JPH05136810A - Internal route selection system for atm exchange - Google Patents

Abstract

PURPOSE:To enable deciding a high speed route without congestion by selecting a route with the least use bands at the time of selecting the internal route of an ATM exchange. CONSTITUTION:When a call processing part 3 decides the utilization band, an input switch number and an output switch number, a route decision processing part 20 refers to an intra-switch utilization band base 21 in a route selection part 22 while it decides the high speed route where congestion is hardly occurred. A utilization band 21a storing an intra-switch logical band, namely, utilization band information which a user reports, and a route search selection processing part 22a searching all the routes based on the utilization band and selecting the route with the least utilization bands are provided on the decision processing 20. The output of the selection processing part 22a is inputted to an ATM switch 10 through a permission judgement processing part 2. Switch cells 1 are arranged in a matrix in accordance with plural input highways and plural output highways for the switch 10 and the selected route is set to a utilization state.

Description

Detailed Description of the Invention

[0001]

The present invention relates to an asynchronous transfer mode (ATM: Asyn) having a plurality of routes to the same outgoing route.
The present invention relates to an internal route selection system in a Chronous Transfer Mode switch.

As the next-generation switching system, ATM switching technology is C
It has been agreed with CITT (International Telegraph and Telephone Consultative Committee), and research is actively conducted by each institution as a technology for realizing a broadband ISDN (Integrated Services Digital Network).
On the other hand, in ATM communication, various traffics having different bearer speeds (transfer speeds) and burstinesses of information such as voice, data, moving images, etc. are handled in a unified manner. The fluctuation of is large. Therefore, there is a problem that the quality of service is deteriorated due to cell discard and delay, and its solution is desired.

Therefore, an exchange having a plurality of routes for the same outgoing route has been proposed, and a switch for distributing a traffic load by providing a plurality of routes for the same outgoing route within the switch has been proposed. However, the route selection method for switches with multiple routes has not been studied yet. Therefore, it is necessary to consider an algorithm that selects the optimum route at high speed.

[0004]

2. Description of the Related Art As a conventional exchange technology, STM (Sy
The mainstream method is an exchange transfer mode. FIG. 27 is a conceptual diagram of the STM method. The STM method is a time division multiplexing method that is premised on frame synchronization. One frame of 125 μs is divided into fixed-length time slots, and the data of each channel is divided and placed.

In the figure, the four channels A, B, C1 and C2 are time-divided by the switch SW1 on the input path side and taken in by a fixed length. On the outgoing path side, the multiplexed data is separated by a switch that operates in synchronization with the switch SW1. By setting the number of frames according to the amount of data, it is possible to transfer the required amount of data for each channel.

FIG. 28 is a conceptual diagram of the ATM system. AT
The M method divides the information of each channel into short blocks,
A header indicating the destination etc. is attached to the beginning of the block and the blocks are sequentially sent out. Here, the block to which the header is added is called a cell. The network sees only the contents of the header, exchanges it in cell units, and delivers it to the other party.

[0007] In the conventional STM exchange system, few have an internal switch having a plurality of routes. In addition, even if there were, the media was limited, so the route was determined by the bandwidth used. Therefore, it is an unsuitable exchange system for ATM exchanges handling various media.

[0008]

In the ATM switching system,
Congestion occurs with a certain probability, but it is necessary to establish an intra-switch route selection method that minimizes this and maximizes switch utilization efficiency. The algorithm is also calculated online, so it should be performed as fast as possible.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an internal route selection system for an ATM exchange, in which congestion is unlikely to occur and a route can be determined at high speed. ..

[0010]

FIG. 1 is a block diagram showing the principle of the present invention. In the figure, there are multiple input highways,
An ATM having a plurality of output highways in which a plurality of switch cells 1 are arranged in a matrix, and the switch cells 1 in each stage are interconnected with the switch cells 1 in the preceding stage or the succeeding stage, and which have a plurality of routes to the same output route. It is a switch. However,
The switch cells in the first stage are interconnected only with the switch cells in the latter stage, and the switch cells in the last stage are interconnected only with the switch cells in the previous stage.

