JPH10117194A - Atm switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To flexibly cope with demand fluctuation relating to distribution connection by completely single-link-connecting switches and disposing the distribution function of ATM cells to a line interface part and a link interface part. SOLUTION: A cell copying circuit C is provided in line interface circuits 111-INM, link interface circuits 411-4MN and 711-7NM and line output interface circuits 91-9NM. Then, information inputted from a line input interface circuit 11 is outputted to a link output interface circuit 31M at an input switch part 201 and quadri-sected in a link input interface circuit 4M1. One of them is outputted to the link output interface circuit 6M1 and another one is outputted to the link output interface circuit 6MN in a relay switch part 50M. The information led from the link output interface circuit 6M1 to the link input interface circuit 7lM is divided into three in the link input interface circuit 71M.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ATM (Asynchronou).
s Transfer Mode) Used for communication. The present invention is suitable for use in ATM switching equipment.

[0002]

2. Description of the Related Art In ATM communication, information is mounted on fixed-length packets called cells, and communication is performed by transmitting and receiving the information in an ATM communication network. When a communication device on the transmission side transmits a cell, it transmits routing information in its header.

[0003] ATM switches arranged in a large number in an ATM communication network read the routing information of the header thereof,
Distribute cells to the desired route. At this time, one transmission-side communication device can transmit cells to one reception-side communication device (one-to-one communication), or
One transmitting communication device can also transmit cells to a large number of receiving communication devices (one-to-many communication).

Conventionally, as a configuration method of an ATM switch capable of performing one-to-many communication in addition to one-to-one communication, a configuration method in which a distribution function is provided in a line interface portion of the ATM switch, and a copy trunk in the ATM switch There have been configuration methods using a self-routing switch that can be deployed and distribution connections.

[0005] Of these, an example of a conventional method of disposing a distribution function in a line interface unit and an example of a method of providing a copy trunk will be described with reference to FIG. In FIG. 7, reference numeral 1001 denotes a k-input k-output self-routing switch; 1011 to 101k denote line input interface units; and 1021 to 102k denote line output interface units.

FIG. 7 shows a line input interface unit 101.
1 to 101k and a line output interface unit 1021
This is an example of a configuration in which a distribution function is provided in 102k to 102k. In the connection path 2001, the information input to the first line is distributed in the line input interface unit 1011 and each distributed information is changed by the switch unit 1001 as a self-routing switch to different line output interface units 1021 to 102k. , And the required number is also distributed to the line output interface units 1021 and 102k.

[0007] In the connection path 2001, information distribution is performed where the bold line is described as changing to a thicker line. In the example of 2001, the line input interface unit 1011 and the line output interface unit 102 are used.
1, 102k indicates that information distribution is being performed.

As can be seen from the connection path 2001, in the configuration in which the distribution function is provided in the line input interface units 1011 to 101k, in order to distribute information to a plurality of output lines, the line input interface units 1011 to 10
Information distribution must be performed in 1k. Therefore, for example, when a large number of pieces of information to be distributed and connected are accommodated in the first input line, it is necessary to distribute and connect all of the many pieces of information in the line input interface unit 1011.
Line input interface unit 1011 and switch unit 100
The speed of the information line 1041 between 1 becomes a bottleneck and limits the number of connections.

In other words, in the configuration in which the distribution function is provided in the line input interface unit, blocks occur when information to be distributed is concentrated on a specific input line. In order to avoid the block, it is necessary to disperse and accommodate the information to be distributed without being biased to a specific input line, which imposes restrictions on a network-wide routing method between a number of VCHs.

As a configuration method of an ATM switch that performs distribution connection without blocks even when information to be distributed to a specific input line is biased, there is a configuration in which a copy trunk is provided in an ATM switch. The extension 1001 'of the self-routing switch and the copy trunk 1 described by the broken line in FIG.
031 is a configuration example thereof. In the configuration in which the copy trunk 1031 is provided, there is a problem of calculating the number of facilities in accordance with the demand for the distribution connection. Also, the switch scale needs to be expanded.

