JP2741798B2 - Internal route selection system for ATM exchange - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

ATM switching technology is the next generation switching system.
Agreed by CITT (International Telegraph and Telephone Consultative Committee), research is being actively conducted in various organizations 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 burstiness of information, such as voice, data, and moving images, are handled in a unified manner. Fluctuates greatly. For this reason, there is a problem that the quality of service is degraded due to cell discarding or delay, and a solution is desired.

For this reason, 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 in a switch has been proposed. However, the route selection method of a switch having multiple routes has not been studied yet. For this reason, it is necessary to consider an algorithm for selecting an optimal route at high speed.

[0004]

2. Description of the Related Art As a conventional switching technique, STM (Sy
(Chronically Transfer Mode) exchange method is the mainstream. FIG. 27 is a conceptual diagram of the STM method. The STM method is a time division multiplex method on the premise of frame synchronization. One frame of 125 μs is divided into fixed-length time slots, and data of each channel is divided and carried.

In the figure, four channels A, B, C1 and C2 are time-division-divided by a switch SW1 on the entrance side, and only a fixed length is fetched. On the output side, the multiplexed data is separated by a switch that operates in synchronization with the switch SW1. If the number of frames is set according to the amount of data, a necessary amount of data of each channel can be transferred.

FIG. 28 is a conceptual diagram of the ATM system. AT
The M method divides information of each channel into short blocks,
The block is sequentially sent out with a header indicating the destination or the like attached to the top of the block. Here, the block to which the header is added is called a cell. The network checks only the contents of the header and exchanges them in units of cells, and delivers them to the destination.

[0007] In the conventional STM switching system, few switches have a plurality of internal switches. Also, even if there is, the route is determined by the band used because the media is limited. Therefore, this switching system is not suitable for an ATM switch handling various media.

[0008]

In the ATM switching system,
Although congestion occurs at a certain probability, it is necessary to establish an intra-switch route selection method so as not to cause this as much as possible and to increase the use efficiency of the switch as much as possible. In addition, since the algorithm is obtained online, it is necessary to execute the algorithm as fast as possible.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to provide an internal route selection system of an ATM exchange which is less likely to cause congestion and can determine a route at a 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 output highway in which a plurality of switch cells 1 are arranged in a matrix, and an ATM having a plurality of routes for the same departure path interconnected with the preceding or subsequent switch cells 1 between the switch cells 1 in each stage. Switch. However,
The first-stage switch cells are interconnected only with subsequent switch cells, and the last-stage switch cells are interconnected only with preceding switch cells.

3 is the declared value of the band used, the ON switch NO
(Call number) and an output switch NO (number). The call processing unit 20 receives the output of the call processing unit 3 and
A route determination processing unit for determining a route of the switch 10;
Is a permission determination processing unit that receives an output of the route determination processing unit 20 and determines whether a request call of a user can pass through the route.

The route determination processing unit 20 determines how much the switch cell 1 in the ATM switch 10 is used,
It also includes an in-switch use band database (DB) 21 for storing information indicating how much space is available, and a route selection unit 22 for determining a route of the ATM switch with reference to the database 21.

In the ATM switch 10, the first-stage switch cell 1 is M × N (the number of inputs is M and the number of outputs is N; the same applies hereinafter), the middle-stage switch cell 1 is K × L, and the last-stage switch cell 1 is L × P.

[0014]

When the call processing section 3 determines the band to be used, the ON switch NO, the outgoing switch NO, and the like, the route determination processing section 20
Then, the route selection unit 22 refers to the in-switch used band database 21 to determine a route that is less likely to cause congestion and has a higher speed. That is, a route with the least bandwidth is selected. As a result, the probability of congestion occurring in each switch cell 1 in the ATM switch 10 can be reduced, and a high-speed route can be determined.

[0015]

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

FIG. 2 is a block diagram showing a main part of one embodiment of the present invention, and shows an example of the configuration of a route determination processing unit 20. In the figure, reference numeral 21a denotes an in-switch logical usage band DB for storing logical usage band (user-declared usage band) information in the ATM switch 10 as a DB, and 22a searches all routes based on the in-switch logical usage band DB 21a. Then, it is an all-routes search selection processing unit that selects the route with the least bandwidth usage.

FIG. 3 shows the in-switch logical use band DB 21a.
It is a figure showing the example of contents of. In the figure, the link name and the bandwidth of the logical use bandwidth are stored. Here, a link connecting the first-stage switch cell and the intermediate-stage switch cell is denoted by 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 route search selection processing section 22a. In the figure, the free band of the link L _IJK is V _IJK , I is the column number of the incoming switch, K is the column number of the outgoing switch, r is the selected root number (column number of the second-stage switch cell), and M is 2 It is the number of the last row of the stage switch.

