CN114050994A - SRv 6-based network telemetry method - Google Patents

SRv 6-based network telemetry method Download PDF

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CN114050994A
CN114050994A CN202111333786.5A CN202111333786A CN114050994A CN 114050994 A CN114050994 A CN 114050994A CN 202111333786 A CN202111333786 A CN 202111333786A CN 114050994 A CN114050994 A CN 114050994A
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measurement
node
sid
network
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CN114050994B (en
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程光
赵玉宇
顾周超
吴桦
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Southeast University
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/12—Shortest path evaluation
    • H04L45/123—Evaluation of link metrics
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L43/00—Arrangements for monitoring or testing data switching networks
    • H04L43/08—Monitoring or testing based on specific metrics, e.g. QoS, energy consumption or environmental parameters
    • H04L43/0823—Errors, e.g. transmission errors
    • H04L43/0829—Packet loss
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L43/00—Arrangements for monitoring or testing data switching networks
    • H04L43/08—Monitoring or testing based on specific metrics, e.g. QoS, energy consumption or environmental parameters
    • H04L43/0852—Delays
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L43/00—Arrangements for monitoring or testing data switching networks
    • H04L43/08—Monitoring or testing based on specific metrics, e.g. QoS, energy consumption or environmental parameters
    • H04L43/0876—Network utilisation, e.g. volume of load or congestion level
    • H04L43/0888—Throughput
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L43/00—Arrangements for monitoring or testing data switching networks
    • H04L43/08—Monitoring or testing based on specific metrics, e.g. QoS, energy consumption or environmental parameters
    • H04L43/0876—Network utilisation, e.g. volume of load or congestion level
    • H04L43/0894—Packet rate
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L43/00—Arrangements for monitoring or testing data switching networks
    • H04L43/10—Active monitoring, e.g. heartbeat, ping or trace-route
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L43/00—Arrangements for monitoring or testing data switching networks
    • H04L43/10—Active monitoring, e.g. heartbeat, ping or trace-route
    • H04L43/106—Active monitoring, e.g. heartbeat, ping or trace-route using time related information in packets, e.g. by adding timestamps
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/12—Shortest path evaluation
    • H04L45/124—Shortest path evaluation using a combination of metrics
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/34—Source routing
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

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  • General Health & Medical Sciences (AREA)
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Abstract

The invention discloses a network telemetering method based on SRv6, which comprises the steps of adding traditional in-band network telemetering INT to SRv6, collecting and storing real-time information of each node and each link in a network view, and carrying out network telemetering, wherein the measurement comprises point telemetering, throughput rate packet loss rate in flow telemetering, average time delay in path telemetering, available bandwidth and the like. The present invention divides the SID in SRH into three parts: SID header, SID data part, SID tail, and the format of SID will vary accordingly according to different measures. In addition, the feasibility of the method is verified through cases such as congestion control and time delay measurement.