Reference numeral 3 is a reported value of a band used, and an ON switch NO.
(Number) and an output switch NO (number), a call processing unit 20 receives the output of the call processing unit 3, and receives the ATM data.
A route determination processing unit that determines the route of the switch 10, 2
Is a permission determination processing unit that receives the output of the route determination processing unit 20 and determines whether the call requested by the user can pass through the route.

The route determination processing section 20 determines how much the switch cell 1 in the ATM switch 10 is used.
Further, it is composed of an in-switch bandwidth database (DB) 21 that stores information indicating how much space is available, and a route selection unit 22 that refers to the database 21 and determines the route of the ATM switch.

In the ATM switch 10, the switch cell 1 in the first stage is M × N (the number of inputs M and the number of outputs N are shown. The same applies hereinafter), the switch cell 1 in the middle stage is K × L, and the switch cell 1 in the final stage is L × P.

[0014]

When the call processing unit 3 determines the used band, the input switch NO, the output switch NO, etc., the route determination processing unit 20
Then, the route selection unit 22 refers to the intra-switch band usage database 21 so that congestion is unlikely to occur and the route is determined at high speed. That is, the route with the least bandwidth used is selected. As a result, the ATM switch 10
The probability of congestion occurring in each switch cell 1 can be suppressed to a low level, and high-speed route determination can be performed.

[0015]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 2 is a block diagram showing the essential parts of an embodiment of the present invention, showing an example of the structure of the route determination processing part 20. In the figure, 21a is a switch logical use band DB that stores the logical use band (use band declared by the user) information in the ATM switch 10 as a DB, and 22a searches all routes based on the switch logical use band DB 21a. Then, the all-routes search selection processing unit selects the route with the least used bandwidth.

FIG. 3 shows the logical use bandwidth DB 21a in the switch.
It is a figure which shows the example of the content of. In the figure, the link name and the logically used bandwidth are stored. Here, the link connecting the first-stage switch cell and the intermediate-stage switch cell is L
And ₁₁₁ ~L _1KM, a link connecting the intermediate stage switch cell and the final stage switch cells and _L 211 _{~L 2ML.}

FIG. 4 is a flow chart showing the operation of the all-routes search selection processing section 22a. In the figure, the free bandwidth of the link L _IJK is V _IJK , I is the column number of the input switch, K is the column number of the output switch, r is the selected route number (column number of the second-stage switch cell), and M is 2. It is the last row number of the stage switch.

First, a variable Mindata indicating data having a small used band is initialized to 0 (S1). Next, the following steps are repeated from j = 1 to M (S2). Here, M is the number of outputs of the switch cell 1 at the input stage.

First, the switch logical use bandwidth DB 21a
Band data Min (V _1IJ , V
_2JK ) and the variable Mindata (S3). The used bandwidth data Min (V _1IJ , V _2JK ) represents the amount of free space in the link connecting the first-stage switch cell 1 and the second-stage switch cell 1. Here, if Mindata <Min (V _1IJ , V _2JK ), this Min (V _1IJ , V _2JK ) is used as new used band data (S4). Here, the selected route number is stored in r.

Next, j and M are compared (S5). j <
In the case of M, the process returns to step S2 and the data comparison is repeated. When j> M, the processing is ended because the search of the used band data for all the data is completed.

FIG. 5 is a configuration block diagram showing the main part of another embodiment of the present invention, showing an example of the configuration of the route determination processing section 20. In this embodiment, the all route selection processing unit 22b
The ascending order table of the in-switch logically used bandwidth database 21a is constantly updated in the ascending order of the used bandwidth of the output highway of the first-stage switch cell 1 in the ATM switch 10, and if there is a call request, the highest rank of that table The route of is selected.

FIG. 6 shows a logical use bandwidth DB 21a in the switch.
It is a figure which shows the structural example of the ascending order table in FIG. A highway number (NO) and the number of free bands are stored as a pair. The highest highway has more free bands. An existing sorting technique such as a binary tree search method can be used as a method of updating the table in the order of increasing free bandwidth (in order of decreasing used bandwidth).

FIG. 7 is a structural block diagram showing the main part of another embodiment of the present invention, and shows a structural example of the route determination processing section 20. In the figure, reference numeral 21a is a switch logical use bandwidth storage database that stores all link use bandwidth information from the incoming highway to the outgoing highway, and 23 is a traffic monitoring device unit that monitors the actual measurement value of each highway usage state inside the ATM switch 10. , 21b are in-switch actual measurement use band databases for storing information sent from the traffic monitoring device section 23, and 22c are two data of in-switch logical use band database 21a and in-switch actual measurement value use band database 21b. It is an all-routes search selection processing unit that selects a route with the least used bandwidth.

