one.

  Also, a packet (internal control packet) for controlling the operation of the route relay device 30 or the line concentrators 10a and 10b is broadcast as necessary. The route relay device 30 can be a router, a bridge, or the like.

<Operation example>
An operation example of the network system described above will be described in detail with reference to the drawings. First, referring to FIG. 5, preprocessing of the network system, that is, one of the line concentrator 10a and the line concentrator 10b obtains a unique number of the interface unit 13 that receives packets transmitted from the address holding servers 110a and 110b. The procedure to do is explained.

  First, it is assumed that the address request unit 22 is executed by the CPU 12 in one of the line concentrator 10a and the line concentrator 10b. Then, a “DISCOVER (discovery request)” packet is issued.

  This “DISCOVER request” packet is broadcast. That is, it is transmitted to all the communication lines in the broadcast domain and transmitted to the address holding server 110a and the address holding server 110b <step S101>.

  When each of the address holding servers 110a and 110b receives a "DISCOVER (discovery) request" packet from the concentrator 10a or the concentrator 10b, "OFFER (presentation) including a network address for the" DISCOVER (discovery) request "packet. The response “packet is broadcast <step S102>.

  The “OFFER (presentation) response” packet is received from each interface unit 13 of each of the line concentrators 10a and 10b, and when stored in the buffer memory 14, the type of the packet is analyzed by the packet discrimination unit 21. As a result of this analysis, when the packet discriminating unit 21 determines that the packet stored in the buffer memory 14 is an “OFFER (presentation) response” packet, the line information storage unit 50 stores the “OFFER (presentation) response in the line information storage table 24. “The unique number of the interface unit 13 that has received the packet is stored <step S103>.

The unique number of the interface unit 13 is “OFFER” from the address holding server 110a.
Both the unique number of the interface unit 13 that has received the (presentation) response “packet” and the unique number of the interface unit 13 that has received the “OFFER (presentation) response” packet from the address holding server 110b are stored.

As described above, when the unique numbers of the interface units 13 accommodating the communication lines connected to the address holding servers 110a and 110b are stored in the line information storage table 24, the procedure canceling unit 31 is executed by the CPU 12, A RELEASE request packet is transmitted from each interface unit 13 in the broadcast domain. Then, each address holding server 110a, 110b receives a “RELEASE request” packet <
Step S104>.

When each of the address holding servers 110a and 110b receives the “RELEASE (Release) Request” packet, it recognizes that the procedure for acquiring the server address or the like has been interrupted, and stops its operation <Step S105>.

Through these processes, each of the line concentrators 10a and 10b is stored in the line information storage table 24.
The unique number of the interface unit 13 that receives packets from the address holding servers 110a and 110b is stored.

  Then, in the operating state of the network system for which preprocessing has been completed, when the concentrator 10a or the concentrator 10b receives a “DISCOVER (discovery request)” broadcast packet transmitted from any of the terminal devices 100a to 100n, <step S106 The operation of the concentrator 10a or 10b at that time is as follows.

  That is, an address assignment request broadcast packet is received by the interface unit 13 and temporarily stored in the buffer memory 14. Then, the packet determination unit 21 is executed by the CPU 12 to determine that the accumulated packet is a “DISCOVER (discovery) request” packet, and the communication line control unit 60 indicates that the packet is a “DISCOVER (discovery) request” packet. Send.

  When the communication line control unit 60 receives from the packet discrimination unit 21 that the packet is a “DISCOVER (discovery) request” packet, the communication line control unit 60 stores the unique number of the interface unit 13 that has received the “OFFER (presentation) response” packet. While reading from the table 24, the interface unit 13 with the unique number is turned on, and a control amount for turning off the interface unit 13 in another broadcast domain is given.

In response to this control amount, the switch control unit 15 turns on or off the switch of each interface unit 13 in the broadcast domain. Then, the “DISCOVER (discovery request)” packet is transmitted from the buffer memory 14 via the interface unit 13 in the broadcast domain and received by each of the address holding servers 110a and 110b.

As a result, the concentrator 10a or the concentrator 10b does not broadcast the input “DISCOVER (discovery) request” packet, but the address holding servers 110a and 110b.
“DISCOVER (discovery) request” packet is transmitted to <step S107>.

  Next, an operation example in the case where the stored contents of the line information storage table 24 are updated in the network system for which preprocessing has been completed will be described with reference to FIG. In the network system in the operating state, data is transmitted and received between the terminal devices 100a to 100n via the line concentrators 10a and 10b or the route relay apparatus 30, and each of the line concentrators 10a and 10b has a fixed time by a timer 16. Measured <Step S111>.

  When one of the timers 16 of the line concentrators 10a and 10b tells a certain time (timeout), the CPU 12 executes the traffic amount measuring unit 25 (step S112).

  Then, the traffic volume measuring unit 25 measures the communication traffic volume in the network system <Step S113>. That is, the traffic volume measuring unit 25 first measures the number of packets stored in the buffer memory 14 per unit time, thereby measuring the communication traffic volume. Next, the measurement result is compared with the reference traffic amount stored in the reference traffic amount storage table 26.

