DE4422546A1 - Route list regulation method for switching data network - Google Patents

Abstract

The method uses route lists (LA,...LE) stored in memory in individual nodes (A,B,C,D,E) in a data network (N) to allow switching of connections. The nodes are coupled together by means of transmission connections (1,...10). The network is controlled by a central network computer (ZR). A determination of routes to be included in the lists is carried out repeatedly until two or more halting criteria are reached. The network computer (ZR) has a controller (PR) which carries out the iterative determination. The controller (PR) can control a data carrier (DT) on which data is stored, and interacts with the nodes using connections (D1-D5). The data includes information to enable the determination to be carried out.

Description

The present invention relates to a method for determining Routing lists in a communication network for switched connections according to the preamble of claim 1, and a calculator according to the preamble of claim 8 and a data carrier according to the preamble of claim 9.

It is known that in such a communications network Switching nodes - hereinafter referred to as VNK - information about a connection request using signaling messages be communicated. If such a connection request meets in one the VNK of the communication network, depending on various parameters of the connection request, such as For example, origin of the connection request or selected Telephone number, etc., outgoing from the VNK Transmission facilities examined for free channels. Becomes a suitable free channel is found, then this free channel occupied and the connection request through a coupling network of the VNK switched through. If this is not the case, then the  Connection request usually lost. Aim effective Traffic control is u. a. that as few connection requests as possible in the news network is lost.

It is also known that rules originating from the VNK Transmission facilities when editing the Search for a connection request on a free channel, in Route lists are set. Using routing lists Traffic flows are directed so that everyone can be reached Target node is guaranteed at local stress peaks Alternative ways can be used, one as uniform as possible Utilization of the transmission facilities is reached and the Traffic performance of the communications network is maximized.

A method for determining routing lists in the above News network described is from US patent 4,704,724. In the process described there, in predetermined time intervals based on the Network configuration, past, present and one Estimation of future traffic volumes calculated by the network and entered in routing lists. At the If a connection request occurs, blocking values that are a measure of the traffic load, for different, walkable Paths between two switching nodes are calculated and the path with the lowest blocking value selected, provided it has a fixed one Falls below the threshold that characterizes a traffic load, that are not exceeded by the additional traffic to be expected shall be. If the threshold is exceeded, then the Connection request rejected.

It is an object of the present invention to be effective Determination of route lists in a communication network for mediated connections and high performance of the Ensure news network.  

According to the invention, this object is achieved through the technical teaching of Claim 1, and claims 8 or 9, solved.

An advantageous embodiment of the method according to the invention is to have a way of selecting criteria for Determination of the routing lists during the execution of the procedure to be able to change.

Further advantageous embodiments of the invention The procedure can be found in the dependent patent claims.

For a better understanding of the invention and its advantages, a message network and three exemplary embodiments are described below with reference to FIGS. 1 to 4. Show it:

Fig. 1 shows a known communication network, in which the inventive method is applied,

Fig. 2 is a flow diagram of an embodiment of the inventive method,

Fig. 3 is a flow diagram of one embodiment of the process step according to the invention for determining a critical traffic relationship and

Fig. 4 is a flow diagram of one embodiment of the process step according to the invention for determining a routing path for the next critical traffic relationship.

With the invention it is possible to be flexible, based on the specifications of an operator adjustable behavior of the message network to ensure efficient routing lists, especially if if the traffic demands are not exclusively via direct routes can be operated. This is especially the case when a  Participant behavior occurs that the long-term planning of the News network was not based or the structure of the communications network, for example, due to technical defects deviates from the long-term planned structure.

With the help of several predefinable and changeable criteria, the described in more detail below, are iterative about the entire communications network determines the routes. The criteria are to the operator strategies, such as B. Achieve as little as possible Busy signal for subscribers to the message network, customizable.

Fig. 1 shows a communication network N with a number of five switching nodes A, B, C, D and E, each via transmission facilities, which contain a set of channels, which in turn are combined into one or more bundles, in the following manner are connected:

A is connected via the transmission device 1 to B, via the transmission device 2 to C, via the transmission device 3 to D and via the transmission device 4 to E, furthermore B is via the transmission device 5 to C, via the transmission device 6 to D and via the transmission device 7 is connected to E, furthermore C is connected to D via the transmission device 8 and E to the transmission device 9 and the connection between D and E is realized via the transmission device 10 . In the application example, the transmission devices are mutually operated transmission devices. However, they can also be directional transmission devices. The message network N is preferably a fully meshed message network without establishing a hierarchy between the switching nodes A to E. However, the application of the method according to the invention is by no means restricted to fully meshed, non-hierarchical message networks.

