JPH04100352A - Exchange system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention provides an ATM (Asynchronous Tr.
The present invention relates to a switching system to which the (ansferMode) technology is applied, and particularly to a switching system constructed including a narrowband 15DN and a private branch exchange system using existing 37M lines.

(Conventional technology) Individual service networks such as telephone networks, data networks, and fax networks that have been developed, constructed, and operated over a history of more than 100 years are integrated into the L5DN (Integrated Serial Network).
Vices Digital Network), efforts are being made in various parts of the world to integrate networks into one network system.

As the first step toward l5DN, narrowband l5DN began to be used in advanced countries including Japan in 1988. In addition, broadband l5D based on ATM technology
The completion of the 15DN network, including its integration with the broadcasting network, has been completed by N, and the development of its technology is being carried out at major research institutes around the world, led by the CCITT (Consultative Committee for International Telegraph and Telephone).

By the way, ATM technology is a method in which information to be transmitted is divided into fixed-length container packets called cells, and basically when information is generated, cells are generated according to the amount of information generated. In this respect, STM (Synchronous T
ransrer Mode) technology.

By applying the ^TM technology, the concept of channels that are fixedly occupied by each terminal is eliminated, and high-speed, wideband information transmission can be performed efficiently.

Generally, the above cell consists of a 48-octet information field 1 and a 5-octet cell header 2, as shown in FIG.
It is constructed by adding . Then, the exchange transmits and exchanges cells while referring to the information in the cell header 2.

Figure 9 is a diagram showing an example of a private branch exchange system to which such ATM technology is applied.
It is assumed that users who have already constructed a private branch exchange system using TM lines or who are in a transitional period when they begin to introduce a broadband 1sDN-based private branch exchange system with the start of broadband ISDN leased line service are assumed.

In the figure, 3 is a broadband switching node, and this broadband switching node 3 accommodates a narrowband switching node 5 to which a plurality of narrowband I5DN terminals 4 are connected via a line 6. Furthermore, the broadband switching node 3 is connected to another private branch exchange system 8 via a broadband 15DN dedicated line 7.

Here, the user reference point in the broadband I5DN applying ATM technology is called the S3 point or the TB point, and is 155
It has a basic speed of Mb/s and is theoretically capable of simultaneously multiplexing 128,000 calls.

By the way, point Sa or TB of the broadband switching node 3
In order to efficiently operate the 17th floor, which is a
It is desirable that the ratio of the accommodated bandwidth of F to the average used bandwidth per INF be close to 1, but when the INF at the SB point or TB point accommodates a narrowband switching node, the average used bandwidth per call is narrow. Extremely high call processing capacity is required for each INF of the broadband switching node 3.

This will be explained more specifically.

The number of terminals accommodated by the narrowband switching node 5 is 18,000, which is considered to be the largest scale for a private branch exchange system.
Assume that the terminal has an average of 9 cal I/h per terminal, and that half of the calls are connected to a broadband I5DN leased line. Although most of the remaining half of calls are connected to the public network, there is no problem assuming that the narrowband ISDN public network is connected to a narrowband switching node accommodated.

At this time, the call processing capacity for each INF of the broadband switching node 3 is required to be 16000 Xo, 5 X9-72000 (BHC), which is comparable to the processing capacity of a large-scale central office exchange.

(Problems to be Solved by the Invention) When constructing a private branch exchange system that flexibly applies ATM technology, including a private branch exchange system using narrowband 1sDN and existing STM lines, it is necessary to
A problem arises in that extremely high call processing capacity is required for each F.

Therefore, an object of the present invention is to provide a switching system that can reduce the call processing capacity of each INF of a broadband switching node in such a case.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems, the present invention provides a plurality of wideband input/output ports that multiplex transmit cells consisting of fixed-length information fields and headers, and switching means for demultiplexing the cells to the plurality of broadband input/output ports by identifying label values in the broadband switching node; In a switching system comprising a narrowband switching node that exchanges or transmits information using a division multiplexing method, the broadband switching node connects a broadband input/output port connected to the narrowband switching node and another broadband input/output port. , which can be connected using a permanent virtual connection.

(Function) When the broadband input/output port connected to the narrowband switching node and the other broadband input/output ports are connected using permanent virtual connections, there is a constant connection between the narrowband switching node and other nodes. Since it will be in a state where
The call processing capacity per I/P of the broadband switching node can be reduced.

(Example) Hereinafter, details of embodiments of the present invention will be explained based on the drawings.

FIG. 1 is a diagram showing the configuration of an exchange system according to an embodiment of the present invention.

