JPH07321847A - Packet length control method and data communication equipment - Google Patents

Abstract

PURPOSE:To prevent the transfer delay of data and the deterioration of performance of a system from occurring in data communication equipment which provides connectionless type network service equipped with a convergence function corresponding to a connection type network. CONSTITUTION:A sub network managing part 17, when connection being established via a sub network, acquires packet division length decided by negotiation via a connection type network access control part 13, and updates the paket division length of a corresponding entry in a sub network managing table. A data transmission/reception part 15 divides data to be transmitted based on the packet division length in the table, and sends it out to a destination.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an OSI connectionless network service, and more particularly, to a packet length control method for providing a network service using a connection-oriented network as a subnetwork, and a connection-oriented network. The present invention relates to a data communication device that provides a connectionless network service having a convergence function.

[0002]

2. Description of the Related Art There are two types of network services, connection type and connectionless type. The connection type refers to a method of setting a logical connection before data transfer, and the connectionless type refers to a method of immediately transmitting data without setting a connection when a data transmission request is received. .

The OSI connectionless network service (hereinafter, CLNS) assumes a connectionless network such as a LAN in a lower layer, but has a function for making a subnetwork appear to offer a connectionless service. By using (hereinafter, a convergence function), a connection-type subnetwork can be used as a communication medium. This convergence function is located between the CLNS and the connectionless network, and performs connection management such as opening a connection with a destination prior to data transfer and disconnecting the connection after data transmission is completed.

In the following description, an upper layer including CLNS and its control unit is called a network layer, and a lower layer including a connection type network and its control unit is called a sub-network layer.

Generally, the connection-oriented service is often used in a network having a low quality of service such as a wide area network. In such a network, the packet length sent to the line is determined by negotiation performed when establishing a connection with the destination. On the other hand, in a network such as a LAN in which a connectionless service is used, the data length that can be transmitted is predetermined depending on the type of network.

In any network service, the maximum data length (hereinafter, maximum SDU length) accepted by one data transfer request is determined. CLN
In S, the maximum SDU length is set to be larger than the maximum packet length that can be sent to the network (hereinafter, maximum packet length), and when a data transmission request of a size larger than the maximum packet length is received, It has a dividing / assembling function of dividing a packet according to the maximum packet length on the transmitting side and assembling and restoring the divided data on the receiving side.

[0007]

When a sub-network in which the maximum packet length that can be transmitted is predetermined is used as the lower layer, such as Ethernet, the packet division size can be set in advance in accordance with this. However, when using a sub-network in which the maximum packet length that can be transmitted is determined at the time of establishing a connection, the packet division size cannot be determined in advance. The connection-type subnetwork also has a function of dividing / assembling data similar to CLNS, but as shown in FIG. 9, the data division size of the network layer 1 is set to the maximum SDU length of the subnetwork layer 2. , The sub-network layer 2 further divides the packet divided by the network layer 1 into the packet length determined by the negotiation, and then sends the packet to the communication medium 3.
Data division / assembly (in reverse order) will occur in both network layer 1 and sub-network layer 2.

Generally, data division / assembly processing is
The divided packets are ordered, and the packets are reordered in the order in which they were received, or after holding packets for a certain period of time, those that cannot be assembled (such as when some packets are lost during transfer) are discarded. Etc. involves very complicated processing. For this reason, double division / assembly on the same system is not preferable because it increases the data transmission delay and deteriorates the system performance.

It should be noted that Japanese Patent Laid-Open No. 4-216244 discloses a method of maintaining and releasing a connection of a connection type network used as a connectionless type sub-network without a transport connection used during connection type transport data transfer. A network connection control method has been proposed in which control is performed based on the value of an activity monitoring timer. However, this connection control method relates to the control of the timer that disconnects the connection, and no consideration is given to the division / assembly of data that occurs on the same system.

It is an object of the present invention to provide a packet length control method and a data communication device which do not require data division / assembly in the sub-network layer and prevent data transmission delay and system performance degradation. And

[0011]

A packet length control method according to a first aspect of the present invention is a packet length control method for providing a connectionless network service in which a connection network is connected to a subnetwork. When the connection is established via, the connectionless service is notified of the packet size determined by the negotiation with the destination,
The connectionless service is characterized in that data is divided according to the packet size notified from the sub-network while the connection with the sub-network is established. A data communication apparatus according to a second aspect of the present invention is a data communication apparatus that provides a connectionless network service having a convergence function corresponding to a connection-type network, and sets a packet size for dividing data to be transmitted into packets. A packet size holding unit that holds the data in association with the network, a network layer processing unit that divides / transmits the data to be transmitted based on the packet size held by the packet size holding unit, and a connection establishment via a connection-oriented network. Correspondingly, there is provided a packet size updating unit for updating the packet size held by the packet size holding unit to the packet size determined by negotiation with the destination when the connection is established.

