Network loopback message test requests and responses

Abstract

The present invention relates to a network device for transmitting a message to another network device according to a network protocol and receiving a loopback reply message, the loopback reply message comprising, in a payload, at least a portion of the message, the at least a portion comprising at least one header of the message. The packet includes loopback request information in a header of a layer of the network model. The loopback request information requests the other network device to transmit the loopback reply message to the network device. There is provided a network device for receiving a message from another network device according to a network protocol, and transmitting a loopback reply message to the other network device in response to the received message including loopback request information in a header of a layer of a network model, the loopback reply message includes at least a portion of the received message, the at least a portion including at least one header.

Description

Technical Field

[0001] The present invention relates to network equipment and methods. Background Art

[0002] The present invention relates to a network comprising network devices that can communicate with each other. The network device is a network node of the network. The Internet protocol (IP) is an example of a network protocol that can be used for communication between network devices. Summary of the invention

[0003] The inventors made the following considerations:

[0004] The network layer protocols IPv4 and IPv6 are examples of network protocols that support header extensions. Each of these protocols can use a fixed-size basic header: a 20-octet header in IPv4 and a 40-octet header in IPv6. Each of these protocols allows the basic header to be followed by optional extensions. In IPv4, there can be no, one, or more header options. In IPv6, there can be no, one, or more extension headers.

[0005] Each IPv6 extension header may include one or more type-length-value (TLV) options. A router or host that receives a message including an IPv6 header and one or more extension headers may skip the extension header and ignore the extension header. The skipping operation may be performed or implemented by iteratively tracking the "length" portion of each TLV.

[0006] The host (i.e., the source (which may be referred to as the source network device or source network node)) that sends an IPv6 message may include an extension header in the message. These extension headers may be used or updated by intermediate network devices (i.e., routers). For example, a router may push path tracking information and / or performance-related information so that the extension header includes per-hop information about the path and / or performance. Optionally, a segment routing header (SRH) may be used by the router for segment routing. Segment routing may indicate that the source (source network device) instructs the router (intermediate network device) how to route the message to the destination (destination network device). The router may update the SRH. The terms "send" and "transmit" may be used as synonyms.

[0007] The internet control message protocol (ICMP) can be used to detect networks and report errors. In the network layer model (transmission control protocol / internet protocol five-layer network model, i.e., TCP / IP five-layer network model), IPv4 / IPv6 is part of the network layer (i.e., layer 3), and ICMP is an intermediate layer above layer 3 (i.e., the intermediate layer between layer 3 and layer 4), which is used to detect and handle faults in layer 3. In the present invention, the term "transmission control protocol / internet protocol five-layer network model" is abbreviated as the term "TCP / IP five-layer network model". ICMP has two variants, wherein ICMP is used for IPv4 and ICMPv6 is used for IPv6.

[0008] Both ICMP variants may include the ability to send an echo request to a destination host (i.e., a destination network device) and receive an echo reply. The destination (or responder) that receives the echo request may send an echo reply to the IP address from which the echo request was received. Many applications may use echo request / reply messages, such as the "ping" application that may be used to test host reachability.

[0009] A different protocol that can perform a process similar to ICMP echo is the simple two-way active measurement protocol (STAMP). STAMP is a protocol that can be used for performance measurement between two network nodes (i.e., network devices), a session sender and a session reflector. Performance measurements can be performed using STAMP test messages. A session sender can send one or more STAMP session sender messages, and the session reflector can reply to each test message by sending a session reflector test message back to the session sender. STAMP test messages can be sent via the user datagram protocol (UDP), which can be used over IP (IPv4 or IPv6). The STAMP test message may not include an optional type-length-value (TLV) field, or it may include one or more optional TLV fields. The TLV field is defined in the STAMP specification as "an optional extension encoded using a type-length-value (TLV)". Specifically, these TLVs extend the STAMP header, which is similar to the way an extension header extends the IPv6 header.

[0010] While several protocols use extension headers to probe and gather per-hop (per-router) information, there is no common or standard way to return that information to the sender (i.e., the source network device). These protocols can update the IP extension headers of an IP packet that ultimately reaches an IP destination (i.e., the destination network device), but the information in the updated IP extension headers along the path (from source to destination) is not propagated back to the source, which is typically the host that actually needs the information. For example, an application such as a "ping" application may find it useful for the source to receive the extension headers from the forward path again from the responder and present the extension headers to the user along with the other information that was presented when the "ping" application was invoked.

[0011] In view of the above, the present invention aims to provide a network device and method, when a source network device transmits a message to a destination network device according to a network protocol, the network device and method can return information to the source network device. The purpose of the present invention can be to provide a network device and method that can return information to the source network device in a universal or standard manner.

[0012] These and other objects are achieved by the solutions of the invention as described in the independent claims. Advantageous implementations are further specified in the dependent claims.

[0013] A first aspect of the present invention provides a network device. The network device is used to transmit a message to another network device according to a network protocol, and receive a loopback reply message, wherein the loopback reply message includes at least a part of the message in a payload, and the at least a part includes at least one header of the message. The message includes loopback request information in a header of a layer of a network model. The loopback request information requests the other network device to transmit the loopback reply message to the network device.

[0014] In other words, the first aspect proposes a general way to return information (e.g., network layer extension field information) of a message sent from a source network device (i.e., a network device according to the first aspect) to a destination network device (i.e., another network device) to the source network device, wherein the general way is independent of the information format (e.g., extension field format) of the message. The term "independent" can be used as a synonym for the term "independent".

[0015] The term "feedback" may be used as a synonym for the term "loopback". Thus, for example, the term "feedback request information" may be used as a synonym for the term "loopback request information". The network protocol may be an Internet protocol (IP). For example, the network protocol may be IPv4 or IPv6. The network device may be used to transmit a message to another network device through one or more intermediate network devices according to the network protocol. The one or more intermediate network devices may be one or more routers. The loopback request information is or includes a loopback request.

[0016] In the case of transmitting a message, a network device may be referred to as a source or source network device. In the case of transmitting a message, another network device may be referred to as a destination or destination network device. A network device and another network device may be referred to as network nodes. The term "part" may be used as a synonym for the term "portion". A network device may be used to generate a message (to be transmitted to another network device).

[0017] A network device may communicate with another network device according to a network protocol. For example, a network device may transmit a message to another network device according to a network protocol. A network device may receive a loopback reply message according to a network protocol. A network device may receive a loopback reply message from another network device.

[0018] The network device may be implemented by software and / or hardware. Another network device may be implemented by software and / or hardware. The network device may include means for communicating (e.g., transmitting messages and receiving loopback reply messages). The means for communicating may include one or more antennas.

[0019] Another network device may be the network device according to the second aspect of the present invention. The network device according to the first aspect of the present invention may be a server, a network interface card (NIC), a switch (network switch), a router, etc., or may be a part of a server, a network interface card (NIC), a switch (network switch), a router, etc.