First, a variable Mindata indicating data with 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 in the input stage.

First, the in-switch logical use band DB 21a
Used band data Min (V _1IJ , V
_2JK ) and the variable Mindata (S3). The used band data Min (V _1IJ , V _2JK ) indicates 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 ( _V1IJ , _V2JK ), this Min ( _V1IJ , _V2JK ) is set 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 to repeat the data comparison. If j> M, the search for the used band data for all data has been completed, and the process is terminated.

FIG. 5 is a block diagram showing a main part of another embodiment of the present invention. In this embodiment, the all route selection processing unit 22b
The ascending order table of the in-switch logical use band database 21a is constantly updated in ascending order of the use band of the outgoing highway of the first-stage switch cell 1 in the ATM switch 10, and when there is a call request, the top of the table Is selected.

FIG. 6 shows the in-switch logical use band DB 21a.
FIG. 3 is a diagram showing a configuration example of an ascending order table in FIG. The highway number (NO) and the number of available bands are stored in pairs. The highest-order highway has a larger number of available bands. In addition, as a method of updating the table in the order of the available bandwidth (in the order of the used bandwidth), an existing technique of sorting such as a binary tree search method can be used.

FIG. 7 is a block diagram showing a main part of another embodiment of the present invention, and shows an example of the configuration of the route determination processing unit 20. In the figure, reference numeral 21a denotes an in-switch logical use band storage database for storing all link use band information on an ingress highway to an outgoing highway, and 23 denotes a traffic monitoring device for monitoring actual measurement values of each highway use state inside the ATM switch 10. , 21b check the actual data used band database in the switch for storing the information sent from the traffic monitoring unit 23, and 22c check the two data of the logical used band database 21a in the switch and the measured value used band database 21b in the switch. The entire route search selection processing unit that selects the route that uses the least bandwidth.

In the device configured as described above, the traffic monitoring unit 23 monitors the measured value of the usage status of each switch cell 1 in the ATM switch 10 and stores the monitored value in the measured value used band DB in the switch.

FIG. 8 shows the actually used value used band DB 21 in the switch.
It is a figure showing the example of contents of b. The buffer usage rate (%) is shown for each link name. FIG. 9 is a flowchart showing the operation of the traffic monitoring device unit 23 that updates the data in the in-switch actual measurement value use band 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 / number of allowable cells of buffer) × 100 Then, the obtained buffer usage rate is stored in the buffer usage rate column on each link in the in-switch actual measurement value usage bandwidth DB 21b (S3). ).

FIG. 10 shows an all route search selection processing section 22c.
6 is a flowchart showing the operation of the first embodiment. The all route search selection processing unit 22c includes a logical use bandwidth database 21a within the switch and an actual measurement use bandwidth database 21b within the switch.
By examining the above two data, a route using the least bandwidth is selected.

First, the variable Mindata is initialized to 0 (S1). Next, the following sequence is repeated from j = 1 to M (S2). Next, Mindata and the used band data Min (V _1IJ , V
_2JK ) (S3). Used bandwidth data Min
(V _1IJ , V _2JK ) represents the amount of free space. Here, if Mindata <Min ( _V1IJ , _V2JK ), this Min ( _V1IJ , _V2JK ) is set 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. If j> M, it means that the search for the used band data for all data has been completed.

Next, the actually 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 below (S7), and if so, the process is terminated. If not, the next process is executed again 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 a main part of another embodiment of the present invention, and shows an example of the configuration of the route determination processing unit 20. In the figure, reference numeral 22d denotes a random route selection processing unit for randomly selecting a route from the passable routes. FIG. 12 is a flowchart showing the operation of the random route selection processing unit 22d. First, random numbers from r = 1 to M are generated (S1), and then a route with r as the second switch number is selected (S2).

FIG. 13 is a block diagram showing the configuration of a main part of another embodiment of the present invention, and shows an example of the configuration of the route determination processing unit 20. In the figure, reference numeral 22e denotes a cyclic route selection processing section for selecting a route next to the route selected last time. The operation is as shown in FIG.

First, a variable r is initialized to 0 (S1).
Next, it is checked whether there is a route selection request (S
2) In some cases, r = r + 1 is updated (S3), and r and M are compared (S4). If r> M, set r = 1 (S5), select a route with r as the second switch number (S6), and prepare for the next selection request. If 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 a main part of another embodiment of the present invention. In the figure, reference numeral 22f denotes a requested call speed judging unit for judging whether the call to be connected by the user is a low speed call or a high speed call. Reference numeral 24 denotes a high-speed call selector for selecting a high-speed call when the result of the determination is a high-speed call, and reference numeral 25 denotes a low-speed call selector for selecting a low-speed call when the result of the determination is a low-speed call.

