CN114500163A

CN114500163A - Communication scheduling method, device and storage medium

Info

Publication number: CN114500163A
Application number: CN202011147238.9A
Authority: CN
Inventors: 杜宗鹏; 耿亮; 刘鹏
Original assignee: China Mobile Communications Group Co Ltd; China Mobile Communications Ltd Research Institute
Current assignee: China Mobile Communications Group Co Ltd; China Mobile Communications Ltd Research Institute
Priority date: 2020-10-23
Filing date: 2020-10-23
Publication date: 2022-05-13

Abstract

The invention discloses a communication scheduling method, a communication scheduling device and a storage medium, wherein the method comprises the following steps: periodically sending a first message; the first packet is at least used to identify the beginning of the corresponding period of the first node.

Description

Communication scheduling method, device and storage medium

Technical Field

The present invention relates to the field of networks, and in particular, to a communication scheduling method, apparatus, communication device, and storage medium.

Background

In a specific scenario of future fifth Generation mobile communication (B5G, Beyond5 Generation)/sixth Generation mobile communication (6G, 6th Generation), strict deterministic service capability requirements are proposed, such as industrial control, telemedicine, holographic communication, etc., which cannot be met by conventional IP forwarding. Therefore, a Deterministic Internet Protocol (DIP) network is an important development trend of future networks, and the above-mentioned Deterministic service capability requirement also puts new requirements on the message scheduling of the DIP network.

Disclosure of Invention

In view of the above, the present invention mainly aims to provide a communication scheduling method, apparatus, communication device and storage medium.

In order to achieve the purpose, the technical scheme of the invention is realized as follows:

the embodiment of the invention provides a communication scheduling method, which is applied to a first node and comprises the following steps:

periodically sending a first message; the first packet is at least used to identify the beginning of the corresponding period of the first node.

In the above scheme, the first packet includes first period information; the first period information includes at least one of:

the method comprises the steps of a first period number, a first period identifier, a first period length, a first mapping mode, a second mapping mode, a reserved field, a period sequence number and a Maximum Transmission Unit (MTU) message limitation.

In the foregoing scheme, the first packet is an extended protocol packet or a specific Virtual Local Area Network (VLAN) packet.

The embodiment of the invention also provides a communication scheduling method, which is applied to a second node and comprises the following steps:

periodically receiving a first message from a first node; the first packet is at least used to identify the beginning of the corresponding cycle of the first node.

In the above scheme, the first packet includes first period information corresponding to the first node; the first period information includes at least one of:

the method comprises the steps of counting a first period, a first period identifier, a first period length, a first mapping mode, a second mapping mode, a reserved field, a period sequence number and a limit MTU message;

the second node has period related information; the period related information comprises at least one of the following:

second cycle number, second cycle length, third mapping mode, reserved field.

In the above scheme, the method further comprises:

when a second node has a first mapping relation, determining that the first period information corresponds to period related information of the second node, and determining that the transmission can be correctly carried out;

when the second node does not have the first mapping relation, determining the first mapping relation of the second node based on the first period identifier and the period for receiving the first message;

the first mapping relation represents the relation between the sending period of the message sent by the second node and the sending period of the message sent by the first node along the upstream of the specific link.

In the foregoing solution, the first period information corresponds to the period-related information possessed by the second node, and includes at least one of:

the first period number is consistent with the second period number;

the first period length is consistent with the second period length;

a first mapping pattern in the first period information is consistent with the third mapping pattern in the period-related information;

the cycle order numbers in the first cycle information are consecutive.

In the above scheme, the method further comprises:

receiving a data message when the second node has a first mapping relation; the data message carries a period identifier of the data message;

determining a sending period of the data message based on the period identifier of the data message and a first mapping relation of the second node;

the sending period represents a period for the second node to send the data message.

In the foregoing solution, the period of receiving the first packet includes: completing a first receiving period for receiving the data message related to the first message and a second receiving period for starting to receive the first message; the related data message represents a data message sent by a first node sending the first message in a corresponding sending period;

the determining a first mapping relationship and a sending period based on the first period information and the period of receiving the first packet includes:

taking a period subsequent to the first receiving period as the sending period; or, taking a period after the second receiving period is separated by at least one period as the sending period;

and establishing a first mapping relation between the determined sending period and the first period identifier.

In the above scheme, the method further comprises: when the periodic updating condition is met, updating the first mapping relation;

the satisfying of the periodic update condition includes at least one of:

the receiving period corresponding to at least one second message is different from the first receiving period corresponding to the first message; the second message represents a subsequent message which is periodically sent after the first message is sent from the first node;

at least one receiving period does not receive the first message or the second message;

the interface of the second node is flashed;

and receiving the first message for the first time.

In the above scheme, the corresponding message is an extended protocol message or a specific VLAN message.

The embodiment of the invention provides a communication scheduling device, which comprises: the first sending module is used for periodically sending a first message; the first packet is at least used to identify the beginning of the corresponding period of the first node.

the MTU message comprises a first period number, a first period identifier, a first period length, a first mapping mode, a second mapping mode, a reserved field, a period sequence number and a limit MTU message.

In the above scheme, the first packet is an extended protocol packet or a specific VLAN packet.

The embodiment of the invention provides a communication scheduling device, which is characterized by comprising the following components: a first receiving module, configured to periodically receive a first packet from a first node; the first packet is at least used to identify the beginning of the corresponding cycle of the first node.

second cycle number, second cycle length, third mapping mode, reserved field.

In the above scheme, the apparatus further comprises: a second processing module; the second processing module is configured to determine that the first period information corresponds to period-related information that a second node has when the second node has a first mapping relationship, and determine that correct transmission is possible;

the first period number is consistent with the second period number;

the first period length is consistent with the second period length;

the cycle order numbers in the first cycle information are consecutive.

In the foregoing solution, the first receiving module is further configured to receive a data packet when the second node has a first mapping relationship; the data message carries a period identifier of the data message;

the second processing module is configured to determine a sending period of the data packet based on the period identifier of the data packet and the first mapping relationship that the second node has;

In the above scheme, the receiving the first packet cycle includes: completing a first receiving period for receiving the data message related to the first message and a second receiving period for starting to receive the first message; the related data message represents a data message sent by a first node sending the first message in a corresponding sending period;

the second processing module is configured to use a period subsequent to the first receiving period as the sending period; or, taking a period after the second receiving period is separated by at least one period as the sending period;

In the foregoing solution, the second processing module is further configured to update the first mapping relationship when a periodic update condition is met;

the satisfying of the periodic update condition includes at least one of:

the interface of the second node is flashed;

and receiving the first message for the first time.

