JPS63292846A - Data communication system - Google Patents

Abstract

PURPOSE:To realize smooth and stable data transfer and to improve a throughput, by performing data transfer control in a network system based on the data reception performance information of the protocol converter of a DT packet reception side equipment. CONSTITUTION:A protocol control part 32, in the case of receiving a DT packet, stores a received packet in a reception data buffer storage area 41 in a memory 35. The protocol control part 32 receiving state report data which represents the available number of the storage area of a channel stores the state report data (X) in a DT packet flow control counter. And it resets a DT packet flow control flag, and sets a state at a DT packet transmittable state. Then, it checks whether or not the DT packet to be sent in a processing is held. If it is held, queuing data is read out, then, the processing is completed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is connected to a network system in which a plurality of communication control devices are connected to each other via a communication medium, and the communication between the network system and other systems is The present invention relates to a data communication method in a system having a protocol converter that enables data communication using the HDLC protocol.

[Prior Art] Conventionally, in data communication using the HDLC protocol (CCITT, X, 25 protocol), the D
Transmission of "bit-0" allows the delivery confirmation of the DT packet to be reported at a certain point within the network rather than from the other party's terminal.Therefore, using this has the advantage of improving data transfer throughput. When this method is applied to a private bucket network using a LAN system, by confirming the delivery of the D bit "0" of the DT packet at the sending protocol converter, the throughput within the LAN can be utilized to the maximum. Transfer becomes possible.

Figure 9 shows a LAN using a conventional protocol converter.
Show the system.

In the figure, 1 is HDLC protocore 1/ (CCITT,
, 25 protocol) terminal that transmits and receives data, 2
is a protocol converter, 3 is a LAN transmission path, and 4 is a relay network.

A functional hierarchy diagram of the protocol converter 2 shown in FIG. 9 is shown in FIG.

In the figure, 10 is a protocol converter control unit, 11 is x
, 25 control section, 12 LAP-B control section, 13 x, 2
5 protocol physical control unit, 14 x, 25 protocol transmission line, 15 LAN control unit, 16 LAN physical control unit, and 17 LAN transmission line.

Further, FIG. 11 shows an example of the intra-LAN data communication control procedure when the D bit of the DT packet is "0". here,
20 is a transmitting side protocol converter, and 21 is a receiving side protocol converter.

A conventional data communication control procedure will be explained using FIG.

The sending side protocol converter 20 receives a request to send the D bit "0" of the DT packet from the terminal side, and transmits the LAN
22 is the D bit “0” of this DT packet, code 2
Transmit as shown in 3. When this data is received by the receiving protocol converter 21, the
A reception response at the intra-LAN level is sent back to the sending protocol converter 20. Therefore, the sending side protocol converter 20 that received this sends the "R" as a delivery confirmation.
R'' packet 25 is sent to the terminal side.

By performing the above procedure, it becomes possible to transfer data by taking advantage of the transfer speed within the LAN.

[Problems to be Solved by the Invention] However, in the above communication control procedure, the transmitting side protocol converter 20 and the receiving side protocol converter 2
1, and if the received DT packets start to be delayed at the receiving side protocol converter 21, more data than necessary will be received, which will increase the load on the receiving side protocol converter 21. There is a problem in that this leads to a decrease in functionality and a decrease in the overall throughput of data transfer within the LAN.

[Means for Solving the Problems] The present invention has been made for the purpose of solving the above-mentioned problems, and as a means for achieving this purpose, this embodiment has the configuration shown in FIG. .

That is, a system that is connected to a network system in which a plurality of communication control devices are connected to each other via a communication medium, and that includes a protocol converter 110 that enables data communication using the HDLC protocol between the network system and other systems. The receiving means 111 includes a receiving means 111 that receives packets according to the HDLC protocol to the protocol converter 110, a transmitting means 112 that transmits the received packets to the LAN, and a receiving means 111. A detection means 113 for detecting D bit-“0” type DT packet transfer, and a buffer 11 for temporarily holding transmitted and received packets.
4, the reception capability is calculated based on the state of the buffer 114 when the detection means 113 detects the D bit-"O" type DT packet, and the produced reception capability information is returned in the transmission packet of the transmission means. and return means 115.

[Operation] In the above configuration, the protocol converter receives the D bit from the HDLC protocol from the line network =
When transferring a ``'0'' type DT packet into the network system, the conventional example At the same time, it is possible to eliminate the drawbacks of the above, and at the same time achieve smooth and stable data transfer and improve throughput.

[Example] Hereinafter, an example according to the present invention will be described in detail with reference to the drawings.

This embodiment also constructs a LAN network system similar to that shown in FIG. In this embodiment, the configuration of the protocol converter 2 in FIG. 9 is as shown in FIG. 2. The configuration of the protocol converter of this embodiment will be explained below with reference to FIG.

In FIG. 2, 30 is a LAN transmission line, 31 is a node unit connected to the LAN transmission line 30 and controls data transmission with the LAN transmission line 30, and 32 is connected to the node unit 31 and a transmission line 37 on the HDLC protocol side. protocol control section,
37 is an HDLC protocol (CCITT, X, 25 protocol) side transmission line.

In the protocol control unit 32, 33 is a transmission/reception control unit that controls the interface with the node unit 32, and 34 is a ROM.
34a is a microprocessor that controls the entire device according to the program stored in 34a; 34a is a ROM that stores various parameters, etc. in addition to the above-mentioned programs;
3 is a memory for storing control information, transmission/reception data, etc.;
6 is a transmission/reception control unit which is an HDLC side interface of the x, 25 protocol, and 37 is a transmission line on the HDLC protocol side.

An example of the format of the received data buffer in the memory 35 is shown in FIG. 3, in which 40 is a usability flag and 41 is a received data storage area.

The data communication control processing of the transmitting side protocol converter of this embodiment having the above configuration will be explained below with reference to FIG.

The protocol control unit 32 is the HDLC protocol side transmission line 3
It monitors whether or not the DT packet D bit="0" is received from the terminal 1 via the terminal 7, and when this DT packet is received, the process shown in FIG. 4 is executed.

First, in step S1, it is determined whether or not this DT packet is the first DT packet with the D bit="o" after the call is set up. Here, if it is the first DT packet, step S5
Proceed to ``set'' the DT packet flow control flag (not shown) and ``reset'' the DT packet counter.
In the following step S6, a DT packet (LAN data) is generated by adding status report request data to this DT packet, and this is transmitted into the LAN via the node section 31.

On the other hand, in step S1, if this DT packet is not the first DT packet after the call is set up, the process advances to step S2, and it is checked whether the DT packet flow control flag is set.

When the DT packet flow control flag is set,
When receiving a transmission request for the DT packet D bit "0", the process proceeds to step S8, where the protocol control unit 32 executes a DT packet transmission waiting process and holds the DT packet in a transmission waiting state.

Further, if the DT packet flow control flag is reset in step S2, the process advances to step S3, where the DT bucket counter is incremented by one, and in the subsequent step S4, the value of the DT packet counter is changed to the value shown in FIG. 6, which will be described later. It is checked whether it is equal to the value "X" of the DT packet flow control counter set by the process of step S20. If the two values are not equal, data transfer is enabled and the DT packet transmission process in step S7 is executed, the received DT packet is transmitted to the LAN via the node unit 31, the process is terminated, and the process returns.

On the other hand, if the two kakunta values are equal, the process proceeds to step S5 to check the status of the receiving side protocol control unit 32, and executes the same process as described above.

Details of the DT packet transmission waiting process in step S8 in the above process will be explained below with reference to FIG.

Upon receiving the DT packet, the protocol control unit 32 stores the received packet in the received data buffer storage area 41 of the memory 35 in step S10. and step S
At step 36, a usability flag 40 is set. Then, in the following step S12, it is checked whether this DT packet is a status report request, and if it is a status report request, the process advances from step 512 to step S13, where the usable number of storage areas of the memory 35 is checked, and in step 314, the number of usable storage areas is checked. The receivable amount is determined from the usable number, and in step S15, the value is reported to the DT packet transmitting side protocol control unit 32 as status report data, and the process returns.