Further, as a conventional technique, a configuration using a self-routing switch that can also perform a distribution connection requires a special configuration of a self-routing switch. Therefore, in order to change the existing one-to-one connection switching node to provide a one-to-many connection service with a small amount of traffic, first, the entire self-routing switch must be completely different. Must be changed to In addition, since the distribution is performed inside the self-routing switch, the address information for routing must be added to the ATM cells by increasing the number of distributions, and a non-standard ATM cell format having a large overhead must be adopted. . Furthermore, in order to adopt a non-standard ATM cell format, a large number of line corresponding parts also need to be changed.

[0012]

Problems with the prior art are as follows.
As described above, in the configuration in which the distribution function is provided in the line interface section, (1) In the configuration in which a copy trunk is provided, a connection block occurs unless information to be distributed is distributed and accommodated in each input line. Difficulty in forecasting demand for distribution connections, making it difficult to calculate the number of facilities
(3) The size of the self-routing switch must be increased, and in a configuration using a self-routing switch capable of distributed connection, (4) A special self-routing switch for one-to-many connection must be adopted. (5) A non-standard cell format having a large overhead must be adopted.

SUMMARY OF THE INVENTION The present invention has been made in such a background, and is capable of flexibly responding to fluctuations in demand related to distribution connection by using a general one-to-one connection self-routing switch. It is intended to provide a switch. An object of the present invention is to provide a large-capacity ATM switch that can cope with an increase in traffic in the future.

[0014]

According to the present invention, a self-routing switch of an ATM has a P-stage connection configuration, switches of each stage are completely connected by a single link, and an ATM cell of a line interface unit and a link interface unit are connected. The most important feature is to provide a distribution function.

According to the present invention, a plurality of small-scale self-routing switches are used to form an ATM switch having a P-stage configuration, so that the switch can be easily extended to a very large-scale ATM switch. Also, since there are a plurality of link paths from a specific input line to a specific output line, and the information can be distributed and connected through the plurality of link paths, a bottleneck of a specific common resource is eliminated, and distribution connection traffic is reduced. Flexible against bias and fluctuations in demand for distribution connection traffic,
It is possible to perform exchange connection with almost no connection block inside the switch.

That is, the present invention relates to an ATM switch in which N (N = L / M) M input M output inputs are connected to L input lines each having M (M <L) inputs. A switch unit, N M-input M-output switch units each having M output lines connected to its output, and a P stage interposed between the input switch unit and the output switch unit And N relay switches of N inputs and N outputs,
The input switch unit, each stage of the relay switch unit, and the output switch unit are mutually connected via one link, and each switch unit connects the cell to an output line according to destination information of the input cell. An ATM switch including means for performing

Here, the feature of the present invention resides in that the means for copying a cell is dispersedly arranged at an input or output interface of each switch unit.

It is preferable that the interface in which the means for copying the cell is arranged has a memory table for designating the destination of the copied cell in accordance with the contents recorded in the header of the incoming cell.

Thus, cells can be copied and transferred in accordance with a predetermined rule without traffic being biased to a specific common resource.

The memory table may be provided with control means for rewriting the entire ATM switch.

Thus, when the traffic condition changes, the change can be handled by rewriting the memory table.

The control means includes means for monitoring the traffic of each switch unit, means for calculating the contents of the memory table in accordance with the monitoring output of the monitoring means, Means for rewriting the contents of the memory table.

Thus, the entire ATM switch is monitored, a cell copy and transfer method is calculated so that traffic deviation does not occur in a part, and a memory table is rewritten according to the calculation result to obtain an optimum distribution. Control can be performed.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram of an ATM switch according to an embodiment of the present invention.