The embodiment of the invention provides communication equipment, which comprises a memory, a processor and a computer program which is stored on the memory and can run on the processor, wherein the processor executes the program and realizes the steps of the communication scheduling method at any one of the first node sides; or,

the processor implements the steps of the communication scheduling method of any one of the above second node sides when executing the program.

An embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, implements the steps of the communication scheduling method on any one of the above first node sides; or,

the computer program realizes the steps of the communication scheduling method of any of the above second node sides when executed by a processor.

The embodiment of the invention provides a communication scheduling method, a communication scheduling device and a storage medium, wherein the method comprises the following steps: a first node periodically sends a first message; the first message is at least used for marking the beginning of a corresponding period of the first node; correspondingly, the second node periodically receives the first message from the first node; the first packet is at least used for marking the beginning of a corresponding period of the first node; in this way, an explicit indication is given to the beginning of each cycle, so as to manage the cycle mapping relationship.

Drawings

Fig. 1 is a schematic diagram of a CQF scheduling method;

fig. 2 is a diagram illustrating the effect of forwarding delay of a CQF;

FIG. 3 is a schematic diagram of a DIP mechanism;

FIG. 4 is a schematic diagram of a self-learning method of periodic mapping relationships;

fig. 5 is a flowchart illustrating a communication scheduling method according to an embodiment of the present invention;

fig. 6 is a flowchart illustrating another communication scheduling method according to an embodiment of the present invention;

fig. 7 is a schematic structural diagram of a first packet according to an embodiment of the present invention;

fig. 8 is a schematic diagram of information included in a first message according to an embodiment of the present invention;

FIG. 9 is a diagram illustrating a scenario for relearning mapping relationships in accordance with an embodiment of the present invention;

fig. 10 is a schematic structural diagram of a communication scheduling apparatus according to an embodiment of the present invention;

fig. 11 is a schematic structural diagram of another communication scheduling apparatus according to an embodiment of the present invention;

fig. 12 is a schematic structural diagram of a communication device according to an embodiment of the present invention.

Detailed Description

The present invention will be described in further detail with reference to examples.

As mentioned above, DIP networks are an important development trend in future networks. Because the traditional IP message is based on statistical multiplexing, the Service Level Agreement (SLA) indexes such as time delay, bandwidth, packet loss and the like can not be promised by best effort; for a specific 5G/6G scene, strict deterministic service capability requirements are provided, which cannot be met by traditional IP forwarding. For example: the telemedicine requires that the end-to-end time delay is less than 50ms and the jitter is less than 200 us; in order to ensure the accuracy of relay protection in a smart grid scene, the difference of one-way time needs to be less than 200us, and the jitter is less than 50 us.

In the related art, a Time Sensitive Networking (TSN) technology standardized by the Institute of Electrical and Electronics Engineers (IEEE) provides a series of standards for congestion control and queue scheduling, but is itself designed according to an Ethernet (Ethernet) local area network, and some preconditions of Time synchronization, flow-by-flow identification, etc. are not realistic on a large network, and scalability and maintainability are the greatest challenges for the certainty of a three-Layer (L3, Layer3) network.

Therefore, in the related art, an idea of DIP based on periodic scheduling is proposed to hopefully provide the certainty of a large-scale backbone network, but there are some problems in terms of lack of deployment practice, convenience in maintenance, and the like.

To explain the DIP mechanism in the prior art, a related art round-robin queue forwarding (CQF) is explained below. The CQF is a queue management method applied to a deterministic network in the related art.

The CQF inherits the concept of Time Aware Shaping (TAS) gating and introduces a circular queue mechanism for processing a data stream (Critical stream) with a severe delay requirement. As shown in the schematic diagram of the CQF scheduling method in fig. 1, for example, two queues, namely queue (queue)2 and queue3 are used; queue2 and queue3 are alternately opened and closed, i.e. when queue2 is opened to transmit data, queue3 is closed and receives data, after which queue3 is opened to transmit data and queue2 is closed and receives data. In this mechanism, frames of the Critical stream are sent one by one (or called a cycle) and sent one by one), for example, white frames in the figure, they must arrive in a certain time window and enter a specific queue (queue 2 or queue 4 in the figure), and in the same time window, queue3 or queue 5 needs to complete sending, so that the whole mechanism can operate normally. If the link delay and processing delay are negligible relative to the cycle duration, then for a particular deterministic network, the mechanism uses two buffers (buffers) in concert (e.g., only queue2 and queue3 in the figure), otherwise the mechanism requires the use of more queues. If the devices in the network all support the CQF, the packet of the Critical flow can enter a period at the network edge node, and then stays for about a period of time after each intermediate node, so that the packet of the Critical flow can be transmitted deterministically and reaches the edge node of the opposite network in a fixed period. In the CQF mechanism, from the perspective of each packet, the time of each hop stays around one cycle (the shortest is close to 0, and the longest is close to two cycles), but from the perspective of the overall CQF system, the overall delay of each node in a packet set of one entry cycle is one cycle. As shown in fig. 2, fig. 2 is a schematic diagram of the forwarding delay effect of the CQF.

The above scheme has problems: the time synchronization of the whole network equipment is required, and the distance between two nodes cannot be too long (namely, the link delay is required to be short).

A scheduling scheme of DIP in the related art is explained as follows. Regarding the scheduling of DIP, time synchronization of the whole network is no longer assumed, but frequency synchronization of the whole network is assumed, and the DIP scheduling mechanism is supported. Because the optical fiber delay cannot be ignored for a large-scale and long-distance network, more queues are set, for example, 3 queues are different from a queue of a CQF that rotates from one transmission queue to the other reception queue, a time of two periods is used here to ensure that a message of one period is received and then transmitted, that is, three queues are matched to circulate, for example, three periods of red, green and yellow, and are respectively set as follows according to the corresponding situation of the queue (queue):

red period: queue1 sends status, queue2 receives status, queue3 receives status;

green period: queue1 receives status, queue2 sends status, queue3 receives status;

yellow period: queue1 receives status, queue2 receives status, queue3 sends status;

and the process is circulated.

