The present disclosure relates to the field of computer networks and to performance evaluation in such networks. The performance measurement is performed by a network node using a status field with a performance bitmap.

BACKGROUND

Performance measurement and fault detection are critical capabilities in communication networks. Moreover, these are key capabilities for autonomous networks, which has been a quickly evolving technology over the last few years. Measurement data is typically collected by a central management server, which analyzes the data and takes intelligent decisions (potentially based on artificial intelligence) that affect the network, including for example network paths, network resource allocation, and network security policies.

Two examples of network performance measurement approaches are in-band network telemetry (INT) and in situ operations, administration and maintenance (IOAM). These approaches collect per-hop measurement data along a network path, allowing detailed information about performance and failures, but require a large per-packet overhead.

That is, conventional measurement solutions suffer from high overheard when performing per-hop measurement.

SUMMARY

In view of the above-mentioned problem, embodiments of the present invention aim to improve the conventional solutions for performance measurement. It is an objective to provide a solution which enables error detection and error localization based on per-hop information, while keeping a low per-packet overhead. In other words, the solution according to the present invention allows for carrying a per- hop status indication over a network path with a low and constant size overhead per packet, using a status bitmap where each bit represents the status of one of the devices along the network path.

The objective is achieved by the embodiments of the invention as described in the enclosed independent claims. Advantageous implementations of the embodiments of the invention are further defined in the dependent claims.

A first aspect of the present invention provides a network node for supporting performance evaluation, wherein the network node is configured to obtain a packet comprising a status field, wherein the status field includes a hop count value and a performance bitmap; update a bit in the performance bitmap based on performance information obtained in the network node and based on the hop count value; increment the hop count value; and forward the updated packet.

This is beneficial, as per-hop status information can be collected without creating large unnecessary overhead.

In particular, the network node for performance measurement may also be called transit node, or forwarding node.

In particular, the network node is a switch, a router, a middle box, a network interface controller, NIC, or any device that can send, receive, and/or forward packets.

In particular, the packet is a data-packet or a probe-packet.

In particular, the status field is of any predefined length. More specifically, the length of the status field is 32 bits. More specifically, 5 bits is allocated to the hop count value, and 27 bits is allocated to the status bitmap value. This e.g. allows for indicating the status/performance of 27 hops (which is enough for most network scenarios) in the bitmap. Since the length hop count value is 5 bits, a range of integers from 0 to 31 can be stored, which also allows to count to a number even larger than 27. Thus, a 32-bit status field is enough for most network scenarios.

In particular, the hop count value is an integer. In particular, the hop count value is incremented by 1.

In particular, the performance bitmap is an array of bits. That is, a performance bitmap of length 27 e.g. is an array of 27 bits. Each bit can be addressed by an index-value. E.g. a first bit of the array can be addressed by the index value “0”, a second bit of the array can be addressed by the index value “1”, and so on.

In an implementation form of the first aspect, the performance information includes information whether a queue of the network node in which the packet is enqueued is congested, or whether a latency experience by the packet in the network node exceeds a predefined threshold.

This is beneficial, as information regarding the queue of the network node, or the latency in the network node can be collected on a per-hop basis very efficiently.

In particular, the performance information can be any kind of metric which can be compared to a threshold value or a condition. In particular, the network node can be configured as to what kind of information (e.g. metric) is included in the performance information.

In a further implementation form of the first aspect, the updating the bit in the performance bitmap comprises setting the bit to “0” or to “1” depending on the performance information.

This is beneficial, as the per-hop information can be stored in the bitmap on a smallest level of a data-structure, i.e. on a per bit level.

In particular, the bit is updated to “0” if a queue of the network node in which the packet is enqueued is not congested. In particular, the bit is updated to “1” if a queue of the network node in which the packet is enqueued is congested. In particular, the bit is updated to “0” if a latency experience by the packet in the network node is below a predefined threshold. In particular, the bit is updated to “1” if a latency experience by the packet in the network node exceeds a predefined threshold.

In a further implementation form of the first aspect, the network node is further configured to add a node identifier, ID, of the network node to the status field if the bit in the performance bitmap is updated to “1”.

This is beneficial, as it allows for efficient identification of the nodes to which a bit that is set to “1” in the bitmap corresponds.