The present invention relates to an ATM switch, in which N (N = L / M) M inputs M in which L input lines IN _{11 to} IN _NM are connected to their inputs M (M <L) at a time. Output input switch units 201 to 20N and L output lines OUT ₁₁
N output switches 801 to 80N of M inputs and M outputs, each of which is connected to its output by M OUT _NM to input switches 201 to 20N and output switches 801 to 8
0N, one stage of N N-input / N-output relay switch units 501 to 50M, and the input switch unit 2
01-20N, each stage of the relay switch units 501-50M and the output switch units 801-80N are connected to each other via one link, and each switch unit outputs the cell according to the destination information of the input cell. Line OUT
₁₁ to an ATM switch including a self-routing circuit R as a means for connecting to OUT _NM .

Here, the feature of the present invention resides in that a cell copying circuit C as a means for copying a cell is dispersedly arranged at an input or output interface of each switch section.

In the three-stage switch network based on the complete single link connection, there are M types of link paths from a specific input to a specific output, and the degree of freedom of connection is large.

In the embodiment of the present invention, the cell copy circuit C is provided in the line input interface circuits 111 to 1NM, the link input interface circuits 411 to 4MN and 711 to 7NM, and the line output interface circuits 911 to 9NM.

Link input interface circuits 411 to 4
Link output interface circuits 311 to 311 instead of MN
The cell copy circuit C can be provided in the link output interface circuits 611 to 6MN instead of the NM and the link input interface circuits 711 to 7NM.

FIG. 2 is a diagram for explaining an example of a connection path in the embodiment of the present invention, and the configuration is the same as that of FIG. The ATM switch shown in FIG. 2 includes cell copy circuits in the line input interface circuits 111 to 1NM, the link input interface circuits 411 to 4MN and 711 to 7NM, and the line output interface circuits 911 to 9NM.

In FIG. 2, reference numeral 2002 denotes an example of a one-to-one connection path. This is simply the line input interface circuit 1.
The information input to the line 11 passes through the input switch unit 201, the link output interface circuit 311, the link input interface circuit 411, the relay switch unit 501, the link output interface circuit 611, the link input interface circuit 711, and the output switch unit 801. This indicates that the data is output to the output interface circuit 911.

FIG. 2 shows a reference numeral 2003 in the embodiment of the present invention.
An example of a many-to-many connection path is shown. In the connection path 2003, similar to the description of the connection path 2001 in FIG. 2, information distribution is performed where the bold line is described so as to change further. That is, the information input from the line input interface circuit 111 is transmitted to the link output interface circuit 31M by the input switch unit 201.
Output to the link input interface circuit 4M1.
Be distributed. One of them is output to the link output interface circuit 61M in the relay switch unit 50M, and the other is output to the link output interface circuit 6MN.

Information guided from the link output interface circuit 6M1 to the link input interface circuit 71M is divided into three pieces by the link input interface circuit 71M, and one is output to the line output interface circuit 911 by the output switch section 801 and another is output. One is further divided and output by the line output interface circuit 91M.

The other link output interface circuit 6MN to the link input interface circuit 7NM
The information guided to the link input interface circuit 7NM
And one of them is further distributed and output by the line output interface circuit 9NM.

This connection path 2003 is connected to the ATM of the present invention.
The relay switch units 501 to 50 are merely examples of how the distribution connection is performed by the switches.
M, link input interface circuits 411 to 4MN for distributing information on the input side of the output switch units 801 to 80N;
711 to 7NM can be freely selected for each piece of information to be distributed.

Therefore, unlike the conventional ATM switch, even if the information to be distributed is not dispersedly accommodated in each input line, no connection block occurs. In addition, the ATM switch of the present invention can flexibly cope with a large change in the traffic demand ratio between one-to-one connection calls and one-to-many connection calls simply by increasing the installation ratio of interface circuits capable of distributed connection. This is possible and has the advantage that the size of the switch does not need to be increased.

Further, in the ATM switch of the present invention, since information is distributed by the interface circuits before and after each switch unit, the switch units at each stage can use simple self-routing switches for one-to-one connection. In addition, there is an advantage that it is not necessary to adopt a non-standard format having a large overhead for distributing distribution information in a header of an ATM cell.

