Method of increasing switch capacity

Disclosed a method of increasing the whole switch capacity by utilizing the presently used switch network as it is. The present invention, the method of increasing a switch capacity in a switch network system in which three or more switch stages including a plurality of switching elements are connected in serial by using a predetermined logical circuit, the method comprising the steps of: adding switch stage including a plurality of switching elements to correspond to the each switch stage; grouping switching elements of a first switch stage and last switch stage in the switch stage and the added switch stage by a predetermined unit, respectively; and connecting the grouped switching elements of the first stage with corresponding switching elements of an intermediate switch stage which is placed between the first stage and last stage, respectively, and connecting the grouped switching elements of the last switch stage with the corresponding switching elements of the intermediate switch stage, respectively.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a cross connect system. In particular, the present invention relates to a switch capacity increasing method which can increase the switch capacity by utilizing the existing switch network as it is.

2. Background of the Related Art

Generally, a 3-stage Clos switch network as shown inFIG. 1has been widely used in a cross connect system. Referring toFIG. 1, the 3-stage Clos switch network comprises a first stage10having a plurality of switching elements10a–10n, a second stage20having a plurality of switching elements20a–20nconnected to the switching elements10a–10nof the first stage10in a many-to-many relationship, and a third stage30having a plurality of switching elements30a–30nconnected to the switching elements20a–20nof the second stage20in a many-to-many relationship.

Here, the whole switch capacity N of the switch network is predetermined when the switch network is designed. If the number of input/output of a switching element is defined by n, the ratio of the input number to the output number of each switching element in the first stage10becomes n×2n, and the ratio of the input number to the output number of each switching element in the third stage30becomes 2n×n.

Also, the ratio of the input number to the output number of each switching element in the second stage20becomes N/n×N/n. Accordingly, the first stage10and the third stage30have a symmetrical arrangement based on the second stage20.

Such a switch network as described above has the reduced number of cross points and high accessibility of crossbars, and a non-blocking is effected when two terminal points are connected to each other since at least one path is provided through the network to connect the two terminal points together. Because of the above reason, there is a tendency to apply the switch network as shown inFIG. 1, for instance, to the product name DACS IV (digital access communication system IV) manufactured by Lucent in the United States and to the product name 1631SX manufactured by Alcatel in the United States.

In the above-described switch network, the switching elements in the respective stages10–30are inserted into a shelf of the cross connect system in the form of a module or unit. On the rear surface of the shelf is provided a mother board in which a plurality of patterns for connecting input/output terminals of the respective modules as designed. Accordingly, the designer of the cross connect system should design or produce the switch network after determining the whole switch capacity of the switch network required at the present time and in the future.

In the conventional cross connect system as shown inFIG. 1, the method of increasing the whole capacity of the switch network may be classified into two.

One method is to produce the switch network having the switch capacity of 2N if the designer judges that the whole switch capacity required at the present time is N, but the switch capacity of 2N will be required thereafter. Another method is to produce and use the switch network having the switch capacity of N, and if required thereafter, to produce a new switch network having the switch capacity of 2N without using the previous switch network having the switch capacity of N any more.

However, the former method has problems that unnecessary expenses are spared on producing the switch network having the switch capacity of 2N though the switch capacity of N is only required at the present time. The latter method also has problems that excessive expenses are spared on producing a new switch network having the switch capacity of 2N since the previous switch network having the switch capacity of N is not used any more.

Such problems are caused by the fixed structure of the produced switch network. Specifically, the fixedly patterned structure of the shelf and the mother board of the cross connect system, which is just like a printed circuit board (PCB), causes the problems in case of increasing the switch capacity of the present switch network.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a switch capacity increasing method that substantially obviate one or more of the problems due to limitations and disadvantages of the related art.

An object of the present invention is to provide a method of increasing switch capacity which can increase the whole switch capacity by utilizing the presently used switch network as it is.

To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, a method of increasing a switch capacity in a switch network system in which three or more switch stages including a plurality of switching elements are connected in serial by using a predetermined logical circuit, the method comprising the steps of: adding switch stage including a plurality of switching elements to correspond to the each switch stage; grouping switching elements of a first switch stage and last switch stage in the switch stage and the added switch stage by a predetermined unit, respectively; and connecting the grouped switching elements of the first stage with corresponding switching elements of an intermediate switch stage which is placed between the first stage and last stage, respectively, and connecting the grouped switching elements of the last switch stage with the corresponding switching elements of the intermediate switch stage, respectively.