In the device thus constructed, the traffic monitoring device section 23 monitors the actual measurement value of the usage status of each switch cell 1 in the ATM switch 10 and stores it in the intra-switch actual measurement value usage band DB.

FIG. 8 shows a measured value used band DB21 in the switch.
It is a figure which shows the example of the content of b. The buffer usage rate (%) is shown for each link name. FIG. 9 is a flow chart showing the operation of the traffic monitoring device unit 23 for updating the data in the actually measured value bandwidth used in the switch DB 21b. First, the number of cells in the buffer on each output link is counted (S1), and the buffer usage rate is calculated by the following equation (S2).

Buffer usage rate = (number of counted cells / allowable cell number of buffer) × 100 Then, the calculated buffer usage rate is stored in the buffer usage rate column on each link in the actually measured value usage bandwidth DB21b in the switch (S3). ).

FIG. 10 shows an all-routes search selection processing section 22c.
3 is a flowchart showing the operation of FIG. The all-routes search selection processing unit 22c uses the in-switch logical use bandwidth database 21a and the in-switch actual measurement use bandwidth database 21b.
The two data are checked and the route with the least bandwidth is selected.

First, the variable Mindata = 0 is initialized (S1). Next, the following sequence is repeated from j = 1 to M (S2). Next, the used bandwidth data Min (V _1IJ , V read from Mindata and the database)
_2JK ) (S3). Bandwidth data Min
(V _1IJ , V _2JK ) represents the amount of free space. Here, if Mindata <Min (V _1IJ , V _2JK ), this Min (V _1IJ , V _2JK ) is used as new used band data (S4). Then, the selected route j is registered in r. Next, j and M are compared (S
5). If j <M, the process returns to step S2 to repeat the data comparison. When j> M, it means that the search for the used band data for all the data is completed.

Next, the measured value of the used band on the determined link is checked (S6). And the measured value data is 70%
It is checked whether it is the following (S7), and if so, the process is terminated. If not, the next process is re-executed for routes other than the route indicated by r (S8). Note that 70% of the data can be changed.

FIG. 11 is a block diagram showing the configuration of the main part of another embodiment of the present invention, showing a configuration example of the route determination processing part 20. In the figure, 22d is a random route selection processing unit that randomly selects a route from passable routes. FIG. 12 is a flowchart showing the operation of the random route selection processing unit 22d. First, a random number from r = 1 to M is generated (S1), and then a route having r as the second switch number is selected (S2).

FIG. 13 is a configuration block diagram showing the main part of another embodiment of the present invention, showing an example of the configuration of the route determination processing section 20. In the figure, 22e is a cyclic route selection processing unit that selects a route next to the previously selected route. The operation is as shown in FIG.

First, the variable r is initialized to 0 (S1).
Next, it is checked whether there is a route selection request (S
2) If any, r = r + 1 is updated (S3), and r and M are compared (S4). When r> M, r = 1 is set (S5), a route having r as the second switch number is selected (S6), and the next selection request is prepared. When r> M is not satisfied in step S4, the process proceeds to step S6 without passing through step S5.

FIG. 15 is a block diagram showing the configuration of the main part of another embodiment of the present invention, showing a configuration example of the route determination processing part 20. In the figure, reference numeral 22f is a request call speed determination unit that determines whether the call the user is trying to connect to is a low speed call or a high speed call. Reference numeral 24 is a high-speed call selecting unit that selects a high-speed call when the determination result is a high-speed call, and 25 is a low-speed call selecting unit that selects a low-speed call when the determination result is a low-speed call.

