JP2569638B2 - Transport protocol with local protocol - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method in which a gateway device and a host computer directly connected to a packet-switched network use OSI (OPEN SYSTEMS INTERCONNECT) for a protocol above a transport layer.
ION).

[Conventional technology]

As a transport protocol when this kind of OSI procedure is adopted, there are X.224 class 0 protocol and JIS model protocol recommended by CCITT. In the following description, the transport protocol of the CCITT recommendations widely used at present is described as an example.

Conventionally, in devices using the X.224 class 0 protocol recommended by CCITT, the JUST-PC
VC (PERMANENT VIRTUAL CIRCUIT) and VC (VIR
TUAL CALL). That is,
When using the JUST-PC procedure in a packet-switched network, it was necessary to set a VC when setting up a session and release the VC when releasing the session.

[Problems to be solved by the invention]

As mentioned above, the reason for the inability to use this service is that JUST-PC
The transport protocol in the procedure is to disconnect the transport connection because the lower-level connection (VC and PVC in the case of a packet switching network) must be disconnected in order to disconnect the transport connection. If the lower connection of the transport connection cannot be disconnected each time communication ends, such as a fixed VC that does not release the VC until the system is stopped while the VC is established when the system is started, the JUST-PU
Procedure not available.

Therefore, an object of the present invention is to obtain a transport protocol which can be used in a PVC and a fixed VC in a packet switching network by an ISO procedure.

[Means for solving the problem]

According to the present invention, in a class 0 transport protocol of an OSI transport layer used in a network mechanism in which a gateway device and a host are directly connected to a packet switching network, each transport layer of the gateway device and the host includes: A transport disconnection protocol comprising a transport disconnection protocol data unit and a transport disconnection procedure, which is added as a local protocol, so that the procedure of the OSI model can be used in the PVC or the fixed VC of the packet switching network. Thus, a transport protocol to which a local protocol is added can be obtained.

〔Example〕

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

FIG. 1 is a diagram showing a format of a JUST-PC transport disconnection protocol data unit (TCQ) according to an embodiment of the present invention.

Reference numeral 101 denotes a header length, which is an essential item of 1 octet represented by a binary number of 1 or 3 or 5. The TCQ range indicated by the length of 101 indicates the length of the portion of 102, 103 and 104 excluding one octet of 101, but the disconnection reason of 103 and the diagnostic code of 104 are optional (104 is 103 Cannot be present if is not present), the header length is indicated by 1 or 3 or 5.

A code 102 is a mandatory item of one octet represented by a binary number 00001001.

A disconnection reason 103 is a 2-octet optional item indicating a reason for disconnecting the transport connection. The coding for this reason is not specified and depends on each system.

Reference numeral 104 denotes a diagnostic code, which is an optional two-octet item used to indicate a more detailed reason that cannot be indicated by the disconnection reason of 103 alone. The encoding of this diagnostic code is not particularly defined and depends on each system. Further, in order to define the diagnostic code, the disconnection reason of 103 must be set.

FIG. 2 is a state transition diagram of the JUST-PC transport protocol including the present invention. The JUST-PC transport disconnection procedure will be described with reference to FIG. The part added for transport disconnection is the transition between 201 and 202.

201 indicates that the event R-TCQ occurs in the idle state, that is, when the TCQ is received, state transition is not performed and the idle state remains, and 202 indicates that the event S-TCQ occurs in the data transfer state. When the TCQ is transmitted, or when the event R-TCQ occurs, that is, when the TCQ is received, it indicates that the state transits from the data transfer state to the idle state.

203 indicates a state transition direction when the transport connection request protocol data unit (TCR) is transmitted in the idle state, and 204 indicates a state transition when the transport connection disabled protocol data unit (TCC) is received in the TCR transmitted state. 205 indicates the state transition direction when the TCR is transmitted in the idle state, and 206 indicates the TCR received state in the TCR received state.
Indicates the state transition direction when CC is received.

207 indicates a state transition direction when a transport connection acceptance protocol data unit (TCA) is received in the TCR transmitted state, 208 indicates a state transition direction when the TCA is transmitted in the TCR received state, and 209 indicates a data transition direction. The state transition direction when a transport data transfer protocol data unit (TDT) is transmitted or received in the transfer state is shown.

210 indicates a state transition direction when a transport rejection protocol data unit (TDT) is transmitted or received in all states, and 211 indicates a state transition direction when a lower layer connection is disconnected in all states.

The idle state of 212 indicates a state in which a transport connection has not been set.
Waiting for TCA or TCC by sending CR, 214
The TCR received state is a state in which the TCR is received and it is determined whether to accept the transport connection setting.The data transfer state of 215 is a state in which the transport connection is set and data transmission / reception is possible. It is.

The transition of the JUST-PC transport protocol state including the present invention is as described above, and in the data transfer state,
By transmitting the TCQ or receiving the TCR, the transport connection is disconnected. TCR cannot be transmitted in a state other than the data transfer state. No operation is performed even if a TCR is received in the idle state.

FIG. 3 and FIG. 4 are diagrams respectively showing examples of the network configuration and the layer configuration implementing the present invention.