In another aspect, a method of increasing a switch capacity in a switch network system in which three or more switch stages including a plurality of switching elements are connected in serial by using a predetermined logical circuit, the method comprising the steps of: adding switching elements to an intermediate switch stage which is placed between the first stage and last stage, respectively; and connecting extra input/output terminals of switching elements in first and last switch stages with the added switching elements, respectively.

According to the aspects of the present invention as described above, the whole switch capacity can be increased by adding a new switch network to the presently used switch network and manually changing the connection of the respective switching elements.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 2is a block diagram illustrating the construction of the switch network whose switch capacity is increased by the integral number of times according to a first embodiment of the present invention.

Referring toFIG. 2, the switch network according to the first embodiment of the present invention includes first stages40and70having a plurality of switching elements40a–40nand70a–70n, second stages50and80having a plurality of switching elements50a–50nand80a–80nrespectively connected to the switching elements40a–40nand70a–70nof the first stages40and70in a many-to-many relationship, and third stages60and90having a plurality of switching elements60a–60nand90a–90nrespectively connected to the switching elements50a–50nand80a–80nof the second stages50and80in a many-to-many relationship.

Here, if the input number of the switching element is defined by n and the whole switch capacity of the switch network is defined by N, the ratios of the input number to the output number of the switching elements provided in the first, second, and third stages are n×2n, N/n×N/n, and 2n×n, respectively.

Accordingly, the switch network according to the first embodiment of the present invention has a symmetrical arrangement based on the second stages50and80. Also, the switching elements provided in the first stages40and70and the second stages50and80and the switching elements provided in the second stages50and80and the third stages60and90are respectively connected through communication lines (for instance, cables) which can change the input/output connection ports of the switching elements. Accordingly, in case of increasing the switch network, the shelf or mother board of the existing cross connect system are used as they are, and only the input/output connection ports thereof are changed according to the first embodiment of the present invention.

Hereinafter, the switch capacity increasing method for a cross connect system according to the first embodiment of the present invention will be explained in detail.

First, a new switch network is added to the existing switch network. Thereafter, the switching elements40a–40n,70a–70n,60a–60n, and90a–90nrespectively provided in the first stages40and70and the third stages60and90of the existing switch network and the new switch network are classified into pairs.FIG. 2shows 2 pairs of the switching elements45a,45b,75a,75b,65a,65b,95a, and95bin each stage. Then, the first switching elements40a,40n-1,70a, and70n-1of the pairs45a,45b,75a, and75bof the switching elements in the first stages40,70,60, and90of the existing switch network and the new switch network are connected to the switching elements50a–50nprovided in the second stage50of the existing switch network in a many-to-many relationship, and the second switching elements40b,40n,70b, and70nof the pairs45a,45b,75a, and75bof the switching elements are connected to the switching elements80a–80nprovided in the second stage80of the new switch network in a many-to-many relationship. Thereafter, the first switching elements60a,60n-1,90a, and90n-1of the pairs65a,65n,95a, and95nof the switching elements in the third stages60and90of the existing switch network and the new switch network are connected to the switching elements50a–50nprovided in the second stage of the existing switch network in a many-to-many relationship, and the second switching elements60b,60n,90b, and90nof the pairs65a,65n,95a, and95nof the switching elements are connected to the switching elements80a–80nprovided in the second stage80of the new switch network in a many-to-many relationship.

As described above, the switch network is increased by classifying the switching elements provided in the first stages40and70and the third stages60and90into pairs and then connecting the input/output terminals of the switching elements in a manner as described above.FIG. 3illustrates the equivalent circuit of the increased switch network ofFIG. 2.

According to the first embodiment of the present invention, the whole switch capacity of the increased switch network becomes 2Ntimes as large as that of the previous switch network by adding the second switch network70,80, and90which is identical to the existing first stage40, second state50, and third stage60. For example, the whole switch capacity of the switch network can be increased from 2 to one of 4, 8, 16, 32, . . . .