In the connection path 2003, distribution is not performed by the line input interface circuits 111 to 1NM.
If there is room in the bandwidth of the information lines between the line input interface circuits 111 to 1NM and the input switch units 201 to 20N, the information may be distributed by the line input interface circuits 111 to 1NM.

Line input interface circuits 111 to 1N
M, link input interface circuits 411-4MN and 711-7NM, line output interface circuit 911
.About.9NM are provided with a memory table MT for specifying the destination of the copied cell according to the contents recorded in the header of the incoming cell. FIG. 3 is a diagram showing a configuration of the memory table MT.

In FIG. 3, the information enclosed by <> in the virtual channel information indicates the output terminal number of the self-routing switch. The chaining information in the memory table MT in FIG. 3 indicates whether there is a continuation of the chain (1) or not (0). For the input of the cell of the virtual channel having the address “15”, the address “15” Since the chaining information is “0”, it is only necessary to change the virtual channel to “<2> 3” and output it.
First, for the input of the virtual channel called “<1>
The cell to which the virtual channel information “21” is added is output, and the chaining information of the memory table MT is “1”.
Therefore, “<5> 7” described at the address “<1> 21” and “<6> 2” described at the address “<5> 7” in the memory table MT. It outputs three ATM cells of the same payload (B) given by the virtual channel information. The contents of the memory table MT shown in FIG. 3 show an example of a one-to-one connection and a one-to-three connection, respectively. The number of copies and the number of connection information can be set arbitrarily within the range of the capacity of the memory table MT.

FIG. 4 is a diagram showing a routing situation in the relay switch unit 501. In the first link input interface circuit 411 of the relay switch unit 501, FIG.
, And the cell A input thereto is used as the second link output interface circuit 61.
2 and the cell B is copied and output to the first, fifth, and sixth link output interface circuits 611, 615, and 616.

The memory table MT is stored in the ATM table.
A traffic monitoring unit T is provided as control means for rewriting the entire switch. FIG. 5 shows the traffic monitoring unit T
FIG. 3 is a diagram showing an ATM switch. FIG. 6 is a block diagram of the traffic monitoring unit T.

The traffic monitoring unit T includes a monitoring unit T1 as means for monitoring the traffic of each switch unit, and a memory table MT according to the monitoring output of the monitoring unit T1.
And a rewriting unit T3 as means for rewriting the contents of each memory table MT based on the operation result of the operation unit T2.

The monitoring unit T1 collects traffic information of each switch unit. Specifically, the status of the traffic is displayed in a stepwise value, and this value is input to the calculation unit T2 as a parameter. The arithmetic unit T2 performs an arithmetic operation in accordance with the parameters, and generates an instruction for performing the distributed control so that a traffic bias does not occur in each switch unit in the ATM switch. This instruction is input to the rewriting unit T3, and the value of each memory table MT is rewritten so that the instruction can be executed.

In the embodiment of the present invention, the traffic situation is
Indicated by the values of the steps (α, β, γ). The calculation unit T2 generates an instruction that can optimally correspond to each of α, β, and γ by calculation.

Thus, while monitoring the traffic condition of each switch unit, each memory unit is set to an optimum state.
The table MT can be rewritten.

(Summary of Embodiment) In the embodiment of the present invention, a three-stage ATM switch configuration has been described. However, it is well known that a larger-scale ATM switch can be generally configured by using a multi-stage connection configuration. That is, even in a multi-stage configuration, by distributing information distribution functions to interface circuits before and after the switch unit,
Obviously, the advantages described in the embodiments of the present invention occur.

Further, the input switch section is set to M × Q (Q>
M), Q relay switches, Q × M output switches
It is also well known that by increasing the number of paths that can be selected, a switch having a lower possibility of connection blocks can be realized, and the present invention is also effective.