Description

SRv 6-based network telemetry method
Technical Field
The invention belongs to the field of crossing of network security and network measurement, and particularly relates to a method for enabling SRv6 to carry out in-band network remote control.
Background
Segment Routing (SR) is a source Routing technology, a network architecture facing path connection is formed based on an SDN concept, the multilevel programmable requirement of a future network is supported, and the connection requirement under the application scene of 5G super-large connection and slicing can be met. SR-MPLS is an SR solution formed based on the current mainstream MPLS forwarding plane; SRv6 is an extended SR solution based on IPv 6. SR-MPLS follows MPLS forwarding mechanisms, evolves naturally, and has found widespread application in transport networks. SRv6 further enhances network programmability, supports network and service programmability. With the advent of new technologies such as SRV6 and the ever-increasing size of users, networks have been characterized as "high-rate, large-scale, multi-access, unpredictable". Traditional network management and control methods and means have been difficult to solve the challenges of existing networks and future networks. Therefore, a network manager needs to subvert the conventional network monitoring and troubleshooting method, and provides a real-time flexible measurement solution capable of dealing with scene use cases such as network state measurement, network failure detection, fault location and recovery, for example, an in-band network telemetry scheme based on SRV 6.
In-band network telemetry is a framework for the network data plane to collect and report network status without intervention by the network control plane. In an in-band network Telemetry architecture, a switching device forwards and processes data packets carrying Telemetry instructions (telemetering instructions). These telemetry commands tell network devices with network telemetry capabilities what network state information should be collected and written to as the telemetry data packets pass through the device.
In summary, the present invention uses SRv6source routing technology and makes it possible to support in-band network telemetry through SID modification.
Disclosure of Invention
Aiming at the problems, the invention provides a network telemetry method based on SRv6, which dynamically acquires real-time information of current resource views of equipment such as a switch and the like, wherein the real-time information comprises point telemetry, throughput rate packet loss rate in stream telemetry, average time delay in path telemetry, available bandwidth and the like. And the information is uniformly stored in the monitoring server cluster for analysis and processing, and corresponding service is provided for the user. The core problem of this invention is how to modify the SID so that it supports in-band network measurements.
In order to realize the purpose of the invention, the technical scheme of the invention is as follows: an SRv 6-based in-band network telemetry method is characterized in that effective information such as network links, nodes and the like of loads, hop counts and the like is obtained by using SRv6 relevant fields, and network interest network measures of users are calculated on a SRv6 supporting platform according to the information. The method comprises the following steps:
(1) the user determines the dimension of the measurement and informs the user interface, the user interface sends the dimension to the SRV6source router, and the router sets the protocol bit in the SID according to the dimension (the format of the SID is different if the protocol bit is different);
(2) the datagram is transmitted in the network, when arriving the router which supports SRv6, obtain and process the telemetering data according to the requirement of the agreement; when the router does not support SRv6, the router directly forwards the datagram because the SRH cannot be processed;
(3) when the datagram reaches the SRV6 sink router, the monitoring server cluster extracts all telemetering data in the datagram, restores the datagram and delivers the datagram to a receiving end, and therefore transparency of a user is achieved;
(4) the SRV6 sink router may process the data obtained from the above steps and deliver the processed data to the user interface, and when the user interface receives a new datagram, it may determine the route for the datagram or flow according to the user's needs.
As an improvement of the invention, the specific method of the step (1) is as follows:
(1.1) the user determines the measurement of the network remote measurement, wherein the measurement comprises point remote measurement, the throughput rate packet loss rate in stream remote measurement, the average time delay and the available bandwidth of path remote measurement and the like;
(1.2) the user issues the measure task to the user interface;
(1.3) adding an SRH part to each arrived datagram by the user interface according to the task of the user, and setting a corresponding protocol bit, so that when a subsequent node receives the datagram, measurement information can be directly written according to the protocol bit;
(1.4) the user interface forwards the processed datagram to the next hop according to the SR.
By the method, the method is not limited to single measurement, the measurement defined by the user is realized, and higher controllability is achieved.
As an improvement of the invention, the design method for processing and writing the telemetering information by the node in the step (2) is as follows:
(2.1) SRv6, the network telemetry method uses key-value pair mode to store data, the primary key has two forms, one is node ID, and the other is link ID; when the primary key is the node ID, the node attribute column family comprises a timestamp of reaching the node, the node utilization rate and the like; when the primary key is a link identification serial number, the link attribute column family comprises a link utilization rate, a link bandwidth and the like;
(2.2) based on the understanding that the approximate value of the telemetry data is usually enough to satisfy most application programs, in order to reduce a certain overhead, when the node writes the key-value pair into the datagram, the approximate value is used instead of the precise value, and the key-value pair is subjected to huffman compression at the cost of a certain error, that is, the following processing is performed:
suppose the ID of the jth node is pjThe corresponding measured value is a character string sjThe original binary string sjThe 5 bits are divided into one group, which corresponds to 26 small-case English letters plus A-F from 0 to 31, and 5 characters are taken as an example for the purpose of more simply explaining the specific implementation of Huffman coding. Assume five characters a, B, C, D, E, and the frequency of occurrence, i.e., the weight, of each is 5,4,3,2, 1. Then in the first step, two minimum weights are taken as left and right subtrees to construct a new tree, i.e. 1, 2 are taken to construct a new tree, the node is 1+ 2-3,
the dotted line is the newly generated node, then the second step puts the newly generated node with weight value of 3 into the rest set, so the set becomes {5,4,3,3}, then according to the second step, takes the minimum two weight values to form a new tree, like a graph, and so on, finally generates a complete Huffman tree,
replacing the corresponding characters with the weights to obtain the corresponding codes of the characters as follows:
a- >11, B- >10, C- >00, D- >011, E- > 010. The encoding mode enables the encoding of characters with high occurrence frequency to be shorter, and the encoding of characters with low occurrence frequency to be longer, so that the compression effect of the binary string is realized.