When the method is applied, the message is selected to enter a period at the network edge node, and then stays for about two periods every time an intermediate node passes, so that the message of the Critical flow can be transmitted deterministically and reaches the edge node of the opposite network in a fixed period.

As shown in fig. 3, fig. 3 shows a control flow of the control plane and the data plane in the DIP mechanism; in the DIP mechanism, after a data plane supports convergence of Critical streams, that is, after different Critical streams enter a DIP node, if an outgoing interface is the same and an outgoing period is the same, the different Critical streams at the node are all delayed by a time of about 2T (assuming that T represents the time of one period) and then sent out to a next hop. The DIP node only needs to process the label/destination address to find the outgoing interface and process the cycle mapping table to match the appropriate outgoing cycle without identifying each traffic flow. Each Critical flow should conform to the limit of the related traffic bandwidth, for example, as the limit of the formula in fig. 4, for one Critical flow (i.e., flowi in the figure), the sent data amount should be the sum of the traffic corresponding to the reserved bandwidth and the bursty traffic, the deterministic request of the sender should be submitted to the Network through a User Network Interface (UNI) Interface, and an Operation, Administration, and Maintenance (OAM) toolset should also be provided in the Network to provide performance monitoring of the deterministic related function.

The following explains a learning mechanism of the DIP mechanism in the related art. The improvement of the existing DIP mechanism on the traditional CQF is still in the early stage of the technology as a whole, only provides some basic core mechanisms, and has problems in specific deployment and maintenance operation. For example, there is a problem: and periodically mapping the neighbor nodes.

In a deterministic network (such as the DIP network described above), there is a stable periodic mapping between each pair of neighboring nodes (such as neighboring routers). The periodic mapping relationship guides the packet forwarding behavior of the subsequent router. The construction of the periodic mapping relationship can be realized through centralized configuration of a Software Defined Network (SDN) controller or through distributed learning in a self-adaptive manner.

In the existing method, the DIP node is required to ensure that the message from some upstream period is located after all messages are received in the sending period of the node. When the delay between two nodes changes due to the scenarios such as link switching, the periodic mapping relationship should be learned again, and meanwhile, the periodic mapping relationship with the neighboring DIP node needs to be learned when the DIP node is just on line. In the learning of the period mapping relationship, as shown in fig. 4, the upstream node a and the downstream node B are each cyclically numbered with a period of 0 to 2. The upstream node a sends a learning packet from the beginning of a certain period (e.g., period 1), the learning packet reaches the downstream node B via link transmission, and the downstream node B records the time when the first bit (bit) is received (assuming that the time falls in period 0 of the node B). The downstream node B deducts the time of a period length T from the time when the first bit is received, and the obtained time value means that all data packets sent from the upstream node a in the period 1 have arrived at the downstream node B. The point in time at which the packet transfer is completed corresponds to the time at which the last 1bit of the upstream node a arrives at the downstream node B at the latest, which in the example of fig. 4 falls within the period 1 of the downstream node B. From this time point, the first complete cycle is searched, which corresponds to the cycle No. 2 in this example, and accordingly, a cycle mapping relationship 1 → 2 between the upstream node a and the downstream node B is constructed (the cycle mapping relationship means that the data packet sent by the upstream node a in the cycle No. 1 is completely forwarded in the cycle No. 2 of the downstream node B). Similarly, the message sent by the upstream node a in the period 2 needs to be forwarded by the downstream node B in the period 3, and so on. According to the period mapping relationship, the data message only needs to carry the current period number of the sending equipment before each hop is sent. After receiving the data message, the downstream node can determine in which cycle the received message needs to be forwarded again according to the locally maintained cycle mapping relation table.

However, a specific process of relearning the periodic mapping relationship is not given by a DIP mechanism in the related art, and if the DIP is a network scene with a large scale, the service is more, and the influence is larger.

As can be understood from the above description, the DIP mechanism in the related art has the following problems: the maintenance mode of the periodic mapping relation is complex; the upstream node judges that the downstream node has no periodic mapping relation after being started or the periodic mapping relation is changed due to the link failure, and then the learning message is sent, so that the triggering condition and the learning mechanism are complex.

Based on this, in the method provided in the embodiment of the present invention, the first node periodically sends the first packet; the first packet is at least used to identify the beginning of the corresponding period of the first node. Correspondingly, the second node periodically receives the first message from the first node; the first packet is used at least to identify the beginning of the corresponding cycle of the first node.

Fig. 5 is a flowchart illustrating a communication scheduling method according to an embodiment of the present invention; as shown in fig. 5, the method is applied to a first node, and the method includes:

step 501, periodically sending a first message; the first packet is at least used to identify the beginning of the corresponding period of the first node.

The first node is a node in the DIP network, and may be, for example, a router employed in the DIP network.

The first message is a data stream (called Critical stream) with a strict delay requirement.

Here, the first packet includes first period information;

the first period information includes at least one of:

The first cycle number represents the cycle number corresponding to the first node, such as: three cycles. In view of the jitter Δ, it is also possible to extend on a three-period basis, i.e. the first number of periods may also be four periods, without changing the principle.

The first period mark represents a period corresponding to a first message which is currently sent.

The first period length represents the length of a period corresponding to a first message sent currently; for example 10 us.

The first mapping mode characterizes a mapping mode adopted downstream along a specific link, which is known by the first node, the downstream can be a second node (the second node is a certain node in a DIP network, for example, can be a router adopted in the DIP network), and the first mapping mode can be obtained after the second node sends the first node; the mapping mode may be used to determine a transmission period corresponding to the reception period.

Specifically, the second node may also periodically send a third packet to the first node, and if the third packet and the first packet are in a common path but in the opposite direction, the second node may place its own mapping mode in the first packet direction in the second mapping mode of the third packet and notify the second mapping mode of the third packet to the first node, or vice versa.

At the first node, the second mapping mode represents the mapping mode in the third packet direction of the second mapping mode (i.e., the first node). The second mapping mode may also be addressed to the peer (i.e., the second node) so that the second node knows the mapping mode of the first node upstream thereof on the same link.