[0020] In an implementation manner of the first aspect, the message includes one or more extension fields in a header of layer 3 of the network model.

[0021] The header of layer 3 of the network model may include an IP header (e.g., an IPv4 header or an IPv6 header) and optionally one or more extension fields (e.g., one or more IPv4 extension options or one or more IPv6 extension headers). The layer 3 of the network model may be layer 3 of the TCP / IP five-layer network model. The header of layer 3 may be referred to as a "layer 3 header".

[0022] In the case of IPv4, one or more extension fields of the layer 3 header may be referred to as "one or more extended options". In the case of IPv6, one or more extension fields may be referred to as "one or more extended headers". The one or more extension fields may be updated by one or more intermediate network devices, which may be present in a flow from a network device as a source to another network device as a destination. The update of the optional one or more extension fields in the layer 3 header by one or more intermediate network devices may include information about at least one of the following: the status and / or performance of the corresponding intermediate device (e.g., a timestamp or counter), the identification of the corresponding intermediate network device, and the routing decision of the corresponding intermediate network device.

[0023] In an implementation of the first aspect, the header of the layer of the network model is a header of an intermediate layer between layer 3 and layer 4 of the network model, and the message includes the loopback request information in the header of the layer of the network model. The header of the intermediate layer can be called an "intermediate layer header".

[0024] The middle layer between layer 3 and layer 4 of the network model can be the middle layer between layer 3 and layer 4 of the TCP / IP five-layer network model. That is, the middle layer can be the middle layer of the TCP / IP five-layer network model. If the network protocol is IPv4, the middle layer can be ICMP. If the network protocol is IPv6, the middle layer can be ICMPv6. The message can be called a "loopback request message".

[0025] In an implementation manner of the first aspect, the loopback request information is or includes one or more values ​​of a type field of the header of the intermediate layer, and the one or more values ​​indicate a loopback request.

[0026] The type field may be the type field of the ICMP header or the ICMPv6 header. The code field of the intermediate layer header may be constant and unused. The code field may be the code field of the ICMP header or the ICMPv6 header.

[0027] In an implementation manner of the first aspect, the network device is used to add an identification field and / or a sequence number field to the header of the intermediate layer.

[0028] In an implementation manner of the first aspect, the network device is used to allocate a different identification field to each flow.

[0029] For example, a flow can be defined as a pair of source and destination (e.g., {source address, destination address} pair) of communication, i.e., a pair of source network device and destination network device. For this purpose, the addresses of the source and destination can be used optionally. For example, a network device that transmits a message is a source, and another network device to which the message is to be transmitted is a destination.

[0030] For example, a flow can be defined as a tuple of source, destination, and segment routing (SR) policy (e.g., a {source address, destination address, SR policy} tuple). To this end, the address of the source, the address of the destination, and the SR policy can be used. The SR policy can explicitly define the path from the source to the destination and route through the path using a segment routing header (SRH). The path can pass through one or more intermediate network devices (e.g., routers).

[0031] In an implementation manner of the first aspect, the network device is used to use the identification field and / or the sequence number field to track the replied loopback request and / or the loopback request that needs to be retransmitted.

[0032] In an implementation manner of the first aspect, the header of the layer of the network model is a header of layer 3 of the network model, and the message includes the loopback request information in the header of the layer of the network model.

[0033] In other words, the message can be a data packet, and the network device can be used to piggyback the loopback request information onto the data packet. Layer 3 of the network model can be Layer 3 of the TCP / IP five-layer network model. The header of Layer 3 can be called a "Layer 3 header." The header of Layer 3 can include an IP header (for example, an IPv4 header or an IPv6 header) and optionally one or more extension fields (for example, one or more IPv4 extension options or one or more IPv6 extension headers). The loopback request information can be in the IP header. In addition or alternatively, the loopback request information can be in at least one of the optional one or more extension fields of the Layer 3 header, or it can be at least one of the optional one or more extension fields of the Layer 3 header.

[0034] In an implementation manner of the first aspect, the loopback request information is or includes an indication about a loopback request.

[0035] Alternatively, the indication may be a field in a field of the IP header. For example, a reserved value (or a series of reserved values) in a Differentiated Services Code Point (DSCP) field of the IP header may indicate that the message is subject to a loopback request.

[0036] In an implementation manner of the first aspect, the header of the layer of the network model is a header of layer 5 of the network model, and the message includes the loopback request information in the header of the layer of the network model.

[0037] The 5th layer of the network model may be the 5th layer of the TCP / IP 5-layer network model. The header of the 5th layer may be referred to as a "5th layer header".

[0038] In an implementation manner of the first aspect, the loopback request information is a type-length-value (TLV) field or resides in a TLV field.

[0039] The header of layer 5 may be a simple two-way active measurement protocol (STAMP) header. The TLV may be a STAMP header extension.

[0040] In an implementation manner of the first aspect, the network device is used to obtain information from the payload of the loopback reply message.

[0041] In order to implement the network device according to the first aspect of the present invention, part or all of the implementation methods and optional features of the first aspect may be combined with each other.

[0042] A second aspect of the present invention provides a network device. The network device is used to receive a message from another network device according to a network protocol, and in response to the received message including loopback request information in a header of a layer of a network model, transmit a loopback reply message to the other network device. The loopback reply message includes at least a portion of the received message in a payload, and the at least a portion includes at least one header of the received message.

[0043] Since the network device can return at least a portion of the received message without knowing the format of the received message (e.g., the extended format), the at least a portion includes at least one header of the received message (e.g., the extended information of the message), the network device provides a general way to return information of the received message, which is independent of the format of the message (e.g., independent of the extended field format). The portion of the received message included in the loopback reply message may include path-based information, such as performance and / or routing information.

[0044] The above description of the network device according to the first aspect may be correspondingly valid for the network device according to the second aspect. The network protocol may be an Internet protocol (IP). For example, the network protocol may be IPv4 or IPv6. The network device may be used to receive a message from another network device through one or more intermediate network devices according to the network protocol. The one or more intermediate network devices may be one or more routers. In the case of transmitting a message to the network device, the other network device may be referred to as a source or source network device. In the case of transmitting a message to the network device, the network device may be referred to as a destination or destination network device. The network device and the other network device may be referred to as network nodes. The network device may be used to generate a loopback reply message (to be transmitted to another network device).

[0045] A network device may communicate with another network device according to a network protocol. For example, a network device may receive a message from another network device according to a network protocol. A network device may transmit a loopback reply message to another network device according to a network protocol.

[0046] The network device may be implemented by software and / or hardware. Another network device may be implemented by software and / or hardware. The network device may include means for communicating (e.g., receiving messages and transmitting loopback reply messages). The means for communicating may include one or more antennas.