In a further implementation form of the first aspect, the updating a bit in the performance bitmap based on the hop count value includes that the hop count value is used as an index value of the bit in the performance bitmap of which the status is updated.

This allows for an efficient way of addressing the relevant bit in the bitmap.

In a further implementation form of the first aspect, the network node is further configured to provide the updated status field to an evaluation device.

In a further implementation form of the first aspect, the network node is further configured to remove the status field from the packet; and forward the packet without the status field.

In particular, this is why the network node can also be called egress node.

In particular, the status field is provided to the evaluation device proactively, or upon request.

A second aspect of the present invention provides a network node for preparing a packet for performance evaluation, wherein the network node is configured to add a status field to the packet, wherein the status field comprises a hop count value and a performance bitmap; and forward the packet to a network node for performance measurement. This is beneficial, as an efficient way of storing information on a per-hop basis is introduced to the packet.

In particular, the network node for preparing the packet for performance measurement may also be called ingress node.

In particular, the ingress node is a switch, a router, a middle box, a network interface controller, NIC, or any device that can send, receive, and/or forward packets.

In an implementation form of the second aspect, the network node is further configured to initialize the hop count value to zero, and/or to initialize at least one bit in the performance bitmap to zero.

In a further implementation form of the second aspect, the status field is incorporated in a tunnel header of the packet, or as an extension field in a header of the packet.

A third aspect of the present invention provides an evaluation device for performance evaluation of a packet, wherein the evaluation device is configured to obtain a status field from a network node, wherein the status field comprises a hop count value and a performance bitmap; and evaluate a performance of a packet, based on the hop count value and the performance bitmap.

This allows for efficient evaluation of a performance on a packet, wherein the evaluation in particular is based on per-hop information that is stored in the packet without unnecessary overhead.

In particular, the evaluation device is part of the network node for completing performance measurement.

In an implementation form of the third aspect, the evaluation device is further configured to evaluate the performance of the packet based on a node identifier, ID, in the status field. In particular, the evaluation device can apply countermeasures to a network node, based on the node ID and a result of evaluating the performance of the packet.

In a further implementation form of the third aspect, the evaluation device is further configured to obtain the status field by removing the status field from a tunnel header of the packet or by removing the status field from an extension field in a header of the packet.

A fourth aspect of the present invention provides a method for supporting performance evaluation, wherein the method comprises the steps of obtaining, by a network node, a packet comprising a status field, wherein the status field includes a hop count value and a performance bitmap; updating, by the network node, a bit in the performance bitmap based on performance information obtained in the network node and based on the hop count value; incrementing, by the network node, the hop count value; and forwarding, by the network node, the updated packet.

In an implementation form of the fourth aspect, the performance information includes information whether a queue of the network node in which the packet is enqueued is congested, or whether a latency experience by the packet in the network node exceeds a predefined threshold.

In a further implementation form of the fourth aspect, the updating the bit in the performance bitmap comprises setting the bit to “0” or to “1” depending on the performance information.

In a further implementation form of the fourth aspect, the method further includes adding, by the network node, a node identifier, ID, of the network node to the status field if the bit in the performance bitmap is updated to “1”.

In a further implementation form of the fourth aspect, the updating a bit in the performance bitmap based on the hop count value includes that the hop count value is used as an index value of the bit in the performance bitmap of which the status is updated. In a further implementation form of the fourth aspect, the method further includes providing the updated status field to an evaluation device

In a further implementation form of the fourth aspect, the method further includes removing, by the network node, the status field from the packet; and forward the packet without the status field.

The fourth aspect and its implementation forms include the same advantages as the first aspect and its respective implementation forms.

A fifth aspect of the present invention provides a method for preparing a packet for performance evaluation, wherein the method comprises the steps of adding, by a network node, a status field to the packet, wherein the status field comprises a hop count value and a performance bitmap; and forwarding, by the network node, the packet to a network node for performance measurement.

In an implementation form of the fifth aspect, the method further includes initializing, by the network node, the hop count value to zero, and/or to initialize at least one bit in the performance bitmap to zero.

In a further implementation form of the fifth aspect, the status field is incorporated in a tunnel header of the packet, or as an extension field in a header of the packet.

The fifth aspect and its implementation forms include the same advantages as the second aspect and its respective implementation forms.