In the figure, 11 is a broadband switching node, and this broadband switching node 11 includes a plurality of narrowband l5DN terminals 1.
2 is connected via a line 14. Further, the broadband switching node 11 has a broadband switching node 11.
It is connected to another private branch exchange system 16 via a 5DN dedicated line 15. Note that 17 is a maintenance terminal (MAC).

FIG. 2 is a diagram showing the configuration of the broadband switching node 11. As shown in FIG.

As shown in the figure, the broadband switching node 11 has a 1/F 18 that interfaces with the narrowband switching node 13 and an I/P that interfaces with the broadband 15DN dedicated line 15.
A control bus 20 and a connection channel 21 are connected to these I/Fs 18 and 19. The control bus 20 includes a system control processor 22.
An ATM switch 23 is connected to the connection channel 21 .

FIG. 3 is a diagram showing the configuration of the above-mentioned 1/P18.19.

As shown in the figure, the I/F 18.1 includes a cell receiving section 24 that receives cells, and a header adding section 2 that adds an additional header such as a routing header to the header of an input cell.
5. A cell transmitter 26 that transmits a cell, a header remover 27 that removes an additional header prior to transmission, a header conversion table 28 that describes information regarding the header to be added;
It is composed of a cell receiving section 24, a cell transmitting section 26, and an I/F control processor 29 that controls a header conversion table 28.

FIG. 4 is a diagram showing the configuration of the cell.

As shown in the figure, a cell is constructed by adding a 5-octet cell header 2 to a 48-octet information field 1. Then, when an additional header such as a routing header is added, the format becomes as shown in FIG. 5.

Next, the operation of the exchange system configured as described above will be explained.

Cell transfer by the ATM switch 23 is performed using a routing tag added to the beginning of the cell before it enters the AT14 switch 23.

This routing tag is connected to I/F 18. as follows.
19 is added.

First, if the input cell is a cell for a call setup request, it is separated to the I/F control processor 29 side in the cell receiving section 24 and sent to the system control processor 22 via the I/F control processor 29 and control bus 20. is transmitted to.

Here, the system control processor 22 determines the requested connection destination, the state of the ATM switch 23, etc., creates routing information that determines the routing from the I/F 18 to the I/F 19 inside the ATM switch 23, and creates other cell information. The information necessary for the transfer is notified to the I/F control processor 29.

Then, the 1/F control processor 29 writes this information into the header conversion table 28.

Here, the information written in the header conversion table 28 is searched by the label value written in the cell header 2 of the cell.

Therefore, if a cell has information to be transferred to the other terminal,
When a cell is input to the header adding unit 25 via the cell receiving unit 24, additional information (including a routing tag) corresponding to the label value written in the cell header 2 of the cell is searched from the header conversion table 28, and the search is performed. The additional information added is added to the beginning of the cell (see FIG. 5). Then, the cell is exchanged via the ATM switch 23,
The additional header is removed by the header removing section 27 within the exchanged L/P, and the cell is transferred to the other party's network via the cell transmitting section 26.

In addition, the exchange system of this embodiment has broadband exchange notebook 1.
1, a permanent virtual connection is set between the narrowband switching node 13 and the broadband 1sDN dedicated line 15 at the time of restart processing due to the occurrence of a failure, or in response to a request from the maintenance terminal (MAC) 17. Has a function.

A virtual connection refers to the following connection form.

Generally, a connection type is a TDM network identified by a time position within a TDM frame, such as in a conventional STM network.
A connection identified by a label attached to the beginning of the information element to be transferred (LC: Label
d Connection).

In a multiplexed bus with multiple connections, TDM
Connections are assigned deterministically by the number of time slots in the TDM, whereas in the latter connection type they are statistically assignable. Therefore, it is possible to effectively utilize line resources. This latter type of connection is called a virtual connection. A virtual connection is broadly defined as an LC set between virtual connection terminators (VCTs), and provides a logical direct link between the VCTs.

In order to make effective use of limited line resources and guarantee the quality of each communication (transfer delay amount, cell loss rate, etc.), it is necessary to understand the communication traffic characteristics of communication terminals that share the line resources. There is a need. Therefore, each terminal is required to declare the traffic characteristics (average traffic amount, peak traffic amount, etc.) of the call when making a call. The network that manages line resources compares the declared parameters from the terminal with the network resource usage status at the time of the declaration, and checks whether the communication quality of the declared call can be guaranteed or whether the new call is From the viewpoint of whether there is any impact on
It determines whether a call can be accepted and allocates resources (communication band) to calls that can be accepted (this is called call admission control).