The operation of the requested call speed determination unit 22f in the apparatus thus configured will be described with reference to FIG.
First, the signal from the call processing unit 3 (see FIG. 1) is received, and the peak value of the call requested by the user is checked (S1). The peak value of the call is compared with 10 Mbps (S2).
Here, the reference value of whether the call is a high speed call or a low speed call is 1
Although it is set to 0 Mbps, it may be any other value. If the peak value> 10 Mbps, it means that the call is a high-speed call, so control is passed to the high-speed call selecting unit 24, and the high-speed call selecting unit 24 calls the all-routes search method shown in FIG. 2 (S3). ). The route selection method for a high-speed call is not limited to the all-routes selection method shown in FIG. 2, and other types of route selection methods can be selected. For example, a method using the ascending table shown in FIG. 5 or two data of the intra-switch logical use bandwidth database 21a and the intra-switch actual measurement use bandwidth database 21b shown in FIG. A method of selection can be used.

If the peak value is 10 Mb in step S2
If it is less than or equal to ps, control is passed to the low-speed call selection unit 25, and the low-speed random search method shown in FIG. 11 or the cyclic route selection method shown in FIG. 13 is used ( S4). In this way, the optimum route selection method can be selected according to whether the requested call is high speed or low speed.

FIG. 17 is a block diagram showing the essential parts of another embodiment of the present invention, showing an example of the structure of the route determination processing section 20. In the figure, 21c is a switch load information DB storing load information in the ATM switch 10 and 2
A load determination unit 2g receives a call setting request from the user and refers to the contents of the in-switch load information DB 21c to determine whether the load is high or low.

Reference numeral 24 is a high speed call selecting section for selecting a high speed call when the result of the determination is high load, and 25 is a low speed call selecting section for selecting a low speed call when the result of the determination is low load. ..

FIG. 18 is a diagram showing an example of the contents of the in-switch load information DB 21c. (A) shows the load status of each outgoing link, and (b) shows the load status of each incoming link. In (a), "1" is set to the high load link for the M outgoing links of the switch number of the first stage. In (b), “1” is set for a high load link with respect to the M incoming links having the third switch number.

FIG. 19 is a flow chart showing the route selection operation in the embodiment of FIG. First, the load determination unit 22g obtains an on switch (S1). Here, the incoming switch number is i. Next, load information D in the switch
The load status bit data of each outgoing link of the switch cell S _1i is checked with reference to B21c (S2).

Then, it is checked whether all the load status bit data are "0" (S3). When all are "0", it means that the load is low. In this case, the output switch is requested (S4). Here, the output switch number is j. Next, the switch load information DB 21c
The load status bit data of each incoming link of the switch cell S _3j is checked (S5).

Then, it is checked whether the load status bit data of each outgoing and incoming link are all "0" (S6). The case where all are "0" is the case of low load. In this case,
The route selection method for low speed is used (S7). If all are not "0", the high-speed route selection method is used including the case where all are not "0" in step S3 (S).
8). Here, as a route selection method for high speed, FIG.
Check the two data of the all-route selection method shown in Fig. 5, the method using the ascending order table shown in Fig. 5, and the in-switch logical use bandwidth database 21a and the in-switch actual measurement use bandwidth database 21b shown in Fig. 7. It is possible to use a method of selecting a route with the least used bandwidth.

The low speed route selection method is, for example, a low speed random search method as shown in FIG.
A cyclic route selection method as shown in FIG. 13 can be used.

Next, the selected route is assigned to each selection unit 24,
When the bandwidth used for the notified route exceeds 70% of the total, the corresponding bit of the in-switch load information DB 21c is set to "1" (S10). Other values may be used for 70% as the reference value.

FIG. 20 is a configuration block diagram showing the main part of another embodiment of the present invention, showing an example of the configuration of the route determination processing part 20. The same parts as those in FIG. 17 are designated by the same reference numerals. In the figure, 22h is a route selection method classification unit that refers to an optimum switch route from the requested call speed and the contents of the in-switch load information DB 21c. The route selection method classifying unit 22h selects the high load selecting unit 24 when the call is a high-speed call and has a high load, and selects the low load selecting unit 25 in other cases.

FIG. 21 is a flow chart showing the operation of the embodiment shown in FIG. First, the route selection method classification unit 22
h checks the peak value of the call requested by the user (S
1). Then, it is checked whether the peak value is larger than 10 Mbps (S2).

If the peak value is larger than 10 Mbps, the high-speed load selecting unit 24 is selected (S3), and the selected route is notified from the high-load selecting unit 24 (S).
5). And the used bandwidth of the notified route is 7
When it exceeds 0%, the switch load information DB 21c
The corresponding bit in each is set to "1" (S6). If the peak value is 10 Mbps or less in step S2,
The algorithm shown in FIG. 19 is executed (S4).

