CN111901178B

CN111901178B - Risk pre-judging method, device and equipment for network flow direction

Info

Publication number: CN111901178B
Application number: CN202010815141.4A
Authority: CN
Inventors: 王洪涛
Original assignee: Unihub China Information Technology Co Ltd
Current assignee: Unihub China Information Technology Co Ltd
Priority date: 2020-08-13
Filing date: 2020-08-13
Publication date: 2023-04-28
Anticipated expiration: 2040-08-13
Also published as: CN111901178A

Abstract

The embodiment of the invention provides a risk prediction method, device and equipment for network traffic flow direction. Reading a network topology structure of equipment and link cost between every two equipment in the network topology structure, numbering the equipment, extracting every two interconnection relations between every equipment and other equipment, and generating an input data list; when the cost between the first equipment and the second equipment is changed, calculating all paths and cost from the first equipment to the second equipment before and after the cost is changed, and identifying the path with the minimum cost as an optimal path; judging whether the optimal paths before and after the cost change are the same, if so, no risk exists; otherwise there is a risk. In this way, the cutting efficiency can be improved, the occurrence rate of cutting accidents can be reduced, and the labor cost can be reduced by rapidly pre-judging the risk generated by cutting.

Description

Risk pre-judging method, device and equipment for network flow direction

Technical Field

The embodiments of the present invention relate generally to the field of network device cutover, and more particularly, to a risk prediction method, apparatus, and device for network traffic flow direction.

Background

The most critical step in network transformation is network cutover, also called network migration, which means that the operation of the network is changed physically or logically, and the operation of the line and equipment in use will directly affect the service carried thereon.

In the process of network cutting, an engineer needs to modify the link overhead value of a certain device to change the link overhead value, which may cause problems such as packet loss or link error of the link, so as to directly influence the forwarding of the service or cause congestion. It is generally the case that engineers tend to focus only on the impact associated with the device, without prejudging that a cutover may risk global network traffic flow direction.

Disclosure of Invention

According to the embodiment of the invention, a risk prediction scheme for the flow direction of network traffic is provided.

In a first aspect of the present invention, a risk prediction method for a network traffic flow direction is provided. The method comprises the following steps:

reading a network topology structure of equipment and link cost between every two equipment in the network topology structure, numbering the equipment, extracting every two interconnection relations between every equipment and other equipment, and generating an input data list;

when the cost between the first equipment and the second equipment is changed, calculating all paths and cost from the first equipment to the second equipment before and after the cost is changed, and identifying the path with the minimum cost as an optimal path;

judging whether the optimal paths before and after the cost change are the same, if so, no risk exists; otherwise there is a risk.

Further, the devices are hierarchically divided according to the topological relation among the devices in the network topological structure, so that the devices in adjacent layers have interconnection relation.

Further, the extracting the interconnection relationship between each device and other devices includes:

extracting interconnection relation and cost between equipment and equipment at the same level; and

the directed connection relation and the cost of the device to the subsequent sequential hierarchy device are extracted.

Further, the input data list includes a plurality of device relationship sets, each device relationship set corresponding to an interconnection relationship starting from a device, including a hierarchy item and a relationship item composed of an initial device, an end device, and an overhead from the initial device to the end device.

Further, the calculating all paths and overheads from the first device to the second device before and after the overheads are changed includes:

step 1: extracting a relation item taking the second equipment as an end point from the input data list to serve as a first relation item set; the first relation set comprises direct relation and/or non-direct relation; the direct relation is a path of the first equipment directly related to the second equipment, and no intermediate equipment exists on the path; the non-direct relationship is a path of a non-first device associated to the second device;

step 2: extracting a relationship item taking the starting point of the non-direct relationship item in the first relationship item set as an end point from the relationship item which does not contain the second device in the input data list, and taking the relationship item as a second relationship item set;

step 3: splicing each relation in the second relation set with each relation in the first relation set until all relation with the first equipment as a starting point and the second equipment as an end point are obtained, and generating a spliced relation set;

step 4: and outputting the direct connection relation item and the spliced relation item set.