[0047] The network device described in the second aspect of the present invention can be a server, a network interface card (NIC), a switch (network switch), a router, etc., or it can be a part of a server, a network interface card (NIC), a switch (network switch), a router, etc.

[0048] The other network device (from which the network device according to the second aspect can receive messages) may be the network device according to the first aspect of the present invention.

[0049] In an implementation of the second aspect, the loopback reply message includes the entire received message or a portion of the received message in the payload, and the portion includes the at least one header of the received message.

[0050] In other words, the loopback reply message may include in the payload the entire received message (including all its headers) or a truncated version of the received message including at least one header of the received message.

[0051] In an implementation of the second aspect, the loopback reply message includes, in the payload, a header of layer 3 of the network model of the received message as the at least one header of the received message.

[0052] The third layer of the network model may be the third layer of the TCP / IP five-layer network model. The header of the third layer may be referred to as a "third layer header".

[0053] In an implementation of the second aspect, when the received message includes the loopback request information in a header of an intermediate layer between layer 3 and layer 4 of the network model, the loopback reply message includes the header of the intermediate layer of the received message in the payload as the at least one header of the received message and / or includes the payload of the intermediate layer of the received message.

[0054] The intermediate layer between layer 3 and layer 4 of the network model can be the intermediate layer between layer 3 and layer 4 of the TCP / IP five-layer network model. That is, the intermediate layer can be the intermediate layer of the TCP / IP five-layer network model. If the network protocol is IPv4, the intermediate layer can be ICMP. If the network protocol is IPv6, the intermediate layer can be ICMPv6.

[0055] In an implementation of the second aspect, when the received message includes the loopback request information in a header of layer 3 of the network model, the loopback reply message includes the payload of layer 4 of the network model of the received message in the payload.

[0056] The 4th layer of the network model may be the 4th layer of the TCP / IP five-layer network model. The payload of the 4th layer of the network model may be an IPv4 payload or an IPv6 payload. The payload of the 4th layer of the network model may include a transmission control protocol (TCP) header and a TCP payload.

[0057] Optionally, in a case where the received message includes the loopback request information in a header of layer 3 of the network model, the loopback reply message may include a header and payload of layer 4 of the network model of the received message in the payload.

[0058] The header and payload of layer 4 of the network model may be an IPv4 header and an IPv4 payload or an IPv6 header and an IPv6 payload.

[0059] In an implementation of the second aspect, when the received message includes the loopback request information in a header of layer 5 of the network model, the loopback reply message includes the header of layer 5 of the network model of the received message in the payload as the at least one header of the received message.

[0060] The 5th layer of the network model may be the 5th layer of the TCP / IP 5-layer network model. The header of the 5th layer may be referred to as a "5th layer header".

[0061] Optionally, in the case where the received message includes the loopback request information in the header of layer 5 of the network model, the loopback reply message may include, in addition to the header of layer 5 of the received message, at least one of the following in the payload: the header of layer 3 of the received message, the payload of layer 3, the header of layer 4, the payload of layer 4, and the payload of layer 5. For example, in the case where the received message includes the loopback request information in the header of layer 5 of the network model, the loopback reply message may include the headers and payloads of layers 3, 4, and 5 of the network model of the received message in the payload.

[0062] In an implementation manner of the second aspect, the loopback reply message includes a loopback reply indication in a header of an intermediate layer between layer 3 and layer 4 of the network model.

[0063] In an implementation of the second aspect, when the header of layer 3 of the network model of the received message includes one or more extension fields, the network device can be used to skip at least one of the one or more extension fields when parsing the received message.

[0064] The description of the network device according to the first aspect of the present invention may be correspondingly valid for the network device according to the second aspect of the present invention. Optionally, the network device according to the second aspect of the present invention is the network device according to the first aspect of the present invention. The description of the network device according to the second aspect of the present invention may be correspondingly valid for the network device according to the first aspect of the present invention.

[0065] The network device according to the second aspect and its implementation manner and optional features achieve the same advantages as the network device according to the first aspect and its corresponding implementation manner and corresponding optional features.

[0066] In order to implement the network device according to the second aspect of the present invention, part or all of the implementation methods and optional features of the above-mentioned second aspect can be combined with each other.

[0067] A third aspect of the present invention provides a method, wherein the method comprises: a network device transmits a message to another network device according to a network protocol, and the network device receives a loopback reply message, wherein the loopback reply message includes at least a part of the message in a payload, and the at least a part includes at least one header of the message. The message includes loopback request information in a header of a layer of a network model. The loopback request information requests the other network device to transmit the loopback reply message to the network device.

[0068] The above description of the network device according to the first aspect is correspondingly valid for the method according to the third aspect. The network device executing the method according to the third aspect may be the network device according to the first aspect of the present invention. Another network device may be the network device according to the second aspect of the present invention.

[0069] The method according to the third aspect and its implementation manner and optional features achieve the same advantages as the network device according to the first aspect and its corresponding implementation manner and corresponding optional features.

[0070] In an implementation manner of the third aspect, the message includes one or more extension fields in a header of layer 3 of the network model.

[0071] In an implementation of the third aspect, the header of the layer of the network model is a header of an intermediate layer between layer 3 and layer 4 of the network model, and the message includes the loopback request information in the header of the layer of the network model.

[0072] In an implementation manner of the third aspect, the loopback request information is or includes one or more values ​​of the type field of the header of the intermediate layer, and the one or more values ​​indicate a loopback request.

[0073] In an implementation manner of the third aspect, the method includes: the network device adds an identification field and / or a sequence number field to the header of the intermediate layer.

[0074] In an implementation manner of the third aspect, the method includes: the network device assigning a different identification field to each flow.

[0075] In an implementation manner of the third aspect, the method includes: the network device uses the identification field and / or the sequence number field to track the replied loopback request and / or the loopback request that needs to be retransmitted.

[0076] In an implementation manner of the third aspect, the header of the layer of the network model is a header of layer 3 of the network model, and the message includes the loopback request information in the header of the layer of the network model.

[0077] In an implementation manner of the third aspect, the loopback request information is or includes an indication about a loopback request.

[0078] In an implementation manner of the third aspect, the header of the layer of the network model is a header of layer 5 of the network model, and the message includes the loopback request information in the header of the layer of the network model.

[0079] In an implementation manner of the third aspect, the loopback request information is a type-length-value field (TLV field) or resides in a TLV field.

[0080] In an implementation manner of the third aspect, the method includes: the network device obtaining information from the payload of the loopback reply message.

[0081] The method according to the third aspect of the present invention can be used in or by a server, a network interface card (NIC), a switch (network switch), a router, etc. The method according to the third aspect can be used to enhance various network protocols including segment routing (SR), in-band network telemetry, etc.

[0082] In order to implement the method according to the third aspect of the present invention, part or all of the implementation modes and optional features of the third aspect may be combined with each other.

[0083] A fourth aspect of the present invention provides a method, wherein the method includes: a network device receives a message from another network device according to a network protocol, and in response to the received message including loopback request information in a header of a layer of a network model, the network device transmits a loopback reply message to the other network device. The loopback reply message includes at least a portion of the received message in a payload, and the at least a portion includes at least one header of the received message.

[0084] The above description of the network device according to the second aspect is correspondingly valid for the method according to the fourth aspect. The network device executing the method according to the fourth aspect may be the network device according to the second aspect of the present invention. Another network device may be the network device according to the first aspect of the present invention.

[0085] The method according to the fourth aspect and its implementation and optional features achieve the same advantages as the network device according to the first aspect and its corresponding implementation and optional features and the network device according to the second aspect and its corresponding implementation and optional features.

[0086] In an implementation of the fourth aspect, the loopback reply message includes the entire received message or a portion of the received message in the payload, and the portion includes the at least one header of the received message.

[0087] In an implementation manner of the fourth aspect, the loopback reply message includes, in the payload, a header of layer 3 of the network model of the received message as the at least one header of the received message.

[0088] In an implementation of the fourth aspect, when the received message includes the loopback request information in a header of an intermediate layer between layer 3 and layer 4 of the network model, the loopback reply message includes the header of the intermediate layer of the received message in the payload as the at least one header of the received message and / or includes the payload of the intermediate layer of the received message.

[0089] In an implementation of the fourth aspect, when the received message includes the loopback request information in the header of layer 3 of the network model, the loopback reply message includes the payload of layer 4 of the network model of the received message in the payload.

[0090] In an implementation of the fourth aspect, when the received message includes the loopback request information in a header of layer 5 of the network model, the loopback reply message includes the header of layer 5 of the network model of the received message in the payload as the at least one header of the received message.

[0091] In an implementation manner of the fourth aspect, the loopback reply message includes a loopback reply indication in a header of an intermediate layer between layer 3 and layer 4 of the network model.

[0092] In an implementation of the fourth aspect, when the header of the third layer of the network model of the received message includes one or more extension fields, the method includes: the network device skips at least one of the one or more extension fields when parsing the received message.

[0093] The method according to the fourth aspect of the present invention can be used in or by a server, a network interface card (NIC), a switch (network switch), a router, etc. The method according to the fourth aspect can be used to enhance various network protocols including segment routing (SR), in-band network telemetry, etc.

[0094] In order to implement the method according to the fourth aspect of the present invention, part or all of the implementation modes and optional features of the fourth aspect mentioned above may be combined with each other.

[0095] It should be noted that all devices, elements, units and devices described in this application can be implemented in software or hardware elements or any type of combination thereof. All steps performed by various entities described in this application and the functions to be performed by various entities described are intended to refer to the corresponding entities for performing the corresponding steps and functions. Although in the description of the following specific embodiments, the specific functions or steps to be performed by the external entity are not reflected in the description of the specific detailed elements of the entity performing the specific steps or functions, it should be clear to the technician that these methods and functions can be implemented by corresponding hardware or software elements or any combination thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0096] In conjunction with the accompanying drawings, the following description of specific embodiments will illustrate the above aspects and their implementation methods. In the drawings:

[0097] Figure 1 Two examples of network devices according to embodiments of the present invention are shown;

[0098] Figure 2 and Figure 3 Examples of methods according to embodiments of the present invention are respectively shown;

[0099] Figures 4 to 6 Examples of a message and a loopback reply message according to an embodiment of the present invention are respectively shown;

[0100] Figure 7 An example of the format of a message and a loopback reply message according to an embodiment of the present invention is shown.

[0101] In the figures, corresponding elements are marked with the same reference numerals. DETAILED DESCRIPTION

[0102] Figure 1 Two examples of network devices according to embodiments of the present invention are shown. Figure 1 The network device 1a on the left side of (A) and (B) in FIG. 1 is an example of a network device according to the first aspect of the present invention. The description of the network device according to the first aspect of the present invention is for Figure 1 The left-hand network device 1a is correspondingly effective. Figure 1 The network device 1b on the right side of (A) and (B) in FIG. 1 is an example of a network device according to the second aspect of the present invention. The description of the network device according to the second aspect of the present invention is for Figure 1 The right-hand network device 1b is correspondingly effective.

[0103] like Figure 1 As shown in (A), the network device 1a (which may be referred to as the first network device) is used to transmit a message 2 to another network device 1b (which may be referred to as the second network device) according to a network protocol, and receive a loopback reply message 3, wherein the loopback reply message 3 includes at least a portion of the message 2 in the payload, and the at least a portion includes at least one header of the message 2. The message 2 includes loopback request information in the header of the layer of the network model. The loopback request information requests the other network device 1b to transmit the loopback reply message 3 to the network device 1a.

[0104] The second network device 1b is used to receive a message 2 from the first network device 1a (i.e., from another network device) according to the network protocol, and in response to the received message 2 including loopback request information in the header of the layer of the network model, transmit a loopback reply message 3 to the first network device 1a. The loopback reply message includes at least a portion of the received message 2 in the payload, and the at least a portion includes at least one header of the received message 2.

[0105] The network protocol may be an Internet protocol (IP). For example, the network protocol may be IPv4 or IPv6. In the case of transmitting message 2, the first network device 1a may be referred to as a source or source network device. In the case of transmitting message 2, the second network device 1b may be referred to as a destination or destination network device. The first network device 1a and the second network device 1b may be referred to as network nodes.

[0106] The first network device 1a and the second network device 1b may be implemented by software and / or hardware. The first network device 1a and / or the second network device 1b may include a device for communication. The device for communication may include one or more antennas.

[0107] The first network device 1a may include a processor or processing circuit (not shown) for executing, performing or starting various operations of the first network device 1a described herein. The processing circuit may include hardware and / or the processing circuit may be controlled by software. The hardware may include analog circuits or digital circuits, or both. The digital circuit may include components such as an application-specific integrated circuit (ASIC), a field-programmable array (FPGA), a digital signal processor (DSP) or a multi-purpose processor. The first network device 1a may also include a memory circuit that stores one or more instructions that can be executed by a processor or processing circuit, especially under software control. For example, the memory circuit may include a non-transitory storage medium storing executable software code, which, when executed by a processor or processing circuit, enables the execution of various operations of the first network device 1a. In one embodiment, the processing circuit includes one or more processors and a non-transitory memory connected to the one or more processors. The non-transitory memory may carry an executable program code, which, when executed by one or more processors, enables the first network device 1a to execute, perform or start the operations or methods described herein.

[0108] The second network device 1b may include a processor or processing circuit (not shown) for executing, performing or starting various operations of the second network device 1b described herein. The processing circuit may include hardware and / or the processing circuit may be controlled by software. The hardware may include analog circuits or digital circuits, or both. The digital circuit may include components such as an application-specific integrated circuit (ASIC), a field-programmable array (FPGA), a digital signal processor (DSP) or a multi-purpose processor. The second network device 1b may also include a memory circuit that stores one or more instructions that can be executed by a processor or processing circuit, especially under software control. For example, the memory circuit may include a non-transitory storage medium that stores executable software code, which, when executed by a processor or processing circuit, enables the execution of various operations of the second network device 1b. In one embodiment, the processing circuit includes one or more processors and a non-transitory memory connected to the one or more processors. The non-transitory memory may carry an executable program code, which, when executed by one or more processors, enables the second network device 1b to execute, perform or start the operations or methods described herein.

[0109] like Figure 1 As exemplarily shown in (B), the first network device 1a can be used to transmit a message 2 to the second network device 1b through one or more intermediate network devices R0, R1, R2, R3, R4 and R5 according to a network protocol. Figure 1The number of intermediate network devices between the two network devices 1a and 1b shown in (B) is for example only and may be different. The path from the first network device 1a to the second network device 1b for transmitting the message 2 is for example only and may be different. One or more intermediate network devices R0, R1, R2, R3, R4 and R5 may be one or more routers. Accordingly, the second network device 1b may be used to receive the message 2 from the first network device 1a through one or more intermediate network devices R0, R1, R2, R3, R4 and R5 according to the network protocol. The second network device 1b may be used to: in response to the received message 2 including loopback request information in the header of the layer of the network model, transmit the loopback reply message 3 to the first network device 1a through one or more intermediate network devices R0, R1, R2, R3, R4 and R5. The path from the second network device 1b to the first network device 1b for transmitting the loopback reply message 3 is for example only and may be different. The two network devices 1a and 1b and the one or more intermediate network devices R0 , R1 , R2 , R3 , R4 and R5 may be network nodes of the network.

[0110] Figure 2 and Figure 3 Examples of methods according to embodiments of the present invention are respectively shown. Figure 2 The method is an example of the method according to the third aspect of the present invention. The description of the method according to the third aspect of the present invention is for Figure 2 The method is accordingly effective. Figure 3 The method is an example of the method according to the fourth aspect of the present invention. The description of the method according to the fourth aspect of the present invention is for Figure 3 The method is accordingly effective. Figure 1 The network device 1a and / or the network device 1b may be used to perform Figure 2 methods and / or Figure 3 method.

[0111] Figure 2 The method comprises: in a first step 21, (the network device) transmits a message to another network device according to a network protocol. The method comprises: in a second step 22 after the first step 21, (the network device) receives a loopback reply message, the loopback reply message includes at least a part of the message in the payload, and the at least a part includes at least one header of the message. The message includes loopback request information in a header of a layer of the network model. The loopback request information requests another network device to transmit a loopback reply message to the network device.

[0112] Figure 3The method comprises: in a first step 31, (the network device) receives a message from another network device according to a network protocol. The method comprises: in a second step 32 after the first step 31, in response to a received message including loopback request information in a header of a layer of a network model, (the network device) transmits a loopback reply message to another network device. The loopback reply message includes at least a portion of the received message in a payload, the at least a portion including at least one header of the received message.

[0113] Figures 4 to 6 Examples of a message and a loopback reply message according to an embodiment of the present invention are respectively shown. Figures 4 to 6 Examples of the contents of a message and a loopback reply message are shown respectively. Figures 4 to 6 The message can be Figure 1 An example of a message. Figures 4 to 6 The loopback reply message can be Figure 1 In the following description, refer to Figure 1 A first network device 1a and a second network device 1b. Figures 4 to 6 The description is mainly for the case where the network protocol is IPv6. This is only an example and does not limit the present invention. Therefore, Figures 4 to 6 The description is correspondingly valid in the case of other network protocols such as IPv4.

[0114] According to an example, the first network device 1a may transmit the message 2 to the second network device 1b in the form of a loopback request message according to the network protocol (i.e., through the network protocol). The first network device 1a may generate the message 2. Optionally, the transmission of the message 2 may be performed through one or more intermediate network devices, such as Figure 1 As shown in (B) in FIG. 1 , the first network device 1a may be called a source, a transmitter or a sender. The second network device 1b may be called a responder.

[0115] Message 2 may not include an extension field, or may include one or more extension fields. The loopback request information of message 2 may reside after one or more optional extension fields. For example, the loopback request information may be a message type of ICMPv6, or the loopback request information may be implemented as a STAMP session transmitter test message, which has an optional TLV for requesting a loopback. One or more optional intermediate network devices (e.g., one or more routers) may update one or more optional extension fields. The update performed by the corresponding intermediate network device may include information about the state and / or performance (e.g., one or more timestamps or one or more counters) of the corresponding intermediate network device. In addition or alternatively, the update performed by the corresponding intermediate network device may include information about the identification of the corresponding intermediate network device and / or information about the routing decision of the corresponding intermediate network device.

[0116] The second network device 1b may receive a message 2 including loopback request information. The second network device 1b may detect the loopback request information of the received message 2. That is, the second network device 1b may detect or determine that the received message 2 is or includes a loopback request. The second network device 1b may skip one or more of the optional one or more extension fields of the received message 2 or optionally all of the extension fields during its parsing process (when the second network device 1b parses the received message 2).

[0117] The second network device 1b does not need to be familiar with (or does not need to know) the structure of the optional one or more extension fields of the received message 2. The second network device 1b can generate a loopback reply message 3, and the loopback reply message 3 includes at least a portion of the received message 2 in the payload, and the at least a portion includes at least one header of the received message 2. In other words, the loopback reply message 3 can include the received message 2 (i.e., the loopback request message) or a truncated portion of the received message 2 in the payload. The second network device 1b can transmit the loopback reply message 3 to the first network device 1a (because the received message 2 includes loopback request information in the header of the layer of the network model).

[0118] The first network device 1a may receive the loopback reply message 3 from the second network device 1b. The first network device 1a may retrieve / obtain information from the optional one or more extension fields of the loopback request message 3 residing in the payload of the loopback reply message 3 and use the information.

[0119] Figure 4 An example of the message 2 and the loopback reply message 3 described above according to the example in which the first network device 1a uses the message 2 to request the loopback reply message 3 from the second network device 1b is shown.

[0120] like Figure 4 As shown, message 2 may include one or more optional extension fields in the header of layer 3 of the network model. In other words, the header of layer 3 of the network model of message 2 may include an IP header (e.g., an IPv6 header) and optionally one or more extension fields (e.g., one or more IPv6 extension headers).

[0121] One or more extension fields of message 2 may be updated by one or more intermediate network devices, which may be present in a flow from a first network device 1a as a source to a second network device 1b as a destination. The update of one or more optional extension fields in the header of layer 3 by one or more intermediate network devices may include information about at least one of the following: the status and / or performance of the corresponding intermediate device (e.g., a timestamp or a counter), the identification of the corresponding intermediate network device, and the routing decision of the corresponding intermediate network device. In addition, as Figure 4 As shown, the header of the layer of the network model may be an intermediate layer L between the third layer and the fourth layer of the network model. intm The header of message 2 includes loopback request information in the header of the layer of the network model. For example, the middle layer L intm It can be ICMPv6, so the middle layer L intm The header of the packet may be an ICMPv6 header including loopback request information. Message 2 may include an intermediate layer L intm For example, message 2 may include ICMPv6 data (eg, ICMPv6 payload), such as Figure 4 shown.

[0122] like Figure 4 As shown, the loopback reply message 3 may include one or more optional extension fields in the header of the layer 3 of the network model. In other words, the header of the layer 3 of the network model of the loopback reply message 3 may include an IP header (e.g., an IPv6 header) and one or more optional extension fields (e.g., one or more IPv6 extension headers). Figure 4 As shown, the loopback reply message 3 can be in the middle layer L between the third layer and the fourth layer of the network model. intm The header of the packet includes a loopback reply indication. intm It can be ICMPv6, so the middle layer L of loopback reply message 3 intm The header may be an ICMPv6 header including a loopback reply indication.

[0123] like Figure 4 As shown, the loopback reply message 3 may include the entire received message 2 in the payload. For example, the loopback reply message 3 may include in the payload: a header of layer 3 of the network model of message 2, including an IP header (e.g., an IPv6 header) and optionally one or more extension fields (e.g., one or more IPv6 extension headers); a header of the middle layer L of the network model of the received message 2; intm header (e.g., ICMPv6 header), including loopback request information; the intermediate layer L of the received message 2 intmAlternatively, the loopback reply message 3 may include only a portion of the received message 2, the portion including the middle layer L of the network model of the received message 2. intm header (for example, an ICMPv6 header) as at least one header of the received message 2.

[0124] In the above example where the first network device 1a uses message 2 to request a loopback reply message 3 from the second network device 1b, the first network device 1a may optionally add an identification field and / or a sequence number field (e.g., an identification field and / or a sequence number field in ICMPv6) to message 2 (i.e., the loopback request message). The second network device 1b may copy the field or fields to the loopback reply message 3, i.e., to the payload of the loopback reply message 3.

[0125] Optionally, the first network device 1a can assign different identification fields to each flow. For example, a flow can be defined as a pair of sources and destinations of communication (e.g., a {source address, destination address} pair), that is, a pair of source network devices (e.g., the first network device 1a) and a destination network device (e.g., the second network device 1b). To this end, the addresses of the source and destination can be used, optionally. For example, a flow can be defined as a tuple of source, destination, and segment routing (SR) policy (e.g., a {source address, destination address, SR policy} tuple). To this end, the addresses of the source and destination and the SR policy can be used. The SR policy can explicitly define the path from the source to the destination and route through the path using a segment routing header (SRH). The path can pass through one or more intermediate network devices (e.g., routers).

[0126] The first network device 1a may be configured to use the identification field and / or the sequence number field to track the replied loopback requests and / or the loopback requests that need to be retransmitted.

[0127] According to another example, in addition to or alternatively to the above example, the first network device 1a can piggyback the loopback request information onto the message 2, which is a data packet. In other words, the message 2 can be a data packet, and the first network device 1a can piggyback the loopback request information onto the data packet. The first network device 1a can piggyback the loopback request information onto the message 2 (data packet) using an indication in the header of the data packet. Therefore, the header of the layer of the network model can be the header of layer 3 of the network model, and the message 2 includes the loopback request information in the header of the layer of the network model.

[0128] The loopback request information (e.g., indication) may be in the IP header. In addition or alternatively, the loopback request information may be in at least one of the optional one or more extension fields of the layer 3 header, or may be at least one of the optional one or more extension fields of the layer 3 header. For example, the loopback request information of message 2 may be or may include a reserved value (or a series of values) in a differentiated services code point (DSCP) field, which indicates that message 2 is affected by the loopback request (i.e., includes the loopback request). The loopback request information (e.g., indication) may be or may include a specific option in one of the one or more optional extension fields (e.g., IPv6 extension fields), etc., and the extension field indicates that the destination (i.e., the second network device 1b) responds to the loopback request of message 2 (by transmitting the loopback reply message 3).

[0129] The second network device 1b may forward the message 2 (data packet) to the application layer when detecting the loopback request information of the header of the layer 3 of the network model of the received message 2 (received from the first network device 1a). The second network device 1b may generate a loopback reply message 3, which may include the received data packet 2 (and its header) in the payload. Optionally, the second network device 1b may truncate the received data packet 2 to prevent the loopback reply message 3 from exceeding the maximum transfer unit (MTU) of the network. That is, the loopback reply message 3 includes at least a portion of the received message 2 in the payload, and the at least a portion includes at least one header of the received message 2. According to this other example, the loopback reply message includes the header of the layer 3 of the network model of the received message 2 in the payload as at least one header of the received message 2.

[0130] Figure 5 An example of the message 2 and the loopback reply message 3 described in accordance with the above another example in which the first network device 1a uses the message 2 to request the loopback reply message 3 from the second network device 1b is shown. Figure 4 The description can be Figure 5 Message 2 and loopback reply message 3 are correspondingly effective.

[0131] like Figure 5 As shown, message 2 may include one or more optional extension fields in the header of layer 3 of the network model. In other words, the header of layer 3 of the network model of message 2 may include an IP header (e.g., an IPv6 header) and optionally one or more extension fields (e.g., one or more IPv6 extension headers).

[0132] One or more extension fields of message 2 may be updated by one or more intermediate network devices, which may be present in a flow from a first network device 1a as a source to a second network device 1b as a destination. The updates of one or more optional extension fields in the header of layer 3 by one or more intermediate network devices may include information about at least one of the following: the status and / or performance of the corresponding intermediate device (e.g., a timestamp or a counter), the identification of the corresponding intermediate network device, and the routing decision of the corresponding intermediate network device. Figure 5 In an example, the header of the layer of the network model is the header of the layer 3 of the network model, and the packet 2 includes loopback request information in the header of the layer of the network model. The loopback request information may be in an IP header (e.g., an IPv6 header). In addition or alternatively, the loopback request information may be in at least one of the optional one or more extension fields of the layer 3 header (e.g., one or more IPv6 extension headers), or may be at least one of the optional one or more extension fields of the layer 3 header. Figure 5 As shown, message 2 may include a payload of a network protocol. For example, message 2 may include an IPv6 payload (eg, a TCP header and a payload).

[0133] like Figure 5 As shown, the loopback reply message 3 may include one or more optional extension fields in the header of the layer 3 of the network model. In other words, the header of the layer 3 of the network model of the loopback reply message 3 may include an IP header (e.g., an IPv6 header) and one or more optional extension fields (e.g., one or more IPv6 extension headers). Figure 5 As shown, the loopback reply message 3 can be in the middle layer L between the third layer and the fourth layer of the network model. intm The header of the packet includes a loopback reply indication. intm It can be ICMPv6, so the middle layer L of loopback reply message 3 intm The header may be an ICMPv6 header including a loopback reply indication.

[0134] like Figure 5As shown, the loopback reply message 3 may include the entire received message 2 in the payload. For example, the loopback reply message 3 may include in the payload: a header of layer 3 of the network model of message 2, including an IP header (e.g., an IPv6 header) and optionally one or more extension fields (e.g., one or more IPv6 extension headers); a payload of the network protocol of message 2, such as an IPv6 payload (e.g., a TCP header and a payload). Alternatively, the loopback reply message 3 may include only a portion of the received message 2, the portion including a header of layer 3 of the network model of message 2 as at least one header of the received message 2.

[0135] According to another example, in addition to the above example and / or the above another example and alternatively, the first network device 1a can transmit a message 2 including loopback request information in the header of the 5th layer of the network model. The loopback request information can be a type-length-value field (type-length-value field, TLV field) or reside in the TLV field. The header of the 5th layer can be a simple two-way active measurement protocol (STAMP) header. TLV can be a STAMP header extension. In other words, the first network device 1a can transmit a STAMP test message to the second network device 1b, and the STAMP test message can include "reflection TLV" or "loopback request TLV". The TLV can indicate a loopback request to the second network device 1b. In the forward direction (i.e., transmitting a message 2 from the first network device 1a to the second network device 1b), TLV (e.g., reflection TLV) can be used to indicate that the first network device 1a requests a loopback reply message 3 to the second network device 1b. In the reverse direction (ie, transmitting the loopback reply message 3 from the second network device 1b to the first network device 1a), a TLV (eg, a reflective TLV) may include the message 2 (or a truncated version thereof) received by the second network device 1b in the payload of the loopback reply message 3 .

[0136] Figure 6 An example of the message 2 and the loopback reply message 3 described in the above further example in which the first network device 1a uses the message 2 to request the loopback reply message 3 from the second network device 1b is shown. Figure 4 and Figure 5 The description can be Figure 6 Message 2 and loopback reply message 3 are correspondingly effective.

[0137] like Figure 6As shown, message 2 may include one or more optional extension fields in the header of layer 3 of the network model. In other words, the header of layer 3 of the network model of message 2 may include an IP header (e.g., an IPv6 header) and optionally one or more extension fields (e.g., one or more IPv6 extension headers).

[0138] One or more extension fields of message 2 may be updated by one or more intermediate network devices, which may be present in a flow from a first network device 1a as a source to a second network device 1b as a destination. Updates to one or more optional extension fields in a layer 3 header by one or more intermediate network devices may include information about at least one of: the state and / or performance of the corresponding intermediate device (e.g., a timestamp or counter), an identification of the corresponding intermediate network device, and a routing decision of the corresponding intermediate network device. Message 2 may include a header of layer 4 of a network model (e.g., a user datagram protocol (UDP) header).

[0139] according to Figure 5 In the example of , the header of the layer of the network model is the header of the layer 5 of the network model, and the message 2 includes loopback request information in the header of the layer of the network model. The loopback request information can be a type-length-value field (type-length-value field, TLV field, such as a reflection TLV) or reside in a TLV field. The header of the layer 5 can be a simple two-way active measurement protocol (STAMP) header. The TLV can be a STAMP header extension. Figure 6 As shown, the loopback request information can be implemented as a STAMP session sender test message, which has an optional TLV for requesting a loopback.

[0140] Figure 5 The loopback reply message 3 may include one or more optional extension fields in the header of layer 3 of the network model. In other words, the header of layer 3 of the network model of the loopback reply message 3 may include an IP header (e.g., an IPv6 header) and optionally one or more extension fields (e.g., one or more IPv6 extension headers). The loopback reply message 3 may include a header of layer 4 of the network model (e.g., a user datagram protocol (UDP) header).

[0141] like Figure 6 As shown, the loopback reply message 3 can be implemented as a STAMP session reflector test message. Figure 6As shown, the loopback reply message 3 may include the entire received message 2 in the payload. For example, the loopback reply message 3 may include in the payload: a header of layer 3 of the network model of message 2, including an IP header (e.g., an IPv6 header) and optionally one or more extension fields (e.g., one or more IPv6 extension headers); a TLV field (e.g., a reflection TLV) of the received message 2 and optionally one or more higher-layer headers and a payload. Alternatively, the loopback reply message 3 may include in the payload only a portion of the received message 2, the portion including a header of layer 5 of the network model of the received message 2 as at least one header of the received message 2.

[0142] Figure 7 An example of the format of a message and a loopback reply message according to an embodiment of the present invention is shown. Figure 7 The message can be Figure 1 An example of a message. Figure 7 The loopback reply message can be Figure 1 An example of a loopback reply message.

[0143] Figure 7 The example corresponds to Figure 4 In other words, the header of the layer of the network model is the intermediate layer L between the 3rd and 4th layers of the network model. intm The header, Figure 7 The packet 2 includes loopback request information in the header of the layer of the network model. The loopback request information may be or may include the intermediate layer L intm The type field of the header ( Figure 7 The type field may be a type field of an ICMP header or an ICMPv6 header. intm The Code field of the header may be constant (e.g., zero) and unused. Figure 7 The "code" shown) can be the code field of the ICMP header or the ICMPv6 header.

[0144] according to Figure 7 , the loopback reply message 3 can be sent in the intermediate layer L between the third layer and the fourth layer of the network model. intm The loopback reply indication may be or may include the intermediate layer L of the loopback reply message 3. intm The type field of the header ( Figure 7 The type field may be a type field of an ICMP header or an ICMPv6 header. The middle layer L of the loopback reply message 3 intmThe Code field of the header may be constant (e.g., zero) and unused. Figure 7 The "code" shown) can be a code field of an ICMP header or an ICMPv6 header. The payload of the loopback reply message 3 may include the received message 2 (i.e., the loopback request message) or a portion of the received message 2, which portion includes at least the header of layer 3 of the network model of the received message 2. That is, the payload of the loopback reply message 3 may include at least the IP header of the received message 2 (e.g., an IPv6 header) and optionally one or more extension fields (e.g., one or more IPv6 extension headers).

[0145] Identifier of loopback reply message 3 ( Figure 7 The "identifier" shown) and the serial number ( Figure 7 The "sequence number" shown) can be copied from message 2 (i.e., the loopback request message).

[0146] In the description of the accompanying drawings, each layer of the network model (for example, the third layer, the intermediate layer L between the third layer and the fourth layer) intm , Layer 4 and Layer 5) may be layers of a TCP / IP five-layer network model. In the accompanying drawings, a header of Layer 2 of the network model (eg, an Ethernet header) is not shown.

