JPH0650862B2 - Data communication control method - Google Patents

Description

The present invention relates to a data communication control method, for example, in a network system in which a plurality of local area networks each having a plurality of terminals are systematized using a gateway. The present invention relates to a communication control method.

[Prior Art] Generally, a plurality of local area networks (hereinafter referred to as LA
N) systems are connected to each other via an inter-network communication control device (hereinafter, referred to as a gateway) to constitute one network system as a whole, and a communication control device (hereinafter, referred to as a network system) connected to a certain LAN system. In order to send a data packet from a node) to a node on another local network, the following method has been conventionally used.

The node sends out (broadcast) to the transmission packet LAN by simultaneous broadcast communication, and each gateway connected to the system receives this packet. Then, the gateway that receives this packet determines whether or not it should be transmitted (relayed) to another LAN via its own device, and if it is a packet to be relayed via its own device, it is received as it is. Another LAN connected to the device
And send the send packet to the target node.

Each node holds all network configuration information, and when sending a packet to another LAN system node, adds all relay data including the route to the desired destination node in the transmission packet. Each gateway will relay and transmit the packet according to this relay data.

[Problems to be Solved by the Invention] In the above method, since the destination address of the transmission packet (destination address in the data link) is a broadcast address, it is confirmed whether the transmission packet has been correctly received by the gateway. Can't
Successful reception response (hereinafter referred to as ACK or acknowledgment) or unsuccessful reception response (hereinafter referred to as NAK or negative response)
There is a drawback in that it is impossible to confirm the transmission / reception by using the above.

In the method (1), each node must always have the information on the network configuration, and therefore each node must have a storage unit with a large storage capacity, which imposes a heavy burden on each node. There was a drawback.

[Means for Solving Problems] The present invention aims to eliminate the above-mentioned drawbacks of the prior art, and has the following configuration as one means for solving such problems.

That is, a communication control method in a network system in which a plurality of local area networks each having a plurality of terminals are systematized using a gateway, wherein a plurality of terminal devices and a plurality of gateways are provided in one local area network. And a transmitting side terminal which is one of the terminal devices transmits data to a receiving side terminal which is one of the terminal devices of another local area network via the gateway, the transmitting side Prior to data transmission, the terminal sends a transfer request packet containing information designating the receiving terminal to the plurality of gateways connected to the local area network to which the terminal is connected, by broadcast communication. And the gateway that has received the transfer request packet transmits the transfer request packet. Based on the the net work structure table for holding the contents and the device itself bracts, the transfer determines whether it is necessary to relay the own device, the determination result,
The relay gateway, which has determined that relay is necessary, transmits a response packet notifying that the own device relays to the transmission side terminal, and the transmission side terminal which has received the response packet causes the relay gateway and the reception. A data packet is transmitted to the relay gateway with the side terminal as a destination, and the relay gateway transmits a confirmation packet indicating whether or not the data packet is normally received to the transmission side terminal, and also relays the data packet. After that, the receiving terminal notifies the transmitting side terminal that the data packet is normally received.

[Operation] According to the above configuration, when a transmitting side node on a certain LAN transmits data to a receiving side node on another LAN via the gateway, prior to the data transmission, By transmitting the transfer request packet by the broadcast communication and receiving the response packet from the gateway that determines that the relay is necessary, the gateway to which the data is transmitted can be recognized.

Therefore, the node on the LAN does not need to hold the configuration information of the entire network system, and can easily and quickly recognize the gateway to which the data should be transmitted, and perform efficient data communication. be able to.

Further, since the transmitting side node recognizes the gateway to be relayed and transmits the data with the gateway as an arm tip, it is possible to obtain the reception success response or the reception failure response from the gateway for the transmission.

[Embodiment] An embodiment according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing a configuration example of a communication control apparatus according to an embodiment of the present invention, which is connected between a plurality of LAN systems and relays communication data between the systems.

The first communication control device connected to a plurality of LAN systems via the transmission lines 1a and 1b includes a holding means 10 for holding network configuration information and a communication device connected to the network system. According to the information held in the holding means 10, the transmitting / receiving means 11a, 11b for transmitting / receiving data, the response sending means 12 for sending a reception confirmation response to the received data from the sending / receiving means 11a, 11b And relay means 13 for relaying the received information.

