JPH11252170A - Line exchange network - Google Patents

Abstract

PROBLEM TO BE SOLVED: To relay a packet with a transmission control protocol TCP-Internet protocol IP address via a synchronous transfer mode STM network. SOLUTION: A subscriber LS-2 exchange that contains terminals TE-2 being destinations from a TCP-IP address of an Internet protocol TCP/IP packet is identified, time slot exchange information that is route information in an STM network 1 up to the subscriber exchange is generated and packets are transferred in the STM network according to the time slot exchange information.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an STM (Synchronous
Transfer Mode) Used for communication networks. The present invention relates to TCP-
IP (Transmission Control Protocol-Internet Protocol)
ol) A technology for transferring data having an address via an STM connection.

[0002]

2. Description of the Related Art The operation and problems of a conventional circuit switching network based on STM will be described with reference to FIGS. FIG.
FIG. 1 is a diagram showing a main part configuration of a conventional circuit switching network based on STM. FIG. 5 is a diagram showing a main part configuration of a conventional subscriber exchange. In an STM communication network, signals on a physical channel are multiplexed into time slots and circuit-switched, so that the delay time during communication is extremely short, and an ATM (Asynchronous Transfer Mode) header using virtual paths and cells is used. There is no overhead. Also, no cell loss or the like occurs during communication.

For example, if the voice of a telephone has a delay of 20 to 30 ms or more, there is a problem in quality, and an echo canceller is required. In general, not only telephone calls but also two-way video conferences should have a small delay. From the above points, STM is a transfer mode suitable for the digital telephone network.

As shown in FIG. 4, in a conventional circuit switching network based on STM, a user inputs a telephone number of a destination to a CCITT.
No. defined in the Recommendation The transmission in the STM mode by transmitting to the exchange through the common line signaling network allows the physical transmission to be independent of the E.7. 164 addresses (ITU
-T is mapped to an ISDN address standardized by -T for communication. That is, ST in the STM network
The MTM connection is established, and the user data is transferred to the E.M. 164 addresses and transferred to the destination exchange.

In such a conventional circuit switching network based on STM, switching is performed by exchanging time slots of information multiplexed by 8 bytes on a frame. This operation is realized by, for example, sequential write random read as shown in FIG. That is, the sequential counter CT
R writes data to the data buffer memory DBM at sequential addresses with a sequential address, and the address control memory ACM changes the reading order to perform time slot conversion.

[0006]

SUMMARY OF THE INVENTION Such a conventional ST
As described above, the circuit switching network based on M has the advantages that the delay time is extremely short and that there is no overhead as compared with the ATM network or the like. However, in such a conventional circuit switching network using STM, it is necessary to set up an STM connection in advance from a terminal of a calling user to a terminal of a called user, and transfer data via the STM connection. It is.

FIG. 6 shows an image of a dedicated STM connection. For this reason, as shown in FIG. 6, there is a problem that the application can only be used as a dedicated data line between large-scale offices.

On the other hand, regarding data communication performed by the TCP-IP architecture, a TCP-IP address, which is an identification number of a terminal, is written in a header of a packet and sent to a communication network such as the Internet that supports the TCP-IP. Each router such as an exchange searches for the existence of the address and transfers the datagram without having to set up a connection between two terminals with which communication is desired.
Thus, a dedicated connection is not required, and data can be transferred by a very simple procedure.
However, in this case, the delay time is longer than that of the circuit switching network based on STM, and overhead is required.

The inventors have considered constructing a new circuit switching network having both the advantages of the circuit switching network using the STM and the advantages of data communication using the TCP-IP address.

The present invention has been made in such a background, and can be provided only as a mere dedicated line by providing a relay network by STM based on a TCP-IP address used for data communication. Missing S
An object of the present invention is to provide a circuit switching network capable of dynamically providing a TM circuit. SUMMARY OF THE INVENTION It is an object of the present invention to provide a circuit switching network having a small delay time and a small overhead.

[0011]

SUMMARY OF THE INVENTION The present invention provides a TCP-IP
In a packet having a header in which an address is written, route information to a subscriber exchange accommodating a terminal serving as a destination indicated by the TCP-IP address is set in advance in the subscriber exchange accommodating the originating terminal. The most important feature is that the packet is transferred to a desired destination terminal via an STM network by adding a header. At this time, the transit exchange switches the packet in the time slot based on the route information described in the header of the arrived packet. As a result, the switch receiving the packet sets the time slot in which the packet is to be loaded at that time without setting up a dedicated connection in the STM network in advance, so that it is as if the entire network is a huge router. In addition, high-speed data transfer can be performed with simplicity like data communication performed by the above-described TCP-IP architecture.

