JPH06252949A - Packet switching device - Google Patents

Abstract

PURPOSE:To provide a packet switching device which can register the switching destination of fixed connection of the opposite party and can perform the automatic switching to the registered destination against a fault of communications due to the fault of the opposite party side, etc., in a packet switching network. CONSTITUTION:A table storing part 1 stores a fixed connection control table 4 where plural terminals of the opposite party side are registered for each fixed connection of the opposite party to each necessary outgoing terminal. A communications control part 2 selects one of terminals out of the table 4 and always secure a packet communications channel between the outgoing terminal and the selected terminal of the opposite party side. A switch control part 3 selects another terminal out of the table 4 and switches the packet communications channel for fixed connection of the opposite party to the packet communications channel set between both selected terminals when a reset instruction packet having the prescribed contents is received from the terminal of the opposite party side set on the packet communications channel for fixed connection of the opposite party.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packet switching apparatus in a packet switching network in which a so-called fixed connection (PVC) remote terminal can be automatically switched to a connection with another remote terminal when required. Regarding

[0002]

2. Description of the Related Art FIG. 2 is a diagram for explaining a packet switching network. Terminals 12a, b and c are connected to a packet switching network 10 by required lines 11a, b and c. The terminals 12a, b, and c are the packet switching network 10.
The packet exchange by means of the above makes it possible to exchange communication packets with each other. The packet switching network 10 is generally constructed by connecting a required number of packet switching devices 13a, 13b, 13c, etc. to each other.

As is well known, in the packet exchange, a partner selection (VC) connection and a partner fixed (PVC) connection are possible. In the partner selection connection, a predetermined call packet is used to connect each time a call is made. The partner terminal is designated, and the switching network sets up a packet communication path with the designated partner terminal to enable packet transmission / reception.

Further, in the fixed connection of the opposite party, the opposite party terminal is fixedly registered for each required terminal in the switching network, and the packet communication path between each of the two registered terminals is always maintained. For example, when the terminals 12a and 12b in FIG. 2 are registered in the permanent fixed connection, the logical connection shown by the broken line in the figure is always configured, and the data packets transmitted from the terminals 12a and 12b are always immediate. Is being transferred to the other terminal.

FIG. 3 (a) is a diagram for explaining the fixed connection management table. The calling side line number, the calling side logical channel name, the partner line number, and the partner logical channel name are set for each other side fixed connection. It is composed of.

The communication control unit of each packet switching device of the packet switching network uses the logical channel of the calling side logical channel name of the line of the registered calling side line number and the partner logic of the line designated by the partner line number. A packet communication path with the logical channel of the channel name is set and always held.

[0007] A packet communication path is a logical packet transmission path maintained in a packet switching network for relaying communication packets between originating and terminating terminals, irrespective of partner selection connection and partner fixed connection. When a required packet communication path is set, a pair of originating and terminating line numbers and logical channel names is set for each packet communication path in the call state management table of the necessary packet switching device as illustrated in FIG. 3 (b). Then, the communication is specified, and the status information of the communication (information indicating the status such as "communication in fixed connection with other party") is held and used for controlling the communication.

That is, in the control of each communication, when a packet as shown in FIG. 4A is received from a terminal connected to a line of a certain line number, the line number and the logical channel name attached to the packet (see FIG. 4 (a) LCGN (logical channel group number) and LCN (logical channel number)), the call state management table is indexed to determine the line number and logical channel name of the other party Relay to.

In FIG. 4 (a), GFI is a general format identifier indicating the type of control procedure, TYP is a packet type identifier indicating whether the type of packet contents is general data or various control information, etc. When it is displayed that the data is general data, it indicates that general data is placed at the DATA position, and the International Telegraph and Telephone Advisory Committee (CC1TT)
The format conforms to the X.25 specifications.

The above-described fixed connection with the other party is used in, for example, financial business for communication between the counter terminal and the host computer. In such use, in order to maintain the serviceability of the business system, in addition to the main computer of the host, a sub computer that backs up the main computer is installed in an appropriate place, and the main computer and the communication function to it are damaged. In the case of, the service is switched to the sub computer so that the service can be continued.

Therefore, in such a system, when communication with the main computer becomes impossible,
It is necessary to promptly switch the window terminal or the like connected to it so as to connect to the sub computer.

