JP2800725B2 - Communication control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication control method in an information processing device such as a data terminal device. The present invention relates to a communication control method for executing a control procedure.

[0002]

2. Description of the Related Art Conventionally, JIS (Japa) has been used as a transmission control procedure used for data communication in a data terminal device or the like.
nese Industrial Standard) X510
4, high-level data link control procedures (referred to as “HDLC procedures”) defined in X5105 and X5106.

[0003] The HDLC procedure is a typical transmission control procedure for realizing confirmation type data communication involving error control and flow control by retransmission, but recently, as a new transmission control procedure to replace the HDLC procedure, A cell relay procedure for transmitting data in fixed-length cell units, specifically,
TU-T (International Telecommunication Union-Te
lecommunication Standardization Sector, International Telecommunication Union-Telecommunication Standardization Sector) Recommendation G. The cell relay procedure specified in 804 is being used.

[0004] The cell relay procedure is a transmission control procedure for high-speed communication of information such as large-volume data and video.
All information is divided into data units of 48 octets (1 octet = 8 bits), and a header of 5 octets length is added as destination label information to each of the divided data units, so that a fixed length of 53 octets in total is added. And transmits information by forming a frame (also referred to as a "cell"). By performing high-speed switching by hardware based on header information attached to the cell,
This enables large-capacity and high-speed data communication.

[0005] The cell relay procedure having such excellent features is expected to occupy a central place to replace the HDLC procedure in the future in the trend of increasing data communication capacity and speeding up. However, during the transition period up to that point, naturally, HDLC, which has been generally adopted,
And a new transmission control procedure, a cell relay procedure,
Are used together.

However, a frame that follows the HDLC procedure,
Since the data format is different from the frame according to the cell relay procedure, if the frame according to each of these transmission control procedures appears on the same line in a mixed manner, the conventional apparatus transmits and receives data (particularly, Receiving).

Therefore, in this type of conventional device,
In order to correspond to each transmission control procedure of the HDLC procedure and the cell relay procedure, hardware / firmware for performing the protocol processing of the HDLC procedure and hardware / firmware for performing the protocol processing of the cell relay procedure are separately prepared. A line is individually accommodated for each piece of hardware / firmware, and protocol processing for transmission control is performed.

[0008]

However, in the above-described conventional apparatus, hardware / firmware is required for each of the transmission control procedures of the HDLC procedure and the cell relay procedure. This not only increases the complexity and cost, but also hinders the miniaturization and weight reduction of the device.

Further, since it is necessary to prepare at least two lines corresponding to the respective transmission control procedures of the HDLC procedure and the cell relay procedure, a line usage fee increases and two lines can always be used effectively. However, there is a problem that the line utilization rate also decreases.

Accordingly, the present invention has been made in view of the above problems, and enables transmission and reception of data (protocol multiplex processing) according to different transmission control procedures using the same hardware / firmware. It is an object of the present invention to provide a communication control method that enables simplification, miniaturization and weight reduction of a device.

Further, the present invention adopts a communication control system capable of reducing a line charge and improving a line use efficiency by adopting a configuration which can accommodate only one line. The purpose is to provide.

[0012]

In order to achieve the above object, the present invention provides JIS X5104, X5105, and X5
A frame (“received frame”) in which a frame according to a high-level data link control procedure (referred to as “HDLC procedure”) defined by H.106 and a frame according to a cell relay procedure for transmitting data in fixed-length cell units are mixed.
A communication control method for receiving the received frame, based on a data format of the received frame, an identification unit for identifying a type of a transmission control procedure followed by the received frame, and the type identified by the identification unit. Means for controlling a transmission control procedure to be performed on the received frame in accordance with the communication control method.

Further, the present invention relates to JIS X5104, X
5105 and a frame that complies with a high-level data link control procedure (referred to as “HDLC procedure”) defined in X5106 and a frame that complies with a cell relay procedure for transmitting data in fixed-length cell units (“Reception”). A communication control method for receiving the received frame (serial data) into parallel data, based on a data format of the parallel data converted by the conversion means. Identification means for identifying a type of a transmission control procedure followed by the received frame; means for processing the received frame according to the HDLC procedure when the type identified by the identification means is the HDLC procedure; If the type identified by the means is the cell relay procedure, It provides a communication control method characterized by comprising means for processing the received frame according Rurire procedure, a.

[0014] Preferably, in the communication control method of the present invention described above, the identification means includes the reception frame.
For the cell relay procedure or the HDLC procedure.
It is preferable that an error detection is performed as a frame, and a type of a transmission control procedure followed by the received frame is identified based on an error detection code of the received frame.

Still preferably, in the above-described communication control system of the present invention, after the identification means performs primary identification based on the length of the received frame, the identification means may add an error detection code to the received frame. It is preferable that secondary identification is performed based on the received identification information to identify the type of the transmission control procedure that the received frame follows.

The principle and operation of the present invention will be described below.

In the communication control method according to the present invention, the type of the transmission control procedure that the received frame follows according to the data format of the received frame is identified, and the appropriate transmission for the received frame is performed according to the identified type. By selecting and executing a control procedure, even when receiving a frame in which a frame according to the HDLC procedure and a frame according to the cell relay procedure are mixed, if the traffic on the line is small, each transmission control procedure is performed. In addition, two different transmission control procedures can be supported by the same hardware / firmware without separately preparing a line, hardware / firmware, and the like.

In the communication control method described above,
When the received frame identifies the type of the transmission control procedure, the error detection code of the received frame is arranged at a predetermined position in the received frame, and is arranged in the case of the HDLC procedure and the case of the cell relay procedure. Utilizing the fact that the positions are different, the type of the transmission control procedure followed by the received frame is identified.

Further, in the above-described communication control system, when identifying the type of the transmission control procedure that the received frame follows, the fact that the length of the frame that follows the cell relay procedure is fixed is used, After the primary identification is performed based on the error detection code, the secondary identification is performed based on the error detection code of the received frame, thereby shortening the identification time.

[0020]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing a partial configuration of an information processing device such as a data terminal device according to an embodiment of the present invention.

The communication processing control section 6 shown in FIG. 1 is built in a data terminal device or the like, and performs control for data transmission and / or reception, and is connected to the network 1 via a line. Have been.

In this embodiment, the number of lines accommodated in the communication processing control unit 6 from the network 1 is one.
After the data link according to each transmission control procedure of the DLC procedure and the cell relay procedure is set, transmission and reception of frames of different data formats according to each transmission control procedure are performed via the same line.

The communication processing control unit 6 includes therein the serial-parallel conversion unit 2, frame identification unit 3, HDLC processing unit 4, and cell relay processing unit 5.

The serial-parallel converter 2 converts a frame (serial data) received from the network 1 via a line into parallel data, and conversely converts a frame to be transmitted (parallel data) into serial data. It is for.

The frame identification section 3 identifies the type of the transmission control procedure that the received frame follows, based on the data format of the received frame (parallel data) converted by the serial-parallel conversion section 2.

The HDLC processing unit 4 is provided with the JI
SX5104, X5105, and X5106, which perform protocol processing in accordance with the HDLC procedure specified in X5104, X5105, and X5106. 804 (ATM (Asyn)
chronous Transfer Mode, asynchronous transfer mode, etc.).

When the communication processing control unit 6 receives from the network 1 a frame (serial data) in which a frame conforming to the HDLC procedure and a frame (cell) conforming to the cell relay procedure are received, first, a serial-parallel signal is received. The conversion unit 2 converts serial data in a form on a line into parallel data in a form used in a higher-level device such as a data terminal device.

Then, based on the data format of the converted reception frame (parallel data), the frame identification unit 3 determines whether the reception frame follows the HDLC procedure or the cell relay procedure. Done.

As a result of the identification, the frame according to the HDLC procedure and the frame (cell) according to the cell relay procedure are separated, and the upper layer protocol processing is performed on the separated frame according to each transmission control procedure.

That is, the protocol processing according to the HDLC procedure is performed in the HDLC processing unit 4 for the frame according to the HDLC procedure, and the protocol processing according to the cell relay procedure is performed in the cell relay processing unit 5 for the frame according to the cell relay procedure. Processing is performed.

Here, the data format of a frame according to each transmission control procedure of the HDLC procedure and the cell relay procedure will be described.

FIG. 2 is a diagram for explaining the data format (format) of a frame according to the HDLC procedure.

Referring to FIG. 2, the data format of a frame according to the HDLC procedure will be described.

The frame according to the HDLC procedure is “011”.
Starting from a head flag 201 having a pattern of "11110", fields of an address field 202, a control field 203, an information field 204, and an FCS (frame check sequence) 205 are arranged.
A data format in which a tail flag 206 having a pattern of “0” is arranged is adopted.

The address field 202 is a field (8 bits) for indicating the address of the communication partner terminal or the own terminal.

The control field 203 is a field (8 bits) used for a command command to the partner terminal or a response from the partner terminal. (1) Information transfer (I) used in a frame for information transfer
Format, (2) monitoring (S) format used for notifying frame reception confirmation, retransmission request, etc. according to information transfer (I) format, and (3) non-number for performing other control functions There are three formats (U).

The information field 204 is a section for storing user information, control information, and the like, and has a variable length of 0 to 4096 octets depending on the amount of data to be transmitted and received.

The FCS 205 is an error detection code field (16 bits) for confirming whether or not the address field 202, control field 203, and information field 204 have been correctly transmitted to the partner terminal. Here, a CRC code (Cyclic Redundancy Check Code, cyclic redundancy code) having a small error oversight rate is used for error detection.

FIG. 3 is a diagram for explaining the data format of a frame (cell) according to the cell relay procedure.

Referring to FIG. 3, the data format of a frame (cell) according to the cell relay procedure will be described.

Frame (cell) according to cell relay procedure
Starts with a head flag 301 consisting of a pattern of “01111110”, header parts 302 and 303 and a user information part 304 are arranged. Finally, a tail flag 305 consisting of the same pattern of “01111110” as the head flag is arranged. Data format is adopted.

The header sections 302 and 303 indicate destination information for transmitting data to the partner terminal, and include information such as flow control between terminals and communication paths.

Note that the entity of the destination information is located in the header (1) to header (4) 302 from the first octet to the fourth octet, and in the fifth octet,
An error detection HEC (Header Error Control) 303 for confirming whether the destination information arranged from the first octet to the fourth octet has been correctly transmitted to the partner terminal is arranged.

The HEC 303 is a CRC code (Cyclic Redunda) having a small error oversight rate, like the FCS described above.
ncy Check Code, cyclic redundancy code) and header (1)
Or error detection of the header (4) 302.

User information section 304 is for storing user information to be transmitted to the partner terminal, and has a fixed length of 0 octets or 48 octets.

The data formats of the frames according to the transmission control procedures of the HDLC procedure and the cell relay procedure have been described above. When the frames according to these transmission control procedures are compared with each other, the characteristic differences of the data formats are as follows. 2
Points.

In the following description, the head flag 201 is used to specify the length of the frame, the position in the frame, and the like.
And 301, and the last flags 206 and 305 are not included.

First, the length of a frame according to the HDLC procedure is 4 to 4100 depending on the amount of data to be transmitted and received.
While the octet has a variable length, the length of a frame (cell) according to the cell relay procedure is always a fixed length of 5 octets or 53 octets regardless of the amount of data to be transmitted and received.

Second, a frame that follows the HDLC procedure is:
The CRC code (FCS205) for the CRC check is always located at the end of a frame having a length of 4 to 4100 octets and is composed of 2 octets, whereas the frame (cell) according to the cell relay procedure starts from the top. At the fifth octet, a CRC code (HEC 303) of one octet for CRC check is located.

Therefore, by utilizing the difference in the data format of the frame according to each of the transmission control procedures of the HDLC procedure and the cell relay procedure, it is possible to identify the type of the received frame appearing coexisting on the same line.

FIG. 4 is a flowchart for explaining the processing in the communication processing control section 6 according to the present embodiment shown in FIG.

Referring to FIG. 1 to FIG. 4, the communication processing control unit 6 identifies and separates the types of received frames appearing together on the line, and separates each of the separated frames into a predetermined format. A series of processes up to execution of a protocol process according to the transmission control procedure will be described.

First, the serial-parallel converter 2 counts the number of octets of a received frame converted into parallel data (step 401).

Next, it is determined whether or not the number of octets of the portion sandwiched between the head flag and the tail flag consisting of the pattern "01111110" is 5 octets or 53 octets (step 402).

If the number of octets is 5 octets or 53 octets (YES in step 402), the 5th octet counted from the first flag is set to the CR
As a C code, a CRC check is performed on data from the first octet to the fourth octet (step 40).
3).

If the result of the CRC check is normal (YES in step 403), it is determined that the received frame follows the cell relay procedure.

Then, the received frame determined to be a frame following the cell relay procedure is sent to the cell relay processing unit 5, and the upper layer protocol processing is performed (step 40).
4).

On the other hand, if it is determined in step 402 that the number of octets is not 5 octets or 53 octets (NO in step 402), and if it is not determined in step 403 that the frame complies with the cell relay procedure (step 403). In the case of NO), the two octets immediately before the last flag are set as the CRC code and 1
A CRC check is performed on the data from the octet to the (n-2) octet when the total number of octets of the frame is n (step 405).

If the result of the CRC check is normal (YES in step 405), it is determined that the received frame complies with the HDLC procedure.