In case that the whole switch capacity of the existing switch network is N, and that of the new switch network is 2N, the number and the input/output number of the switching elements provided in the respective stages of the existing switch network and the new switch network are identical.

FIGS. 4ato4cillustrate the first embodiment of the present invention exemplifying that the whole switch capacity of the switch network is increased from 2 to 4.

FIG. 4ais a block diagram illustrating the construction of the switch network having the whole switch capacity of 2.FIG. 4bis a block diagram illustrating the construction of the switch network whose switch capacity is increased from 2 to 4 according to the switch capacity increasing method of the present invention.FIG. 4cis a block diagram illustrating the construction of the switch network initially designed to have the whole switch capacity of 4. Upon comparing the switch networks inFIGS. 4band4c, it can be recognized that the same switching paths are provided.

FIGS. 5aand5bshow the switch network according to the second embodiment of the present invention wherein the switch capacity is increased fraction times.

FIG. 5ais a block diagram illustrating the construction of the switch network having the switch capacity of 4×4, andFIG. 5bis a block diagram illustrating the construction of the switch network whose switch capacity is increased from 4×4 to 6×6 according to the second embodiment of the present invention.

Referring toFIGS. 5aand5b, the switch network according to the second embodiment of the present invention includes a first stage300ahaving a plurality of switching elements SE41and SE42, a second stage400bhaving a plurality of switching elements SE51–SE56connected to the switching elements SE41and SE42of the first stage300ain a many-to-many relationship, and a third stage500ahaving a plurality of switching elements SE61and SE62connected to the switching elements SE51–SE56of the second stage400bin a many-to-many relationship.

Here, if the input number of the switching element is defined by n and the whole switch capacity of the switch network is defined by N, the ratio of the input number to the output number of the first stage300abecomes 1.5 times 2×4 (i.e., 3×6), the ratio of the input number to the output number of the second stages400a–400cbecomes 2×2, and the ratio of the input number to the output number of the third stage500abecomes 1.5 times 4×2 (i.e., 6×3).

According to the second embodiment of the present invention, when the connection ports of the input/output terminals of the switching elements in the first stage300aand the third stage500aare initially connected, the input/output terminals indicated as dotted lines inFIGS. 5aand5bare not connected. Thereafter, if the increase of the switch capacity by 1.5 times is required due to the increase of subscribers, only the second stage400cis added to the existing switch network as shown inFIG. 5a, and the input/output terminals which have not been used as indicated as the dotted lines inFIG. 5aare connected in a many-to-many relationship to the switching elements SE55and SE56of the newly added second stage400c. Also, according to the second embodiment of the present invention, the switching elements provided in the first stage300aand the second stage400aand the switching elements provided in the second stage400aand the third stage500aare respectively connected through communication lines which can change the input/output connection ports of the switching elements. Accordingly, in case of increasing the switch network, the existing shelf or mother board of the existing cross connect system are used as they are, and only a portion of the input/output connection ports thereof is changed according to the second embodiment of the present invention.

Hereinafter, the switch capacity increasing method for a cross connect system according to the second embodiment of the present invention will be explained in detail.

First, the new second stage400cis added to the existing switch network to increase the whole switch capacity. Thereafter, the input/output terminals, which have not been used (shown as the dotted lines inFIGS. 5aand5b), of the switching elements SE41, SE42, SE61, and SE62provided in the first stage300aand the third stage500aare respectively connected to the switching elements SE55and SE56of the newly added second stage400cin a many-to-many relationship. InFIGS. 5aand5b, each dotted block tying the switching elements indicates a module, and the increase of the switch capacity is performed in the unit of a module.

The switch capacity increasing method according to the second embodiment of the present invention wherein the whole switch capacity is increased by 1.5 times will be a more economical and effective method if the whole switch capacity of the switch network becomes larger.

As described above, according to the present invention, the switch capacity of the switch network can be increased by adding a new switch network to the existing switch network, and changing the connection of the communication lines as proposed by the present invention. At this time, the increase of the switch network by both 2Ntimes of 2N and 1.5 times of 2Nis possible.

Consequently, according to the present invention, a switch network having a proper switch capacity can be produced when designing or manufacturing a cross connect system, and in case of increasing the switch capacity of the switch network, the existing switch network can be used as it is, thereby preventing unnecessary or excessive expenses from being spared.