That is, the present invention relates to a circuit switching network,
A plurality of subscriber exchanges accommodating one or more terminals, and a transit exchange for connecting the subscriber exchanges to each other, wherein the subscriber exchange and the transit exchange are connected via a STM network. It is. It is a feature of the present invention that the local exchange has a T
Means for receiving a packet having a header in which a CP-IP address is written, a table in which an address in the STM network accommodating a destination terminal corresponding to the TCP-IP address is recorded; Means for adding a header in which time slot exchange information, which is route information corresponding to an IP address, is written to the header; and means for transferring the packet in a corresponding time slot based on the added header. There.

The transit exchange includes means for referring to a header in which the route information of the packet written in the time slot is written, and rewrites the packet in the header according to the reference result of the referencing means. It is preferable to provide a means for switching to a time slot corresponding to the inserted route information. This route information is preferably time slot exchange information. Here, the time slot exchange information is information on a time slot replacement order when a packet is transferred in the STM network. The reordering order indicates the reordering order of the time slots performed for each relay exchange or for each subscriber exchange accommodating the destination terminal.

It is preferable that the apparatus further comprises means for temporarily storing the packet when the time slot does not have a vacancy until the time slot has a vacancy.

[0015] Thus, even when there is no empty time slot, it is possible to prevent the packet from being discarded.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram showing a configuration of a circuit switching network according to an embodiment of the present invention. FIG. 2 is a block diagram showing a main part block configuration of the local exchange according to the embodiment of the present invention. FIG. 3 is a diagram showing a block configuration of a main part of the transit exchange according to the embodiment of the present invention.

The present invention relates to a circuit switching network, as shown in FIG. 1, wherein local exchanges LS-1 and LS-2 accommodating terminals TE-1 and TE-2, and local exchanges L
Transit exchange TS for connecting between S-1 and LS-2
-1 and TS-2, and the local exchange LS-1,
LS-2 and the transit exchanges TS-1 and TS-2
It is a circuit switching network connected via the M network 1.

In the embodiment of the present invention, description will be made on the assumption that a packet is transferred from the terminal TE-1 to the terminal TE-2. Therefore, although the local exchange LS-1 is the originating local exchange and the local exchange LS-2 is the destination local exchange, it will be described as if it were a different device. The exchanges LS-1 and LS-2 are the same device, and their positions can be switched.

Here, the feature of the present invention is that the local exchange LS-1, as shown in FIG.
And a receiving unit 2 for receiving a TCP / IP packet having an IP header, which is a header in which a TCP-IP address coming from 1 is written, and route information in the STM network 1 corresponding to the TCP-IP address The receiving unit 2 adds a header in which the route information corresponding to the TCP-IP address obtained by referring to the table 3 is written to the IP header,
The transmission unit 4 is means for transferring the TCP / IP packet in a time slot corresponding to a destination route from the local exchange LS-1.

As shown in FIG. 3, the transit exchange TS includes, as shown in FIG. 3, a header reference unit 5 which is a means for referring to a header in which the route information of the packet written in the transferred time slot is written. A relay unit for reloading the packet into a time slot corresponding to the route information written in the header according to the reference result of the header reference unit;

The route information is time slot exchange information, and is information on a time slot replacement order when a packet is transferred in the STM network 1. This reordering sequence indicates the reordering sequence of the time slots performed for each of the transit exchanges TS-1 and TS-2 or for each of the subscriber exchanges LS-2 accommodating the terminal TE-2.

The packet is temporarily stored in the local exchange LS-1 shown in FIG. 2 and the transit exchanges TS-1 and TS-2 shown in FIG. 3 until the time slot becomes empty. A burst buffer 7 is provided. Although not shown, the local exchange L
The transmitting unit 4 of S-2 is the transmitting unit 4 of the local exchange LS-1.
And a burst buffer 7 is provided.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. The TCP / IP packet transferred from the terminal TE-1 is provided with time slot exchange information as route information by the receiving unit 2 in the subscriber exchange LS-1. That is, in the STM network 1, refer to Table 3 to search for time slot exchange information that is route information to the local exchange LS-2 in which the terminal TE-2 serving as the destination of the TCP-IP address is accommodated. I do. In Table 3, time slot exchange information corresponding to the TCP-IP address is recorded in advance.

Thus, the I / O of the TCP / IP packet
The header in which the time slot exchange information is written is added to the P header, and the header is input to the transmitting unit 4. At the same time, the information on the route sent from the local exchange LS-1 is transferred to the control circuit 9. The control circuit 9 transfers data according to the route information. The basic operation at this time is the same as the operation of the conventional time slot exchange shown in FIG. 5, but the apparatus according to the embodiment of the present invention temporarily stores packets when no time slot is available. And a burst buffer 7 for storing.