A corresponding mapping schema comprising: plus one mapping, plus two mapping, plus three mapping (for a scene with three cycles); alternatively, it comprises: plus one map, plus two maps, plus three maps, plus four maps (for a scene with four cycles).

That is, the method of the embodiment of the present invention is applicable to a three-cycle and four-cycle scenario;

when applied to a three-cycle scenario (i.e., the first node and the second node interact with each other in three cycles), the mapping mode includes: adding a first mapping, adding a second mapping and adding a third mapping;

when applied to a four-cycle scenario (i.e., the first node and the second node interact with each other in four cycles), the mapping mode includes: plus one mapping, plus two mapping, plus three mapping, plus four mapping.

Regarding the setting of the four-period scenario, considering that there may be some jitter on the chip and the link, if the jitter is not large (i.e., the jitter is not negligible with respect to the time of one period), the downstream transmission period may be shifted backward correspondingly, that is, if the downstream cannot guarantee that the messages of the upstream period 1 are collected in two periods, for example, three periods are required, the downstream needs to use four queues to cooperate, and the whole DIP network is configured with four periods during design.

The reserved field is used as an extension field and can be used for sending some information which needs to be informed to the downstream node.

The cycle sequence number represents a cycle sequence number corresponding to a first message currently sent, and in general, the cycle sequence number corresponding to each first message sent by the first node may be increased by 1 every time the first message is sent, so that the cycle sequence numbers carried by the first messages are continuous. The period identifier is distinguished from the first period identifier, and the period identifier corresponds to the current period represented by the first period identifier, for example, in an application scenario of three periods, the period identifier is used for identifying the first period, the second period, and the third period; and the periodic sequence number can be increased by one after each message is sent, so that the second node can judge whether a lost message exists according to whether the periodic sequence number is continuous with the periodic sequence number of the previous message.

The first message is an extended protocol message for period information comparison or a specific Virtual Local Area Network (VLAN) message.

The protocol message refers to a new protocol type, for example, a corresponding new type value may be carried in a type field of the ethernet message, and the protocol message points to the protocol against which the periodic information is compared;

the specific VLAN message refers to a network administrator dividing a specific exclusive VLAN for the first message to use.

A first message for marking the start of a corresponding period of a first node is sent, and an explicit start mark is given to the start of each period of a DIP link; meanwhile, some DIP related information can be notified to a downstream node (such as a second node described below) through the first message, which is convenient for DIP management, operation and maintenance.

The method further comprises the following steps: step 502, sending a data message. The data packet may carry a period identifier of a corresponding period.

Correspondingly, the embodiment of the invention also provides another communication scheduling method which is applied to the second node. The first node and the second node may communicate. The first node may be a first router; the second node may be a second router.

Fig. 6 is a flowchart illustrating a communication scheduling method according to an embodiment of the present invention; as shown in fig. 6, the method is applied to the second node, and the method includes:

step 601, periodically receiving a first message from a first node; the first packet is at least used to identify the beginning of the corresponding cycle of the first node.

In an embodiment, the first packet includes first period information corresponding to a first node; the first period information includes at least one of:

a first cycle number, a first cycle identifier, a first cycle length, a first mapping mode (referring to the mapping mode of a second node known by a first node), a second mapping mode (referring to the mapping mode of the first node in the reverse direction of a first message), a reserved field, a cycle sequence number, and a limit MTU message;

second cycle number, second cycle length, third mapping mode, reserved field.

Here, the first mapping pattern characterizes the mapping pattern employed downstream along the particular link that is known to itself (i.e. the first node); taking an upstream first node and a downstream second node as an example for illustration, a first mapping mode of the first node represents a mapping mode which the second node knows by the first node itself and in the first message direction should have; the second mapping mode represents a mapping mode that is adopted by the second node in a third packet direction (i.e., a direction in which the second node sends a packet to the first node).

The first node may obtain the third mapping mode sent to the first node by the second node (i.e., the second mapping mode of the second node described above) as the first mapping mode of the peer that the first node maintains.

Initially, the first node does not know the mapping mode of the interface corresponding to the second node along the link, and the first mapping mode of the first node side may be set to null.

After determining the mapping mode of the second node (i.e., the third mapping mode), the second node may carry information of the third mapping mode of the second node in a third message that the second node periodically sends to the first node along the link, and send to the second node;

the MTU-limited message means that the first node can encapsulate a MTU-limited message in a TLV (format of data encoding, format of (Type, Length, Value)) and send the TLV-limited message to the second node; after the second node decapsulates the TLV, the second node continues to process and forward the message according to the message header; during forwarding, the packet may continue to be encapsulated in a periodic packet sent by the second node to a further downstream node.

The limitation of the MTU means that the size of the first packet is limited (e.g. 64bytes), so that the packet that can be encapsulated is relatively small.

In an embodiment, the method further comprises:

the first mapping relation represents the relation between the sending period of the message sent by the second node and the sending period of the message sent by the first node along the upstream of the specific link. That is, the first mapping relationship actually reflects the mapping mode, i.e., the first mapping relationship may be an plus one mapping, a plus two mapping, a plus three mapping, or a plus four mapping.

Here, the first period information corresponds to period-related information that the second node has, and includes at least one of:

the first period number is consistent with the second period number;

the first period length is consistent with the second period length;

a second mapping pattern in the first period information is consistent with the third mapping pattern in the period-related information;

the cycle order numbers in the first cycle information are consecutive.

For example, the second node detects whether the first packet can be transmitted correctly, for example, the first mapping pattern included in the first packet (i.e., the second node sends its third mapping pattern to the first node, and the third mapping pattern is stored by the first node as the first mapping pattern of the first node) is matched with its third mapping pattern, and if the first mapping pattern and the third mapping pattern are not matched, an error is reported.

The first mapping mode of the first node actually refers to the third mapping mode of the second node, and specifically refers to the periodic mapping rule at the ingress port of the second node downstream of the specific link known to the first node. For example, a first transmission period of a first node maps to a second transmission period of a second node. The specific link refers to a link connecting the first node and the second node through which the first packet passes.

In an embodiment, the method further comprises:

For the first packet and the data packet, where the first packet is a protocol packet (which is also an important packet in general, but the packet does not carry data), it only needs to be sent at both ends of the link to reach the second node, and may not need to be forwarded further. After the first packet, data packets (a Critical packet, which belongs to the period) follow, where the data packets may be data packets with low delay requirements and need to be further forwarded, and the data packets may also carry an identifier of the transmission period of the first node.