If it is determined in step 312 that the state is not in the requested state, the process immediately returns.

Next, the processing of the protocol control unit 32 that has received the status report data in step S14 described above will be described below with reference to FIG.

Upon receiving the status report data indicating the usable number of channel storage areas, the protocol control unit 32 performs step S2.
0, this status report data "X" is stored in the DT packet flow control counter.

Then, in the following step S21, the DT packet flow control flag is reset to enable DT packet transmission. In step S22, it is checked whether or not the DT packet to be sent is on hold during the above processing, and if so, the queuing data is read out in step S23, the process is ended, and the process returns to step S1 in FIG. 4. .

Details of the transfer data packet of this embodiment used in each of the above processes are shown in FIGS. 7 and 8.

FIG. 7 shows the format of an intra-LAN packet to the protocol control unit 32 to which status report request data has been added; in the figure, 50 is a LAN destination address, 51 is a control code indicating a status report request, and 52 is an HDLC packet. It is.

FIG. 8 shows the format of a LAN storage packet to which status report data is added. In the figure, 53 is a LAN destination address, and 54 is a control address indicating the status report data.
Code 55 is the channel number to be reported, and 56 is report data.

[Effects of the Invention] As explained above, according to the present invention, by using data flow control within the LAN system regarding DT packet D bit = ``0'', the load on the protocol converter can be efficiently reduced. Data transfer that is more stable and guarantees higher throughput becomes possible.

[Brief explanation of the drawing]

FIG. 1 is a functional block diagram of an embodiment according to the present invention, FIG. 2 is a block diagram of a protocol converter according to an embodiment of the present invention, and FIG. 3 is the received data in the memory shown in FIG. 2. A diagram showing an example of the configuration of a buffer storage area, FIGS. 4 to 6 are processing flowcharts of the transmitting side protocol control unit of this embodiment, and FIG. 7 is a diagram showing a LAN status report request data format of this embodiment, Fig. 8 is a diagram showing the LAN status report data format of this embodiment, Fig. 9 is a general LAN system configuration diagram, Fig. 10 is a hierarchical configuration diagram of a conventional protocol converter, and Fig. 11 is a conventional FIG. 2 is a control diagram showing an intra-LAN communication control procedure. In the diagram! ...Terminal, 2...Protocol converter, 3...LAN transmission line, 4...Relay network, 10...
Protocol converter control unit, 11...-X, 25 control unit, 12...LAP-B control unit, 13...X, 2
5 protocol physical control section, 14...-X, 25 protocol transmission path, 15... LAN control section, 16... LA
N physical control unit, 17... LAN transmission line, 20...
Sending side protocol converter, 21... Receiving side protocol converter, 30... LAN transmission path, 31.
...Node part, 32...Protocol control part, 37...
・HDLC protocol side transmission transmission line...transmission/reception control unit, 34...microprocessor, 34a...R
OM, 35... Transmission/reception control unit, 37... HDLC protocol side transmission transmission line... Usability flag, 41...
...Received data storage area, 50...Destination address within LAN, 51°54...Control code, 52
...'HD LC packet, 53... LAN destination address, 55... channel number, 56... report data. Patent applicant: Canon Co., Ltd. Figure 1 Figure 2 Figure 31! f Figure 6 Figure 7 Figure 8 Figure 9

Claims (2)

[Claims] (1) HD is a local area network system consisting of multiple communication control devices connected to each other via a communication medium.
A data communication method for a data communication system having a protocol converter that enables connection to a line network that performs data communication based on the LC protocol, wherein the protocol converter receives data from the line network according to the HDLC protocol with D bit = "0" type. A data communication method characterized in that, when a DT packet is transferred within the network system, data transfer control within the network system is performed based on data reception capability information of a protocol converter of a DT packet receiving side device. (2) The data receiving capability information of the DT packet receiving device is determined by the memory capacity of the protocol converter that can store received packets, and the DT packet receiving device sends the data receiving capability information to the network system to communicate with other connected devices. Claim 1, characterized in that
Data communication method described in section.