The control circuit 9 includes a data buffer memory DBM
Is monitored to determine the availability of a time slot, and if there is no available time slot, a packet to be written to that time slot is temporarily stored in the burst buffer 7. Thereafter, when a vacancy occurs in a desired time slot, the packet temporarily stored in the burst buffer 7 is again input to the data buffer memory DBM via the delay circuit 10. The delay circuit 10 compensates for the control delay of the control circuit 9 and places the packet in a desired time slot.

As shown in FIG. 3, the relay exchanges TS-1 and TS-2 copy the packet for each time slot by the data copying unit 11 and input the copied packet to the header reference unit 5.
The header reference unit 5 virtually reproduces the input packet to search for a header in which the time slot exchange information included in the packet is written. The retrieved time slot exchange information is transferred to the control circuit 9.
The subsequent operations are the same as those of the local exchange LS-1, such as setting the address control memory ACM and temporarily storing the packets in the burst buffer 7 if there is no free space. Also, in the local exchange LS-2 accommodating the destination terminal TE-2, the transit exchanges TS-1 and TS
-2 is performed, and the packet is transferred to the terminal TE-2.

As described above, the transit exchanges TS-1 and T-1
The time slot exchange information is read from the packet by the S-2 and the local exchange LS-2, and the packet is reloaded into a predetermined time slot, so that the packet is received without the need for a preset dedicated line. When the transit exchanges TS-1 and TS-2 and the local exchange LS-2 transfer bursts, data is transferred on a link-by-link basis by temporarily holding a time slot carrying the packet. Can be. Therefore, it is possible to hold the line only during the data transfer and release the line when the transfer is completed.

Thus, a link can be established at a high speed, network resources can be occupied only during a data transfer period, and released during other periods. Therefore, A
When data transfer by TM is used as a comparative example, ATM
In this case, one cell has 53 bytes, of which 5 bytes have overhead, but this embodiment does not require this overhead. In addition, since there is no fear of fluctuation and no cell loss, it is easy to assemble a packet on the receiving side.

[0029]

As described above, according to the present invention,
Based on the TCP-IP address used for data communication,
By providing a transit network by TM,
An STM line that could only be provided as a mere dedicated line can be dynamically provided. As a result, a circuit switching network with a small delay time and a small overhead can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a circuit switching network according to an embodiment of the present invention.

FIG. 2 is a diagram showing a block configuration of a main part of the local exchange according to the embodiment of the present invention.

FIG. 3 is a diagram showing a main block configuration of a transit exchange according to the embodiment of the present invention.

FIG. 4 is a diagram showing a main configuration of a conventional circuit-switched network based on STM.

FIG. 5 is a diagram showing a main configuration of a conventional subscriber exchange.

FIG. 6 is a diagram showing an image of a dedicated STM connection.

[Description of Signs] 1 STM network 2 Receiver 3 Table 4 Transmitter 5 Header reference unit 6 Relay unit 7 Burst buffer 8 Header copy unit 9 Control circuit 10 Delay circuit 11 Data copy unit ACM Address control memory CTR Sequential counter DBM Data buffer Memory LS-1, LS-2 Subscriber exchange TS-1, TS-2 Transit exchange TE-1, TE-2 Terminal

Claims (4)

[Claims] A plurality of subscriber exchanges accommodating one or more terminals, and a transit exchange for connecting the subscriber exchanges to each other, wherein the subscriber exchange and the transit exchange comprise:
In a circuit-switched network connected via an STM (Synchronous Transfer Mode) network, the local exchange has a TCP-I signal coming from the terminal.
P (Transmission Control Protocol-Internet Protoco
l) means for receiving a packet having a header in which an address is written, a table in which route information in the STM network corresponding to the TCP-IP address is recorded, and a table obtained by referring to this table. Means for adding a header in which the route information corresponding to the TCP-IP address is written to the header, and means for referring to the added header and transferring the packet in a time slot corresponding to the route information Circuit switching network. 2. The transit exchange includes means for referring to a header in which the route information of a packet written in a time slot is written, and renews the packet in accordance with a reference result of the referring means. 2. The circuit switching network according to claim 1, further comprising: means for changing the time slot to a time slot corresponding to the route information written in the network. 3. The circuit switching network according to claim 1, wherein said route information is time slot exchange information. 4. The circuit switching network according to claim 1, further comprising means for temporarily storing the packet when the time slot is not empty until the time slot becomes empty.