JP3122998B2 - Packet switching device and control method therefor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a packet switching device for performing packet switching and a control method thereof.

[Prior Art] In a packet exchange service in ISDN, packet communication is provided not only by an information channel B channel but also by a signal channel D channel. Also,
If the D-channel packet communication is performed using the basic interface of ISDN, the two B-channels can be used for other communication purposes. Therefore, the usefulness of the D-channel packet communication has been proposed.

Against this background, with the spread of ISDN in recent years,
ISDN packet terminals that support D-channel packet communication are increasing. However, the future packet exchange system must accommodate not only the D-channel packet but also a data terminal that supports the B-channel packet, and as a packet exchange control device having two packet processing functions of the B-channel and the D-channel. A packet handler module (hereinafter referred to as PHM) is required.

FIG. 4 is a block diagram showing an example of the system configuration of a conventional packet exchange. In the figure, the packet switching apparatus 100 has a hardware configuration, and in order to reduce the cost burden of a user who uses only the D-channel packet terminal, the PHMB 104 and the PHMB 104 that perform a B-channel packet switching process as a packet handler module (PHM). It is divided into PHMD105 which performs channel packet exchange processing,
Users have the option to use PHM.

In the packet exchange shown in FIG. 4, a local line ISDN primary group interface 101, a local line ISDN basic interface 102,
Alternatively, the B-channel packet arriving at the extension ISDN basic interface 103 is transmitted to the PHMB 104 via the transmission path 111 and the communication path switch 106 under the control of the central control unit (CC) 107. In addition, the D channel packet is the central control unit (CC) 10
Under the control of 7, the data is sent to the PHMD 105 via the control bus 112. The control bus 114 has a central control unit (CC) 107 of PHMB10.
4 to control.

[Problems to be Solved by the Invention] However, in the conventional packet exchange shown in FIG. 4, since the function of the PHM is divided into two, a PHMB 104 and a PHMD 105, packet communication using the B channel, for example,
When a B-channel packet is transmitted from the PHMB 104, a failure occurs in the B-channel or the packet cannot be transmitted if the B-channel is busy, so that the exchange service in the packet exchange cannot be smoothly performed.

[Means for Solving the Problems] In order to solve the above problems, the present invention can reliably exchange received packets even if a failure occurs in a channel of the type used for reception after receiving the packets. The purpose is to be.

In order to achieve the above object, an apparatus according to the present invention comprises:
A packet switching device capable of performing packet switching using a channel of the first type and packet switching using a channel of the second type, comprising: receiving means for receiving a packet using the channel of the first type; When exchanging a packet received by the receiving means, a judging means for judging whether packet exchange using a first type of channel used for receiving the packet is possible, and a judgment by the judging means. Accordingly, control means is provided for controlling a packet received using the first type of channel to be exchanged using the second type of channel.

The method according to the present invention is a control method for a packet switching device capable of performing packet exchange using a first type of channel and packet exchange using a second type of channel, the method comprising: Receiving a packet using the first type of channel; and exchanging the packet received in the receiving step using a first type of channel used for receiving the packet. A judging step of judging whether or not the packet is received, and a control of controlling a packet received using the first type channel to be exchanged using the second type channel, according to the judgment in the judging step. And a step.

[Operation] According to the present invention, even if a failure occurs in a channel of the type used for reception after receiving a packet, it is possible to reliably exchange the received packet. For example, when a received packet is exchanged after receiving a packet on a B channel or a D channel in ISDN, no problem occurs even if the B channel or the D channel used for reception has a failure due to busy or the like. It can be exchanged by the type of channel.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the configuration of a packet exchange according to one embodiment of the present invention.

In FIG. 1, a central control unit (CC) 107 controls the entire packet exchange 100, and controls an ISDN primary rate interface 101.
(Hereinafter, referred to as PRT) and an ISDN 120 via an ISDN basic interface 102 (hereinafter, referred to as BRT). Also,
An ISDN packet terminal 121 (hereinafter, referred to as DTE) is connected to the extension ISDN basic interface 103 (hereinafter, referred to as BRI). Each interface transmits layer 3 information of a D channel packet of SAPI (Service Access Point Identifier) = 16 as a packet data transfer service to a D channel packet handler module to be described later.

B channel packet handler module (hereinafter PHMB)
104) is responsible for the storage and exchange of B channel packets,
A D-channel packet handler module (hereinafter referred to as PHMD) 105 manages storage and exchange of D-channel packets. Further, the PHMB 104 has a built-in protocol conversion unit 108 which controls the layer 2 of the B channel packet exchange and has a link level protocol conversion function for establishing a data link with the PHMD 105.