Each switching node A to E is by means of data lines D1 to D5 connected to a central network computer ZR, preferably on-line. This central network computer ZR has a processor PR that controls the implementation of the method according to the invention. To the processor PR are fed data stored on a data carrier DT are stored and exact information for the implementation of the method according to the invention included. The disk DT is located in a reading device of the central network computer ZR.

Each switching node A to E also has an associated one Storage device in which the respective switching node assigned routing list LA to LE is stored. The charts 1A to 1E show examples of the routing lists LA to LE:

Table 1A

Switching node A, routing list LA

Table 1B

Switching node B, routing list LB

Table 1C

Switching node C, routing list LC

Table 1D

Switching node D, routing list LD

Table 1E

Switching node E, routing list LE

The routing lists 1A to 1E enter one in the first column Origin node from which the path to a destination node that is in the second column is specified, should be built. How one can easily see is that of the relevant routing list LA, . . . , LE assigned switching nodes A,. . . , E in the first four Entries in the routing list itself and in the remaining entries a transit node. The third column of the Tables indicate the type of traffic that is transmitted via the route. In the present application example it is a Pure voice transmission V. Data and Image transmission. In the fourth column, a Proportional distribution of traffic, d. H. a division of the Traffic on different routes if there are multiple routes be determined. Here 100% of the traffic is always through one specified route. Proportional division is in Message network N not supported for the sake of simplicity. The fifth Column of the routing lists LA to LE gives the direct routes of the respective routing list LA to LE assigned switching nodes A to E to the desired destination node. Columns six, seven and eight contain certain according to the inventive method Alternative routes. On the news network and in the following All traffic must have exemplary embodiments over a maximum of two Path sections are routed to the destination node. First of all, that's one arbitrary definition, but prevents loops and thus an unnecessary burden on the news network N. For this For this reason, alternative routes are only specified if the Switching nodes A to E assigned to the respective routing list Is the origin node.

In preparation for carrying out the method according to the invention parameters and data for the message network structure, for Network operator strategy and a matrix with traffic data in the central network computer ZR as calculation basis and Input information and, if available, incomplete  Routing lists entered in the switching nodes. There is the Possibility to define primary routes and alternative routes and these in to enter the route lists. These entries can be set like this that they can only be read, d. H. when the Routing lists, these entries remain unchanged. in the present message network N are all direct routes between two Mediation nodes whose first routes. However, this is not Prerequisite for the application of the method according to the invention. Now, before the method according to the invention is applied, first a traffic calculation in the message network N by the central network computer ZR. A more precise one A description of the traffic calculation is given below.

FIG. 2 shows a flow chart of an exemplary embodiment of the method according to the invention, which is used in the message network N according to FIG. 1. In a first step 100, a critical traffic relationship is determined using one or more first criteria. Traffic relationship means the traffic interest from one of the switching nodes as the origin to another of the switching nodes as the destination. For this traffic relationship, the method according to the invention is to be used to make an entry in the routing lists of the relevant switching nodes. The determination of this critical traffic relationship is discussed in more detail below in FIG. 3. In a subsequent step 200, a next route is then selected for this critical traffic relationship using one or more second criteria. This route is entered in the route lists of the switching nodes that relate to this route. In Fig. 4 will be discussed in more detail below on the selection of the next routing path. In a subsequent third step 300, the traffic calculation already mentioned above and described below is carried out again, but taking into account the newly determined route and entered in the route lists. In a fourth step 400 there is then the possibility of changing the one or more criteria for determining the critical traffic relationship and the one or more criteria for selecting the next route for the critical traffic relationship. An operator or another method can change these criteria or the order of their checking or their number. This step 400 is not necessary for carrying out the method according to the invention, but increases flexibility and the results can improve. Finally, in a fifth step 500, one or more termination criteria are checked. If this or the termination criteria are not met, the method according to the invention is repeated starting with step 100. If one of the termination criteria is met, the method according to the invention is ended. Depending on the selection of the termination criteria, it can also be determined that several termination criteria must be met in order to end the method according to the invention. The termination criteria are freely definable. Termination criteria can include the following:

• - The maximum number of alternative routes is already for everyone Traffic relationships set.
• - A target value specified by the operator of the communications network N. the transport performance, for example the highest possible Transferability of traffic or the highest possible achievement of fees has been reached.
• - The end-to-end losses remain for all traffic relationships below a predetermined limit.