FIG. 2 shows an example in which a plurality of LAN systems according to an embodiment of the present invention constitute one composite network system via a gateway.

In FIG. 2, reference numerals 21 to 27 denote individual LAN systems L01 to L07, respectively.
A node and a gateway are connected to 07. 31-
36 is each gateway G1-G6, 41-52 is each node N1-N12.

In the above configuration, each of the gateways G1 to G6 (31
To 36) have a routing table having a network structure, and have a function of determining a transmission path of a packet to be relayed in consideration of, for example, a traffic state. Therefore, each node N1 to N12 (41 to 52) does not need to store all the network configurations in its own device. It is sufficient for each of the nodes N1 to N22 (41 to 52) to hold only the system configuration in the LAN to which its own device is connected.

Different L in the network system having the above configuration
Data communication control between AN systems will be described below.

First, communication control of the nodes N1 to N12 (41 to 52) will be described with reference to the flow chart of FIG.

In steps S1 and S2, the node receives a reception packet addressed to the own node from the transmission path connected to the own device, or determines whether there is a transmission request from the information processing device connected to the own node. Is constantly monitored. Here, for example, when a transmission request is issued from the information processing device to another node or the like, the process proceeds from step S2 to step S3 to check whether or not the destination node is a node in the LAN to which the own node is connected. Since the node inputs and holds information about the LAN configuration to which the node is connected from the gateway etc. as necessary, it is the destination (destination).
It is possible to easily determine whether the node is in its own LAN.

If the destination node is within the same LAN, the process proceeds to step S4, and the transmission data packet is transmitted to the destination node by a known procedure. Then, in step S5, A is sent from the destination node.
It is checked whether or not the CK packet has been sent. If the ACK packet has not been received, the process returns to step S4, and the previously transmitted transmission data packet is retransmitted. Also, ACK
When the packet is received, it means that the transmission data packet has been normally transmitted, the transmission process is terminated, and step S1 is executed.
Return to. If there is transmission data, the process proceeds to step S4 again to transmit the next transmission data packet.

If the destination node to be transmitted in step S3 is not in the same LAN, it must be transmitted via the gateway, and in step S6 all gateways connected to the same LAN can be broadcast simultaneously. Sends a transfer request packet to another network (multicast).

Hereinafter, the node N1 (4) of the LAN system L01 (21)
From 1), node N10 of LAN system L06 (26)
The case of transmitting a data packet to (50) will be described as a specific example.

In this case, the node N1 (41) is the LAN system L0.
1 and all gateways connected to L01, that is, gateways G1 (31), G2 (3
2), a transfer request packet to another network is transmitted to G3 (33) by simultaneous broadcast communication (broadcast, multicast). During this transfer request packet,
The transmission request information to the node N10 (50) of the LAN system L06 is included.

The gateway that received the transfer request packet, in the process described later, in order to transfer the packet to the destination node, checks whether or not it should be transferred via its own gateway, and when it should relay its own device, A response indicating that the packet to be transmitted via the own gateway should be transmitted is output to the request transmitting node. Therefore, the node which transmitted the transfer request packet in step S6 waits for a response from the gateway in the following step S7.

If there is no response within the fixed time, it means that the destination node is not operating on the network system or does not exist on the network system. Therefore, the information processing apparatus which has output the transmission request in step S8. Then, error processing such as notifying that the transmission is impossible is performed and the process returns to step S1.

On the other hand, if there is a response from the gateway, the process proceeds from step S7 to step S9, and the gateway with the response, for example, the gateway G3 in the above specific example.
Since (33) returns a response to the node N10 (50) indicating that the packet is to be transmitted via this gateway, a packet addressed to the node N10 (50) having this gateway G3 (33) as the destination address is transmitted. To do.

Then, the gateway G3 (3
3) sends an ACK packet indicating successful reception if the packet reception from the node N1 (41) is normally completed without error, and if the reception is not normally completed, the reception is unsuccessful. Send a NAK packet indicating.
For this reason, the transmitting node checks the response from the gateway in step S10, and if it is an ACK packet, terminates the processing and returns to step S1, and if it is a NAK packet, returns to step S9 and retransmits the transmitting packet.