A central control unit (CC) 107 controls a communication path switch 106 to control each interface of PRT101, BRT102, BRI103 and PHMB104.
Form a communication path with The transmission line 111 is for B channel packet transmission, the control bus 112 is for transmitting D channel packet, and the central control unit (CC) 107 is for PRT101, BRT102, BRI.
103 for controlling each interface.
The central control unit (CC) 107 controls the PHMB through the control bus 114.
104 and the PHMD 105, and from the PHMB 104 via the transfer path 113.
An X.25 packet level protocol (hereinafter, referred to as X.25PLP), which is packet layer 3 information, is directly transferred to the PHMD 105.

Next, with reference to the flowchart shown in FIG. 2, a packet processing procedure in the packet exchange in this embodiment will be described.

The B channel packet or the D channel packet from the ISDN 120 is received by the PRT 101 or the BRT 102, and the B channel packet or the D channel packet transmitted from the DTE 121 which is the extension terminal of the packet exchange 100 is
Received by BRI103.

In step S1 of FIG. 2, when the reception of the B-channel packet or the D-channel packet is detected in the above-mentioned interface, the interface receiving the packet receives the packet via the control bus 112 in the next step S2. Notifying the central control unit (CC) 107 of the completion. Upon receiving the notification, the central control unit (CC) 107 proceeds to step S3 where B
In the case of receiving a channel packet, the communication path switch 106 is controlled so that the interface receiving the packet and the PHMB 10
A packet transmission path is formed between the BMB and the PHB 104, and the received B channel packet is stored in the PHMB 104. If the received packet is a D-channel packet, the received packet is stored in the PHMD 105 via the control bus 112.

Next, if the received packet is a B-channel packet,
Since the determination in step S18 is YES, the process proceeds to step S4. That is, the PHMB 104 starts transmission of the stored B channel packet, and in step S4, the central control unit (CC) 10
Ask 7 to check all accessible B channels. Upon receiving the request, the central control unit (CC) 107
In step S5, the B channel used for the B channel packet communication is checked to determine whether there is a busy or a failure. If the result of the determination in step S5 is YES, that is, if there is a failure in the B channel, the process proceeds to step S6, and the central control unit (CC) 107 sets a data link on the D channel to the PHMD 105. Request. Then, in the following step S7, it is determined whether the link setting has been completed.

If the result of the determination in step S7 is that the data link has been set up normally, the central control unit (CC) 107 obtains a determination of YES in step S19, and then in step S8 the layer 3 of the packet with respect to the PHMB 104. Permits transfer of information, X.25PLP, to PHMD105. Then, in the following step S9, PHMB10
4 performs protocol conversion to establish a data link with PHMD 105, and transmits X.25PLP to PHMD 105 via transfer path 113.
Transfer to The PHMD 105 sequentially stores the transferred X.25PLP.

Next, in step S10, the PHMD 105 analyzes the header of the X.25 PLP and specifies an interface for transmitting the X.25 PLP. In the following step S11, the PHMD 105 transmits the stored packet via the control bus 112 to the interface specified in step S10.

If it is determined in step S5 that the B-channel packet communication is enabled, the process proceeds to step S12, where the central control unit (CC) 1
07 requests the PHMB 104 to set up a data link on the B channel for the B channel packet. Then, in step S13, it is determined whether the setting of the data link is completed. When the data link is set normally, the central control unit (CC) 107 transmits a packet to the PHMB 104 in the next step S14. To give permission.

The PHMB 104, which has received the packet transmission permission, proceeds to step S15.
Analyzes the header part of X.25PLP and specifies the interface for transmitting X.25PLP. The central control unit (CC) 107
Controls the communication path switch 106 in step S16 to
111 and PHMB 104 are connected, and a packet is transmitted to the interface specified in step S15.

If the received packet in step S3 is a D-channel packet, the determination in step S18 is NO, and the process proceeds to step S6. That is, when transmitting the D-channel packet stored in the PHMD 105, the central control unit (CC) 107
In step 6, the PHMD 105 is requested to set a data link on the D channel, and in the next step S7, the completion of the link setting is determined.
When the link setting is completed, N is set in the next step S19.
After receiving the determination of O, the process proceeds to step S10, and the X.25P in the PHMD 105 is
Analyze the header of LP. The central control unit (CC) 107 specifies an interface based on the analysis result, and transmits a packet to the specified interface via the control bus 112.

If it is determined in step S7 or S13 that the requested link cannot be set, step S1 is executed.
Proceed to 7 to notify the calling side that the packet communication is impossible and reject the incoming call.