First, each part in FIG. 4 will be described. 401 is a CCITT V.27 ter recommendation as a physical layer (CCITT is omitted in the drawing; the same applies hereinafter), and 402 is a CCITT T. data link layer.
71 Recommendation (LAP-X), 403 is the CSDN network layer protocol of the CCITT T.70 recommendation, 404 is the transport layer class 0 protocol of the CCITT X.224 recommendation, and 405 is the CCITT X.22
BCS function group of session layer of 5 recommendation, 406 includes user application program including functions of application layer and presentation layer, 407 indicates CCITT network layer protocol (X.25PLP) of X.25 recommendation, 408 indicates CCITT
X.25 Recommendation of Data Link Layer Protocol (LAP-B), 4
09 indicates the CCITT X.21 recommendation for the physical layer.

410 and 418 are physical connections, 411 and 417 are data link connections, 412 and 416 are network connections, 413 is a transport connection, 414 is a session connection, 415 is a logical connection of a user application program, and 419 is CCITT X.224. A protocol obtained by adding the local protocol of the present invention to the recommendation class 0 protocol, 420 indicates the local protocol of the present invention.

Next, referring to Fig. 3, reference numeral 301 denotes a JUST-PC terminal that realizes the steps from the physical layer to the session layer by the JUST-PC procedure, and 302 denotes the transport layer and the session layer by the JUST-PC procedure. A JUST-PC host computer that realizes the procedure up to the network layer by connecting to the PVC of the packet switching network 305 and adds the local protocol of the present invention to the transport layer. Reference numeral 303 denotes a JUST-PC from the physical layer to the network layer. This is a gateway device having a function of converting between a packet switching procedure and a packet switching procedure, and further employing only the local protocol of the present invention in the transport layer on the packet switching network 305 side. Also 30
4 is a public telephone network, and 305 is a packet switching network.

In this example, a JUST-PC terminal 301 is connected to a JUST-PC host computer 32 connected to a packet switching network 305 via a public telephone network 304 and a gateway device 303. The network connection 416 of the packet switching network 305 is a PVC. The transport connection 413 is set between the JUST-PC terminal 301 and the JUST-PC host computer 302 to perform data transfer. The gateway device 303 does not participate in this operation. However, when the transport connection is disconnected, the gateway device 30
3 is disconnected by the procedure of the local protocol of the present invention, and the JUST-PC terminal 301 and the gateway device 30 are disconnected.
In order to disconnect the transport between the three, the network connection of 412 is disconnected according to the procedure of the protocol of X.224 class 0. (In fact, since the network connection of T.70 (CSDN) is not set from the beginning, the data link connection of 411 is Disconnecting), the transport connection can be disconnected.

Although the above description has been given of the JUST-PC procedure, the GIS procedure can be similarly described. That is, OS in a broad sense
The same can be said for the protocol of the I procedure.

In the above description, the use of PVC has been described, but the same effect can be obtained for VC.

〔The invention's effect〕

As described above, by adding the local protocol of the present invention to the transport layer of the OSI procedure, it is possible to construct a system that realizes the transport layer of the OSI procedure or higher on the PVC and the fixed VC in the packet switching network. Becomes possible.

The effect of using a PVC and a fixed partner VC in a packet-switched network, which is obtained when such a system is constructed, will be described. When using the transport layer of the OSI procedure or higher on a packet switching network, the network connection and the session connection are one-to-one and are not multiplexed. Therefore, if a PVC and a fixed partner VC are used, the operation of setting a network connection every time a session connection is set becomes unnecessary, and the session connection is set and the communication of the application program is started earlier. Another advantage is that if only VCs can be used in a packet-switched network, and VCs are set up to the number of VCs that can be set up, no more VCs can be set up. When constructing a system that wants to provide a service that allows communication at any time, PVC and the other party's fixed VC
If users are connected to them by using, the users can communicate at any time.

[Brief description of the drawings]

FIG. 1 is a diagram showing the format of the JUST-PC transport disconnection protocol data unit (TCQ) of the present invention, FIG. 2 is a state transition diagram of the JUST-PC transport protocol including the present invention, and FIG. 3 is the present invention. FIG. 4 is a diagram showing an example of a network configuration in which the above is implemented, and FIG. 4 is a diagram showing the layer configuration of FIG. Explanation of symbols 212 is idle state, 213 is TCR transmitted state, 214 is TCR received state, 215 is data transfer state, 301 is JUST-PC terminal, 302 is
JUST-PC host computer, 303 is a gateway device, 3
04 indicates a public telephone network, and 305 indicates a packet switching network.

Claims (1)

(57) [Claims] In a class 0 transport protocol of an OSI transport layer used for a network mechanism in which a gateway device and a host are directly connected to a packet switching network, a transport is provided to each of the transport layers of the gateway device and the host. A port disconnection protocol, comprising a transport disconnection protocol composed of a data unit and a transport disconnection procedure, added as a local protocol, so that the procedure of the OSI model can be used in the PVC or fixed fixed VC of the packet switching network. A transport protocol with a local protocol added.