In an embodiment, the receiving the first packet cycle includes: completing a first receiving period for receiving the data message related to the first message and starting a second receiving period for receiving the first message; the related data message represents the data message sent by the first node sending the first message in the corresponding sending period;

and establishing a mapping relation between the determined sending period and the first period identifier.

Specifically, the first packet is a packet for informing an opposite end of starting a period, and after the first packet is sent, the related data packets may be continuously sent, so that the first packet and the data packets may be understood as a whole and sent in the same period, and because the number of the data packets is different, the data packets may not be completely received by the opposite end in the same period, and therefore, it is necessary to determine a first receiving period in which the related data packets of the first packet are completely received.

Here, when the application scenario is a scenario including three periods, the period after at least one period, specifically, the period after one period after the second receiving period may be a period after one period as a sending period;

when the application scenario is a scenario including four periods, the period after at least one period may be a period after two periods after the second receiving period. It should be noted that, the scenario of four cycles is adopted, which takes into account the problem of possible network jitter; the effect of jitter on the period determination is addressed here by adding one more period on a three period basis.

In an embodiment, the method further comprises: updating the first mapping relation when a periodic updating condition is met;

the satisfying of the periodic update condition includes at least one of:

an interface of the second node is flashed (for example, if the interface board card of the second node is restarted to cause a short open circuit, the problem that the message cannot be received may occur in all periods, that is, the first message or the second message is not received in at least one receiving period);

the first message is received for the first time (e.g., just started).

Specifically, the second node checks that it has not received the packet for a period of time and/or that the cycle sequence number (which may be referred to as seq. No.) corresponding to the received packet is not continuous, considers that the switching of the underlying link occurs, and then checks whether the mapping relationship is changed. If so, relearning of the mapping relationship is automatically performed, forwarding to downstream nodes, and triggering an update of the reserved bandwidth (taking into account the change in the mapping relationship, which results in a change in the resources previously reserved for a certain period). In addition, how many periods of messages are lost can be specifically described according to the period sequence number.

In one embodiment, the corresponding packet is an extended protocol packet or a specific VLAN packet.

Here, the first packet may be a new layer 2 packet, which is sent one at the beginning of each period to indicate the beginning of the corresponding period of the first node.

The size of the message may be fixed, for example, it may be the smallest ethernet message (size of 64 bytes); if the size of the carried information is not sufficient, pad stuffing (pad in Ethernet technology) can be used.

Thus, if the protection switching of Dense Wavelength Division Multiplexing (DWDM) is finished, after the first packet reaches the downstream second node, the second node may directly obtain the current periodic mapping relationship (which is equivalent to the first mapping relationship) through the first packet, so as to quickly recover the cyclic (looping) forwarding of the packet.

The first packet may be an extended protocol packet or a specific VLAN packet. The extended protocol message may be a new L3 type (L3 type is used for marking message type, e.g., 0x88BB) message of the application, or an operator controlled assignment of an exclusive VLAN to identify the message (VLAN number is used for marking message type, e.g., 4000). FIG. 7 is a diagram of a first message format; as shown in fig. 7, all the fields are standard fields of Ethernet, and corresponding extensions can be made for the type part; the first part is the preamble and the Start-of-Frame limiter (SFD), followed by the destination MAC Address (Media Access Control Address) and the source MAC Address, followed by the length field and the type field, followed by the data and padding fields, and finally the checksum.

Fig. 8 is a schematic diagram of information included in a first message according to an embodiment of the present invention; as shown in fig. 8, the information includes:

version number (version), cycle number (cycle number), cycle identification (cycle No.), first mapping mode (mode), reverse second mapping mode (reverse mode), reserved field (resv.);

the method can also comprise the following steps:

the period length of the current period (e.g., 10 us);

the periodic sequence number (seq. no, records several periods, for example, a value that increases from 1) of the current packet;

the bandwidth (one bandwidth value) that has been reserved for the current period;

limit MTU messages (e.g., IP messages for management) such as a small MTU encapsulated by a Type Length Value (TLV).

In the above, the first mapping mode is a mapping mode of the second node sent by the second node (downstream node) to the first node (upstream node as the second node), so that the first node knows the mapping mode of the second node.

Of course, in practical application, other fields can be extended according to needs, and are used for synchronization and functions of other information.

According to the method provided by the embodiment of the invention, on one hand, the boundary of each period is clearer through the expanded first message. Compared with the prior art, the method and the device have the advantages that the starting of the period is judged according to the first occurrence condition of each data message containing the identifier (such as a flag), the problem that no message exists in a certain period or the problem that the message is not at the head of the period possibly occurs, the scheme provided by the embodiment of the invention can support the downstream node to learn the periodic mapping relation of the link more conveniently through the clearly-divided message, and the correct mapping relation can be checked and the packet loss condition can be reported as long as the first message is frequently sent and a new first message is received.

On the other hand, the first packet may also be used for information interaction between an upstream node (such as the first node) and a downstream node (such as the second node) in the DIP network; and, it can also be used for consistency check of upstream node and downstream node configuration in DIP network, for example, check the number of cycles (e.g. 3), and mapping relationship of cycles (flag x- > flag x +1, so-called plus one mapping, e.g. mapping from upstream transmission cycle 1 to downstream transmission cycle 2).

On the other hand, the first message also carries the cycle serial number (seq. no) of the current message, so that protection switching occurs on the bottom layer optical network link, and besides cycle relearning, the loss condition of the link message can be counted.

On the last hand, the defined new TLV carries more information to the downstream node, for example, it may carry some smaller control packets, make some status notification/synchronization, occupy this part of bandwidth, and forward quickly (two packets may be sent simultaneously in this channel and the normal data channel to ensure notification as soon as possible), or make an OAM channel, check the network condition, and at the same time, it will not affect the existing network traffic.

The embodiment of the invention also provides another communication scheduling method; the method comprises the following steps:

after the DIP device (such as the first node and the second node) configures the number of cycles, the cycle length, and the like in advance, when each cycle starts, the first node sends a cycle _ start packet (which is equivalent to the first packet in the methods shown in fig. 5 and fig. 6), and a mapping relationship (mode) is initially set to be null.