  If the measured value of the communication traffic volume falls below the reference traffic volume in the comparison result, the CPU 12 executes the address request unit 22 and issues a “DISCOVER (discovery request)” packet. This “DISCOVER (discovery) request” packet is transmitted from the interface unit 13 to all of the broadcast domains, and is received by the address holding server 110a and the address holding server 110b <step S114>.

On the other hand, when the measured value of the communication traffic volume is equal to or exceeds the reference traffic volume, the network address update process is stopped. When each of the address holding servers 110a and 110b receives a “DISCOVER (discovery) request” packet from the concentrator 10a or the concentrator 10b, it broadcasts an “OFFER (presentation) response” packet (step S115).

  This “OFFER (presentation) response” packet is received from the interface unit 13 of the concentrator 10 a or the concentrator 10 b and stored in the buffer memory 14. The type of packet of this “OFFER (presentation) response” packet is analyzed by the packet discriminating unit 21, and if it is determined to be an “OFFER (presentation) response” packet, the line information storage unit 50 performs the “OFFER (presentation)” The unique number of the interface unit 13 that has received the "response" packet is stored in the line information storage table 24 (step S116). As a result, the stored contents of the line information storage table 24 are updated.

Thus, when the contents stored in the line information storage table 24 are updated, each of the line concentrators 10a or the line concentrators 10b broadcasts a “RELEASE (release) request” packet <step S117>. When each address holding server 110a, 110b receives a “RELEASE request” packet, the address assignment request procedure is interrupted <step S118>.

At this time, in the line concentrator 10a or the line concentrator 10b in which the stored contents of the line information storage table 24 are updated, when the procedure canceling unit transmits a “RELEASE (release) request” packet, the setting of the timer 16 is reset. Starts measuring for a certain time again. That is, the operation returns to step S111 <step 119>.

  In this way, each of the line concentrators 10a and 10b updates the stored contents of the line information storage table 24. Each of the line concentrators 10a and 10b shown in FIG. 2 can solve the problem of the present invention even if it does not have the timer 16 and the traffic amount measuring unit 25. However, it is preferable to have either the timer 16 or the traffic amount measurement unit 25 because the operation of the address request unit 22 can be automated.

  The operation example of the network system using the line concentrators 10a and 10b when the timer 16 is removed from the line concentrators 10a and 10b shown in FIG. 2 or when the operation is stopped will be described below with reference to the sequence diagram shown in FIG. explain.

  As shown in FIG. 7, when the terminal devices 100a to 100n transmit / receive data to / from each other, the traffic volume measuring unit 25 of each of the line concentrators 10a and 10b always measures the communication traffic volume of the network system. <Step S121>. That is, the traffic volume measuring unit 25 continuously compares the measured value of the communication traffic volume with the reference traffic volume stored in the reference traffic volume storage table 26.

When the communication traffic volume smaller than the reference traffic volume is detected in one of the line concentrators 10a and 10b, the address request unit 22 is executed and “DISCOVER (discovery)” is executed.
"Request" packet is transmitted to the address holding servers 110a and 110b <Step S12
2>.

As described in the update of the line information storage table 24, the concentrator 10a or the concentrator 10b receives the “OFFER (presentation) response” packet from the address holding servers 110a and 110b <step S123> The unique number of the interface unit 13 that has received this "OFFER (presentation) response" packet is stored in the line information storage table 24 (step S124). As a result, the stored contents of the line information storage table 24 are updated.

Then, the procedure cancellation unit 31 broadcasts a “RELEASE (release) request” packet to the address holding servers 110a and 110b (step S125). Is interrupted <step S126>.

When the concentrator 10a or the concentrator 10b that has updated the storage contents of the line information storage table 24 sends out a “RELEASE request” packet, the traffic volume measuring unit 2 again.
5 is executed and the measurement of the amount of communication traffic is continued. That is, the operation returns to step S121.

  As described above, when the line concentrators 10a and 10b of the network system do not have the timer 16, the stored contents of the line information storage table 24 are updated when the communication traffic volume falls below the reference value.

  Further, when each of the line concentrators 10a and 10b does not have the traffic amount measuring unit 25, or when the operation of the traffic amount measuring unit 25 is in a stopped state, the operation is performed as shown in FIG.

  That is, in a situation where the terminal devices 100a to 100n transmit and receive data, the timer 16 of the line concentrators 10a and 10b measures a certain time <step S131>, and when the certain time elapses (timeout), the address request unit 22 The "DISCOVER (discovery) request" packet is issued by <step S132> and transmitted to the address holding servers 110a and 110b <step S133>.

Subsequent procedures are the same as those described in the update of the line information storage table 24 (steps S134 to S137). In step 136, when a “REQUEST (request) signal” packet is broadcast from each of the concentrators 10a and 10b, the timer 16 is reset <step S138>, the operation returns to step S131, and a predetermined time is measured again. .

  As described above, when the line concentrators 10a and 10b constituting the network system do not have the traffic monitoring unit 25 or the operation is in a stopped state, the “DISCOVER” is sent from the line concentrator 10a or the line concentrator 10b every certain time. (Discovery) request "packets are sent to the address holding servers 110a and 110b, and the stored contents of the line information storage table 24 are updated.

  As described above, the network system stores the network address of the address holding server in each of the line concentrators 10a and 10b as preprocessing. Next, in the network system in a state where the preprocessing is completed, an operation example when any of the terminal devices 10a to 100n requests to give the network address of the terminal device that is the data transmission destination will be described with reference to FIG. To do.