Next, the algorithm shown in FIG. 21 will be described in more detail. FIG. 22 is a diagram showing an example of request call information. The request call information includes the incoming switch number, the outgoing switch number, and the peak value of the requested used bandwidth. In the example shown in the figure, the incoming switch number is S ₁₁ , the outgoing switch number is S ₃₃ , and the peak value of the requested bandwidth is 1M.
bps.

FIG. 23 is a block diagram showing a configuration example of an ATM switch used in the embodiment. The switch cell 1 at any stage has a structure of an input highway 3 and an output highway 3. Figure 2 shows the data of the logically used bandwidth and measured values of each link
4 and FIG. 25 respectively. FIG. 26 is a diagram showing an example of load information of switches. (A) shows the switch number of the first stage, and (b) shows the switch number of the third stage.

In such a situation, when the call shown in FIG. 22 is to be connected, first, according to the request call / load determination algorithm shown in FIG. 21, if the request call is 1 Mbps, the algorithm of FIG. 20 is executed. To do. In this algorithm, the load information bit data of the input switch S ₁₁ shown in FIG. 26 is all “0”, so the load information bit data of the output switch S ₃₃ is checked.

Then, since there is "1", an algorithm for checking all routes is called. According to this algorithm, the logically used bandwidth information (FIG. 24) is first checked. According to this, L ₁₁₁ and L ₂₃₃ have the least used bandwidth, and are first selected as candidates. Next, based on the data in FIG. 25, the actual measurement value data is used for the determination. Since the measured value data is 10%, this link is selected without any problem, and the routes in the ATM switch are L ₁₁₁ and L _233.
To decide.

[0052]

As described above in detail, according to the present invention, the route determination processing section 20 can optimally select the route in the ATM switch 10 according to the used bandwidth, the load condition, etc. It is possible to provide an internal route selection system for an ATM exchange that is unlikely to occur and can determine a route at high speed.

[Brief description of drawings]

FIG. 1 is a principle block diagram of the present invention.

FIG. 2 is a configuration block diagram showing a main part of an embodiment of the present invention.

FIG. 3 is a diagram showing an example of contents of a logically used bandwidth DB in a switch.

FIG. 4 is a flowchart showing an operation of an all-routes selection processing unit.

FIG. 5 is a configuration block diagram showing a main part of another embodiment of the present invention.

FIG. 6 is a diagram showing a configuration example of an ascending order table.

FIG. 7 is a configuration block diagram showing a main part of another embodiment of the present invention.

FIG. 8 is a diagram showing an example of contents of a measured value use band DB in a switch.

FIG. 9 is a flowchart showing an operation of a traffic monitoring device unit.

FIG. 10 is a flowchart showing an operation of an all-routes selection processing unit.

FIG. 11 is a configuration block diagram showing a main part of another embodiment of the present invention.

FIG. 12 is a flowchart showing an operation of a random route selection processing unit.

FIG. 13 is a configuration block diagram showing a main part of another embodiment of the present invention.

FIG. 14 is a flowchart showing an operation of a cyclic route selection processing unit.

FIG. 15 is a configuration block diagram showing a main part of another embodiment of the present invention.

FIG. 16 is a flowchart showing an operation of a requested call speed determination unit.

FIG. 17 is a configuration block diagram showing a main part of another embodiment of the present invention.

FIG. 18 is a diagram showing an example of contents of an in-switch load information DB.

FIG. 19 is a flowchart showing a route selection operation in the embodiment of FIG.

FIG. 20 is a configuration block diagram showing a main part of another embodiment of the present invention.

21 is a flowchart showing the operation of the embodiment shown in FIG.

FIG. 22 is a diagram showing an example of request call information.

FIG. 23 is a block diagram showing a configuration example of an ATM switch used in the embodiment.

FIG. 24 is a diagram showing an example of the contents of an in-link logically used band DB.

FIG. 25 is a diagram showing an example of contents of an in-link actual measurement value data storage DB.

FIG. 26 is a diagram showing an example of load information in the switch.

FIG. 27 is a conceptual diagram of the STM method.