Further, the splicing process includes:

and matching the end point of each relation item in the second relation item set with the start point of each relation item in the first relation item set, if the end points are consistent, using consistent equipment as intermediate equipment, using the start point of the corresponding relation item in the second relation item set as the start point, and using the end point of the corresponding relation item in the first relation item set as the end point, so as to obtain the spliced relation item.

Further, each device in the spliced relationship can only appear at most once.

In a second aspect of the present invention, a risk prediction apparatus for network traffic flow direction is provided. The device comprises:

the device comprises a reading module, a processing module and a processing module, wherein the reading module is used for reading a network topology structure of the device and link cost between every two devices in the network topology structure, and numbering the devices in sequence;

the extraction module is used for extracting the interconnection relation between each device and other devices to obtain an input data list;

the computing module is used for computing all paths and overheads from the first equipment to the second equipment before and after the overheads change when the overheads between the first equipment and the second equipment change, and identifying the path with the minimum overheads as an optimal path;

the judging module is used for judging whether the optimal paths before and after the cost change are the same, and if so, the risk is avoided; otherwise there is a risk.

In a third aspect of the invention, an electronic device is provided. The electronic device includes: a memory and a processor, the memory having stored thereon a computer program, the processor implementing the method as described above when executing the program.

In a fourth aspect of the invention, there is provided a computer readable storage medium having stored thereon a computer program which when executed by a processor implements a method as according to the first aspect of the invention.

It should be understood that the description in this summary is not intended to limit the critical or essential features of the embodiments of the invention, nor is it intended to limit the scope of the invention. Other features of the present invention will become apparent from the description that follows.

The invention can quickly and early predict the risk generated by cutting, improve the cutting efficiency, reduce the occurrence rate of cutting accidents and reduce the labor cost.

Drawings

The above and other features, advantages and aspects of embodiments of the present invention will become more apparent by reference to the following detailed description when taken in conjunction with the accompanying drawings. In the drawings, wherein like or similar reference numerals denote like or similar elements, in which:

FIG. 1 illustrates a flow chart of a risk prediction method for network traffic flow according to an embodiment of the present invention;

FIG. 2 shows a network topology diagram according to an embodiment of the invention;

FIG. 3 shows a block diagram of a risk prediction apparatus for network traffic flow according to an embodiment of the present invention;

fig. 4 shows a block diagram of an exemplary electronic device capable of implementing embodiments of the invention.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

In addition, the term "and/or" herein is merely an association relationship describing an association object, and means that three relationships may exist, for example, a and/or B may mean: a exists alone, A and B exist together, and B exists alone. In addition, the character "/" herein generally indicates that the front and rear associated objects are an "or" relationship.

In the process of cutting over by engineers, the link overhead value of a certain device needs to be modified for a certain requirement, but in general, the engineers often only pay attention to the influence related to the device, and do not consider or do not consider the influence on the global. For example, in the topology shown in fig. 2, the optimal path for the data traffic flow between the two B-F devices performs B-D-F, but because the cut-over needs to temporarily adjust the overhead value between D-F from 10 to 200, the traffic between B-F is changed from the original B-D-F to B-D-E-F, because the overhead value of B-D-E-F is the smallest in all paths from B to F. The link overhead between B-F after adjustment is changed from 20 to 120; if the B-D-E-F path has the problems of packet loss, link error and the like, the forwarding of the service can be directly influenced or congestion can be caused due to the problem of link overhead.

According to the invention, the risk generated by cutting is rapidly and early predicted, so that the cutting efficiency is improved, the cutting accident rate is reduced, and the labor cost is reduced.

Fig. 1 shows a flowchart of a risk prediction method for a network traffic flow direction according to an embodiment of the present invention.

The method comprises the following steps:

s101, reading a network topology structure of the equipment and link cost between every two equipment in the network topology structure, and numbering the equipment in sequence.

The devices are numbered sequentially, for example, the devices connected thereto are numbered sequentially starting from a certain device.