  First, one of the terminal devices 100a to 100n transmits a broadcast packet of “DISCOVER (discovery) request”, which is a signal for searching for the address holding server 110, to the line concentrator 10a or the line concentrator 10b (step S141).

When the concentrator 10 a or 10 b receives this “DISCOVER (discovery) request” packet from the interface unit 13, it first temporarily stores it in the buffer memory 14. Next, the CPU 12 executes the packet determination unit 21 to determine whether or not the received packet is a “DISCOVER (discovery request)” packet.

  When the packet discriminating unit 21 discriminates the accumulated packet as the “DISCOVER (discovery request)” packet, the line information storage unit 50 receives the “DISCOVER (discovery) request” packet. Is stored in the line information storage table 24.

  At the same time, the communication line control unit 60 reads information on the unique number of the interface unit 13 that has received the “OFFER (presentation) response” packet in the preprocessing from the line information storage table 24, and reads the interface unit 13 with the unique number. A control amount for turning on the interface unit 13 in another broadcast domain is given.

Upon receiving this control amount, the switch control unit 15 turns on or off the switch of each interface unit 13 in the broadcast domain. Then, the “DISCOVER (discovery request)” packet is transmitted from the buffer memory 14 via the interface unit 13 in the broadcast domain and received by each of the address holding servers 110a and 110b.

  That is, the “DISCOVER (discovery request)” packet is transmitted to the address holding servers 110a and 110b without being broadcasted (step S142). On the other hand, when the packet discriminating unit 21 discriminates that the packet stored in the buffer memory 14 is not a “DISCOVER (discovery) request” packet, or when it is discriminated that the packet is not related to the network address assignment, the communication line If the control unit 60 does not operate and the accumulated packet is a broadcast packet, the broadcast packet is transmitted to all the broadcast domains.

  Upon receiving the “DISCOVER (discovery) request” packet, each of the address holding servers 110a and 110b broadcasts an “OFFER (presentation) response” packet corresponding to the “DISCOVER (discovery) request” packet (step S143).

  Each “OFFER (presentation) response” packet is received by the interface unit 13 of the concentrator 10 a or the concentrator 10 b and stored in the buffer memory 14. The packet discriminating unit 21 discriminates each packet as an “OFFER (presentation) response” packet.

  Then, the communication line control unit 60 reads the unique number of the interface unit 13 that has received the “DISCOVER (discovery) request” packet from the line information storage table 24 and gives a control amount to the switch control unit 15.

  The switch control unit 15 turns on the interface unit 13 that has received the “DISCOVER (discovery) request” packet among the plurality of interface units 13 that form the broadcast domain, and turns off the other interface units 13. To do.

  The “OFFER (presentation) response” packet stored in the buffer memory 14 is transmitted from the interface unit 13. At this time, the “OFFER (presentation) response” packet is transmitted from the ON state interface unit 13 without being broadcast, and is received by any of the terminal devices 100a to 100n that transmitted the “DISCOVER (discovery) request” packet. <Step S144>.

In the line concentrators 10 a and 10 b, the line information storage unit 50 stores the unique number of the interface unit 13 that has received the “OFFER (presentation) response” packet in the line information storage table 24. The stored content is updated <step S145>.

  Any one of the terminal devices 100a to 100n that has received the "OFFER (presentation) response" bucket from each of the address holding servers 110a and 110b selects either the server address of the address holding server 110a or the server address of the address holding server 110b. Select to get.

  Then, the server address selection and acquisition are shown, and a “REQUEST (request) signal” packet that is a signal for requesting the network address assignment of any one of the terminal devices 100a to 100n that is the data transmission destination is broadcast < Step S146>.

The line concentrator 10 a or the line concentrator 10 b receives the broadcast packet of this “REQUEST (request) signal” from the interface unit 13 and stores it in the buffer memory 14. Then, the same operation as when the above-described “DISCOVER (discovery) request” packet is received from any of the terminal devices 100a to 100n is performed, and a “REQUEST (request) signal” packet is received from the concentrator 10a or the concentrator 10b. Each address holding server 110 is not broadcasted.
a, 110b (step S147).

At this time, the line information storage unit 50 stores the unique number of the interface unit 13 that has received the “REQUEST (request) signal” packet in the line information storage table 24.

When each of the address holding servers 110a and 110b receives the “REQUEST (request) signal” packet, it analyzes the contents of the “REQUEST (request) signal” packet. If any of the terminal devices 100a to 100n that has transmitted the “REQUEST (request) signal” determines that it does not select and acquire the network address held by itself, the address holding server 110a or the address holding server 110b The operation is stopped <Step S148>.

On the other hand, in the content analysis of the “REQUEST (request) signal” packet, the terminal devices 100a˜
When it is determined that any one of 100n has selected and assigned a network address held by itself, the address holding server 110a or the address holding server 110b requests a network address assignment from any of the terminal devices 100a to 100n. “Address holding server_ACK signal” packet (hereinafter referred to as “ACK signal” packet) is transmitted (step S149).