After a downstream DIP device (such as the second node) receives a first message of an upstream DIP device (such as the first node), the downstream DIP device analyzes the first message and determines a mapping relation between the upstream DIP device and the downstream DIP device; that is, the message sent by the upstream no.x (a specific cycle identifier) is received in some two cycles of itself and sent out in the next cycle, for example, no.y; according to the mapping relationship between X and Y, it is determined whether the mapping mode is an plus one mode, a plus two mode, or a plus three mode (if applied to a four-cycle scene, it may also be a plus four mode), and the downstream DIP device may send a self-determined cycle mapping mode (reverse mode) to the upstream DIP device, let the upstream DIP device know the mapping relationship of the downstream DIP device, and fill in a mapping mode (mode) field.

The downstream DIP device may record this information and check, based on the cycle sequence number seq.no, whether the first message arrives successfully for each cycle.

The embodiment of the invention provides a method for learning a periodic mapping relationship, which comprises the following steps:

step 01, pre-configuring DIP (dual in-line package) by two adjacent DIP nodes;

the two adjacent DIP nodes may be the first node and the second node;

the first node may be an upstream router a; the second node may be router B downstream relative to router a;

the related configuration includes: periodic scheduling, the number of cycles of periodic scheduling, the cycle length, etc. is enabled on the port.

In step 02, the router a transmits a cycle _ start packet (corresponding to the first packet) to the router B when each cycle of the router a starts.

It should be noted that, the router B also performs similar operations on the downstream router (for example, the router C), and here, the description is given by taking the packet transmission between the router a and the router B as an example.

The cycle _ start packet includes: the configured cycle information of the router a specifically includes: the number of cycles, the cycle identification number of the cycle, the cycle length, etc.

And step 03, the router B receives the cycle _ start message, analyzes the cycle _ start message, and performs corresponding processing according to an analysis result. The method specifically comprises the following steps:

on one hand, comparing the core information, for example, comparing whether the cycle number and the cycle length included in the cycle _ start message sent by the router a are consistent with the cycle number and the cycle length configured by the router a; if the mapping information is consistent with the mapping information, the correct mapping can be performed; if not, reporting error information to the network manager.

On the other hand, when router B determines that it does not have information on the periodic mapping relationship with respect to router a (if the mapping pattern is not determined), it learns the periodic mapping relationship (corresponding to the first mapping relationship).

The learning of the periodic mapping relationship comprises the following steps:

taking at least one cycle after the first receiving cycle in which the router B finishes receiving the cycle _ start message as the sending cycle; and establishing a mapping relation between the determined sending period and the first period identifier.

For example, an interface of a certain DIP link of the router B does not have an upstream-downstream cycle mapping relationship at present, and when the router B receives a cycle identifier (representing an upstream node, that is, a cycle identifier of a current cycle of the router a) in a cycle _ start message; for example, the period identifier is 1 (representing the first period), router B determines, according to the received time (e.g., received in the third period of router B), that the message (referred to as data message) of the period can be received in the third period and the first period (taking three periods as an example, because of three-period cycle, where the first period represents the first period of the next cycle) according to the DIP mechanism, and then sent out in the second period of router B, and the record mapping relationship is an addition mapping. And modifying the period identifier of the message, wherein the period identifier (flag) of the previous message is 1, and after entering the router B, the period identifier is modified to be 2 (namely, the flag is 2).

The cycle _ start message that continues to be received subsequently can be used to verify the mapping relationship, and if several consecutive cycle _ start messages are mapped by one, the record is considered to be stable. After the record is stable, if a cycle _ start message appears in an error cycle, the record is considered to be in error; for example, if a cycle _ start packet sent in the first cycle occurs in the second cycle of the downstream node, it is considered that an error occurs, and the error may be reported to the network manager.

Further, the embodiment of the invention also provides a method for relearning the periodic mapping relationship. Specifically, the method further comprises:

and step 04, determining that the periodic mapping relation changes, and updating the periodic mapping relation according to the cycle _ start message.

The arrival period of the cycle _ start packet may change; for example, a cycle _ start message 1(flag is 1, which represents that the message is sent in the first cycle upstream, that is, the cycle identifier is 1), arrives in the third cycle of router B, and router B also records the corresponding relation, but the subsequent arrival time does not meet the expectation. Here again, two cases can be distinguished:

in the first case, if the cycle _ start packet is not received in a certain continuous period, it may be determined that a problem occurs in the link, and the period mapping relationship may change (if a link switch occurs, some packets may be lost, generally within 50 ms). At this time, when the cycle _ start message is received again, for example, the cycle _ start message 2 is received (assuming that flag is 2, which represents that the message is sent in the second cycle upstream), according to the original mapping relationship, the message should be received in the first cycle, and the message may be received in the second cycle, and then the message may be sent in the third cycle, where the cycle mapping relationship is to add one mapping, but because the underlying network protection is changed, the cycle _ start message 2 is received in the second cycle, and at this time, the mapping relationship of the interface is updated to add two mapping, that is, the message in this cycle is considered to be received in the second cycle and the third cycle, and then the message is sent in the first cycle, thereby implementing fast relearning of the mapping cycle.

In addition, if there is no cycle _ start message in consecutive cycles, but the upstream cycle _ start2 message that should arrive in the first cycle arrives in the second cycle, it will report an error directly and will not trigger fast relearning.

In the second case, if the interface of the downstream router B is flashed, the periodic mapping relationship is lost, and the mapping relationship is triggered to be learned again quickly.

The embodiment of the invention also provides a method for recording the mapping relationship, which comprises the following steps:

step 11, two adjacent DIP nodes (such as the router a and the router B) perform DIP configuration in advance;

wherein the related configuration comprises: periodic scheduling, the number of periods of periodic scheduling, the length of the periods, etc. is enabled on the ports of the DIP node.

Step 12, when the router a (as the upstream DIP node) starts its own cycle, it sends a cycle start packet (which may be referred to as a cycle _ start packet, corresponding to the first packet) to the router B (as the downstream DIP node).

The cycle start packet includes the following information: first cycle information of the configuration of router a, for example: the number of cycles, the cycle identifier of the cycle, the cycle length, etc.