A sixth aspect of the present invention provides a method for performance evaluation of a packet, wherein the method comprises the steps of obtaining, by an evaluation device, a status field from a network node, wherein the status field comprises a hop count value and a performance bitmap; and evaluating, by the evaluation device, a performance of a packet, based on the hop count value and the performance bitmap. In an implementation form of the sixth aspect, the method further includes evaluating, by the evaluation device, the performance of the packet based on a node identifier, ID, in the status field.

In a further implementation form of the sixth aspect, the method further includes obtaining, by the evaluation device, the status field by removing the status field from a tunnel header of the packet or by removing the status field from an extension field in a header of the packet.

The sixth aspect and its implementation forms include the same advantages as the third aspect and its respective implementation forms.

A seventh aspect of the present invention provides a computer program product comprising computer readable code instructions which, when run in a computer will cause the computer to perform the method according to any one of the fourth, fifth or sixth aspect or any of their implementation forms, respectively.

The seventh aspect includes the same advantages as the first, second or third aspect and their respective implementation forms.

A eighth aspect of the present invention provides a computer readable storage medium comprising computer program code instructions, being executable by a computer, for performing a method according to any one of the fourth, fifth or sixth aspect or any of their implementation forms, respectively, when the computer program code instructions runs on a computer.

The eighth aspect includes the same advantages as the first, second or third aspect and their respective implementation forms.

It has to be noted that all devices, elements, units and means described in the present application could be implemented in the software or hardware elements or any kind of combination thereof. All steps which are performed by the various entities described in the present application as well as the functionalities described to be performed by the various entities are intended to mean that the respective entity is adapted to or configured to perform the respective steps and functionalities. Even if, in the following description of specific embodiments, a specific functionality or step to be performed by external entities is not reflected in the description of a specific detailed element of that entity which performs that specific step or functionality, it should be clear for a skilled person that these methods and functionalities can be implemented in respective software or hardware elements, or any kind of combination thereof.

BRIEF DESCRIPTION OF DRAWINGS The above-described aspects and implementation forms of the present invention will be explained in the following description of specific embodiments in relation to the enclosed drawings, in which

FIG. 1 shows a schematic view of a network node for supporting performance evaluation according to an embodiment of the present invention.

FIG. 2 shows a schematic view of a network node preparing a packet for performance evaluation according to an embodiment of the present invention. FIG. 3 shows a schematic view of evaluation device for performance evaluation according to an embodiment of the present invention

FIG. 4 shows an operating example according to the present invention.

FIG. 5 shows a schematic view of a packet according to the present invention.

FIG. 6 shows a schematic view of packets according to the present invention.

FIG. 7 shows a schematic view of a method according to an embodiment of the present invention.

FIG. 8 shows a schematic view of a method according to an embodiment of the present invention. FIG. 9 shows a schematic view of a method according to an embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1 shows a schematic view of a network node 100 according to an embodiment of the present invention. The network node 100 is for supporting performance evaluation, e.g. evaluation which is performed by a separate evaluation device 300, which is going to be described below.

For supporting performance evaluation, the network node 100 obtains a packet 101 comprising a status field 102. The status field 102 includes a hop count value 103 and a performance bitmap 104.

Based on performance information 106 obtained in the network node 100 and based on the hop count value 103, the network node 100 updates a bit 105 in the performance bitmap 104. Although there are three bits 105 shown in FIG. 1, there can be an arbitrary number of bits 105 in the bitmap 104. In other words, the bitmap 104 is an array of bits 105.

The network node 100 then increments the hop count value 103 and forwards the updated packet 101.

Based on the hop count value 103 and the bitmap 104, a performance of the packet can be evaluated by an evaluation device 300.

Then, the network node 100 forwards the packet 101 to another network node, e.g. along the intended path of the packet 101. In this other network node, further processing can be applied to the packet 101. As the network 100 forwards the packet 101 from an ingress node to an egress node, the network node 100 may also be called transit node.

The packet 101 generally can be any kind of network packet. In particular the packet 101 can be a data packet, i.e. a packet that is sent from a source host to a destination host. In particular, the packet 101 can be a control packet, which is sent between network devices.