As described above, according to the present embodiment, the link level protocol converter is provided in the B channel packet handler module, and the packet received by the B channel packet handler module is transmitted to the D channel packet handler. By transferring the packet to the module, even when the packet exchange using the B channel as the packet exchange is impossible, the packet exchange process using the D channel can be performed, so that the packet exchange service can be smoothly performed. There is.

<Other Embodiments> In the above-described embodiment, the control of the PHMB 104 and the PHMD 105 by the central control unit (CC) 107 via the control bus 114 is performed. However, as shown in the block diagram of FIG. Control bus 3 for controlling PHMB 104 and PHMD 105 from central control unit (CC) 107
11 and the transfer path 113 of X.25PLP may be directly connected, and the transfer path and the control bus may be shared.

Further, in the above embodiment, when the packet exchange using the B channel is impossible, the packet exchange process using the D channel is performed. Conversely, a protocol conversion function is provided in the D channel packet handler module. When the packet exchange on the D channel becomes impossible, a packet exchange process using the B channel may be performed as an alternative.

[Effects of the Invention] As described above, according to the present invention, even if a failure occurs in a channel of the type used for reception after receiving a packet, it is possible to reliably exchange the received packet. . For example, when a received packet is exchanged after receiving a packet through a B channel or a D channel in ISDN, no problem occurs even if the B channel or the D channel used for reception becomes defective due to a failure or busy. It can be exchanged by the type of channel.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a packet exchange according to one embodiment of the present invention, FIG. 2 is a flowchart showing a processing procedure of the packet exchange in this embodiment, and FIG. 3 is a packet according to another embodiment. FIG. 4 is a block diagram showing a configuration of a conventional packet exchange, and FIG. 4 is a block diagram showing a configuration of a conventional packet exchange. In the figure, 100: packet exchange, 101: local line ISDN primary interface (PRT), 102: local line ISDN basic interface (BRT), 103: internal line ISDN basic interface (BRI), 104 ... ... B-channel packet handler module (PHMB), 105 ... D-channel packet handler module (PHMD), 106 ... communication path switch, 107 ... Central control unit (CC), 108 ... protocol conversion unit 111: transmission path, 112, 114, 311: control bus, 113: transfer path, 120
... ISDN, 121 ... DTE.

Claims (7)

(57) [Claims] 1. A packet switching device capable of performing packet switching using a first type channel and packet switching using a second type channel, wherein the packet switching device uses the first type channel. Receiving means for receiving a packet, when exchanging a packet received by the receiving means, determining means for determining whether or not packet exchange using a first type of channel used for receiving the packet is possible; Control means for controlling a packet received using the first type channel to be exchanged using the second type channel, in accordance with the determination by the determination means. Characteristic packet switching device. 2. The control means according to claim 1, wherein said control means converts a protocol for performing packet exchange using said first type channel and a protocol for performing packet exchange using said second type channel. 2. The method according to claim 1, wherein
3. The packet switching device according to claim 1. 3. A first packet switching means for performing packet switching using the first type of channel, and a second packet switching means for performing packet switching using the second type of channel. And when the control unit exchanges a packet received using the first type channel using the second type channel, the first exchange unit transmits the packet received from the first type channel. 2
2. The packet switching apparatus according to claim 1, wherein the switching means transfers layer 3 information of the packet. 4. The packet switching apparatus according to claim 2, wherein said first type channel is a B channel in ISDN, and said second type channel is a D channel in ISDN. 5. The packet switching apparatus according to claim 2, wherein said first type of channel is a D channel in ISDN, and said second type of channel is a B channel in ISDN. 6. A packet switching device capable of performing packet switching using a B channel and packet switching using a D channel in ISDN, comprising: a receiving unit that receives a packet using the B channel or the D channel. When exchanging a packet received by the receiving means, if the channel used for receiving the packet is a B channel, determine whether packet exchange using the B channel is possible, When the channel used for receiving the packet is the D channel, a determination unit for determining whether packet exchange using the D channel is possible, and, based on the determination by the determination unit, the B channel The packet received using the D channel is exchanged using the D channel, or the packet received using the D channel is Control means for controlling to perform switching using the B channel. 7. A method for controlling a packet switching apparatus capable of performing packet switching using a first type of channel and packet switching using a second type of channel, the method comprising: A receiving step of receiving a packet using a channel, and, when exchanging the packet received in the receiving step, determining whether or not packet exchange using a first type channel used for receiving the packet is possible. A determination step, and a control step of controlling a packet received using the first type channel to be exchanged using the second type channel, according to the determination in the determination step. A method for controlling a packet switching device, comprising: