JPS6161582B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an information transfer method in a packet terminal device that complies with a network architecture that specifies protocols (communication rules), and particularly relates to a method for transferring information in a packet terminal device that is compliant with a network architecture that specifies protocols (communication rules). It relates to an end-to-end transfer control method between devices. A method for joining a packet switching network as a packet terminal by harmonizing protocols above the transfer control level and protocols below the X.25 level was developed for general terminals (including host computers) that support basic procedures. This is a method that is often used as a means to effectively utilize the software resources that have been created. X・
Mechanisms for consistency with 25-level protocols are generally PAD (PACKET ASSEMBLE).
DEASSEMBLE), and may be built into a packet terminal or implemented as an independent chassis. Regardless of this implementation method, the present invention provides
It is positioned as a protocol defined between PADs.

The prior art will be described below with reference to the drawings. FIG. 1 shows an example of a protocol hierarchy. A packet terminal equipment (DTE) 1 is connected to a packet switching network 3 via a circuit terminating equipment (DCE) 2, and is connected to the other party's DTE 1' via the other party's DCE 2'.
can communicate with. Here, DTE1 and 1' are physical level, data link level,
It is assumed that the protocol has a hierarchical structure of a total of six levels: the transfer control level, the transaction control level, and the business level. The present invention is suitable for a transfer control method at the transfer control level indicated by diagonal lines in the figure, and is particularly suitable for DATA packets (DT packets).
It has a deep relationship with the data format of Figure 2 shows the data format of a DT packet.

Method I is a case where the data format in the basic procedure is directly used as the data format at the transfer control level, and after the packet header (PH) 4, the start framing character (STX) 5 and the data area (DATA/FIELD) 6 are used. and a termination framing character (ETX) 7. Adoption of method I provides good consistency with the basic procedure and facilitates PAD implementation, but it is necessary to send information on the startup sequence and termination sequence in the form of packets. As a result, the ratio of the effective number of data packets/total number of packets becomes small, especially in a query response system where the transfer link (the unit of data transfer between the start sequence and the end sequence) is short, which goes against the economical use of the packet switching network. become. Users who are trying to build a more economical online system using a packet switching network are naturally interested in its specifications, and include measures to reduce the number of packets in their system evaluation. In this respect, the conventional method has the disadvantage of being expensive.

An object of the present invention is to eliminate such conventional drawbacks, and to provide an information transfer system that does not require separate packetization and transmission of information on start-up sequences and end sequences.

The configuration of the present invention that achieves such an object includes a determination unit that determines whether information in the leading area of packetized information in a packet terminal device or a data communication entity is activation information (transfer termination information). When activating (terminating) a communication entity connected to the destination packet terminal device, the activation information and the address of the destination communication entity are placed in the head area of the information to be packetized (or transfer termination information in the rear area). is added, and the determination unit determines whether or not it is activation information (termination information), and activates (terminates) the target communication entity.

Next, embodiments of the present invention will be described with reference to the drawings.

The method shown in FIG. 2 is for explaining the method applied to the embodiment of the present invention.

The method shown in FIG. 2 is for explaining the method of the present invention, and is an example of a data format intended to omit the startup sequence and termination sequence and to ensure status management. In this case, from PH4 onwards, the transfer control header (TCH)
8, consists of a data area (DATA FIELD) 6 and a transfer control trailer (TCT) 9. TCH8
In addition, start code (START・CODE) 8
1. Transfer start identifier (SID) 82 and device
Consisting of address (DA) 83, TCT9 is
End code (END/CODE) 91, transfer end identifier (EID) 92 and reserve (RESERVED) 93
It consists of Both TCH8 and TCT9 are 1 byte long, and if they are replaced as they are in the position of the framing character in the conventional method I, the size of the DADT FIELD 6 in the method can be the same as that in method I. Furthermore, by encoding the framing characters, various characteristics of transfer data or transfer blocks can be reflected in TCH8 or TCT9, which has the advantage of increasing flexibility for future specification changes or expansions. It will be done.