[0012]

When the connection is established via the sub-network, the packet size determined by the negotiation with the destination at that time is notified to the network layer. In the network layer, the notified packet size is held in association with the sub-network, and the data is divided according to the notified packet size while the connection to this sub-network is established.

That is, when the connection is established via the sub-network, the data sent from the network layer is already divided into a size that can be sent to the sub-network, so it is necessary to divide the data in the sub-network layer. Instead, the data can be sent to the destination as it is.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a packet length control method and a data communication device according to the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a functional configuration of an end system to which the packet length control method and the data communication device according to the present invention are applied. The end system 10 is connected to a connection type network 14 (sub-network) and has a predetermined user interface and a data transmission / reception function. Hereinafter, the configuration of the end system 10 will be described with reference to the drawings.

Connectionless network control unit 11
Is for realizing the function of the network layer (hereinafter, synonymous with the network layer), and is configured by the data transmitting / receiving unit 15, the routing unit 16, and the sub-network management unit 17.

The data transmission / reception unit 15 carries out a process of assembling the data passed from the convergence control unit 12 described later and a process of dividing / transmitting the data received from the user. When the data transmission request is received, the sub-network to be used is searched by the routing unit 16, the packet division length in the searched sub-network is acquired by the sub-network management unit 17, and based on this packet division length. Split the packet.

The routing unit 16 manages routing information by a routing table (not shown). Here, the destination network of the packet to be transmitted is searched in the routing table, the system to be transferred next and the sub-network to be used are determined, and the data transmission / reception unit 15
To notify.

The sub-network management unit 17 holds a sub-network management table and manages the maximum data length that can be sent to each sub-network. here,
Connection establishment / connection establishment from the connection-oriented network access control unit 13 through the convergence control unit 12
When the release notification is received, the packet division length of the sub-network management table is updated based on the flowchart of FIG. 4 described later. The sub-network management table is a table that manages the packet division length when dividing data to be transmitted into packets for each sub-network, and is managed in the sub-network management unit 17. An example of the sub-network management table is shown in FIG. The sub-network management table uses the sub-network identifier as an entry, the sub-network type,
Items such as packet division length and maximum SDU size are set.

In the sub-network management unit 17 of this embodiment, when the release of the connection is notified, the packet division length of the sub-network management table is returned to the maximum SDU size of the sub-network. At times, since the packet division length is updated each time by negotiation, the value determined at the time of the previous connection establishment may be retained as it is.

The convergence control unit 12 is for using a connection type network as a sub network of the connectionless type network, and realizes a function for making the sub network appear to provide connectionless service. The convergence controller 12 includes a data transmitter / receiver 18 and a connection controller 19.

When the data transmission / reception unit 18 receives a data transmission request from the user, the data transmission / reception unit 18 inquires of the connection type network access control unit 13 whether or not the connection to the destination is established, and when the connection is established, , And passes the data to the connection-oriented network access control unit 13 as it is. If the connection is not established, the connection control unit 19 is requested to establish the connection, and the data is passed to the connection control unit 19 after the connection is established. When data is received from the connection-oriented network 14, the data is passed to the data transmitter / receiver 15 of the connectionless network controller 11.

The connection control unit 19 receives a request from the data transmission / reception unit 18 and issues a connection establishment request to a destination or a connection disconnection request after the end of data transmission / reception. These control requests are issued to the connection type network access control unit 13. Further, when the connection is established and released, to that effect (including the packet division length notified from the connection-oriented network access control unit 13 in the case of connection establishment), the sub-network management unit of the connectionless network control unit 11 Notify 17.

The connection-oriented network access control unit 13 realizes the function of the sub-network layer (hereinafter, synonymous with the sub-network layer), and establishes a connection based on the connection control request issued from the convergence control unit 12. / Execute the release process.
Further, when the connection is established, the packet division length determined by the negotiation with the destination is notified to the subnetwork management unit 17 of the connectionless network control unit 11 via the connection control unit 19 of the convergence control unit 12. . Further, the data passed from the data transmitting / receiving unit 18 is divided / transmitted based on the packet division length determined by the negotiation when the connection is established. However, the data division / transmission in the connection-oriented network access control unit 13 is executed only when the connection is established, and the data transmission / reception unit 15 of the connectionless network control unit 11 divides / transmits the data while the connection is established. Done.

Next, in the above-mentioned end system 10, a detailed processing procedure when a data transmission request is received from a user will be described with reference to the flowchart of FIG.