This “ACK signal” packet is transmitted to the concentrator 10 a or the concentrator 10 b, temporarily stored in the buffer memory 14 via the interface unit 13, and determined to be an “ACK signal” packet by the packet determining unit 21. The

Then, the communication line control unit 60 reads “REQUEST (request) signal” from the line information storage table 24.
The unique number of the interface unit 13 that has received the packet is read out, the interface unit 13 with the unique number is turned on, and a control amount for turning off the switches of the interface unit 13 other than the unique number is given to the switch control unit 15. .

The switch control unit 15 turns on or off the switch of each interface unit 13 based on the control amount sent from the communication line control unit 60. And the "ACK signal" packet is
The terminal devices 100a to 100a that transmit the “REQUEST (request) signal” without being broadcast and transmitted from the buffer memory 14 via the interface unit 13 that is switched on.
100n is received <Step S150>.

  Next, an operation example when the line concentrator 10a or the line concentrator 10b receives an internal control packet from the route relay apparatus 30 will be described. First, the internal control packet transmitted from the route relay device 30 is received by the interface unit 13 and stored in the buffer memory 14. Next, it is analyzed by the packet determination unit 21 and determined to be an internal control packet.

  Then, the line information storage unit 50 stores the unique number of the interface unit 13 that has received the internal control packet in the line information storage table 24. At the same time, the communication line control unit 60 is notified that it is an internal control packet.

  The communication line control unit 60 gives a control amount for turning off all the switches of the interface unit 13 in the broadcast domain to the switch control unit 15, and the switch control unit 15 receiving this gives an interface in the broadcast domain. All the switches of the unit 13 are turned off. Therefore, the internal control packet cannot be transmitted from the line concentrator 10a or the line concentrator 10b, and is terminated in the line concentrator 10a or the line concentrator 10b.

  This prevents internal control packets from being broadcast within the broadcast domain. Therefore, it is possible to avoid a decrease in throughput due to a decrease in the bandwidth caused by this. Further, by preventing the internal control packet from being received by the terminal devices 100a to 100n, etc., it is possible to keep the content of the internal control packet confidential.

  The network system described above has the following effects. That is, when any of the terminal devices 100a to 100n receives a server address and a network address as a data transmission destination from the address holding server 110a or 110b, the terminal devices 100a to 100n and the address holding server 110a or 110b The unique number of the interface unit 13 that has received a packet exchanged between the interface unit 13 and the interface unit 13 is stored, and on / off of the switch of each interface unit 13 is controlled based on the stored contents.

  For this reason, it is possible to prevent transmission-unnecessary packets from being transmitted through the communication line, and it is possible to prevent a decrease in throughput due to a decrease in bandwidth. Thereby, transmission / reception of data between the terminal devices 100a to 100n can be performed smoothly. Further, since the concentrators 10a and 10b are provided with the timer 16 and the traffic volume measuring unit 25, the communication traffic volume is measured every certain time, and when the measurement result falls below the reference traffic volume, A DISCOVER request packet is sent. As a result, it is possible to automatically update the stored contents of the line information storage table 24 while avoiding the bandwidth reduction.

<Second Embodiment>
Next, a second embodiment of the network system will be described. FIG. 10 shows a second embodiment of the network system. This network system is a LAN system, and includes a plurality of terminal devices 100a to 100e, a plurality of address holding servers 110a and 110b, a plurality of line concentrators 10a and 10b, and a second line concentrator 10B. A plurality of terminal devices 100a to 100c and an address holding server 110a are respectively connected to the line concentrator 10a via communication lines, and the terminal devices 100d and 100e and an address holding server 110b are respectively connected to the line concentrator 10b. Connected via communication line. Each of the line concentrators 10a and 10b is connected to the second line concentrator 10B via a communication line.

Each of the terminal devices 100a to 100e, each of the address holding servers 110a and 110b, and each of the line concentrators 10a and 10b has the same configuration as the terminal device 100, the address holding server 110, and the line concentrator 10 described in the first embodiment. Do the same. Therefore, the description is omitted here.

<Second concentrator>
Next, the second line concentrator 10B will be described. In terms of hardware, the second line concentrator 10B includes a CPU 12, a plurality of interface units 13, a buffer memory 14, and a storage device 20, as shown in FIG. These are the same as those included in the line concentrators 10a and 10b described in the first embodiment.

  However, the contents stored in the storage device 20 are different, and as shown in FIG. 12, the storage device 20 stores an address storage table 45 and a response unit 44 as response means.

  The address storage table 45 stores the addresses of the terminal devices 100a to 100e and the address holding servers 110a and 110b in the network system. Upon receiving the “DISCOVER (discovery) request” packet, the response unit 44 detects a plurality of server addresses in the network system from the address storage table 45 and generates an “OFFER (presentation) response” packet including these server addresses. The "OFFER (presentation) response" packet is unicast to any of the terminal devices 100a to 100e that have transmitted the "DISCOVER (discovery request)" packet.

When the response unit 44 receives the “REQUEST (request) signal” packet, the response unit 44 detects from the address storage table 45 one of the network addresses of the terminal devices 100 a to 100 e that are the data transmission destinations, and the detected address. The response packet is generated and unicasted to any one of the terminal devices 100a to 100e that has transmitted the “REQUEST (request) signal” packet.

  The response unit 44 is an application program stored in the storage device 20, and is a function that is loaded into a main memory included in the storage device 20 as necessary and executed by the CPU 12.