The method can also comprise the following steps: downstream periodic mapping relationships, such as: the x-th cycle at the upstream corresponds to the x + 1-th cycle at the downstream (the upstream selects a start time and starts to cycle according to three cycles, namely, the first cycle, the second cycle and the third cycle (if in a scene with four cycles, the cycle is performed according to four cycles), and the downstream is similar).

The method provided by the embodiment of the invention can be applied to a DIP network with three cycles or four cycles; taking the three-cycle DIP scheduling method as an example, there may be three mapping relationships. Such as:

the first, 1- >1, 2- >2, 3- >3, i.e. adding three mappings;

the second, 1- >3, 2- >1, 3- >2, i.e. adding two mappings;

the third, 1- >2, 2- >3, 3- >1, is plus one mapping.

Initially, the mapping relation is set to 0 (corresponding to the first mapping mode being empty), which means that it is unclear what the specific first mapping mode is. The inverse mapping relationship is also set to 0 (corresponding to the second mapping pattern being also null), indicating that it is unclear what the specific second mapping pattern is.

And step 13, the router B receives the cycle _ start message and analyzes the cycle _ start message. Performing comparison of some core information; for example: comparing whether the cycle number and the cycle length of the router A are consistent with the cycle number and the cycle length of the router A; if not, reporting error information to the network manager, and if consistent, determining that the mapping is correct.

Then, when the router B sends a cycle _ start to a, it will mark the reverse mode as 1 (downstream mapping relation, i.e. determining the first mapping mode);

step 14, the router a receives the cycle _ start message, records the reverse mode information, and subsequently sends the cycle _ start message with the mode set to 1.

FIG. 9 is a diagram illustrating a scenario for relearning mapping relationships in accordance with an embodiment of the present invention; as shown in fig. 9, the mapping relationship between DIP network routers (i.e., between router a and router B) after the underlying network switch can be relearned through the first message.

Compared with the configuration mode of the control plane in the prior art, the method provided by the embodiment of the invention is faster in configuration recovery speed, does not need the processes of reporting and issuing, and is used for directly configuring the data plane. Compared with the existing mechanism for learning the message, the function is more powerful, an overhead management channel above the head of Flexe can be referred to, upstream and downstream configuration check during starting is supported, rapid learning of a periodic mapping relation in a node is supported, and a slice for constructing a small MTU in a network is supported for transmission of some key messages, such as OAM messages.

Fig. 10 is a schematic structural diagram of a communication scheduling apparatus according to an embodiment of the present invention; as shown in fig. 10, the apparatus is applied to a first node, and the apparatus includes:

the first sending module is used for periodically sending a first message; the first packet is at least used to identify the beginning of the corresponding period of the first node.

The first message comprises first period information; the first period information includes at least one of:

the method comprises the steps of a first period number, a first period identifier, a first period length, a first mapping mode of a first node, a second mapping mode of a second node, a reserved field, a period sequence number and a limit MTU message.

The first message is an extended protocol message or a specific VLAN message;

in one embodiment, the apparatus further comprises: and the first processing module is at least used for finishing the relevant operation of determining the first message.

It should be noted that: in the communication scheduling apparatus provided in the foregoing embodiment, when implementing the corresponding communication scheduling method, only the division of each program module is taken as an example, and in practical applications, the processing allocation may be completed by different program modules according to needs, that is, the internal structure of the server is divided into different program modules to complete all or part of the processing described above. In addition, the apparatus provided by the above embodiment and the embodiment of the corresponding method belong to the same concept, and the specific implementation process thereof is described in the method embodiment, which is not described herein again.

Fig. 11 is a schematic structural diagram of a communication scheduling apparatus according to an embodiment of the present invention; as shown in fig. 11, the apparatus is applied to a second node, and the apparatus includes:

a first receiving module, configured to periodically receive a first packet from a first node; the first packet is at least used to identify the beginning of the corresponding cycle of the first node.

Specifically, the first packet includes first period information corresponding to a first node; the first period information includes at least one of:

second cycle number, second cycle length, third mapping mode, reserved field.

Specifically, the apparatus further comprises: the second processing module is used for determining that the first period information corresponds to the period related information of the second node when the second node has the first mapping relation, and determining that the first period information can be transmitted correctly;

Specifically, the first period information corresponds to period related information that the second node has, and includes at least one of:

the first period number is consistent with the second period number;

the first period length is consistent with the second period length;

the cycle order numbers in the first cycle information are consecutive.

Specifically, the first receiving module is further configured to receive a data packet when the second node has a first mapping relationship; the data message carries a period identifier of the data message;

Specifically, the period of receiving the first packet includes: completing a first receiving period for receiving the data message related to the first message and starting a second receiving period for receiving the first message; the related data message represents a data message sent by a first node sending the first message in a corresponding sending period;

Specifically, the second processing module is further configured to update the first mapping relation when a periodic update condition is satisfied;

the satisfying of the periodic update condition includes at least one of:

the interface of the second node is flashed;

and receiving the first message for the first time.

Specifically, the corresponding packet is an extended protocol packet or a specific VLAN packet.

Fig. 12 is a schematic structural diagram of a communication device according to an embodiment of the present invention, and as shown in fig. 12, the communication device 120 includes: a processor 1201 and a memory 1202 for storing computer programs executable on the processor;

when the computer program is executed by the processor 1201, corresponding to the application of the communication device to the first node, the method further comprises: periodically sending a first message; the first packet is at least used to identify the beginning of the corresponding period of the first node.

When the processor runs the computer program, the corresponding process of the first node in each method according to the embodiment of the present invention is implemented, and for brevity, no further description is given here.

When the computer program is executed by the processor 1201, corresponding to the application of the communication device to the first node, the method further comprises: periodically receiving a first message from a first node; the first packet is at least used to identify the beginning of the corresponding cycle of the first node.

When the processor runs the computer program, the corresponding process of the second node in each method according to the embodiment of the present invention is implemented, and for brevity, no further description is given here.

In practical applications, the communication device 120 may further include: at least one network interface 1203. The various components of the communication device 120 are coupled together by a bus system 1204. It is understood that the bus system 1204 is used to enable connective communication between these components. The bus system 1204 includes a power bus, a control bus, and a status signal bus, in addition to a data bus. For clarity of illustration, however, the various buses are labeled as bus system 1204 in fig. 12. The number of the processors 1201 may be at least one. The network interface 1203 is used for communication between the communication device 120 and other devices in a wired or wireless manner.