Next, the functions of each component of TCH8 will be described. START CODE 81 consists of 2 bits and is used to indicate the attributes of the following data. For example, the bit combination is 00: control data, 01: SOH (START OF HEDING), 10:
STX (START OF TEXT), 11: DLE (DATA
By defining LINK ESCAPE), four types of data can be expressed. negative response
NAK (NEGATIVE ACKNOWLEDGE) response ENQ (ENQUIRY), interruption EOT (END OF
Transmission control sequences in basic procedures such as TRANSMISSION) are transferred with START CODE = 00. However, the acknowledgment ACK (ACKN
OWLEDGE) and normal termination sequence EOT are free in the former case to reduce packet charges.
PR (PACKET READY) packet shall be substituted, and in the latter case, EID92 control shall be substituted. Also, when transferring transparent data, START
Set CODE = 11 to distinguish it from non-transparent data transfer. SID82 is a 1-bit flag and is
Used as an identifier to distinguish between DT packets and continuous DT packets. For example, by defining SID=1 as a startup DT packet and SID=0 as a continuation DT packet, a startup sequence becomes unnecessary, contributing to measures to reduce the number of packets. Also,
If a failure occurs between PADs and a discrepancy occurs in the status of both, this identifier is used as a means to ensure status management in order to prevent failure recovery processing from occurring and the sequence operating as if it were normal. can do.

DA83 consists of 5 bits, 32 units (#0
It is used to set the device address assigned to the communication entity (device) up to #31). Traditionally, central booting methods based on basic procedures require device activation in the boot sequence.
However, since the startup sequence is omitted in the present invention, a device address specification area is required in the DT packet, and TCH8
It is defined within.

Next, we will discuss the functions of each element that makes up TCT9. END CODE 91 consists of 2 bits and is used to indicate the attributes of the transfer block. For example, the bit combination is 00: Reserve, 01:
ETB (END OF TRANSMISSION BLOCK),
10:ETX (END OF TEXT), 11:ENQ
By defining (ABORT instruction), four types of blocks including reserve can be expressed. EID92 is a 1-bit flag that is used for one transfer link (starting from a block with SID = 1).
This is used as an identifier to indicate the end of a series of block transfer units that end with the block with EID=1. For example, when EID = 1, the packet terminal device (station) that has the transmission right releases the transfer link,
This means giving back the right to send. After the transmission right is returned, both packet terminal apparatuses (both stations) enter a contention state, and the packet terminal apparatus (station) that generated the transmission request earlier obtains the transmission right. When transmission requests occur at the same time (starting DT packets collide), a table etc. that determines priorities is searched, and a pre-arranged priority station (packet terminal device) obtains the transmission right. In this case, the non-priority station suspends the transmission request and accepts the activation DT packet received from the priority station. Furthermore, when EID=0, the station (packet terminal device) that has the transmission right holds the transmission right and indicates that it intends to continue transmitting continuous DT packets. In this way, EID control eliminates the need for a termination sequence, contributing to measures to reduce the number of packets. In addition, END CODE=10
(ETX), it is possible to set EID=0, and in this case, it indicates that ETX train transmission is being performed.

RESERVED93 is a reserve field consisting of 5 bits, and is reserved in consideration of flexibility in the event that specifications are changed or expanded in the future.

FIG. 3 shows an embodiment of a packet terminal system to which the present invention is applied, where 1 is a DTE (packet equipment) and 10 is a determination unit, which determines whether activation information is included in the head area of packetized information or not. (or whether transfer end information is included in the rear area). Note that the activation information here corresponds to mutual activation by polling, selection, or activation ENQ in the basic procedure, and refers to the transfer start identifier (SID) in the transfer control header (TCH). Therefore, the operation of the receiving side upon receiving the activation information is similar to that of the conventional basic procedure. 11 adds activation information and the address of the communication entity to be activated to the head area of the first data sent when starting communication with the other party's communication entity, and adds transfer termination information to the rear area when terminating the transfer. This is the information editorial department.

Reference numerals 12 and 13 are communication main bodies, which are composed of a keyboard input device, an output device, and the like. Note that 2 is a line termination device.