  The operation example of the network system in the second embodiment will be described below. As preprocessing, each of the line concentrators 10a and 10b stores the unique number of the interface unit 13 that receives packets from the address holding servers 110a and 110b in the line information storage table 24, as in the first embodiment. .

  Assume that, for example, a “DISCOVER (discovery) request” packet is broadcast from the terminal device 100a in a state where the preprocessing has already been completed. This “DISCOVER (discovery) request” packet is received by the concentrator 10a. Then, the line concentrator 10a uses the communication line control unit 60 to interface the communication unit connected to the address holding server 110a, the interface unit 13 accommodating the communication line connected to the second line concentrator, Is turned on and a "DISCOVER request" packet is sent.

  When the second concentrator 10B receives this “DISCOVER (discovery) request” packet, the response unit 44 of the second concentrator 10B detects the server address of the address holding server 110b from the address storage table 45, and this server An “OFFER (presentation) response” packet including an address is generated, and a “OFFER (presentation) response” packet is unicast to the terminal device 100a that has transmitted the “DISCOVER (discovery) request” packet.

  The “OFFER (presentation) response” packet transmitted from the second line concentrator 10B is received by the terminal apparatus 100a that transmitted the “DISCOVER (discovery) request” packet via the line concentrator 10a. Further, the terminal device 100a receives the “OFFER (presentation) response” packet transmitted from the address holding server 110a via the line concentrator 10a.

Next, from the terminal device 100a that has received the “OFFER (presentation) response” packet, for example, a “REQUEST (request) signal” packet requesting the address of the terminal device 100e is broadcast,
When received by the concentrator 10a, the concentrator 10a transmits the “REQUEST (request) signal” packet to the second concentrator 10B and the address holding server 110a.

Then, when the “REQUEST (request) signal” packet is received by the second concentrator 10B, the response unit 44 of the second concentrator 10B detects the address of the terminal device 100e from the address storage table 45, and this terminal A response packet including the address of the device 100e is generated and unicasted to the terminal device 100a.

  In this way, the terminal device 100a can acquire the address of the terminal device 100e and transmit data to the terminal device 100e. According to the second embodiment described above, the effect is substantially the same as the effect in the first embodiment. However, when compared with the first embodiment, a second line concentrator 10 </ b> B is provided instead of the route relay device 30.

Therefore, unlike the route relay device 30, the address request table is detected from the address storage table 45 without broadcasting the received address request broadcast packet as it is, and the terminal device 100 that has made the address request Packets containing the requested address are unicast. Therefore, it is possible to prevent unnecessary broadcast packets from being transmitted on the communication line connecting the second line concentrator 10B and the line concentrators 10a and 10b.

  The storage device 20 of the second line concentrator 10B may be configured to store an address changing unit 43 instead of the response unit 44, as shown in FIG. At this time, the address storage table 45 stores the addresses of the concentrators 10a and 10b, and the terminal devices 100a to 100e and the address holding servers 110a and 110b in the network system corresponding to the addresses of the concentrators 10a and 10b. Stores an address.

  According to such a network system including the second concentrator 10B, for example, a “DISCOVER (discovery) request” broadcast packet for requesting the server address of the address holding server 110b transmitted from the terminal device 100a is transmitted in the concentrator 10a. It is transmitted to the address holding server 110a and the second concentrator 10B without being transmitted to the terminal devices 100b and 100c.

  When the second line concentrator 10B receives the “DISCOVER (discovery) request” packet, the address changing unit 43 determines that the “DISCOVER (discovery) request” packet is a server address request of the address holding server 110b.

  Then, the address changing unit 43 detects the address of the address holding server 110b and the address of the line concentrator 10b from the address storage table 45, and receives a "DISCOVER (discovery) request" packet to the address holding server 110b through the line concentrator 10b. As described above, the content of the information included in the “DISCOVER (discovery request)” packet is changed.

Then, the “DISCOVER (discovery) request” packet is received by the address holding server 110b via the line concentrator 10b. The address holding server 110b that has received the “DISCOVER (discovery) request” packet transmits an “OFFER (presentation) response” packet to the terminal device 100a. This “OFFER (presentation) response” packet is received by the terminal device 100a via the same route as the route on which the “DISCOVER (discovery) request” packet is transmitted.

  Thus, even when the address changing unit 43 is provided in the second concentrator 10B in place of the response unit 44, the throughput due to the reduction in the band between the second concentrator 10B and each of the concentrators 10a and 10b. Decrease can be prevented.

<Third Embodiment>
Next, a third embodiment of the network system will be described with reference to the drawings. Third embodiment of the network system, which according to the Ethernet (registered trademark), the network protocol is the form in the case of IP (Internet Prot o col).

<System overview>
First, the outline of the third embodiment of the network system will be described with reference to FIG. In FIG. 14, a first concentrator 10A, which is a LAN switch (switching HUB), is provided, and a plurality of terminal devices 100 are connected to each first concentrator 10A. Above these line concentrators 10, a second line concentrator 10B, which is a LAN switch (switching HUB), is further provided in a so-called star-type wiring state.

<Terminal device>
Each terminal device 100 has data, and when transmitting the stored data to any of the other terminal devices 100, the IP address and MAC (Media Access) of the terminal device 100 to which the data is transmitted. Control) address.

