JPH0983772A - Facsimile equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the throughput with an optimum combination of a layer and communication control parameters of the layer. SOLUTION: The communication control parameters of the layer 2 are previously set in a parameter setting part 15. The communication control parameters are transmitted to the layer 2 of an opposite station through a layer-2 negotiation part 16. Parameters sent from the opposite station in response to the transmission of the parameters are detected by a layer-2 negotiation part 16 and stored in a layer-2 parameter storage part 17. The parameters are read out to a parameter information part 18 and passed to the control program of the layer 3, and then stored in a layer-3 parameter storage part 19. A layer-3 negotiation part 20 enters into negotiations with the opposite station according to the parameters stored in the layer-3 parameter storage part 19.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a facsimile machine, and more particularly to a facsimile machine capable of determining a communication control parameter for ensuring optimum throughput.

[0002]

2. Description of the Related Art A G4 facsimile communication protocol is divided into seven layers in the OSI reference model. The function of each layer will be described with reference to FIG.
In the figure, the physical layer (layer 1) uses a physical medium such as a telephone line or a coaxial cable as a communication line,
It is a layer that manages electrical, mechanical and physical conditions and guarantees the transmission of bit strings. The data link layer (layer 2) is a layer that sets a data link between nodes connected by a communication line and executes data transmission, error control, and the like. The network layer (layer 3) is a layer that manages relay and routing functions for establishing a communication path with a partner system using various communication networks and guarantees transmission between systems. The transport layer (layer 4) is a layer that guarantees reliable data transfer between processes that are actually communicating in the final system at both ends of the communication network. Session layer (Layer 5)
Is a layer that manages dialogs such as how to send information required by processes, synchronization between processes, and management of resynchronization. The presentation layer (layer 6) is a layer that determines a data structure transferred between processes and performs data conversion with a common data structure as necessary. The application layer (layer 7) is the highest layer and is a layer that executes application protocols for users and management. The OSI reference model is described in JP-A-3-145242.

In such a structure, for example, in order to ensure a good communication function between the same layers between the systems A and B, a protocol between the same layers is defined and so-called horizontality of the protocol is realized. . Further, the interface between layers is defined so that even if the protocol of a certain layer is changed, the independence of the protocol does not affect other layers.

For example, a facsimile apparatus has an independent control program corresponding to each layer in its communication control apparatus, and exchanges data between each control program and instructs and notifies a protocol. The interface exists. In the data transmission, the data of layer 3 and above are all attached to the lower layer with a header attached,
Eventually it will be in the form of a frame that is layer 2 data,
It is transmitted at Layer 1, which is the physical layer. When receiving data, a frame that is layer 2 data is passed from the physical layer to layer 2. If this frame contains upper layer information, that part is passed to the upper layer and, if necessary, further to the layer above it.

Each of the layers has its own communication control parameter, and its value is predetermined as a default or determined by negotiation with the partner station. Conventionally, the control parameters are not related between different layers, and the parameters of a certain layer are not referred to by other communication control programs. The communication control parameters include k parameter (outstanding number) and modulo. The k parameter is a value representing the number of frames that can be continuously transmitted without the acknowledgment of the partner station. The modulo is the upper limit of the number of cycles attached to the frame, in order to prevent the frame from falling out or double capturing.

The structure of the layer 2 parameters, that is, the XID frame for the k parameter and the modulo negotiation will be described with reference to FIG. Prior to the setting of the data link layer, the calling terminal has an information field indicating the profile of the parameters that can be provided, and sets the poll bit P of the control field to "1".
Send a D command frame. The called terminal is the XI
XID with the final bit F of the control field set to "1" to confirm the reception of the D command frame
Send a response frame. These procedures are
Follow O / IEC 4335.