Connectionless network control unit 11
When the data transmission / reception unit 15 receives the data transmission request from the user, the data transmission / reception unit 15 requests the routing unit 16 to search the sub-network to be used (step 101). The routing unit 16 searches the routing table based on the destination address of the data to be transmitted, and passes the subnetwork identifier to the data transmitting / receiving unit 15 (step 10).
2). Subsequently, the data transmission / reception unit 15 requests the sub-network management unit 17 to search for the packet division length. The sub-network management unit 17 searches the sub-network management table based on the searched sub-network identifier, and passes the packet division length of the sub-network to the data transmission / reception unit 15 (step 103). The data transmission / reception unit 15 divides the packet based on the packet division length passed from the sub-network management unit 17, and passes the data to the data transmission / reception unit 18 of the convergence control unit 12 (step 104).

The data transmitter / receiver 18 of the convergence controller 12 checks whether or not the connection to the destination is established before transmitting the data (step 10).
5). If the connection has not been established, the connection control unit 19 is requested to establish the connection. The connection control unit 19 issues a connection establishment request to the connection type network access control unit 13 (step 106). The connection-type network access control unit 13 executes a connection establishment process (step 107). When the connection type network access control unit 13 succeeds in establishing the connection, the connection type network access control unit 13 notifies the convergence control unit 12 of the success of the connection establishment and the packet division length determined by the negotiation with the destination (step 108). In the convergence control unit 12, the connection control unit 19 notifies the subnetwork management unit 17 of the identifier of the subnetwork in which the connection is established and the packet division length. Further, the data transmission / reception unit 18 transfers the queued packet to the connection type network access control unit 13 (step 109). The connection-type network access control unit 13 divides the packet based on the packet division length previously determined by the negotiation, and sends the data to the sub-network (step 1
10).

That is, when the connection is established, the data transmission / reception unit 15 of the connectionless network control unit 11 divides the data (with the packet division length of the sub-network management table before the update), and then the convergence control unit 12 is executed. The data transmission / reception unit 18 divides the data (with the packet division length determined by the negotiation). After that, while the connection is established, the data is divided according to the packet division length after the update of the sub-network management table.

Connectionless network control unit 11
The sub-network management unit 17 searches the sub-network management table and updates the packet division length of the entry corresponding to the sub-network identifier notified from the connection control unit 19 to the notified packet division length (step 111). ).

Here, a processing procedure for updating the packet division length of the sub-network management table will be described with reference to the flowchart of FIG.

If the event notification sent from the connection-type network access control unit 13 through the connection control unit 19 is the establishment of a connection (step 201 "Y"), the sub-network management unit 17 applies the corresponding sub-network management table. The packet division length in the entry is updated to the notified packet division length (step 202). If the event notification indicates that the connection is released (step 201 “N”), the packet division length in the corresponding entry of the sub-network management table is updated to the maximum SDU size (step 203). According to this, when the connection is established, the data division is performed according to the packet division length determined by the negotiation, and when the release of the connection is notified, the packet division length is the maximum SDU of the subnetwork. Will be returned to size.

In the flow chart of FIG. 3, when the connection to the destination is established in step 105, the data transmission / reception section 18 passes the divided packet to the connection type network access control section 13 (step 112). The connection-type network access control unit 13 sends the delivered data to the sub-network (step 113).

Next, the processing procedure for releasing the connection will be described with reference to the flowchart of FIG.

Upon completion of data transmission / reception, the connection control unit 19 of the convergence control unit 12 issues a connection disconnection (release) request to the connection type network access control unit 13 (step 301), and the connection type network access control unit 13 Wait for notification of successful connection disconnection from (Step 30
2). Here, when the connection control unit 19 receives the notification of the successful connection disconnection, the connection control unit 19 notifies the subnetwork management unit 17 of the connectionless network control unit 11 of the identifier of the target subnetwork and the fact that the connection is disconnected (step 303). . The sub-network management unit 17 searches the sub-network management table and updates the packet division length of the entry corresponding to the sub-network notified from the connection control unit 19 to the maximum SDU size of the sub-network (step 3).
04).

Next, the operation of the end system 10 when receiving a data transmission request will be described with a specific example.

The maximum SDU size of the connection type network A to which the end system 10 is connected is set to 1024
Assuming bytes, the sub-network management table in the state where the connection is not established is as shown in FIG.
In this state, the connectionless network control unit 11
When the data transmitter / receiver 15 receives the data transmission request, the data transmitter / receiver 15 searches the routing table based on the destination address and finds that the sub-network A is used. Then, it is known from the sub-network management table that the packet division length is 1024 bytes. The data transmission / reception unit 15 divides the packet based on this packet division length and passes the data to the convergence control unit 12.