For this reason, when the terminal device that is the data transmission source does not have the MAC address of the terminal device 100 that is the data transmission destination, the terminal device 100 that is the data transmission source uses the unknown MAC address. ARP (Address Resolution), which is a packet for searching for an address
Protocol) request packet is transmitted.

  This ARP packet includes, for example, address information such as the IP address of the terminal device that requests the MAC address, the source MAC address, and the destination MAC address.

<First concentrator>
Next, each first concentrator 10A will be described with reference to FIG. The first line concentrator 10A includes an interface unit 13, a switch control unit 15, an analysis unit 41, and an address conversion unit 42 that is a conversion unit.

  A plurality of interface units 13 are provided in each of the first line concentrators 10A. Each interface unit 13 accommodates a communication line and receives a packet as a signal from the terminal device 100 through the communication line. Each interface unit 13 has a switch for turning on / off a packet transmission state.

The switch control unit 15 turns on / off the switch of the interface unit 13. The switch control unit 15 collectively turns on / off the switches of the predetermined number of interface units 13 so that a broadcast domain is formed. A broadcast packet received from any one of the terminal devices 100 in the broadcast domain is transmitted to all the terminal devices 100 in the broadcast domain.
Sent to.

  The plurality of terminal devices 100 connected to each first concentrator 10A are divided into arbitrary broadcast domains A to F. The analysis unit 41 terminates and analyzes the ARP request packet and extracts a destination MAC address included in the ARP request packet. The address conversion unit 42 rewrites the destination MAC address included in the ARP request packet with the MAC address of the second line concentrator 10B.

  The analysis unit 41 and the address conversion unit 42 are hardware application programs stored in a storage device, which are read into the main memory as needed and executed by a CPU (central processing unit). It is a function.

<Second concentrator>
Next, the second line concentrator 10B will be described with reference to FIG. The second line concentrator 10B includes an interface unit 13, an address storage table 45, and a response unit 44. The interface unit 13 is the same as that described in the first line concentrator 10B, and is connected to the first line concentrator 10A via a communication line. The address storage table 45 stores the IP addresses and MAC addresses of all the terminal devices 100 in the network system in association with each other.

  The response unit 44 extracts the IP address of the terminal device that requests the MAC address assignment from the received ARP request packet, searches the address storage table 45 using the extracted IP address, and detects the MAC address corresponding to the IP address To do. Furthermore, an ARP response packet including the detected MAC address is generated and transmitted to the terminal device 100 that transmitted the address request.

  In terms of hardware, the analysis unit 41 and the response unit 44 are application programs stored in a secondary storage such as a hard disk, and are functions that are read into the main memory as necessary and executed by the CPU. . The address correspondence table 45 is stored in secondary storage in hardware.

<Operation example>
An operation example of the network system having the above configuration will be described below with reference to FIGS. For example, it is assumed that an ARP request packet for requesting assignment of the MAC address of the terminal device 100B in the broadcast domain B is broadcast from the terminal device 100A in the broadcast domain A <step S301>. Incidentally, MAC address of the destination in this case is designated as broadcast.

  The ARP request packet is transmitted to the first line concentrator 10A through the communication line, received by the interface unit 13, and analyzed by the analysis unit 41 (step S302).

  If the analysis unit 41 determines that the packet received by the analysis is an ARP request packet, the analysis unit 41 terminates the ARP request packet. At the same time, the analysis unit 41 extracts the destination MAC address of the ARP request packet. That is, the broadcast designation is extracted. The ARP request packet is sent to the address translation unit 42.

Next, in the ARP request packet, the address conversion unit 42 rewrites the broadcast designation, which is the destination address, to the MAC address of the second line concentrator 10B. That is, the destination MAC address of the MAC layer of the ARP request packet is the second concentrator 10.
The MAC address is changed to B's MAC address <step S303>.

  The ARP request packet whose transmission destination MAC address is changed to the second concentrator 10B is unicast from the interface unit 13 on the backbone LAN side to the second concentrator 10B (step S304).

  The second line concentrator 10B receives the ARP request packet at the interface unit 13 <step S305>. The ARP request packet is sent to the response unit 44.

  The response unit 44 extracts the IP address of the terminal device 100B from the received ARP request packet. Then, the address correspondence table 45 is searched based on the extracted IP address, and the MAC address stored corresponding to the IP address of the terminal device 100B is detected. Further, the response unit 44 generates an ARP response packet including the MAC address of the terminal device 100B and having the terminal device 100A as the transmission destination address (step S306).

  Then, the terminal device 100A and the ARP response packet as the transmission destination are unicast from the interface unit 13 <step S307>. This ARP response packet is received by the terminal device 100A via the first line concentrator 10A <Step S308, Step S309>. Note that the terminal device 100A that has acquired the MAC address of the terminal device 100B transmits data to the terminal device 100B.

  According to the network system described above, broadcast designation of the MAC address of the ARP request packet is converted into the MAC address of the second concentrator 10B in the address converter 42 of the first concentrator 10A. Thereby, since the broadcast packet is converted into a unicast packet, it is possible to avoid unnecessary ARP request packets from being transmitted to other terminal devices 100 in the broadcast domain.

  Further, the first concentrators 10A that have been conventionally connected using the route relay device 30 such as a router are connected using the second concentrator 10B. The second line concentrator 10B generates an ARP response packet corresponding to the ARP request packet, and the ARP response packet is unicast and received by the terminal device 100 via the first line concentrator 10A.