The modulo and k parameters are negotiated or indicated by the data link layer subfields. Items to be negotiated or indicated are described in the parameter identifier (PI) of the parameter field. First PI
Is encoded as an HDLC additional function identifier, and the first P
The L field indicates the length of the parameter field. The modulo value is set in the first PV field. Also, the second PI field is encoded as a k parameter transmission identifier, and the value of the transmission k parameter is set in the second PV field. The third PI field is encoded as the k parameter reception identifier. The value of the received k parameter is set in the third PV field.

On the other hand, the recommendation JT-T90 of the TTC standard that defines the G4 facsimile communication protocol provides a recommended table of the combination of the layer 2 and layer 3 parameters for obtaining the optimum throughput ( (See FIG. 8).

[0009]

The conventional facsimile apparatus has the following problems. That is, even though the recommendation table as described above is presented, the conventional facsimile apparatus has no means for realizing the combination of the layer 2 and layer 3 parameters described in the recommendation table. It was

It is an object of the present invention to solve the above problems and to provide a facsimile apparatus capable of obtaining a combination of control parameters for ensuring optimum throughput.

[0011]

SUMMARY OF THE INVENTION To solve the above problems and achieve the object, the present invention provides a layer 2 negotiation means for exchanging layer 2 parameters with a partner station, and a layer 2 parameter determined by the negotiation. The first characteristic is that the notification means for notifying the layer 3 control program and the layer 3 negotiation means for exchanging the layer 3 parameter with the partner station based on the determined layer 2 parameter are provided. A second feature is that the layer 2 parameter including the frame size in layer 2 is included.

According to the above feature, the layer 2 parameter and the layer 3 parameter can be associated with each other. Therefore, for example, as shown in Recommendation JT-T90,
It is possible to realize the combination of parameters according to the recommendation table for obtaining the optimum throughput.

[0013]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below with reference to the drawings. FIG. 2 is a block diagram showing the hardware configuration of the facsimile apparatus according to the embodiment of the present invention. In the figure, an image storage device 1 is for storing transmission originals and received image information read by the reading device 2,
It is a large-capacity storage device including a DRAM and a hard disk. The image processing device 3 encodes or decodes image information, and enlarges or reduces it. The image information read by the reading device 2 is compressed by the image processing device 3 and accumulated in the image storage device 1. The non-volatile memory 4 is a device for storing data that needs to be saved even after the power is cut off, and is composed of, for example, a magnetic disk.

The facsimile device further has communication control units 5 and 6, a modem 7, a digital network control device 8 and an analog network control device 9 as facsimile communication functions.
Having. The modem 7 is a modulator / demodulator having low-speed mode and high-speed mode functions, the analog network controller 9 is a device having an analog network connection function, and a digital network controller 8
Is a device having a function of connecting to a digital network such as an ISDN network.

The communication control unit 5 is a device for communication control suitable for digital networks such as G4, and the communication control unit 6 is G3.
Etc. is a device for communication control suitable for analog networks.
The communication control units 5 and 6 are ROs that store programs.
It is M.

The above components are connected to the system bus 10 and are controlled by the operation of the CPU 12 in accordance with a program stored in advance in the system controller 11. R
The AM 13 is used as a work area for storing control data for control by the CPU 12. The operation display unit 14 includes an input unit including a key for an operator to input an instruction and a display unit that displays a result processed by the CPU 12 according to the instruction and the like. The display unit can be configured by a known display means such as a liquid crystal panel.

Although an apparatus applicable to G3 facsimile communication has been taken as an example here, at least the function of G4 facsimile communication is sufficient for implementing the present invention. That is, the communication control unit 6 and the analog network control device 9 may not be provided.

Next, the operation of the facsimile apparatus having the above configuration will be described. First, the layer 2 control program will be described with reference to the flowchart of FIG. In the figure, in step S1, by the XID frame exchange procedure,
The k parameter and the modulo which are the layer 2 parameters are exchanged with the layer 2 of the partner station. In step S2, the k parameter and modulo to be actually used are determined based on the exchanged k parameter and modulo. Step S3
Then, the layer 2 link is established by the layer 2 data link establishment procedure. In step S4, the layer 3 control program is notified of link establishment by interprocess communication. In step S5, according to the layer 2 data transfer procedure, upper layer data transfer, especially image information transfer is performed. In step S6, according to the layer 2 link disconnection procedure,
Break the link.