As an embodiment of the present invention, the numbering of the devices in sequence may be that, starting from the device of the first hierarchy, the devices of each hierarchy are numbered from top to bottom; the devices are numbered within the hierarchy in a logical order from left to right.

As an embodiment of the present invention, as shown in fig. 2, the topology structure includes 6 devices, and one device is selected, and the number is a, and the device sequentially connected to a on one path is numbered B, C, and the device sequentially connected to a on the other path is numbered D, E and F. The numbering of the devices in the topology is done in the order described above.

The order may be selected as desired, and for example, the selected device may be designated as a, the device in direct interconnection with the selected device may be designated as B, C, or the like.

Furthermore, all the devices can be hierarchically divided according to the read topological relation among the devices, so that the interconnection relation exists among the devices of the adjacent hierarchy.

As an embodiment of the present invention, as shown in fig. 2, 6 devices are a to F, respectively, where the interconnection relationship and the overhead value are:

A-B interconnection, the overhead value is 100; A-D interconnection, the overhead value is 10; B-D interconnection, the overhead value is 10; B-C interconnection, the overhead value is 10; D-E interconnection, the overhead value is 100; D-F interconnection, wherein the overhead value is 10; E-F interconnect, overhead value is 10.

Hierarchical division of the device is completed with A, B and C as the first hierarchy, D, E as the second hierarchy, and F as the third hierarchy.

The hierarchy division is not fixed, for example, in the present embodiment, a may be the first hierarchy, B, D may be the second hierarchy, and C, E, F may be the third hierarchy.

By dividing the hierarchy, among the devices with association relationships in different hierarchies, the device with higher hierarchy can be associated with the device with lower hierarchy in a directed way, and the association between the device with lower hierarchy and the device with higher hierarchy is not needed. As a basis of the splicing process in the following steps, the splicing process cannot be circularly spliced infinitely.

S102, extracting every two interconnection relations between each device and other devices to obtain an input data list.

In the embodiment of the present invention, as shown in fig. 2, the first hierarchical device is A, B, C, the second hierarchical devices are D and E, and the third hierarchical device is F; A-B interconnection, the overhead value is 100; A-D interconnection, the overhead value is 10; B-D interconnection, the overhead value is 10; B-C interconnection, the overhead value is 10; D-E interconnection, the overhead value is 100; D-F interconnection, wherein the overhead value is 10; E-F interconnect, overhead value is 10.

By extracting the information, the relation of every two interconnections and the interconnection cost (cost value) are listed one by one according to the sequence from top to bottom and from left to right, and the statistics can be obtained:

first level:

starting with A, [1, A-10-D, A-100-B ];

starting with B, [1, B-10-D, B-10-C ];

taking C as a starting point, and none;

second level:

starting with D, [2, D-100-E, D-10-F ];

starting from E [2, E-10-F ]

Wherein 1 or 2 represents the hierarchy of the current device; A-10-D represents that A and D have an interconnection relationship, A is a starting point, D is an end point, and the overhead value from A to D is 10; and the other is the same.

The statistical logic is used for counting the interconnection relation and the corresponding overhead value which respectively take each device as a starting point from top to bottom according to the divided layers from the first layer; devices in the same hierarchy may be counted against each other according to the interconnection relationship.

The information is counted into an input data list, namely:

[1，A-10-D，A-100-B]

[1，B-10-D，B-10-C]

[2，D-100-E，D-10-F]

[2，E-10-F]

s103, when the cost between the first equipment and the second equipment is changed, calculating all paths and cost from the first equipment to the second equipment before and after the cost is changed, and identifying the path with the minimum cost as an optimal path.

s103-1: extracting a relation item taking the second equipment as an end point from the input data list to serve as a first relation item set; the first relation set comprises direct relation and/or non-direct relation; the direct relation is a path of the first equipment directly related to the second equipment, and no intermediate equipment exists on the path; the non-inline relationship is a path of a non-first device associated with the second device.