The operation of the request call speed judging section 22f in the apparatus having the above-mentioned configuration will be described with reference to FIG.
First, upon receiving a signal from the call processing unit 3 (see FIG. 1), a peak value of a call requested by a 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 0 Mbps, any other value may be used. If the peak value is greater than 10 Mbps, the control is passed to the high-speed call selector 24 because it is a high-speed call. For example, the high-speed call selector 24 calls the all route search method shown in FIG. 2 (S3). ). The route selection method in the case of a high-speed call is not limited to the all route selection method shown in FIG. 2, but other types of route selection methods can be selected. For example, the system using the ascending order table shown in FIG. 5 or the two data of the in-switch logical use band database 21a and the in-switch actual value use band database 21b shown in FIG. A selection method can be used.

If the peak value is 10 Mb in step S2
If it is equal to or less than ps, the control is passed to the low-speed call selection unit 25, and for example, a low-speed random search method as shown in FIG. 11 or a cyclic route selection method as shown in FIG. 13 is used ( S4). In this way, it is possible to select an optimal route selection method according to whether the requested call is fast or slow.

FIG. 17 is a block diagram showing a main part of another embodiment of the present invention. In the figure, reference numeral 21c denotes an in-switch load information DB storing load information in the ATM switch 10;
Reference numeral 2g denotes a load determination unit that receives a call setting request from a 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 denotes a high-speed call selector for selecting a high-speed call when the result of the determination is high load, and reference numeral 25 denotes a low-speed call selector for selecting a low-speed call when the result of 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 for a high-load link with respect to the M outgoing links having the switch number of the first stage. In (b), “1” is set to the high-load link with respect to the M incoming links of the third-stage switch number.

FIG. 19 is a flowchart showing the route selection operation in the embodiment of FIG. First, the load determination unit 22g obtains an ON switch (S1). Here, the on-switch number is i. Next, switch load information D
Referring to B21c, examining the load status bit data for each outgoing link of the switch cell _{S 1i} (S2).

Then, it is checked whether the load status bit data is all "0" (S3). If all are "0", the load is low. In this case, an outgoing switch is determined (S4). Here, the outgoing switch number is j. Next, the in-switch load information DB 21c
To check the load status bit data of each incoming link of the switch cell _S3j (S5).

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

As a low-speed route selection method, 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 stored in each of the selectors 24,
25 (S9), and when the used bandwidth of the notified route exceeds 70% of the total, the corresponding bit of the in-switch load information DB 21c is set to "1" (S10). It should be noted that another value may be used as 70% as the reference value.

FIG. 20 is a block diagram showing a main part of another embodiment of the present invention. The same components as those in FIG. 17 are denoted by the same reference numerals. In the figure, reference numeral 22h denotes a route selection method classifying unit that refers to an optimum switch route based on the requested call speed and the contents of the in-switch load information DB 21c. The route selection method classification unit 22h selects the high load selection unit 24 when the call is a high-speed call and the load is high, and otherwise selects the low load selection unit 25.

FIG. 21 is a flowchart 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 (S3).
5). Then, the used bandwidth of the notified route is 7
If it exceeds 0%, the switch load information DB 21c
Is set to "1" (S6). If the peak value is less than 10 Mbps 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 illustrating an example of information of a request call. The information on the requested call includes the incoming switch number, the outgoing switch number, and the peak value of the required bandwidth. In the example shown in FIG enters switch number S _11, output switch number S _33, the peak value of the required bandwidth used 1M
bps.

FIG. 23 is a block diagram showing a configuration example of an ATM switch used in the embodiment. Each stage of the switch cell 1 has an incoming highway 3 and an outgoing highway 3. Fig. 2 shows the data of the logical usage band and the actual measurement value of each link.
4 and FIG. FIG. 26 is a diagram showing an example of switch load information. (A) shows the first-stage switch number, and (b) shows the third-stage switch number.

In such a situation, when an attempt is made to connect the call shown in FIG. 22, if the requested call is 1 Mbps according to the required call / load determination algorithm shown in FIG. 21, the algorithm of FIG. 20 is executed. I do. In this algorithm, all the load information bit data containing the switch S ₁₁ shown in FIG. 26 "0", the examining load information bit data output switch S _33.