Next, the layer 3 control program will be described with reference to the flowchart of FIG. In the figure, in step S7, a link establishment notification from layer 2 is waited for. If step S4 is executed and there is a link establishment notification from layer 2, the determination in step S7 becomes affirmative and the process proceeds to step S8. In step S8, the layer 2 parameter included in the link establishment notification is read. In step S9, the layer 3 connection procedure is performed, and the layer 3 parameters, that is, the window size and the packet size are negotiated according to the layer 2 parameters. In step S10, the layer 3 parameters are determined according to the negotiation.

FIGS. 5 and 6 are sequence diagrams of the processing described according to the flowcharts of FIGS. 3 and 4, respectively. In the sequence shown in the figure, step numbers (S ...) Are given to portions corresponding to the processes (steps) of FIGS. 3 and 4, and the correspondence between the sequence diagram and the flowchart is clarified.

In this embodiment, each of the layer 2 control program and the layer 3 control program is a process managed by the operating system, and the parameters determined in layer 2 are transmitted by interprocess communication from layer 2 to layer 3. I decided to do it. However, not limited to this transmission method, if the layer 2 and the layer 3 are configured to operate in the same address space, the layer 3 control program causes the address of the storage area where the parameter managed by the layer 2 control program is held. You can also directly reference the parameter from.

Next, a modification of the above embodiment will be described. This modification is made in view of the following points. In the recommendation table of JT-T90 shown in FIG. 8, the k parameter of layer 2 and the window size of layer 3 are always equal. Further, one frame of layer 2 can accommodate only one packet of layer 3. That is, the frame size is substantially larger than the packet size by the amount of header information, and is substantially the same size. Therefore, if the maximum value of the packet size of the layer 3 is determined, the maximum value of the frame of the layer 2 is also determined in association with the maximum value of the packet size.

Within the recommended range, the frame size of layer 2 is set to the default maximum value of 2 kilobytes, and there is no frame size negotiation itself. Therefore, even if the k parameter (= window size) is determined in layer 2, sent to layer 3, and negotiated with the partner station in layer 3, the packet size in layer 3 is determined by the packet size of the partner station. As a result, the combination of the layer 2 parameter and the layer 3 parameter may not be as recommended.

Further, when the transmission / reception memory is initially set to be divided into the default maximum frame size of layer 2, that is, divided into 2 kilobytes, and is used,
Based on the packet size negotiation result at layer 3, it is possible to reconfigure the memory by setting the divided size of the transmission / reception memory to a value smaller than the 2 kilobytes. In this case, since the negotiation result of layer 3 has to be transmitted to the layer 2 control program that manages the division of the transmission / reception memory, there is a problem that the number of times information is transmitted between the control programs in each layer increases. is there.

In this modification, the frame size is determined by the layer 2 negotiation. This can be realized by modifying the steps S1, S2 and S4 of the layer 2 control program (FIG. 3) described above as follows. First, in step S1, in addition to the k parameter and modulo in the XID frame exchange procedure, the frame size selected so as to be a combination of the recommended tables is exchanged with the partner station. At the layer 2 of the partner station, that is, the called station, the received XID frame is analyzed, and the k parameter, modulo, and frame size are determined so that the recommended table is obtained within the range of the value presented by the calling station. Send to. The calling station analyzes the parameters transmitted from the called station, and the negotiation is established (step S2). The parameters (k parameter, modulo, frame size) thus established are transmitted to the layer 3 communication control program (step S4). Further, the corresponding layer 3 control program negotiates the parameters of the layer 3 with the partner station according to the parameters (k parameter, modulo, frame size) transmitted from the layer 2.

FIG. 7 shows a communication sequence diagram between the control programs in the modified example. This sequence diagram also describes the initialization of the transmission / reception memory (buffer) and the timing of reconfiguring the transmission / reception memory according to the negotiation result.