In the present embodiment, it is assumed that the link overhead between D and F is changed from 10 to 200, where D is the first device and F is the second device. The relation item taking the second device F as an end point in the input data list comprises the following steps: D-10-F, E-10-F, and forming a first relation item set by the two relation items, namely the first relation item set: [ D-10-F, E-10-F ]. In D-10-F, since D is the first device and F is the second device, D-10-F is a direct relationship, i.e. D is directly related to the path of F, and there is no intermediate device between D and F. In E-10-F, E is a non-first device, and F is a second device, so E-10-F is a non-direct relationship, i.e. a path from the non-first device E to the second device F.

S103-2: and extracting a relation item taking the starting point of the non-direct relation item in the first relation item set as an end point from the relation item which does not contain the second equipment in the input data list, and taking the relation item as a second relation item set.

In this embodiment, the relationship items in the input data list that do not include the second device F include: A-10-D, A-100-B, B-10-D, B-10-C, D-100-E; the non-direct connection relation in the first relation set is E-10-F, and the starting point is E. In A-10-D, A-100-B, B-10-D, B-10-C, D-100-E, the relation term ending with E is D-100-E; the second set of relationship terms includes D-100-E.

S103-3: and splicing each relation in the second relation set with each relation in the first relation set until all relation with the first equipment as a starting point and the second equipment as an end point are obtained, and generating a spliced relation set.

And further, matching the end point of each relation item in the second relation item set with the start point of each relation item in the first relation item set, if the end points are consistent, using consistent equipment as intermediate equipment, using the start point of the corresponding relation item in the second relation item set as the start point, and using the end point of the corresponding relation item in the first relation item set as the end point, so as to obtain the spliced relation item.

In an embodiment of the invention, the second relationship is concentrated with D-100-E, and the first relationship is concentrated with D-10-F, E-10-F; and respectively matching the end point E of the D-100-E in the second relation set with the start points D and E in the first relation set, wherein the end point E is failed to match with the D, and the E is consistent with the E, so that the matching is successful, E is taken as an intermediate device, D is taken as the start point, F is taken as the end point, and the splice is carried out, so that D-100-E-10-F is obtained, namely the spliced relation item.

Judging whether starting point devices of the relation items in the spliced relation item set are the first devices or not, and if so, outputting the first spliced relation item set and the direct relation item; otherwise, the relation item which is not the first equipment and is not contained in the second equipment in the input data list in the first spliced relation item set is spliced again until the starting point equipment of the spliced relation item is the first equipment.

And splicing again, namely matching a relation item end point in the second relation item set with a relation item starting point of non-first equipment in the current spliced relation item set, if so, splicing by taking the consistent equipment as intermediate equipment, judging whether the relation item starting point after the current splicing is the first equipment, if not, continuing to execute the splicing process to splice, and if so, outputting the spliced relation item. And splicing again to find all paths between the first equipment and the second equipment, wherein no path is missed.

Each device in the spliced relationship can only appear once at most. For example, if the spliced relationship is E-10-B-10-E-10-F, two E's appear in the spliced relationship at this time, and according to the splicing principle, each device in the spliced relationship can only appear once at most, so that the splicing is not established, and the state before the splicing needs to be restored, namely B-10-E-10-F, and the processing is waited for to continue. Such arrangement is to avoid splice entering circulation splice, resulting in inability to jump out.

As an embodiment of the invention, if the spliced relationship item is B-10-E-10-F and the final needed starting point is D, but no relation exists which can be spliced continuously, and it is stated that a path associating the first device D and the second device F cannot be found based on the current relationship item, the spliced relationship item B-10-E-10-F is deleted and is not output.

S103-4: and outputting the direct connection relation item and the spliced relation item set.

In this embodiment, since there are only two paths from D to F, all the relationship items D-100-E-10-F and D-10-F with D as the start point and F as the end point are already obtained, and at this time, the splicing is completed, and the direct relationship item D-10-F and D-100-E-10-F included in the spliced relationship item set are output.

S104, judging whether the optimal paths before and after the cost change are the same, and if so, judging that the risk is not generated; otherwise there is a risk.