In the virtual connection mode, in addition to call control similar to TDM connection for each call, such call reception $IJ
All is required.

A permanent virtual connection is a virtual connection that is fixedly established between VCTs, does not perform call control or call admission control for each call, and is assigned a fixed value of bandwidth.

As shown in FIG. 6, the present invention provides a wideband switching system with a V
It is characterized in that it is regarded as a CT and is connected by a permanent virtual.

One permanent virtual connection can accommodate multiple calls from multiple terminals.

In the broadband switching system, in order to realize this connection form, the system control processor 22
It is necessary to previously set information necessary for cell transfer (the aforementioned routing tag, terminal declaration parameters, etc.) in the header conversion table 28 in F18.19, and to allocate a band. Since terminal declaration parameters are statistical quantities, it is generally difficult to set them in advance regardless of call attributes.

This system considers that the VCT is composed of multiple narrowband I5DN terminals. Since the traffic characteristics of each terminal are well known (as each terminal is a narrowband I5DN terminal), we can calculate the traffic characteristics by treating it as a wideband I5DN terminal based on the terminal's configuration information and traffic data. represent. Specifically, with transmission in units of 64Kb/s,
Bandwidth is allocated by setting a numerical value such that the usage rate of the line connecting between the narrowband switching node and the broadband switching node is approximately 60 to 80%. Although it is related to simultaneous connections or allocated bandwidth, traffic processing in excess of this is regulated by the number of lines connecting the narrowband switching node 13 and the wideband switching node 11.

Thus, when set up as a permanent virtual connection, the logical channel between the narrowband switching node 13 and the broadband 1sDN leased line 15, as shown in FIG.
It will always be connected. The amount of allocated bandwidth can also be varied depending on the time period. Divide the day into 4 to 5 time periods and calculate the N-I S obtained in each time period.
Each declared parameter is calculated based on the traffic volume data of the DN terminal. By changing the declaration parameters obtained in this way for each time period, the line 15 can be used more effectively.

As a result, the broadband switching node 11 does not need to perform call connection processing, and the broadband switching node 11's I/O
The call processing capacity per F18.19 can be reduced.

The present invention can also be applied to a case where two types of private branch exchange systems 30 and 31 are connected to the broadband exchange node 11, as shown in FIG.

In that case, the call connection is distributed by the narrowband switching node 13.
It will be carried out in

Further, as shown in FIG. 8, the present invention provides a system in which a terminal 32 is directly connected to the broadband switching node 11, and a broadband l5DN dedicated line 15, which is physically one line, is connected to the terminal 32 and the narrowband switching node 1. It can also be applied when shared by

Effects of the Invention As described above, according to the present invention, a broadband switching node can connect a broadband input/output port connected to a narrowband switching node to another broadband input/output port by a permanent virtual connection. Therefore, the call processing capacity of each I/F of the broadband switching node can be reduced.

[Brief explanation of the drawing]

1 is a diagram showing the configuration of a switching system according to an embodiment of the present invention, FIG. M2 is a diagram showing the configuration of the broadband switching node shown in FIG. 1, and FIG. 3 is a diagram showing the configuration of the broadband switching node shown in FIG. FIGS. 4 and 5 are diagrams showing the structure of the cell, FIG. 6 is a diagram for explaining the present invention in detail, and FIGS. 7 and 8 are other embodiments of the present invention. A diagram for explaining, Figure 9 is A
1 is a diagram showing an example of a private branch exchange system to which TM technology is applied. 11...Broadband switching node, 12...Narrowband 15D
N terminal, 13... narrowband switching node 13.14...
Line, 15...Broadband JSDN dedicated line, 16...Private branch exchange system, 17...Maintenance terminal (MAC)
, 18.19...J/F, 20...control bus,
21... Connection channel, 22... System control processor, 23...^TM switch, 24... Cell receiving section, 25... Header addition section, 26... Cell transmitting section, 27. . . . Header removal unit, 28 . . Header conversion table, 29 . . . I/F control processor. Applicant: Toshiba Corporation

Claims (1)

[Claims] (1) A plurality of wideband input/output ports that multiplex transmit cells consisting of fixed-length information fields and headers, and demultiplexing the cells to the plurality of wideband input/output ports by identifying label values in the headers. A switching system comprising: a broadband switching node having switching means; and a narrowband switching node that is directly connected to the broadband input/output port of the broadband switching node and exchanges or transmits information using a time division multiplexing method. A switching system characterized in that the broadband switching node is capable of connecting a broadband input/output port connected to the narrowband switching node and another broadband input/output port by a permanent virtual connection.