FIG. 28 is a conceptual diagram of an ATM system.

[Explanation of symbols]

 1 Switch Cell 2 Permission Determination Processing Unit 3 Call Processing Unit 10 ATM Switch 20 Route Determination Processing Unit 21 In-Switch Bandwidth DB 22 Route Selection Unit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical indication location H04Q 11/04 9076-5K H04Q 11/04 F (72) Inventor Yoshiharu Sato Nakahara-ku, Kawasaki-shi, Kanagawa 1015 Kamiodanaka, Fujitsu Limited

Claims (9)

[Claims] 1. Switch cells (1) having a plurality of input highways and a plurality of output highways are arranged in a matrix, and the switch cells (1) at each stage are interconnected with the switch cells (1) at the preceding stage or the succeeding stage. The ATM switch (10) having a plurality of routes to the same outgoing route, the call processing unit (3) for giving the declared value of the used band, the incoming switch number and the outgoing switch number, and the call processing unit ( A route determination processing unit (20) which receives the output of 3) and determines the route of the ATM switch (10).
And an authorization decision processing section (2) which receives the output of the route decision processing section (20) and decides whether or not the call requested by the user can pass through the route. .. 2. The route determination processing unit (20) stores a logical use bandwidth storage database (21a) in a switch for storing all link use bandwidth information on an incoming highway and an outgoing highway, and information of the database (21a). 2. The inside of the ATM switch according to claim 1, further comprising: an all-routes search selection processing unit (22a) for checking the used bandwidth of all possible routes based on the above, and selecting the route with the smallest used bandwidth. Route selection system. 3. The route determination processing unit (20) stores a switch logical use bandwidth storage database (21a) for storing all link use bandwidth information on an incoming highway and an outgoing highway, and information of the database (21a). Based on the above, the available bandwidths of all possible routes are checked, and when the call is allocated, all routes that operate the in-switch logically used bandwidth storage database (21a) in ascending order of the used bandwidth of the first-stage outgoing highway 2. The internal route selection system for an ATM exchange according to claim 1, wherein the system comprises a search selection processing unit (22b). 4. The route determination processing unit (20) comprises a switch internal logical use bandwidth storage database (21a) for storing all link utilization bandwidth information on an incoming highway and an outgoing highway, and an internal ATM switch (10). Traffic monitoring device section (23) for monitoring the actual measurement value of each highway usage state, and in-switch actual measurement value band database (2) for storing information sent from the traffic monitoring device section (23)
1b), the in-switch logically used bandwidth database (21a) and the in-switch actually used bandwidth database (21b) are checked to select the route with the least used bandwidth from the all-routes search selection processing unit (22c). The internal route selection system for an ATM exchange according to claim 1, wherein the system is configured. 5. The ATM according to claim 1, wherein the route determination processing unit (20) includes a random route selection processing unit (22d) that randomly selects a route from passable routes. Switch internal route selection system. 6. The route determination processing unit (20) is configured to include a cyclic route selection processing unit (22e) for selecting a route next to the previously selected route. An internal route selection system for the ATM exchange described. 7. A request call speed determination unit (22f) is provided in the route determination processing unit (20) for determining whether a call the user is trying to connect to is a low speed call or a high speed call. The route is selected according to the method of claims 2 to 4 when it is fast, and the route is selected according to the method of claim 5 or 6 when the speed of the requested call is slow. ATM switch internal route selection system. 8. An in-switch load information database (21c) for storing load information in the ATM switch (10), and a current bandwidth (only a logical bandwidth or a logical bandwidth) in the route determination processing section (20). A load determination unit (22g) for determining whether the load on the current switch is large or small by examining the used band and the actual measurement value) is provided.
2. An internal route selection system for an ATM exchange according to claim 1, wherein the route selection method is changed according to the magnitude of the load. 9. A load information database (21c) in the switch for storing load information in the ATM switch (10), a function for determining a speed of a request call, and a bandwidth used in the route determination processing unit (20). A route selection method classification unit (22h) having a function of examining the load is provided, and when the speed of the requested call is low or the load is small, the route is selected by the method of the above-mentioned claim 5 or 6 The internal route selection system for an ATM exchange according to claim 1, wherein a route is selected by the method of claim 2 or 3 when the load is large.