The convergence control unit 12 issues a connection establishment request to the destination to the connection type network access control unit 13 prior to data transmission.
When the connection is successfully established, the connection-type network access control unit 13 notifies the convergence control unit 12 of the success of the connection establishment and the packet division length determined by negotiation (here, it is determined to be 128 bytes). In response to this, the convergence control unit 12 notifies the subnetwork management unit 17 of the connectionless network control unit 11 that the identifier of the subnetwork A and the packet division length are 128 bytes, and the data transmission / reception unit 18 of itself.
The packet held in step 1 is passed to the connection type network access control unit 13. The connection-type network access control unit 13 divides the packet based on the packet division length determined by the negotiation and sends the data to the sub-network A.

On the other hand, the sub-network management unit 17 of the connectionless network control unit 11 receives the notification from the convergence control unit 12 and updates the packet division length of the entry corresponding to the sub-network A in the sub-network management table to 128. To do. FIG. 7 shows the state of the sub-network management table at this point. The data transmission / reception unit 15 of the connectionless network control unit 11 divides all packets into 128 bytes while the connection is established after receiving the notification of the update of the packet division length of the subnetwork A, and performs convergence control. Hand it over to section 12. The data transmission / reception unit 18 of the convergence control unit 12 passes the data as it is to the connection type network access control unit 13 while the connection is established. At this point, the packet has already been divided into a size that can be transmitted to the sub-network, so that the connection-type network access control unit 13 can directly transmit the data to the sub-network A without performing division. That is, as shown in FIG. 8, since the packet output from the network layer 1 has already been divided into the packet lengths determined by the negotiation, the sub-network layer 2 does not perform the division and directly sends it to the communication medium 3. Will be done.
Therefore, the data division / assembly occurs only in the network layer 1.

Next, the operation of the end system 10 when the connection is released when the data transmission / reception is completed will be described with a specific example.

It is assumed that the sub-network management table in the initial state (connection established state) is as shown in FIG. When data transmission / reception ends in this state, the convergence control unit 12 sends a connection disconnection request to the connection-type network access control unit 1
Issue to 3. After that, when the connection-type network access control unit 13 receives the notification of the successful connection disconnection, the convergence control unit 12 informs the sub-network management unit 17 of the connectionless network control unit 11 about the identifier of the sub-network A and the fact that the connection is disconnected. Notice. The subnetwork management unit 17 updates the packet division length of the entry corresponding to the subnetwork A in the subnetwork management table to the maximum SDU size. The sub-network management table in this state returns to the state of FIG.

[0041]

As described above, in the packet length control method and the data communication device according to the present invention,
When establishing a connection, the packet size determined by negotiation is held, and while the connection is established, the data is divided according to the currently held packet size, so it can already be sent to the subnetwork when sending data. It is divided into sizes. Therefore, it is not necessary to divide the data in the sub-network layer, and the data can be sent to the destination as it is, so that it is possible to prevent the data transmission delay and the system performance deterioration.

[Brief description of drawings]

FIG. 1 is a block diagram showing a functional configuration of an end system.

FIG. 2 is a diagram showing an example of a sub-network management table.

FIG. 3 is a flowchart showing a processing procedure when a data transmission request is made.

FIG. 4 is a flowchart showing a processing procedure for updating a packet division length of a sub-network management table.

FIG. 5 is a flowchart showing a processing procedure when releasing a connection.

FIG. 6 is a diagram showing a state of a sub-network management table when a connection has not been established.

FIG. 7 is a diagram showing a state of a sub-network management table when a connection is established.

FIG. 8 is an explanatory diagram showing how packets are divided in the embodiment.

FIG. 9 is an explanatory diagram showing how packets are divided in a conventional example.

[Explanation of symbols]

10 ... End system, 11 ... Connectionless network control unit, 12 ... Convergence control unit, 13 ...
Connection type network access control unit, 14 ... Connection type network, 15 ... Data transmission / reception unit, 1
6 ... Routing unit, 17 ... Sub-network management unit,
18 ... Data transmitting / receiving unit, 19 ... Connection control unit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location H04L 29/06 9371-5K H04L 13/00 305 Z

Claims (2)

[Claims] 1. A packet length control method for providing a connectionless network service by connecting a connection-oriented network to a sub-network, wherein when a connection is established via the sub-network, the packet size determined by negotiation is used. A packet length control method characterized in that the connectionless service is notified, and the connectionless service divides the data according to the packet size notified from the sub-network while the connection is established. 2. In a data communication device for providing a connectionless network service having a convergence function corresponding to a connection type network, a packet size holding means for holding a packet size when dividing data to be transmitted into packets. A network layer processing means for dividing the data to be transmitted based on the packet size held by the packet size holding means, and a packet size held by the packet size holding means corresponding to the establishment of a connection via a connection type network And packet size updating means for updating the packet size to a packet size determined by negotiation with the destination when the connection is established.