[0147] As shown above, the loopback request information can reside in one of the protocol headers (i.e., the header of a layer of the network model) or in an extension of one of the protocol headers. Figure 4 As shown, the header of the layer of the network model may be a header of an intermediate layer between the third layer and the fourth layer of the network model, and the message 2 includes the loopback request information in the header of the layer of the network model. For example, the header of the intermediate layer may be an ICMP header or an ICMPv6 header. For example, the loopback request information may be represented by ( Figure 7 The type field is included in the ICMP header or ICMPv6 header. According to another example, Figure 5 As shown, the header of the layer of the network model may be the header of layer 3 of the network model, and message 2 includes loopback request information in the header of the layer of the network model. For example, the loopback request information may reside in an IP header (e.g., an IPv6 header or an IPv4 header) and / or reside in at least one extension field in one or more optional extension fields (e.g., one or more IPv6 extension headers or one or more IPv4 extension options). According to another example, as Figure 6As shown, the header of the layer of the network model can be the header of the 5th layer of the network model, and the message 2 includes the loopback request information in the header of the layer of the network model. For example, the loopback request information can be a type-length-value field (type-length-value field, TLV field) or reside in the TLV field. The header of the 5th layer can be a simple two-way active measurement protocol (STAMP) header. The TLV can be a STAMP header extension.

[0148] The invention has been described in conjunction with various embodiments as examples and implementations. However, from a study of the drawings, the invention and the independent claims, other variations will be understood and implemented by a person skilled in the art in implementing the claimed subject matter. In the claims and in the specification, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" does not exclude a plurality. A single element or other unit may fulfil the functions of several entities or items described in the claims. The fact that certain measures are recited in mutually different dependent claims does not in itself mean that a combination of these measures cannot be used in an advantageous implementation.

Claims

1. A network device (1a), characterized in that: The network device (1a) is used to transmit a message (2) to another network device (1b) according to a network protocol, and receive a loopback reply message (3), wherein the loopback reply message (3) includes at least a portion of the message (2) in a payload, and the at least a portion includes at least one header of the message (2); The message (2) includes loopback request information in a header of a layer of a network model; The loopback request information requests the other network device (1b) to transmit the loopback reply message (3) to the network device (1a).

2. The network device (1a) according to claim 1, characterized in that The message (2) includes one or more extension fields in the header of layer 3 L3 of the network model.

3. The network device (1a) according to claim 1 or 2, characterized in that: The header of the layer of the network model is an intermediate layer L between the third layer L3 and the fourth layer L4 of the network model. intm The message (2) includes the loopback request information in the header of the layer of the network model.

4. The network device (1a) according to claim 3, characterized in that The loopback request information is or includes the intermediate layer L intm One or more values ​​of a type field of the header, the one or more values ​​indicating a loopback request.

5. The network device (1a) according to claim 3 or 4, characterized in that: The network device (1a) is used to connect the intermediate layer L intm An identification field and / or a sequence number field is added to the header.

6. The network device (1a) according to claim 5, characterized in that The network device (1a) is used for allocating a different identification field to each flow.

7. The network device (1a) according to claim 5 or 6, characterized in that: The network device (1a) is used for tracking replied loopback requests and / or loopback requests requiring retransmission using the identification field and / or the sequence number field.

8. The network device (1a) according to claim 1 or 2, characterized in that: The header of the layer of the network model is a header of layer 3 L3 of the network model, and the message (2) includes the loopback request information in the header of the layer of the network model.

9. The network device (1a) according to claim 8, characterized in that The loopback request information is or includes an indication of a loopback request.

10. The network device (1a) according to claim 1 or 2, characterized in that: The header of the layer of the network model is a header of the fifth layer L5 of the network model, and the message (2) includes the loopback request information in the header of the layer of the network model.

11. The network device (1a) according to claim 10, characterized in that The loopback request information is a type-length-value (TLV) field or resides in a TLV field.

12. The network device (1a) according to any one of the preceding claims, characterized in that The network device (1a) is used to obtain information from the effective load of the loopback reply message (3).

13. A network device (1b), characterized in that: The network device (1b) is used to receive a message (2) from another network device (1a) according to a network protocol, and in response to the received message (2) including loopback request information in a header of a layer of a network model, transmit a loopback reply message (3) to the other network device (1a); The loopback reply message (3) includes at least a portion of the received message (2) in a payload, the at least a portion including at least one header of the received message (2).

14. The network device (1b) according to claim 13, characterized in that The loopback reply message (3) includes in the payload the entire received message (2) or a portion of the received message (2), the portion including the at least one header of the received message (2).

15. The network device (1b) according to claim 13 or 14, characterized in that: The loopback reply message (3) includes, in the payload, a header of layer 3 L3 of the network model of the received message (2) as the at least one header of the received message (2).

16. The network device (1b) according to any one of claims 13 to 15, characterized in that: The received message (2) is in the intermediate layer L between the third layer L3 and the fourth layer L4 of the network model. intm In the case where the loopback request information is included in the header of the loopback reply message (3), the loopback reply message (3) includes the intermediate layer L of the received message (2) in the payload. intm as the at least one header of the received message (2) and / or the intermediate layer L including the received message (2) intm of the payload.

17. The network device (1b) according to any one of claims 13 to 15, characterized in that: When the received message (2) includes the loopback request information in the header of layer 3 L3 of the network model, the loopback reply message (3) includes the payload of layer 4 L4 of the network model of the received message (2) in the payload.

18. The network device (1b) according to any one of claims 13 to 15, characterized in that: In the case where the received message (2) includes the loopback request information in the header of layer 5 L5 of the network model, the loopback reply message (3) includes the header of layer 5 L5 of the network model of the received message (2) in the payload as the at least one header of the received message (2).

19. The network device (1b) according to any one of claims 13 to 18, characterized in that: The loopback reply message (3) is located at the intermediate layer L3 between the third layer L3 and the fourth layer L4 of the network model. intm The header of the packet includes a loopback reply indication.

20. The network device (1b) according to any one of claims 13 to 19, characterized in that: When the header of layer 3 L3 of the network model of the received message (2) includes one or more extension fields, the network device (1b) can be used to skip at least one of the one or more extension fields when parsing the received message (2).

21. A method, characterized in that The method comprises: a network device transmitting (21) a message to another network device according to a network protocol, and the network device receiving (22) a loopback reply message, the loopback reply message including at least a portion of the message in a payload, the at least a portion including at least one header of the message; The message includes loopback request information in a header of a layer of a network model; The loopback request information requests the other network device to transmit the loopback reply message to the network device.

22. A method, characterized in that The method comprises: a network device receiving (31) a message from another network device according to a network protocol, and in response to the received message including loopback request information in a header of a layer of a network model, the network device transmitting (32) a loopback reply message to the other network device; The loopback reply message includes at least a portion of the received message in a payload, and the at least a portion includes at least one header of the received message.

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