A new one can also be carried out in this method step 500 Abort criterion set or an already set one again be removed.  

FIG. 3 shows the flowchart of the exemplary embodiment for determining the critical traffic relationship mentioned above, for which the next route is to be defined, as is carried out in step 100. In a step 101, one of the first criteria is first selected, on the basis of which the route lists are to be changed. The first criteria can be freely defined and the following examples can be added as required by the operator. Possible first criteria can be:

• - The traffic relationship has not yet been modified.
• - The traffic relationship has the highest traffic loss.
• - The traffic relationship has the smallest number created Alternative routes.
• - The traffic relationship has the smallest sum of Switching node numbers. Each switching node is there assigned a number that is also chosen arbitrarily can be. The numbers of the switching nodes that the concern the respective traffic relationship are added. This Criterion can be used especially at the beginning of the operation of the Message network N are used, since then none Traffic is present.
• - The traffic relationship has the highest loss of fees because of their loss of traffic.
• - The traffic relationship has the highest probability of loss.
• - The traffic relationship has a highest priority factor. On such priority factor becomes the traffic relationship from Network operators assigned, for example to important customers  prefer to treat or certain types of traffic prefer (for example over telephone traffic Traffic).
• - The traffic relationship has the greatest kilometer distance between the origin and destination nodes.

In a step 102 it is now checked whether all possible ones already exist Traffic relations checked against all specified first criteria or whether a predetermined termination criterion, such as for example the maximum number of alternative routes for all Traffic relations have been achieved, fulfilled. If this is the case, then the iterative processing of the invention Procedure ended. If this is not the case, then a step follows 103, in which for all traffic relations in step 101 selected criterion is checked. In a step 104 then determines whether one of the traffic relationships after the Check the current criterion selected in step 101 as a preferred traffic relationship in the sense of determining the critical traffic relationship can be determined and whether the so determined traffic relationship by a predetermined delta value is more appropriate than any other traffic relationship established after the Check the current criterion in step 103 as the second preferred traffic relationship is identified. Isn't that Case, then the current criterion in the Step 103 no clearly preferred traffic relationship is determined and the process returns to step 101 and there a next first criterion selected. Became one clear preferred traffic relationship found, so the invention The method continues with step 200. It is to ensure that a final criterion is defined, that a enables clear decision. The order of selection of the The first criteria in step 101 can be freely defined.  

FIG. 4 shows the exemplary embodiment for determining the next route for the critical traffic relationship determined in step 100, as is carried out in step 200. In a step 201, it is first checked whether an abort criterion is met. Such a termination criterion can be, for example, that the maximum number of alternative routes permitted for this traffic relationship has already been found, or that none of the possible alternative routes can accommodate the offered overflow traffic for each route section while maintaining the maximum loss probability. If one of the termination criteria is met, this means that no next route can be found for the critical traffic relationship defined in step 100. This is followed by a step 207 in which this determination of the next route is aborted and the current critical traffic relationship is marked as having been determined completely with alternative routes. The traffic calculation is then continued in step 300 of the method according to the invention and a further critical traffic relationship can be determined in the further iterative implementation of the method according to the invention. If the termination criteria are not met, step 202 is reached in which one of the second criteria is selected. The second criteria can also be freely defined and the following examples can be added as required by the operator. Possible second criteria can be, for example:

• - The route is able to comply with the maximum Probability of loss the maximum traffic load take over.
• - The route has the highest route safety. Road safety means that there is a path through different geographic routes is guided so that when a technical defect, for example damage to the Transmission cable through excavator, not blocked the whole way  or that the route to be determined here already has one specific route for the same traffic relationship has a common route section.
• - The route has the shortest kilometric path or the least number of path sections.
• - The route has been least of overflow in Claimed.
• - The route guarantees a for the traffic relationship minimal probability of loss.
• - The route has the smallest sum of priority factors the traffic relations already using this route.