Judging whether the optimal paths before and after the cost change are the same, accumulating the cost values on the paths, and comparing the obtained cost value sum to obtain the optimal path with the minimum value.

In this embodiment, the relation terms output before the cost change are D-100-E-10-F and D-10-F, and it can be obtained that the cost value from D to F is minimum, i.e. D-F is the optimal path.

After the overhead is changed, since the overhead value of D-F becomes 200, the overhead value 110 of D-100-E-10-F is smaller than 200, and D-E-F is the optimal path after the overhead is changed.

It can be seen that, due to the change of the overhead value between D and F, the optimal path is changed, that is, the optimal path before the overhead change and the optimal path after the overhead change are different, so that it can be determined that there is a risk, and a cutting-over accident may occur.

According to the embodiment of the invention, the cutting efficiency is improved, the occurrence rate of cutting accidents is reduced, and the labor cost is reduced by rapidly and early pre-judging the risk generated by cutting.

It should be noted that, for simplicity of description, the foregoing method embodiments are all described as a series of acts, but it should be understood by those skilled in the art that the present invention is not limited by the order of acts described, as some steps may be performed in other orders or concurrently in accordance with the present invention. Further, those skilled in the art will also appreciate that the embodiments described in the specification are alternative embodiments, and that the acts and modules referred to are not necessarily required for the present invention.

The above description of the method embodiments further describes the solution of the present invention by means of device embodiments.

As shown in fig. 3, the apparatus 300 includes:

and a reading module 310, configured to read a network topology of the device and link overhead between every two devices in the network topology, and number the devices in sequence.

As an embodiment of the present invention, the reading module 310 further includes:

the layering module 311 is configured to perform hierarchical division on the devices according to the topological relation between the devices in the network topology structure, so that interconnection relation exists between the devices in adjacent layers.

And the extracting module 320 is configured to extract the interconnection relationship between each device and other devices to obtain an input data list.

As an embodiment of the present invention, the extraction module 320 may be divided into:

the first extraction module 321 is configured to extract an interconnection relationship and an overhead between the device and the devices at the same hierarchy level.

A second extraction module 322 is configured to extract the directed connection relationship and the overhead from the device to the device at the subsequent sequential hierarchy.

The input data list comprises a plurality of device relation sets, and each device relation set corresponds to an interconnection relation taking a device as a starting point and comprises a hierarchy item and a relation item consisting of a starting point device, an end point device and overhead from the starting point device to the end point device.

And a calculating module 330, configured to calculate all paths and overheads from the first device to the second device before and after the overheads change when the overheads between the first device and the second device change, and identify a path with the minimum overheads as an optimal path.

As an embodiment of the present invention, the computing module 330 includes:

a third extracting module 331, configured to extract, from the input data list, a relationship term that uses the second device as an endpoint, as a first relationship term set; the first relation set comprises direct relation and/or non-direct relation; the direct relation is a path of the first equipment directly related to the second equipment, and no intermediate equipment exists on the path; the non-direct relationship is a path of a non-first device associated to the second device;

a fourth extracting module 332, configured to extract, from the relationship items that do not include the second device in the input data list, a relationship item that uses a start point of a non-directly connected relationship item in the first relationship item set as an end point, as a second relationship item set;

a splicing module 333, configured to splice each relationship item in the second relationship item set with each relationship item in the first relationship item set until all relationship items with the first device as a starting point and the second device as an end point are obtained, and generate a spliced relationship item set;

and the output module 334 is configured to output the direct connection relationship item and the concatenation relationship item set.

And the identifying module 335 is configured to identify the path with the smallest overhead as the optimal path.

A judging module 340, configured to judge whether the optimal paths before and after the overhead change are the same, and if yes, there is no risk; otherwise there is a risk.

It will be clear to those skilled in the art that, for convenience and brevity of description, specific working procedures of the described modules may refer to corresponding procedures in the foregoing method embodiments, which are not described herein again.