Then, the received frame determined to be a frame following the HDLC procedure is sent to the HDLC processing unit 4 and
Upper layer protocol processing is performed (step 40).
6).

If the result of the CRC check is not normal (NO in step 405), the HDL
It is determined that the frame does not comply with either the C procedure or the cell relay procedure, and the received frame is discarded (step 407).

By performing the above-described series of processing in the communication processing control unit 6, transmission based on a received frame composed of a plurality of octets in which it is unknown whether the frame complies with the HDLC procedure or the cell relay procedure. The type of control procedure can be identified, and appropriate protocol processing can be performed according to the identified received frame.

In particular, in the present embodiment, the type of the transmission control procedure followed by the received frame is determined mainly based on the easily countable value of the frame length, which is particularly preferable in terms of processing time. .

In the present embodiment, after the primary identification is performed according to the length of the frame, the secondary identification using the CRC check is performed for more accurate identification. The processing time can be significantly reduced as compared with the case where the CRC check is performed uniformly from the beginning.

Further, in this embodiment, by performing a CRC check for final identification, the accuracy of the identification can be made extremely high.

The embodiment of the present invention has been described above.
The present invention is not limited to such an embodiment, but includes various embodiments according to the principle of the present invention.

For example, in the above-described embodiment, the received frame converted into parallel data by the serial-parallel converter 2 is used to identify the received frame in the frame identification unit 3, but is composed of serial data. Naturally, it is also possible to directly identify the received frame with respect to the received frame.

However, when the received frame is identified based on the length of the frame as in the above embodiment, the length of the frame, that is, the length of the frame, More preferably, the number of octets is counted.

In the above-described embodiment, the configuration in which one line is accommodated from the network 1 to the communication processing control unit 6 has been described. However, a configuration in which a plurality of lines are accommodated is also possible.

[0071]

As described above, according to the communication control method of the present invention, a received frame according to a different transmission control procedure is identified based on its data format. Even in a mixed case, the same hardware / firmware can realize the protocol processing in accordance with the respective transmission control procedures, thereby reducing the amount of hardware, efficiently using lines, and reducing line usage fees. Can be achieved.

In the communication control system of the present invention,
Using the identification means described in claim 3 or claim 4,
By identifying the type of the transmission control procedure followed by the received frame, the above-mentioned effect can be obtained more suitably.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a partial configuration of an information processing device such as a data terminal device according to an embodiment of the present invention.

FIG. 2 is a diagram for describing a data format (format) of a frame according to an HDLC procedure.

FIG. 3 is a diagram illustrating a data format of a frame (cell) according to a cell relay procedure.

FIG. 4 is a flowchart for explaining processing in a communication processing control unit 6 shown in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Network 2 Serial-parallel conversion part 3 Frame discrimination part 4 HDLC processing part 5 Cell relay processing part 6 Communication processing control part

Claims (4)

(57) [Claims] 1. JIS X5104, X5105, and X
5106. A frame in which a frame conforming to a high-level data link control procedure (referred to as “HDLC procedure”) defined in 5106 and a frame conforming to a cell relay procedure for transmitting data in fixed-length cell units are mixed (“received frame”)
A communication control method for receiving the received frame, comprising: an identification unit for identifying a type of a transmission control procedure followed by the received frame based on a data format of the received frame; and the type identified by the identification unit. Means for controlling a transmission control procedure to be performed on the received frame in accordance with the communication control method. 2. JIS X5104, X5105, and X
5106. A frame in which a frame conforming to a high-level data link control procedure (referred to as “HDLC procedure”) defined in 5106 and a frame conforming to a cell relay procedure for transmitting data in fixed-length cell units are mixed (“received frame”)
Conversion means for converting the received frame (serial data) into parallel data; and receiving the data based on a data format of the parallel data converted by the conversion means. Identification means for identifying a type of a transmission control procedure followed by a frame, wherein the type identified by the identification means is the HDLC
Means for processing the received frame according to the HDLC procedure, if the type identified by the identification means is the cell relay procedure, means for processing the received frame according to the cell relay procedure, A communication control method comprising: 3. The apparatus according to claim 2, wherein
The frame of the cell relay procedure or the HDLC procedure
Error detection code of the received frame detects an error as
3. The communication control method according to claim 1, wherein a type of a transmission control procedure followed by the received frame is identified based on the correctness of the communication control. 4. The receiving means performs primary identification based on a length of the received frame, and then performs secondary identification based on an error detection code of the received frame. 3. The communication control method according to claim 1, wherein a type of a transmission control procedure followed by the frame is identified.