In a step 203 it is now checked whether all possible ones already exist Routes were checked on all second criteria. Is this the Case, that is, even after checking all possible routes with none of the specified second criteria became clear suitable route for this critical traffic relationship has been found, then in a step 206 the first route for the critical Traffic relationship with a different traffic distribution new To be defined. A definable part of the traffic is over a different route than the first route. The traffic distribution is saved in the relevant route lists. After that returned to step 201 again so the iteration with the changed traffic distribution of the first route again perform. However, if it is found in step 203 that not all possible routes checked against all second criteria step 204 follows, in which all possible routes checked for the current criterion selected in step 202 will. Once that is done, the next step is 205 examines whether a preferred route in the  Meaning of method step 200, determination of the next one Route, was found and this preferred route at least by a predetermined further delta value of one in Step 204 determined the second best suitable route differs. If this is not the case, then the test has started no clear preferred route according to the current criterion is determined and the process returns to step 201 again. The Iteration to determine the next route for the critical Traffic relationship is repeated with another second criterion carried out. But was clearly the preferred one by testing Route identified in step 205, then next with the traffic calculation of the method according to the invention in step 300 continued. It is important to ensure that a final second The criterion defined is that a clear decision enables.

For the traffic calculations, the traffic flows in the message network N as well as bundle losses and end-to-end losses are determined according to rules of the message traffic theory. The end-to-end loss is the sum of all parts of an offered direct traffic that cannot be routed from an origin node to a destination node, based on the total offered direct traffic of one of the transmission devices. The offered direct traffic is one of the transmission facilities 1 ,. . ., 10 Poisson traffic offered, which starts directly from the switching node connected to this transmission device and is to be routed to the other switching node connected to the same transmission device. The end-to-end loss is ultimately the decision criterion for determining one of the alternative routes. The flow of traffic per transmission device is the total traffic offered by the routing of this transmission device, described by an average value M over time and a variance V. The variance V is a measure of the degree of deviation of the offered traffic from the Poisson traffic, which is determined by the average value M is described. This offered traffic can be of different origins. In particular, a distinction is made between the direct traffic and overflow traffic offered by the transmission facilities. The known Wilkinson method is used to determine the overflow traffic rejected by one of the transmission devices. The Wilkinson method is described, for example, in the publication "Telecommunications Network Design Algorithms" by Aaron Kershenbaum, McGraw-Hill Inc., 1993, ISBN 0-07-034 228-8, pages 102-109. The overflow traffic of different origins must be decomposed. In order to be able to describe these partial transports of different origins with mean and variance, the following equations of the known decomposition method according to Wallström-Guerrero are used for the calculation:

In these equations:
M, V the mean and the variance of the total offered traffic,
m, v the mean and the variance of the total overflow traffic,
m _c , V _c the mean and the variance of the total traffic,
n the number of channels of the current transmission device,
i the i-th component of the total traffic flow.

The traffic calculation is carried out iteratively. For this, auxiliary variables for the mean M and the variance V for each of the Transmission facilities set up by means of which Means and variances of the various, decomposed Partial traffic can be added up. An iteration cycle contains the following steps:

• - Acceptance of the values of the auxiliary variables for mean and variance as a representation of traffic flows for everyone Transmission facilities and subsequent deletion of the Auxiliary quantities
• - Determination of the rejected and the successfully accomplished Traffic of all transmission facilities
• - Determine the flow of traffic (M, V) for each Transmission device of a subnet of the communication network N and summing this traffic flow to the corresponding Auxiliary variables of M and V.

The subnet of one of the transmission devices 1 ,. . ., 10 is the amount of transmission devices 1 ,. . ., 10 , which are required to start from one of the switching nodes A,. . . E in accordance with the route lists LA,. . . , LE in the respective switching nodes A,. . . , E predetermined alternative routes, the traffic flows to another of the switching nodes A,. . . To realize E. In the communication network N of Fig. 1, for example, the subnet of the transmission device 1 with respect to the flow of traffic from the switching node A to the switching node B, the amount of transmission devices 1, 3, 6, 4, 7, 2 and 5. 1 is registered in the routing list LA first path of switching nodes A to switching node B. The first alternative route is via the transmission means 3 to the switching node D and in its route list LD is for traffic from A to B, the overflows D, the transfer means 6 registered. The second alternative route is via the transmission means 4 to the switching node E and its routing list in the LE communication device 7 is for traffic from A to B, the overflows E, registered. The registered in the routing list LA Letztweg via the transmission device 2 to the switching node C. In the routing list is LC, the transfer device 5 registered for traffic from A to B, the overflows C. For each transmission device and direction of traffic, the successfully transmitted traffic that reaches its destination, the successfully transmitted traffic that does not reach its destination, the unsuccessfully transmitted traffic that leads to blocking, that is to say the loss of the call, and the unsuccessfully transmitted traffic, which can be routed via one of the alternative routes, determined and added up by means of the above-mentioned auxiliary variables for mean value and variance for the transmission devices involved.