  Therefore, since the ARP response packet is not transmitted to the terminal device 100 other than the terminal device 100 that transmitted the ARP request packet, the throughput decreases due to the decrease in the band between the first concentrator 10A and the second concentrator 10B. Can be prevented.

  The first concentrator 10A may be a conventional concentrator. In this case, the ARP request packet is transmitted to all of the broadcast domain A by the conventional concentrator, and is thereby received by the second concentrator 10B. Even in this case, the second line concentrator 10B generates an ARP response packet, and the ARP response packet is unicast to the terminal device 100 that has transmitted the ARP request packet.

  For this reason, unlike the prior art, the route relay device 30 that has received a broadcast packet from one of the first concentrators 10A does not broadcast the packet to the other first concentrator 10A. Accordingly, it is possible to prevent a reduction in the band between the first concentrator 10A and the second concentrator 10B.

Further, by using the second line concentrator 10B instead of the route relay apparatus 30 such as a router, packet exchange or packet transmission can be performed in hardware. For this reason, it is possible to realize high-speed data transmission as compared with the route relay device 30 such as a router that performs software processing.

  Thus, by solving the shortage of bandwidth caused by the shared media type architecture, it is possible to cope with multimedia applications that are expected to become popular in the future.

<Fourth embodiment>
Next, a fourth embodiment of the network system of the present invention will be described. The network system in the fourth embodiment also relates to Ethernet (registered trademark).

<System overview>
The network system according to the fourth embodiment has the same overall configuration as that of the third embodiment of the network system, and is configured as shown in FIG.

  That is, as shown in FIG. 14, a plurality of terminal devices 100 are connected to each of a plurality of first concentrators 10A via communication lines, and each first concentrator 10A is connected to a second concentrator via a communication line. It is connected to the device 10B.

<First concentrator>
The first concentrator 10A according to the fourth embodiment is configured in the same manner as the concentrator 10A according to the third embodiment. That is, as shown in FIG. 15, the interface unit 13, the analysis unit 41, and the address conversion unit 42 are included. These descriptions are omitted in the third embodiment.

<Second concentrator>
Next, a second concentrator 10B according to the fourth embodiment will be described with reference to FIG. The second line concentrator 10B according to the fourth embodiment includes an interface unit 13, an address storage table 45, and a second address conversion unit 46. Among these, the interface unit 13 is the same as the interface unit 13 according to the third embodiment, and thus description thereof is omitted.

  The address correspondence table 45 stores all the IP addresses in the network system and the MAC addresses of the respective concentrators 10A. The second address conversion unit 46 extracts the IP address of the terminal device 100 that is the data transmission destination from the ARP request packet, searches the address correspondence table 45 using the IP address of the terminal device 100 that is the transmission destination, The MAC address of the first concentrator 10A corresponding to the address is detected.

  The MAC address of the transmission destination of the ARP request packet is converted into the MAC address of the first concentrator detected from the address storage table 45, and transmitted to the first concentrator 10A.

<Operation example>
An operation example of the network system having the above configuration will be described below with reference to FIGS.

For example, assume that an ARP request packet addressed to the terminal device 100B in the broadcast domain B is broadcasted from the terminal device 100A in the broadcast domain A shown in FIG. 14 (step S401). However, the terminal device 100 serving as the data transmission source or the data transmission destination is not limited to the terminal device 100A or the terminal device 100B, and any of the terminal devices 100 may be a data transmission source or a data transmission destination. Can be.

  This ARP request packet is transmitted to the first concentrator 10A through the communication line. The first line concentrator 10A receives the ARP request packet by the interface unit 13 and analyzes it by the analysis unit 41 (step S402).

  If the analysis unit 41 determines that the received packet is an ARP request packet, the analysis unit 41 terminates the ARP request packet. As a result, transmission of the ARP request packet to the terminal device 100 in the broadcast domain A is stopped. At the same time, the analysis unit 41 extracts the MAC address of the transmission destination of the ARP request packet, that is, the broadcast designation.

  Then, this ARP request packet is sent to the address translation unit 42. The address conversion unit 42 rewrites the broadcast designation, which is the MAC address of the transmission destination of the ARP request packet, with the MAC address of the second line concentrator 10B <step S403>.

  The ARP request packet with the destination MAC address converted in this way is transmitted from the interface unit 13 on the backbone LAN side to the second line concentrator 10B <step S404>.

  The second line concentrator 10B receives the ARP request packet at the interface unit 13 <step S405>. The received ARP request packet is sent to the second address conversion unit 46. The second address conversion unit 46 extracts the IP address of the terminal device that is the data transmission destination from the ARP request packet, searches the address correspondence table 45 using the IP address of the terminal device that is the transmission destination, and uses this IP address as the IP address. The MAC address of the corresponding first concentrator 10A is detected.

  Then, the MAC address of the transmission destination of the ARP request packet is converted into the MAC address of the first line concentrator 10A detected from the address storage table 45 (step S406). The ARP response packet is unicast from one of the interface units 13 to the first concentrator 10A to which the terminal device 100 that is the data transmission destination is connected (step S407), and is received by the corresponding first concentrator 10A. <Step S408>.