On the other hand, if there is a reception packet addressed to the own node in step S1, the process proceeds to step S12 to receive the transmitted packet. Then, in the subsequent step S13, it is checked whether or not a reception error has occurred, that is, whether or not the normal reception is possible. If the normal reception is not possible, the NAK is performed in step S14.
The packet is output, and if the packet is normally received, the acceptance packet is sent to the sender. And step S1
Wait for the ACK packet for the accepted packet at 6 and A
If the CK packet is received, the process is terminated and the process returns to step S1. If the ACK packet is not received, step S1 is executed.
At step 5, the received packet is retransmitted again.

Next, the communication control of the gateway of this embodiment will be described below with reference to the flow chart of FIG.

In step S21, the gateway monitors whether a packet addressed to the device itself (including a broadcast packet) is sent. When the packet addressed to the own device is received, the process proceeds from step S21 to step S22, and it is checked whether the received packet is not a communication packet in the same LAN or a relay packet. If the packet is not a relay packet, the process proceeds to step S23, and it is checked whether the request is a transfer request to another LAN by the simultaneous broadcast communication from the node. If it is not a transfer request, it is checked in step S24 whether or not it is a transfer request of the network configuration table held by its own device, and if it is not a transfer request, a process corresponding to the reception packet is executed in step S25. If the packet is a transfer request packet of the network configuration table, step S
Proceed to step 26 to send out the network configuration table. Then, in step S27, it is checked whether or not an ACK packet for the transmission packet has arrived. If the ACK packet is received, the process returns to step S21. If the ACK packet cannot be received, the process returns to step S26 to retransmit the transmission packet. To do.

By sending the above network configuration table transfer request to the gateway, another device (node or gateway) can know the network configuration at any time.

On the other hand, if a transfer request packet to another network is received in step S23, the process proceeds from step S23 to step S30, and the destination address of the received transfer request packet is analyzed by referring to the network configuration table. If, as a result of the analysis, it is not necessary to relay and transmit the own device, the process returns from step S31 to step S21,
Do not reply.

If it is determined to relay and transmit the own device, the process proceeds from step S31 to step S32 to transmit a response packet to the source node of the transfer request packet to the effect that it will be transmitted via the own device. Then, in step S33, the process waits for receiving a transfer packet from the source node to another LAN system. When the transfer packet is received, the process proceeds to step S34 to check whether the packet is normally received. If not received normally, step S
The NAK packet is transmitted at 35 and waits for the transfer packet to be retransmitted at step S33.

On the other hand, when the packet is successfully received, step S3
Proceed to step 6 to send the ACK packet. Then, in the next step S37, the received packet is transmitted to the gateway of another LAN in which the destination node instructed by the source node analyzed in step S30 exists (relay processing).

When transmitting from the above-mentioned node N1 (41) to the node N10 (50), a response is sent from the gateway G3 (33) to the broadcast communication from the node N1 (41) and sent to the transmission packet. On the other hand, reception confirmation can be performed between the node N1 (41) and the gateway G3 (33), and reliable data link can be performed.
Then, the gateway G3 (33) sends this transmission packet to the next gateway G5 (35), the gateway G5 (35) receives this transmission packet, and the destination node is connected to the LAN to which its own device is connected. After confirming that the node is a node, reliable data communication can be performed between the node N10 (50) and the gateway G5 (35) by a data link described later.

In the relay process described above, an example has been described in which the process proceeds from step S32 to step S33 and waits for only the transmission packet from the transmission source node, but the present invention is not limited to this, and step S21 is also used in the relay process. Returning to step 1, the data packet from another node may be controlled so that it can be monitored at the same time.

On the other hand, if the received packet is a relay packet in the previous step S22, the process proceeds to step S40 to check whether the relay packet is a packet addressed to a node in the LAN to which the own device is connected. And own LAN
If the packet is not a relay packet addressed to a node within the LAN, but is a packet addressed to a node within another LAN, the process proceeds from step S40 to step S37, and the received packet is transmitted to the next gateway.

If it is a packet to a node in the LAN to which its own device is connected, the process proceeds from step S40 to step S41 to transmit the packet to the node. Then, in the subsequent step S42, the reception of the ACK packet from the node is waited, and if the ACK packet is confirmed, the process is terminated and the process returns to step S21. On the other hand, when the ACK packet is not confirmed, the process returns to step S41 and the relay packet is retransmitted to the destination node again.