The memory 1202 in embodiments of the present invention is used to store various types of data to support the operation of the communication device 120.

The method disclosed by the embodiment of the invention can be applied to the processor 1201 or implemented by the processor 1201. The processor 1201 may be an integrated circuit chip having signal processing capabilities. In implementation, the steps of the above method may be implemented by integrated logic circuits of hardware or instructions in the form of software in the processor 1201. The Processor 1201 may be a general purpose Processor, a DiGital Signal Processor (DSP), or other programmable logic device, discrete gate or transistor logic device, discrete hardware components, or the like. The processor 1201 may implement or perform the methods, steps, and logic blocks disclosed in embodiments of the present invention. A general purpose processor may be a microprocessor or any conventional processor or the like. The steps of the method disclosed by the embodiment of the invention can be directly implemented by a hardware decoding processor, or can be implemented by combining hardware and software modules in the decoding processor. The software modules may be located in a storage medium located in the memory 1202, and the processor 1201 reads the information in the memory 1202 and performs the steps of the aforementioned methods in conjunction with its hardware.

In an exemplary embodiment, the communication Device 120 may be implemented by one or more Application Specific Integrated Circuits (ASICs), DSPs, Programmable Logic Devices (PLDs), Complex Programmable Logic Devices (CPLDs), Field Programmable Gate Arrays (FPGAs), general purpose processors, controllers, Micro Controllers (MCUs), microprocessors (microprocessors), or other electronic components for performing the aforementioned methods.

An embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored;

when the stored computer program is applied to a first node, the computer program is executed by a processor to execute: periodically sending a first message; the first packet is at least used to identify the beginning of the corresponding period of the first node.

When the computer program is executed by the processor, the corresponding process implemented by the first node in the methods according to the embodiments of the present invention is implemented, and for brevity, no further description is given here.

When the stored computer program is applied to the second node, the computer program is executed by the processor to execute: periodically receiving a first message from a first node; the first packet is at least used to identify the beginning of the corresponding cycle of the first node.

When the computer program is executed by the processor, the corresponding process implemented by the second node in the methods according to the embodiments of the present invention is implemented, and for brevity, no further description is given here.

In the several embodiments provided in the present application, it should be understood that the disclosed apparatus and method may be implemented in other ways. The above-described device embodiments are merely illustrative, for example, the division of the unit is only a logical functional division, and there may be other division ways in actual implementation, such as: multiple units or components may be combined, or may be integrated into another system, or some features may be omitted, or not implemented. In addition, the coupling, direct coupling or communication connection between the components shown or discussed may be through some interfaces, and the indirect coupling or communication connection between the devices or units may be electrical, mechanical or other forms.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, that is, may be located in one place, or may be distributed on a plurality of network units; some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, all the functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may be separately regarded as one unit, or two or more units may be integrated into one unit; the integrated unit can be realized in a form of hardware, or in a form of hardware plus a software functional unit.

Those of ordinary skill in the art will understand that: all or part of the steps for implementing the method embodiments may be implemented by hardware related to program instructions, and the program may be stored in a computer readable storage medium, and when executed, the program performs the steps including the method embodiments; and the aforementioned storage medium includes: a mobile storage device, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.

Alternatively, the integrated unit of the present invention may be stored in a computer-readable storage medium if it is implemented in the form of a software functional module and sold or used as a separate product. Based on such understanding, the technical solutions of the embodiments of the present invention may be essentially implemented or a part contributing to the prior art may be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the methods described in the embodiments of the present invention. And the aforementioned storage medium includes: a removable storage device, a ROM, a RAM, a magnetic or optical disk, or various other media that can store program code.

It should be noted that: "first," "second," and the like are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order.

The technical means described in the embodiments of the present application may be arbitrarily combined without conflict.

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.

Claims

1. A communication scheduling method applied to a first node, the method comprising:

2. The method of claim 1, wherein the first packet includes first periodic information; the first period information includes at least one of:

the MTU message comprises a first period number, a first period identifier, a first period length, a first mapping mode, a second mapping mode, a reserved field, a period sequence number and a Maximum Transmission Unit (MTU) limiting message.

3. The method of claim 1, wherein the first packet is an extended protocol packet or a specific Virtual Local Area Network (VLAN) packet.

4. A communication scheduling method applied to a second node, the method comprising:

5. The method of claim 4, wherein the first packet includes first periodic information corresponding to the first node; the first period information includes at least one of:

second cycle number, second cycle length, third mapping mode, reserved field.

6. The method of claim 5, further comprising:

7. The method of claim 5, wherein the first period information corresponds to period related information possessed by the second node, and comprises at least one of:

the first cycle number is consistent with the second cycle number;

the first period length is consistent with the second period length;

the cycle order numbers in the first cycle information are consecutive.

8. The method of claim 5, further comprising:

9. The method of claim 6, wherein receiving the cycle of the first packet comprises: completing a first receiving period for receiving the data message related to the first message and starting a second receiving period for receiving the first message; the related data message represents a data message sent by a first node sending the first message in a corresponding sending period;

10. The method of claim 9, further comprising: updating the first mapping relation when a periodic updating condition is met;

the satisfying of the periodic update condition includes at least one of:

the first message or the second message is not received in at least one receiving period;

the interface of the second node is flashed;

and receiving the first message for the first time.

11. Method according to any of claims 4 to 10, characterized in that the respective messages are extended protocol messages or specific VLAN messages.

12. An apparatus for communication scheduling, the apparatus comprising: the first sending module is used for periodically sending a first message; the first packet is at least used to identify the beginning of the corresponding period of the first node.

13. An apparatus for communication scheduling, the apparatus comprising: a first receiving module, configured to periodically receive a first packet from a first node; the first packet is at least used to identify the beginning of the corresponding cycle of the first node.

14. A communication device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the steps of the method of any one of claims 1 to 3 are implemented when the program is executed by the processor; or,

the processor, when executing the program, performs the steps of the method of any of claims 4 to 11.

15. A computer-readable storage medium, on which a computer program is stored which, when being executed by a processor, carries out the steps of the method according to any one of claims 1 to 3; or,

the computer program when executed by a processor implements the steps of the method of any one of claims 4 to 11.