  The ARP request packet is sent to the address conversion unit 42, and the MAC address of the transmission destination of the ARP transmission packet is converted from the line concentrator 10A into broadcast designation (step S409).

  Then, the request packet is broadcast from any one of the interface units 13 <Step S410>. The broadcast ARP request packet is transmitted to each terminal device 100 in the broadcast domain and received by the terminal device 100B in the broadcast domain <step S411>.

  Upon receiving the ARP request packet, the terminal device 100B transmits an ARP response packet including its own MAC address to the terminal device 100A <step 412>. The ARP response packet is received by the first concentrator 10A to which the terminal device 100A is connected via the first concentrator 10A and the second concentrator 10B (steps S413 and S414). Then, the terminal device 100A receives the ARP response packet transmitted from the first line concentrator 10A <step S415>. In this way, the terminal device 100A receives the MAC address of the terminal device 100B that is the data transmission destination, and transmits data to the terminal device 100B.

  The effects of the fourth embodiment of the network system described above are substantially the same as the effects of the third embodiment of the network system, but the second concentrator is more effective than the third embodiment of the network system. The contents stored in the address storage table 45 provided in 10B can be reduced.

The block diagram which shows the principle of the network system of this invention A block diagram showing a first embodiment of a network system The block diagram which shows the hardware constitutions of the concentrator which comprises the network system shown in FIG. The figure which shows the memory | storage device of the concentrator which comprises the network system shown in FIG. Sequence diagram showing an operation example of the first embodiment Sequence diagram showing an operation example of the first embodiment Sequence diagram showing an operation example of the first embodiment Sequence diagram showing an operation example of the first embodiment Sequence diagram showing an operation example of the first embodiment Block diagram showing a second embodiment of a network system The figure which shows the hardware constitutions of the 2nd concentrator which comprises the network system shown in FIG. The figure which shows the memory | storage device of the 2nd concentrator which comprises the network system shown in FIG. The figure which shows the memory | storage device of a 2nd concentrator Block diagram showing a third embodiment of a network system The block diagram which shows the 1st concentrator which forms the network system shown in FIG. The block diagram which shows the 2nd line concentrator which forms the network system shown in FIG. The flowchart which shows the operation example of 3rd Embodiment The block diagram which shows the 2nd concentrator in 4th Embodiment of a network system The flowchart which shows the operation example of 4th Embodiment Block diagram showing a conventional network system Block diagram showing a conventional network system

Explanation of symbols

10a, 10b Concentrator 10A First concentrator 10B Second concentrator 16 Timer 21 Packet discriminating unit 25 Traffic volume measuring unit 30 Route relay unit 31 Procedure cancellation unit 42 Address conversion unit 44 Response unit 45 Address storage table 46 Second address conversion 50 Line information storage unit 60 Communication line control units 100a to 100n Terminal devices 110a and 110b Address holding server

Claims (2)

Comprising a plurality of first concentrator for multiple terminal apparatuses are connected via a communication line, and a second concentrator which the plurality of first concentrator is connected via a communication line,
Before SL respective first concentrator,
A plurality of communication interface units for transmitting and receiving packets to and from the terminal device and the second line concentrator connected to the own device;
When an address assignment request packet for obtaining an address of a destination terminal as a data transmission destination of the terminal device is received from a terminal device connected to the own device, the broadcast set as the destination MAC address of the address assignment request packet Conversion means for rewriting the address to the MAC address of the second line concentrator and unicasting the address assignment request packet with the destination MAC address rewritten to the second line concentrator ,
The second concentrator is
An address storage table storing addresses of the plurality of terminal devices connected to the plurality of first concentrators ;
When the address assignment request packet unicast is received from any of the first line concentrators, the address assignment table detects the address of the destination terminal corresponding to the address assignment request packet from the address storage table, and the address assignment A network system comprising: response means for transmitting an address detected from the address storage table to the terminal device that has transmitted the request packet . A plurality of first concentrators to which a plurality of terminal devices are respectively connected via a communication line; and a second concentrator to which the plurality of first concentrators are respectively connected via a communication line;
Each of the first concentrators is
A plurality of communication interface units for transmitting and receiving packets to and from the terminal device and the second line concentrator connected to the own device;
When an address assignment request packet for obtaining an address of a destination terminal as a data transmission destination of the terminal device is received from a terminal device connected to the own device, the broadcast set as the destination MAC address of the address assignment request packet Rewriting the address to the MAC address of the second line concentrator, and giving the address by rewriting the destination MAC address
Conversion means for unicasting the request packet to the second line concentrator,
The second concentrator is
A table storing the MAC address of each first concentrator;
When the unicast address assignment request packet is received from any of the first line concentrators, the MAC address of the first line concentrator that accommodates the destination terminal having the address requested by the address assignment request packet is stored in the table. And the destination MAC address of the address assignment request packet is rewritten to the MAC address of the first concentrator detected from the table, and the address assignment request in which the destination MAC address is rewritten has the destination MAC address. Having a second conversion means for unicasting to one line concentrator;
The conversion means of the first line concentrator, when receiving the unicast address assignment request packet from the second line concentrator, broadcasts the address assignment request packet to a broadcast domain including the destination terminal. Rewriting the destination MAC address of the address assignment request packet to a broadcast address .

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