In the present invention, each switch section is connected by a complete single link. However, this is a necessary condition for obtaining a degree of freedom in selecting a path from an input terminal to an output terminal, and is not a sufficient condition. For example, it is needless to say that the same effect can be obtained by using a multiple link connection instead of a single link connection.

Further, in the embodiment of the present invention, a configuration has been described in which each interface circuit is provided with a memory table MT and is rewritten according to the traffic situation.
If the capacity of the M switch has a margin, it is effective to execute the cell transfer according to a predetermined rule without rewriting the memory table MT.

Here, the predetermined rule may be to randomly select an interface circuit for copying or to select an interface circuit for copying cyclically. By doing so, the above-described traffic monitoring unit T
Since a device for monitoring the entire ATM switch as described above can be omitted, the configuration can be simplified.

As described above, in the ATM switch of the present invention, (1) one-to-one connection, one-to-many connection having almost no connection block even if information to be distributed is not dispersedly accommodated in each input line and accommodated. Connection is possible, (2) distribution connection that can flexibly respond to demand fluctuations related to distribution connection, (3) there is no need to increase the scale of the ATM switch to accommodate equipment dedicated to distribution, ( 4) One-to-many connection is possible without using a special self-routing switch dedicated to distribution. (5) The distribution connection function can be realized without using a non-standard ATM cell format with a large overhead. There is an excellent effect that a large-scale ATM switch capable of one-to-many connection in addition to one-to-one connection can be economically realized.

[0054]

As described above, according to the present invention,
By using a general one-to-one connection self-routing switch, it is possible to flexibly cope with a fluctuation in demand related to distribution connection. Further, it is possible to realize a large-capacity ATM switch capable of coping with an increase in traffic in the future.

[Brief description of the drawings]

FIG. 1 is a block diagram of an ATM switch according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining an example of a connection path in the embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of a memory table.

FIG. 4 is a diagram showing a routing situation in a relay switch unit.

FIG. 5 is a diagram showing a traffic monitoring unit and an ATM switch.

FIG. 6 is a block diagram of a traffic monitoring unit.

FIG. 7 is a diagram showing an example of a configuration in which a distribution function is provided in a line interface unit and a configuration in which a copy trunk is provided in a conventional example.

[Explanation of symbols]

111-1NM Line input interface circuit 201-20N Input switch section 311-3NM Link output interface circuit 411-4MN Link input interface circuit 501-50M Relay switch section 611-6MN Link output interface circuit 711-7NM Link input interface circuit 801-80N Output switch unit 911 to 9NM Line output interface circuit 1001 Switch unit 1001 'Expansion unit 1011 to 101k Line input interface unit 1021 to 102k Line output interface unit 1031 Copy trunk 1041 Information line 2001 to 2003 Connection path C Cell copy circuit R Routing circuit IN _{11 to} IN _NM input line MT memory table OUT _{11 to} OUT _NM output line

Claims (4)

[Claims] 1. An input switch section of N (N = L / M) M inputs and M outputs, each of which has L input lines connected to its input by M (M <L), and L output lines Are connected to the output of each of the M output switches of N M inputs and M outputs, and P N stages of N inputs and N outputs interposed between the input switch and the output switch. A relay switch unit, wherein the input switch unit, each stage of the relay switch unit, and the output switch unit are connected to each other via a single link, and each switch unit is connected in accordance with destination information of the input cell. An ATM switch including means for connecting the cell to an output line, wherein the means for copying a cell is distributedly arranged at an input or output interface of each switch unit. 2. An interface in which means for copying the cell is arranged, comprising a memory table for designating a destination of the copied cell according to contents recorded in a header of an incoming cell. The ATM switch as described. 3. The ATM switch according to claim 2, further comprising control means for rewriting the memory table for the entire ATM switch. 4. The control means includes means for monitoring the traffic of each switch unit, means for calculating the contents of the memory table in accordance with the monitoring output of the monitoring means, and calculation results of the calculation means. Means for rewriting the contents of each memory table on the basis of
TM switch.