As shown in fig. 4, the apparatus includes a Central Processing Unit (CPU) that can perform various suitable actions and processes according to computer program instructions stored in a Read Only Memory (ROM) or computer program instructions loaded from a storage unit into a Random Access Memory (RAM). In the RAM, various programs and data required for the operation of the device can also be stored. The CPU, ROM and RAM are connected to each other by a bus. An input/output (I/O) interface is also connected to the bus.

A plurality of components in a device are connected to an I/O interface, comprising: an input unit such as a keyboard, a mouse, etc.; an output unit such as various types of displays, speakers, and the like; a storage unit such as a magnetic disk, an optical disk, or the like; and communication units such as network cards, modems, wireless communication transceivers, and the like. The communication unit allows the device to exchange information/data with other devices via a computer network, such as the internet, and/or various telecommunication networks.

The processing unit performs the respective methods and processes described above, for example, the methods S101 to S103. For example, in some embodiments, methods S101-S103 may be implemented as a computer software program tangibly embodied on a machine-readable medium, such as a storage unit. In some embodiments, part or all of the computer program may be loaded and/or installed onto the device via the ROM and/or the communication unit. When the computer program is loaded into RAM and executed by the CPU, one or more steps of the methods S101 to S103 described above may be performed. Alternatively, in other embodiments, the CPU may be configured to perform methods S101-S103 by any other suitable means (e.g., by means of firmware).

The functions described above herein may be performed, at least in part, by one or more hardware logic components. For example, without limitation, exemplary types of hardware logic components that may be used include: a Field Programmable Gate Array (FPGA), an Application Specific Integrated Circuit (ASIC), an Application Specific Standard Product (ASSP), a system on a chip (SOC), a load programmable logic device (CPLD), etc.

Program code for carrying out methods of the present invention may be written in any combination of one or more programming languages. These program code may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus such that the program code, when executed by the processor or controller, causes the functions/operations specified in the flowchart and/or block diagram to be implemented. The program code may execute entirely on the machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

In the context of the present invention, a machine-readable medium may be a tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. The machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. The machine-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of a machine-readable storage medium would include an electrical connection based on one or more wires, a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

Moreover, although operations are depicted in a particular order, this should be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several specific implementation details are included in the above discussion, these should not be construed as limiting the scope of the invention. Certain features that are described in the context of separate embodiments can also be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation can also be implemented in multiple implementations separately or in any suitable subcombination.

Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are example forms of implementing the claims.

Claims

1. The risk pre-judging method for the flow direction of the network flow is characterized by comprising the following steps of:

judging whether the optimal paths before and after the cost change are the same, if so, no risk exists; otherwise, risk exists;

all paths and overheads from the first device to the second device before and after the calculation of the overheads, including:

2. The method of claim 1, wherein the devices are hierarchically partitioned according to a topological relationship between the devices in the network topology, such that an interconnection relationship exists between devices in adjacent tiers.

3. The method of claim 2, wherein extracting the pairwise interconnection relationship between each device and the other devices comprises:

4. The method of claim 1, wherein the input data list comprises a plurality of device relationship sets, each device relationship set corresponding to a device-initiated interconnection relationship, including hierarchy items and relationship items consisting of a starting device, an ending device, and a starting device-to-ending device overhead.

5. The method of claim 1, wherein the splicing comprises:

6. The method of claim 1 or 5, wherein each device in the spliced relationship can occur at most once.

7. A risk prediction device for network traffic flow direction, comprising:

the computing module is used for computing all paths and overheads from the first equipment to the second equipment before and after the overheads change when the overheads between the first equipment and the second equipment change, and identifying the path with the minimum overheads as an optimal path; all paths and overheads from the first device to the second device before and after the calculation of the overheads, including:

step 4: outputting the direct connection relation item and the spliced relation item set;

8. An electronic device comprising a memory and a processor, the memory having stored thereon a computer program, characterized in that the processor, when executing the program, implements the method according to any of claims 1-6.

9. A computer readable storage medium, on which a computer program is stored, characterized in that the program, when being executed by a processor, implements the method according to any one of claims 1-6.