As described above, in the modification, the packet size is exchanged based on the frame size determined in the layer 2 in the negotiation of the layer 3. This frame size is determined by negotiation with the partner station, and is considered as the packet size, and is determined by the combination with the k parameter and modulo based on the recommended table. The parameters of layer 3 obtained by negotiation with should be decided according to the recommended table.

Further, according to this modification, the transmission / reception memory is divided into the divided sizes based on the frame size determined by the negotiation result in layer 2 without the procedure of transmitting the negotiation result in layer 3 to layer 2. Can be changed and divided and reconfigured.
Therefore, when the memory is reconfigured (re-divided), it is possible to avoid an increase in the number of times information is transmitted between the layer 2 and the layer 3.

Next, the main function of the facsimile apparatus for executing the above operation will be described with reference to a functional block diagram. In FIG. 1, the parameter setting unit 15 is XI
It is a memory for presetting the layer 2 parameters exchanged in the D frame exchange procedure. The layer 2 communication control parameter set in the parameter setting unit 15 is transmitted to the layer 2 of the partner station via the layer 2 negotiation unit 16.
Sent to. Further, the parameters included in the XID frame transmitted from the partner station in response to this transmission are detected by the layer 2 negotiation unit 16 and stored in the layer 2 parameter storage unit 17.

The parameters stored in the layer 2 parameter storage unit 17 are passed to the layer 3 control program via the parameter notification unit 18. The passed parameters are stored in the layer 3 parameter storage unit 19. And
The layer 3 negotiation unit 20 transmits the parameters stored in the layer 3 parameter storage unit 19 to the layer 3 of the partner station to perform negotiation.

[0031]

As is apparent from the above description, according to the present invention, it is possible to provide a relation between the layer 2 parameter and the layer 3 parameter. Therefore, for example, it is possible to realize the combination of parameters according to the recommendation table shown in Recommendation JT-T90 for obtaining the optimum throughput. In particular, according to the invention of claim 2, since the frame size can be exchanged by the negotiation of the layer 2, the layer 3 is based on the result of the negotiation.
It is not necessary to take the procedure of notifying the layer 2 of the result of the negotiation performed again and determining the frame size again, and the efficiency of the entire process relating to the negotiation can be improved.

[Brief description of drawings]

FIG. 1 is a functional block diagram of a main part of a facsimile apparatus according to an embodiment.

FIG. 2 is a block diagram showing a hardware configuration of a control unit of the facsimile apparatus according to the embodiment.

FIG. 3 is a flowchart showing an operation of layer 2 according to the exemplary embodiment.

FIG. 4 is a flowchart showing an operation of layer 3 according to the embodiment.

FIG. 5 is a sequence diagram showing a layer 2 communication protocol with a partner station.

FIG. 6 is a sequence diagram showing a layer 3 communication protocol with a partner station.

FIG. 7 is a sequence diagram showing a communication protocol between layer 2 and layer 3 and a partner station.

FIG. 8 is a diagram showing combinations of parameters recommended by Recommendation JT-T90.

FIG. 9 is a conceptual diagram showing an OSI reference model.

FIG. 10 is a schematic diagram showing the structure of an XID frame.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Image storage device, 2 ... Reading device, 15 ... Parameter setting part, 16 ... Layer 2 negotiation part, 1
7 ... Layer 2 parameter notification unit, 18 ... Parameter notification unit, 19 ... Layer 3 parameter storage unit, 20 ... Layer 3 negotiation unit

Claims (2)

[Claims] 1. A layer 2 negotiation means for exchanging layer 2 parameters with a partner station, a notification means for transmitting a layer 2 parameter determined by the negotiation to a layer 3 control program, and a partner based on the determined layer 2 parameter. A facsimile apparatus comprising a station and a layer 3 negotiation means for exchanging layer 3 parameters. 2. The facsimile apparatus according to claim 1, wherein the layer 2 parameter exchanged with the partner station includes a frame size in layer 2.