To this end, as is well known, in packet switching, it is possible to set a plurality of logical channels on the same line and perform individual communication. Each fixed connection is identified by a different logical channel name), and the normal logical channel name and the logical channel name when switching of the other party are required can be used properly.

However, in this case, a plurality of fixed connection of the other party are registered and the plurality of packet communication paths are always maintained, so that the resources of the packet switching network are consumed and the calling side is also consumed. The terminal must recognize the switching and properly use the logical channel number, which complicates the process.

As another method, in a system in which the state of the packet switching network is monitored by a network monitoring device or the like,
It is also possible to input a switching command from the network monitoring device when necessary to control the other terminal while maintaining the registered logical channel number on the calling side of the other party fixed connection. However, this method requires a manual switching operation, and a considerable delay is likely to occur from the occurrence of a failure of the other party to the switching.

According to the present invention, one or more switching destinations can be registered for one fixed connection of the other party, and when the communication with the other party to which the packet communication path is set is abnormal, the switching to the registered switching destination is performed. A packet switching device that is automatically operated.

[0016]

FIG. 1 is a block diagram showing the configuration of the present invention. The figure shows the configuration of a packet switching device, which is a packet switching device that controls the transmission and reception of communication packets between two terminals by setting a packet communication path between the two terminals. It has a control unit 2 and a switching control unit 3.

The table storage unit 1 holds a fixed connection management table 4 in which one or a plurality of the other terminals are registered for each one of the required fixed connections to each originating terminal. The communication control unit 2
The partner terminal of 1 is selected from the fixed connection management table 4 in a predetermined priority order, the packet communication path between the originating terminal and the selected partner terminal is set, and the packet communication path is always held.

The switching control unit 3 receives from the partner terminal side on the packet communication path set for the partner fixed connection,
When a reset instruction packet having a predetermined content is received, one of the partner terminals other than the partner terminal is selected from the fixed connection management table 4 in a predetermined priority order, and the packet communication path for the partner fixed connection is selected. The packet communication path set between the calling terminal and the last selected partner terminal is switched.

[0019]

With the packet switching apparatus of the present invention, the switching destination can be registered for the fixed connection of the other party, and in the communication of the fixed connection of the other party, for example, the line failure is caused by the reset instruction packet according to the protocol of the normal packet communication. When the reset cause code is received, the packet switching device identifies it and automatically switches the fixed connection partner.

Therefore, the switching can be performed relatively quickly after the occurrence of a failure or the like, and in this case, the calling terminal can continue the communication with the same fixed connection (that is, the same logical channel name) as that before the switching. Since it is possible, the terminal does not need to be aware of switching for communication, and can easily handle switching.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the present invention, in the fixed connection management table registered in the table storage unit 1, for example, as shown in FIG. Number and partner logical channel name (Fig. 3
(c) "remote line number 1, remote logical channel name 1" ~
“Other party line number n, partner logical channel name n”, etc.) can be registered, and the priority order for selecting the partner terminal in each partner fixed connection is, for example, the arrangement order from the top to the bottom of the drawing.

When such a fixed connection of the other party is registered in the packet switching device 13a of FIG. 2, the communication control unit 1 of the packet switching device 13a selects the first partner terminal in the fixed connection management table 4. Select and perform the packet communication path setting process between the originating line and the selected partner line.
If the fixed connection with the originator 12a and the terminal 12b as the first partner is registered, the packet switching devices 13a and 13b are registered.
Information necessary for packet communication between both terminals is set in the call state management table (see FIG. 3B), and both terminals are managed as a state of always communicating.

Therefore, in this state, the calling terminal 12a uses the packet in which the registered calling logical channel name is set as LCGN and LCN (see FIG. 4 (a)) at any time.
It is possible to exchange packets with b.

FIG. 5 is a diagram for explaining an example of the flow of the switching process of the switching control unit 3, and as described above, the terminal a and the terminal b are in the state of communicating via the packet switching devices a and b. When there is ((a) in the figure), for example, the packet switching device b
By detecting a failure in the line to the terminal b or receiving a reset request packet due to a failure or the like from the terminal b, according to the control procedure such as the CC1TT X.25 specification,
It is assumed that the reset instruction packet is sent to the packet switching device a as shown in (b).