The iterative traffic calculation is ended when the Means and variances between two iteration cycles by no change more than a given value or a given value maximum number of iteration cycles has already been carried out.

In the manner described, a determination of the Routing lists LA to LE made. The determination is in regular intervals with the help of the central network computer ZR repeated. With the application of the method according to the invention completely new routing lists LA,. . . , LE for the Switching node A,. . . , E of the news network N as well incomplete routing lists in the switching nodes to be completed. In the latter case, the Applicability of the method according to the invention for network management given.

Claims (9)

(. LA,.., LE) 1. A method for the determination of Leitweglisten in a communication network (N) for switched connections, a plurality of switching nodes (A, B, C, D, E), the means of transmission means (1,. ., 10 ) are coupled to one another and each have a storage device for storing one of the routing lists (LA,..., LE) and have a central network computer (ZR), characterized in that a determination of in the routing lists (LA, ..., LE) routes to be entered are carried out iteratively until an abort criterion is reached and that at least one first and at least one second criterion is checked in each iteration cycle. 2. The method according to claim 1, characterized in that the method iteratively processes the following method steps on the basis of input information:

• - determining a critical traffic relationship (100),
• - Determination of at least one next route for this critical traffic relationship (200) and entry of this at least one next route in the route lists (LA,..., LE) of the switching nodes (A,..., E) relating to this at least one next route,
• - Determination of the current load situation of the transmission facilities ( 1 ,..., 10 ) and the probability of loss of the traffic relations (300),
• - Check the termination criterion (500) and continue the method with the first method step if the termination criterion is not met.

3. The method according to claim 2, characterized in that in the step of determining the critical traffic relationship (100) any number of first criteria can be checked and in the process step for Determination of the route for the critical traffic relationship (200) any number of second criteria can be checked and the first and second criteria in a predetermined order being checked. 4. The method according to claim 2 or 3, characterized in that a selection of the first and second Criteria and the termination criterion and the order of their Exam is changeable while performing the procedure (400).   5. The method according to any one of claims 2 to 4, characterized in that one of the traffic relations then as the critical traffic relationship in the associated Method step (100) after the test with one of the first Criteria (103) is selected when referring to this one of the first criteria by a predetermined delta value of one distinguishes another of the traffic relations (104) and that otherwise the process step for determining the critical Traffic relationship (100) with testing another one of the first Criteria is performed again. 6. The method according to any one of claims 2 to 5, characterized in that one of the routes is then the next Route for the critical traffic relationship in the associated Method step (200) after the test with one of the second Criteria (204) is determined when referring to this one the second criteria by a predetermined further delta value of another one of the routes (205) and that otherwise the method step for determining the at least one next one Route (200) with testing another of the second criteria is performed again. 7. The method according to any one of the preceding claims, characterized in that the communication network (N) is a complete meshed, non-hierarchical communication network. 8. Computer (ZR) for a communication network (N) for switched connections, which has a plurality of switching nodes (A,..., E) which are coupled to one another by means of transmission devices ( 1 ,..., 10 ) and one each Have storage device for storing a route list (LA,..., LE), and the computer (ZR) is connected to the switching node (A,..., E), characterized in that the computer (ZR) has a control means (PR ) that iteratively carried out a determination of routes to be entered in the route lists (LA,..., LE) until an abort criterion was reached and that checked in each iteration cycle with at least one first and at least one second criterion. 9. Data carrier (DT) with data stored thereon, by means of which a control means (PR) can control a method, for a communication network (N) for switched connections, which has a plurality of switching nodes (A,..., E) which are coupled to one another by means of transmission devices ( 1 ,..., 10 ) and each have a storage device for storing a route list (LA,..., LE) and which has a central network computer (ZR), characterized in that the data is information contain, by means of which a determination of routes to be entered in the route lists (LA,..., LE) is carried out iteratively until an abort criterion is reached and is checked in each iteration cycle with at least a first and a second criterion.