FIG. 2 shows a schematic view of a network node 200 according to an embodiment of the present invention. The network node 200 is for preparing a packet 201 for performance evaluation, e.g. the processing of the packet 201 in another network node.

The network node 200 obtains a regular packet and adds a status field 202 to the packet. The status field 202 comprises a hop count value 203 and a performance bitmap 204. Then, the network node 200 forwards the packet 201 to a network node 100 for performance measurement.

That is, the packet 201 that is forwarded by the network node 200 is the packet 101 that is obtained by the network node 100. In other words, in this document, the packet 101 and the packet 201, the status field 102 and the status field 202, the hop count value 103 and the hop count value 203 and the performance bitmap 104 and the performance bitmap 204 generally refer to the same entity.

The packet 201 generally can be any kind of network packet. In particular the packet 201 can be a data packet, i.e. a packet that is sent from a source host to a destination host. In particular, the packet 201 can be a control packet, which is sent between network devices.

FIG. 3 shows a schematic view of an evaluation device 300 according to an embodiment of the present invention. The evaluation device 300 is for performance evaluation of a packet 101 as e.g. forwarded by the network device 101.

For performance evaluation, the evaluation device 300 obtains a status field 301 from a network node 100. The status field 301 comprises a hop count value 302 and a performance bitmap 303. The status field 301 is the status field 102 of the packet 101 which was provided by the network node 101. The network node 100 however can forward the packet 101 with or without the status field 102. That is, the network node 102 can optionally also remove the status field 102 from the packet 101 before forwarding it to the evaluation device 300. Then, the evaluation device 300 evaluates a performance 304 of the packet 101, based on the hop count value 302 and the performance bitmap 303.

FIG. 4 shows an operating example according to the present invention. As illustrated in FIG. 4, data packets are transmitted from a source to a destination. Intermediate network devices may include: switches, routers or network interface cards (NIC). A NIC is a hardware component that resides either in the source or destination or both.

A first network device (that is, the network node 200 in FIG. 3) pushes a status field into the header of a packet. The first network device in this context may be the source of any of the network devices along a path. Other network devices (that is, instances of the network node 100, which are labelled network node 100 A and network node 100 B in FIG. 4) after the first network device may update the status field. The status field includes two sub-fields: a <Hop Count> and a <Status Bitmap>. These entities relate to the status field 102, the hop count value 103 and the performance bitmap 104 of FIG. 1.

Each device along the path shown in FIG. 4 can update the status field 102. That is, the device 100 A, 100 B can update the corresponding bit in the performance bitmap 104 and can increment the hop count value 103. The status field may be analyzed by a destination device or by a management server, or any other node (that is, by the evaluation device 300).

For example, the status field 102 may be 32 bits long, such that the performance bitmap 104 is 27 bits long, and that the hop count value is 5 bits long. These lengths allow status indications for up to 27 hops, which is more than enough for reasonable network scenarios. Thus, a constant 32-bit status field 102 is enough for most typical network scenarios.

The status bit may indicate whether the queue that the packet was queued in was congested or not. Alternatively, the status bit may be set when the latency through the device exceeds a predetermined threshold.

In particular, the indication regarding congestion is attached to the current packet 101 is, since it is the most recent one to be updated. The packet is can be a special telemetry packet. The point of time in the flow of the network device 100 where this indication is attached to the packet 101 is when the packet 101 is fetched from the queue to be transmitted to the network. The latency of the packet is calculated according to this equation: packet device latency = (Enqueue timestamp - Dequeue timestamp). If packet device latency > threshold, then a congestion indication is attached to the packet, that is, the bit 105 in the bitmap 104 relating to the network node 100 is set to

In other words, the present invention defines a solution for status updating in a network, where a first node in the network (that is, the network node 200) incorporates a status field 202 (respectively a status field 102) into the packet header. The first node may be the source of the packet, or may be a switch/router along the path. The status field may be incorporated in a tunnel header, or as an extension field in an existing header. The status field 102 consists of a hop count value 103, which is initialized to zero by the first node; a performance bitmap 104, also initialized to zero by the first node. Optionally, other fields can be part of the status field 102.