Then, since there is "1", an algorithm for checking all routes is called. According to this algorithm, a check is first made with the logical bandwidth information (FIG. 24). According to this, _L111 and _L233 use the least band, and are listed as candidates first. Next, determination is made based on the actually measured value data based on the data in FIG. Since the measured data is 10%, this link is selected without any problem, and the routes in the ATM switch are L ₁₁₁ and L _233.
Is determined.

[0052]

As described above in detail, according to the present invention, the route in the ATM switch 10 can be optimally selected by the route determination processing unit 20 according to the used band, the load condition, etc., and congestion is reduced. It is possible to provide an internal route selection system of an ATM exchange, which hardly occurs and can determine a route at a high speed.

[Brief description of the drawings]

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

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

FIG. 3 is a diagram illustrating an example of the contents of an in-switch logical usage band DB;

FIG. 4 is a flowchart illustrating an operation of an all route selection processing unit.

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

FIG. 6 is a diagram illustrating 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 the contents of an actually measured value used band DB in a switch.

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

FIG. 10 is a flowchart illustrating an operation of an all route 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 illustrating 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 illustrating 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 illustrating an operation of a request 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 the contents of an in-switch load information DB;

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 illustrating an example of information of a request call.

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

FIG. 24 is a diagram showing an example of the contents of a logical usage band DB within a link.

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

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

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

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Switch cell 2 Permission determination processing part 3 Call processing part 10 ATM switch 20 Route determination processing part 21 In-switch use band DB 22 Route selection part

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yoshiharu Sato 1015 Uedanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Inside Fujitsu Limited (56) References JP-A-2-213250 (JP, A) JP-A-2-63345 (JP, A) JP-A-2-190056 (JP, A) JP-A-63-117535 (JP, A) IEICE Technical Report, SSE 88-171 (1989-2-18), 31−36

Claims (7)

(57) [Claims] 1. A plurality of routes for the same departure route
ATM switch and call processing for giving the value of the bandwidth used for the requested call
Receiving the output of the call processing unit and the ATM switch.
A route determination process for determining a route for the requested call
Receiving the output of the route determination processing unit and the
Permission determination to determine whether the request
Internal route selection system of ATM exchange having processing unit
In the system, the request call is stored in the route determination processing unit at a first speed.
A request call speed determining unit for determining whether the call is a call or a call of the second speed.
The request call speed determination unit is provided when the request call has a first speed.
To check the bandwidth usage information of the link in each route,
A route with a small bandwidth is selected, and if the requested call is a call of the second speed , a route that can be passed is selected.
ATM exchange characterized by selecting a route from
Internal route selection system. 2. The request call speed judging section according to claim 1, wherein
If the call value is greater than the reference value, the
If the peak value of the requested call is smaller than the reference value,
2. The method according to claim 1, wherein the call is determined to be a call having a speed of 2.
An internal route selection system for an ATM exchange as described. 3. The request call speed determination unit according to claim 1, wherein
Is the first speed call, leaving the incoming highway
Check bandwidth usage information for all links on the way
Select a route with less bandwidth or all routes
Investigate the bandwidth used and, when a call is allocated,
Out of the highway
Or check the logical bandwidth and the actual bandwidth
Select a route that uses less bandwidth
3. The internal route selection system for an ATM exchange according to claim 1. 4. The request call speed determination unit according to claim 1, wherein said request call speed determination unit comprises :
Is the second speed call, the
Choose a route to the dam or cycle to the next route
2. The ATM according to claim 1, wherein said ATM is selected.
Switch internal route selection system. 5. An ATM switch in the route determination processing unit.
Switch load information data that stores the load information in the switch
Check the base and current bandwidth used,
And a load determining unit that determines whether the load to be applied is large or small.
To change the route selection method according to the size of the load.
2. The internal route of an ATM exchange according to claim 1, wherein
Selection system. 6. The load judging section judges a current band to be used.
Check the logical usage band by using
Claims characterized by examining a logical usage band and an actually measured value.
6. An internal route selection system for an ATM exchange according to claim 5. 7. A switch for storing load information in said ATM switch in said route determination processing unit .
Load information database and a function to determine the speed of the requested call
Route selection method that has a function to check the load of bandwidth used
And the route selection method classifying unit determines whether the requested call speed is low or negative.
If the load is small, a random route
Select a route or cyclically select the next route
If the request speed is high and the load is heavy,
Check the available bandwidth of all the possible routes, and
Select a route with less area or use all routes.
The call bandwidth is checked, and when a call is allocated,
Select routes in ascending order of bandwidth usage
2. The ATM switch according to claim 1, wherein
Internal route selection system.