The data sent from the communication entity is packetized as packet information by the DTE 1. At this time, when starting communication for the first time, the information editing section 11 creates the TCH 8 shown in the method shown in Fig. 2, and transmits the activation information and the other party. The data is edited to include the address of the communication entity, and then sent from the DTE 1 to the DCE 2 with a packet header 4 that is information regarding the packet terminal to which the destination communication entity is connected.

When the destination DTE 1' receives the system information via the DCE 2', it removes the packet header 4, determines whether the information in the head area is activation information or not in a section corresponding to the determination unit 10, and determines whether the information in the head area is activation information or not. In some cases, the communication entity at the corresponding address is notified that this is the first data to start communication.

Also, if you want to terminate the transfer, since the data transfer channel with the other party's communication entity is currently open, simply add transfer termination information to the rear area of the data, and the discriminator on the receiving DTE side will determine this. This will end the transfer.

Here, the determination section 10 and the information editing section 11 may be provided on each communication entity side, or one of them may be provided in the DTE and used only for reception or for transmission.

The determination unit 10 may be configured with a comparison circuit, a logic circuit, etc., but it can also be realized by a program using a general arithmetic circuit and memory. Information editorial department 1
1 can be similarly realized using a program inside the DTE.

Figures 4 to 6 are sent out in this way.
This shows the status of data transfer between DTE A and destination DTE B.

In these figures, only the data transfer phase is shown, and PH is omitted for simplicity. FIG. 4 shows an example in which station A transfers data to station B in ETB division. here,
The transfer control method is based on the conventional central activation method (with a distinction between the master station and slave stations), and in some cases, the DA83 of the DT packet transferred from the master station to the slave station is the destination device of the slave station. DA83 of the DT packet transferred from the slave station to the master station indicates the source device address of the slave station. In addition, if the transfer control method is based on the conventional mutual activation method (no distinction between master station and slave station), DA8 of the DT packet
3 indicates the destination device address of the other station regardless of the transfer direction. FIG. 5 is an example of ETX train transmission to (from) the same device, and FIG. 6 is an example of ETX train transmission to (from) different types of devices.
The definition of DA83 in the DT packet is the same as in FIG. 4. In this way, the present invention can be applied to ETX transmission without any problem.
It is possible to effectively utilize existing software resources, eliminate independent startup sequences or termination sequences, and realize measures to reduce the number of packets, and is also effective as a means of establishing specifications that take into account reliability of status management. .

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of a protocol layer for explaining the scope of application of the present invention in an easy-to-understand manner, and FIG. 2 is a diagram showing the data format of a DT packet at the transfer control level, which is one aspect of implementing the present invention. A diagram showing
FIG. 3 is a block diagram showing an embodiment to which the information transfer method of the present invention is applied, FIG. 4 is a diagram showing an example of the case where the present invention is applied to transfer control by ETB division, and FIG. to (from) the same device.
FIG. 6 is a diagram showing an example of the case where the present invention is applied to transfer control using ETX train signals to (from) a different type of device. be. 1 is a packet terminal device, 2 is a line termination device, 3 is a
is a packet switching network, 4 is a packet header, 5 is a starting framing character, 6 is a data area,
7 is a final framing character, 8 is a transfer control header, 9 is a transfer control trailer, 10 is a determination section, 11 is an information editing section, 12 is a keyboard input device, and 13 is an output device.

Claims (1)

[Claims] 1 Following the startup sequence that specifies the device address of the other terminal and starts it, STX, SOH,
This method sends a text that starts with a start framing character such as DLE and ends with a end framing character such as ETX, ETB, or ENQ, and packetizes the basic procedure communication that ends with the end sequence. replacing the character by a header of the same size as the starting framing character containing a code identifying the starting framing character, an identifier indicating whether it is a start-up data packet or a continuation data packet, and the device address; A packet header is added to a trailer of the same size as the terminating framing character, which includes a code for identifying the terminating framing character and an identifier indicating whether or not to terminate the transfer link. transmits and receives a packet in which the startup sequence and the end sequence are inserted into the text by receiving the header and trailer and identifying the code, the identifier, and the device address. method.