The reset instruction packet is, for example, as shown in FIG.
As shown in, the description up to (a) is the same up to TYP.When the TYP indicates that the packet is a reset instruction packet, the number indicating the cause is displayed in the reset cause code of CAUSE, and If necessary, the detailed classification code is displayed in the DIAG reset diagnostic code.

In the packet switching apparatus a, the communication control unit 2 analyzes this reset instruction packet, indexes the call state management table by the logical channel name of the packet, and deletes the information of the corresponding call. If the call is a permanent connection and CAUSE = 01 indicates reset due to a failure, the process is passed to the switching control unit 3.

In the processing of FIG. 5, the switching control unit 3 deletes the information of the corresponding call from the call status management table, clears the fixed connection of the other party once, and performs packet switching as shown in (c) of FIG. The reset confirmation packet is returned to the device b.

In the next process, the registration of the partner fixed connection that has just been cleared is checked by the fixed connection management table, and the partner terminal of the next rank is selected. If this terminal is a terminal c connected to the packet switching device c, information on a packet communication path between the terminals a and c is set in the call state management table, and a control packet for setting the communication path is set as follows: Of FIG.
As shown in (d), it is sent to the terminal c via the packet switching device c.

As a result, the packet switching device c also sets the necessary call status management table, and when the confirmation packet is returned from the terminal c as shown in (e), the status of the call status management table is changed by the processing of Communication is enabled ((f) in the figure) as "during fixed connection communication".

Although the operation may be continued as it is, when the failure is recovered, the original communication state can be automatically returned as follows. That is, (f) in FIG.
In this state, when the packet switching device b detects the failure recovery of the line, it sends CAUSE = 09 to the packet switching device a with CAUSE = 09 so that the reset instruction packet indicates "operational" (g).

Therefore, the communication control unit 2 of the packet switching device a analyzes this reset instruction packet and passes the processing to the switching control unit 3. The switching control unit 3 performs the processing of FIG.
The corresponding call information is deleted from the call state management table, the fixed connection of the other party is once cleared, and the reset instruction packet is sent to the packet switching device c as "failure" as shown in (h) of FIG.
Send as CAUSE = 01.

In the next process, the registration of the partner fixed connection that has just been cleared is checked by the fixed connection management table, and the first
The partner terminal (terminal b) of the order is selected, the information of the packet communication path between the terminals a and b is reset in the call state management table, and the control packet for setting the communication path is shown in FIG. As shown in (i) of FIG.
In response to the above, each confirmation packet is returned as shown in (n) and (l), and the fixed remote connection between the reset terminals a and b is in communication.

[0033]

As is apparent from the above description, according to the present invention, it is possible to register a switching destination for a fixed connection in a packet switching network, and to register when a communication abnormality is detected due to a failure of the other party. The switching to the existing switching destination is automatically performed, and there is a remarkable industrial effect that the calling terminal can continue the communication as the same fixed connection of the other party continues regardless of the switching.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention.

FIG. 2 is a diagram illustrating a packet switching network.

FIG. 3 is an explanatory diagram of a management table

FIG. 4 is a diagram illustrating a packet format example.

FIG. 5 is a diagram illustrating a flow of a switching process of the present invention.

[Explanation of symbols]

 1 table storage unit 2 communication control unit 3 switching control unit 4 fixed connection table 10 packet switching network 11a to 11c line 12a to 12c terminal 13a to 13c packet switching device

Claims (1)

[Claims] 1. A packet switching device for controlling transmission and reception of a communication packet between two terminals by setting a packet communication path between the two terminals, the table storage section (1) and the communication control section (2 ) And the switching control unit
(3), and the table storage unit (1) stores 1 for each required originating terminal.
For each fixed connection of the other party, a fixed connection management table in which one or a plurality of the other party terminals are registered is held, and the communication control unit (2)
From the fixed connection management table (4), select the partner terminal of 1 with a predetermined priority, set the packet communication path between the originating terminal and the selected partner terminal, and keep the packet communication path always The switching control unit (3) holds the fixed connection management table when a reset instruction packet having a predetermined content is received from the partner terminal side on the packet communication path set for the partner fixed connection. From (4), one of the partner terminals other than the partner terminal is selected in a predetermined priority order, and a packet communication path for the partner fixed connection is set between the originating terminal and the last selected partner terminal. A packet switching device configured to switch to a packet communication path to be set.