An intermediate node (that is, the network node 100) in the network receives the packet 101 with the status field 102, and determines the node’s 100 current status to be ‘0’ or ‘ . The network node 100 then finds its allocated bit 105 in the performance bitmap

104 (the index of this bit 105 is the hop count value 103). The network node 100 then assigns its current status in its allocated bit 105 in the performance bitmap 104. The network node 100 then increments the hop count value 103 by 1. A last node in the network (e.g. the network node 100 B, an instance of the network node 100) removes the status field 102 from the packet (either by removing it along with a tunnel header that is also removed, or by removing it from an extension field).

The last node 100 B may export the status field 102 to an external analyzer (that is, the evaluation device 300) for further analysis, or the last node may perform the analysis internally (that is, the last node combines the network node 100 and the evaluation device 300). The exported status field 102 may be exported along with the data packet (or with a prefix of the data packet). An analyzer node (that is, the evaluation device 300), analyzes the status field 102 (that is, the hop count value 103 and the performance bitmap 104) and potentially reacts to the status of each node (indicated by the bits 105 in the bitmap 104). The analyzer may be the last node above (labelled 100 B in FIG. 4), or may be a separate node in the network (labelled 300 in FIG. 4).

Optionally, a network node 100 in which the status is ‘ G can push its node ID into the packet 101, allowing the analyzer node to have a list of nodes with a non-zero status. If this extension is implemented, then the status overhead does not have a constant length.

The criterion for setting the status to ‘0’ or ‘ G can be configurable by way of a network management system, which configures the status criterion, which may potentially include a metric and a threshold.

FIG. 5 shows a packet 101 with a status field 102. The status field 102 includes the hop count value 103 and the performance bitmap 104

FIG. 6 shows packets which include status fields 102 pushed by an ingress node. This data may be pushed with a tunnel header (such as VXLAN-GPE), as shown in the second line in the figure, or can be pushed as an extension to an existing header in the packet, such as an IPv6 extension header, as shown in the third line. The first line shows a regular packet without the status field.

FIG. 7 shows a method 700 according to an embodiment of the present invention. The method 700 is for supporting performance evaluation. The method 700 comprises a step of obtaining 701, by a network node 100, a packet 101 comprising a status field 102, wherein the status field 102 includes a hop count value 103 and a performance bitmap 104. The method 700 comprises a step of updating 702, by the network node 100, a bit 105 in the performance bitmap 104 based on performance information 106 obtained in the network node 100 and based on the hop count value 103. The method 700 comprises a step of incrementing 703, by the network node 100, the hop count value 103. The method 700 comprises a step of forwarding 704, by the network node 100, the updated packet 101. FIG. 8 shows a method 800 according to an embodiment of the present invention. The method 800 is for performance evaluation. The method 800 comprises a step of adding 801, by a network node 200, a status field 202 to the packet 201, wherein the status field 202 comprises a hop count value 203 and a performance bitmap 204. The method 800 comprises a step of forwarding 802, by the network node 200, the packet 201 to a network node 100 for performance measurement.

FIG. 9 shows a method 900 according to an embodiment of the present invention. The method is for performance evaluation by an evaluation device 300. The method 900 comprises a step of obtaining 901, by an evaluation device 300, a status field 301 from a network node 100, wherein the status field 301 comprises a hop count value 302 and a performance bitmap 303. The method 900 comprises a step of evaluating 902, by the evaluation device 300, a performance 304 of a packet 101, based on the hop count value 302 and the performance bitmap 303.

The main difference of the present invention and conventional solutions is described in the following: The present invention provides a compact one-bit-per-hop status that includes two main aspects: usage of a status bitmap in-band with data packets; the index to the status bitmap is the hop count. The status bitmap can be used in conjunction with other measurement methods or protocols. Alternatively, it can be used as a trigger for other measurement methods; if one of the bits in the bitmap is set, then a management server may trigger a more different measurement method which provides more details about the status.

The present invention has been described in conjunction with various embodiments as examples as well as implementations. However, other variations can be understood and effected by those persons skilled in the art and practicing the claimed invention, from the studies of the drawings, this disclosure and the independent claims. In the claims as well as in the description the word “comprising” does not exclude other elements or steps and the indefinite article “a” or “an” does not exclude a plurality. A single element or other unit may fulfill the functions of several entities or items recited in the claims. The mere fact that certain measures are recited in the mutual different dependent claims does not indicate that a combination of these measures cannot be used in an advantageous implementation.