For example, from gateway G3 (33) to gateway G5
When the relay packet addressed to the node N10 (50) is sent to (35), the gateway G5 (35) is the packet addressed to the node of the LAN system L06 (26) to which the own device is connected. To node N10
It is possible to perform reliable data link by transmitting to (50) and making a confirmation response. Then, the node N10 (50) which has received this packet, in the case of normal reception, sends the reception packet to the transmission source node to the gateway G5 (3).
5) and receives an ACK packet for the received packet from the gateway G5 (35). On the other hand, the gateway G5 (35) having received the acceptance packet transmits it to the gateway G3 (33),
3 (33) transmits the acceptance packet from the node N10 (50) to the node N1 (41).

FIG. 5 shows the procedure for transmitting the data packet from the node N1 (41) to the node N10 (50).

As described above, according to this embodiment, when data is transmitted from a node on one LAN to a node on another LAN,
As the destination address of the data link for the packet, not the address for bloat cast or the address for multi cast, but the individual address of the gateway on the LAN is used. Therefore, the transmission / reception confirmation response such as ACK packet or NAK packet is sent. It can be used, and by using these, reliable data link can be performed.

In addition, each node does not need to have information on all network configurations, the storage capacity of the memory of each node is small, and there is no need to perform processing such as updating of network configurations, and communication control is simple. , Reliable and efficient data communication can be performed.

Furthermore, according to the present embodiment, if a node can control communication (procedure) with a gateway in the same LAN, it is possible to transmit to a node in another LAN. Even when a node moves from one LAN to another LAN, it is possible to transmit to another LAN as it is with simple communication control. Therefore, the constituent nodes can be easily moved to another LAN.

[Effects of the Invention] According to the present invention as described above, when a transmission side node on a certain LAN transmits data to a reception side node on another LAN via a gateway, prior to data transmission,
By transmitting a transfer request packet to multiple gateways by broadcast communication and receiving a response packet from the gateway that determines that relay is necessary, the gateway to which the data is transmitted can be recognized. it can.

Therefore, the node on the LAN does not need to hold the configuration information of the entire network system, and can easily and quickly recognize the gateway to which the data should be transmitted, and perform efficient data communication. be able to.

Further, according to the present invention, since the transmitting side node transmits the data with the gateway as the destination after recognizing the gateway for relaying, it is possible to obtain the reception success response or the reception unsuccess response from the gateway for the transmission. it can. Further, it can be confirmed via the gateway that the receiving side node, which is the destination of the transmission data, has normally received the data.

Therefore, the transmission side node can recognize whether or not the data has surely arrived at the reception side node on another LAN, which is effective in improving the reliability of data communication.

[Brief description of drawings]

FIG. 1 is a functional block diagram of the present invention, FIG. 2 is a network configuration diagram of an embodiment according to the present invention, and FIG. 3 is a data communication control flow chart of a transmission device constituting the network of the present embodiment, FIG. 4 is a data communication control flow chart of the gateway constituting the network of this embodiment, and FIG. 5 is a view showing a data communication control procedure with another LAN system. In the figure, 1a, 1b ... Transmission line, 10 ... Holding means, 11
a, 11b ... Transmitting / receiving means, 12 ... Response sending means, 1
3 ... Relay means, 21-27 ... LAN system, 31
~ 36 ... gateways, 41-52 ... nodes.

Claims (1)

[Claims] 1. A communication control method in a network system in which a plurality of local area networks each having a plurality of terminals are systematized by using a gateway, wherein one local area network includes a plurality of terminal devices and a plurality of gateways. When the transmitting side terminal, which is one of the terminal apparatuses, transmits data to the receiving side terminal, which is one of the terminal apparatuses of another local area network, via the gateway, the transmitting side terminal Sends a transfer request packet containing information designating the receiving side terminal to the plurality of gateways connected to the local area network to which the own device is connected by broadcast communication prior to data transmission. Each of the gateways receiving the transfer request packet Based on the contents of the request packet and the network configuration table held in the own device, it is judged whether or not the transfer needs to be relayed by the own device, and as a result of the judgment, the relay judged to be necessary to be relayed The gateway transmits a response packet for notifying that the device itself relays, and the transmission side terminal having received the response packet has the relay gateway and the reception side terminal as destinations. A data packet, the relay gateway transmits a confirmation packet indicating whether or not the data packet is normally received to the transmission side terminal, and after relaying the data packet, the reception side terminal A method for controlling data communication, which notifies the transmitting side terminal that the data packet has been normally received.