As an improvement of the invention, the specific method of the step (3) is as follows:
(3.1) the monitoring server cluster firstly extracts the protocol field in the SID so as to judge the measurement task at this time;
(3.2) if the protocol field is 011, the measurement task is congestion control, the data stored in the SID is key value pair, the link ID and the link maximum utilization rate, the server cluster extracts the maximum utilization rate according to the format and stores the maximum utilization rate according to the format, and then a congestion solution is provided for the network according to a congestion control algorithm (such as HPCC, RED and the like);
(3.3) if the protocol field is 010, the measurement task is delay detection of path telemetry, data stored in the SID is a key value pair, a node ID and a timestamp reaching the node, a server cluster extracts the timestamps reaching each node according to a format and calculates the delay between a point and the delay between a sending end and a receiving end, and because a user does not care about the delay of any time point, during storage, in order to reduce excessive redundant overhead, only average delay, maximum delay and minimum delay are stored.
Through the steps, different measuring methods for different measures are defined, and corresponding measures are taken while the method is realized in order to save the same target of expenditure and improvement. Such as storing only average delay information.
As an improvement of the invention, the specific method of the step (4) is as follows:
(4.1) the datagram is transmitted according to the designated path, and each time one hop is passed, a timestamp is collected, link utilization is carried out, and an address is popped from the SID so as to continue transmission;
(4.2) after the datagram arrives at the monitoring server, the monitoring server stores the measurement information of the path, and calculates time delay, bandwidth and the like according to the method;
and (4.3) the monitoring server stores the measurement information of the path, and the monitoring server calculates a path state table according to the measurement information after multiple times of measurement, and can set selection metrics by a user for routing.
Through the steps, information of a plurality of nodes in the topological structure is collected, and compared with the traditional method, due to the controllability of Srv6 routing, specific information of specific nodes can be collected through the method and used for subsequent analysis and function implementation.
Compared with the prior art, the invention has the following advantages: according to the scheme, through a network telemetering method based on SRv6, traditional in-band network telemetering INT is added into SRv6, real-time information of each node and each link in a network view is collected and stored, and network telemetering is performed, wherein the measurement comprises point telemetering, throughput rate packet loss rate in stream telemetering, average time delay in path telemetering, available bandwidth and the like. When the method is realized, in order to save bit overhead, a Huffman coding mode is introduced, data is compressed and then transmitted on the premise of not influencing an experimental result, and a better effect of saving the bit overhead is achieved. Furthermore, due to the particularity of Srv6, the scheme can be used to measure specific information for a particular path, thereby gathering the necessary information for routing.
Drawings
FIG. 1 is a SRV6 network telemetry architecture;
FIG. 2 is a datagram format for transmission in a network;
FIG. 3 is a default SID format;
FIG. 4 is an average time delay SID of measurement path telemetry;
FIG. 5 is a SID measuring link utilization;
FIG. 6 is a graph of the available bandwidth SID for measurement path telemetry;
FIG. 7 is SID at routing;
FIG. 8 is a SID during stream telemetry;
FIG. 9 is a diagram illustrating a new tree constructed by using weights;
FIG. 10 is a diagram of a complete Huffman tree.
The specific implementation mode is as follows:
for the purposes of promoting an understanding and understanding of the invention, reference will now be made in detail to the present invention as illustrated in the accompanying drawings.
Example (b): referring to fig. 1-10, an SRv 6-based in-band network telemetry method obtains effective information such as network links, nodes and the like, such as loads, hop counts and the like, by using SRv6 relevant fields, and calculates user interest network metrics on a SRv 6-supported platform according to the information. The method comprises the following steps:
(1) the user determines the dimension of the measurement and informs the user interface, the user interface sends the dimension to the SRV6source router, and the router sets the protocol bit in the SID according to the dimension (the format of the SID is different if the protocol bit is different);
(2) the datagram is transmitted in the network, when arriving the router which supports SRv6, obtain and process the telemetering data according to the requirement of the agreement; when the router does not support SRv6, the router directly forwards the datagram because the SRH cannot be processed;
(3) when the datagram reaches the SRV6 sink router, the monitoring server cluster extracts all telemetering data in the datagram, restores the datagram and delivers the datagram to a receiving end, and therefore transparency of a user is achieved;
(4) the SRV6 sink router may process the data obtained from the above steps and deliver the processed data to the user interface, and when the user interface receives a new datagram, it may determine the route for the datagram or flow according to the user's needs.
The specific method of the step (1) is as follows:
(1.1) the user determines the measurement of the network remote measurement, wherein the measurement comprises point remote measurement, the throughput rate packet loss rate in stream remote measurement, the average time delay and the available bandwidth of path remote measurement and the like;
(1.2) the user issues the measure task to the user interface;
(1.3) adding an SRH part to each arrived datagram by the user interface according to the task of the user, and setting a corresponding protocol bit, so that when a subsequent node receives the datagram, measurement information can be directly written according to the protocol bit;
(1.4) the user interface forwards the processed datagram to the next hop according to the SR.
The design method for processing and writing the telemetry information into the nodes in the step (2) is as follows:
(2.1) SRv6, the network telemetry method uses key-value pair mode to store data, the primary key has two forms, one is node ID, and the other is link ID; when the primary key is the node ID, the node attribute column family comprises a timestamp of reaching the node, the node utilization rate and the like; when the primary key is a link identification serial number, the link attribute column family comprises a link utilization rate, a link bandwidth and the like;
(2.2) based on the understanding that the approximate value of the telemetry data is usually enough to satisfy most application programs, in order to reduce a certain overhead, when the node writes the key-value pair into the datagram, the approximate value is used instead of the precise value, and the key-value pair is subjected to huffman compression at the cost of a certain error, that is, the following processing is performed:
suppose the ID of the jth node is pjThe corresponding measured value is a character string sjThe original binary string sjThe 5 bits are divided into one group, which corresponds to 26 small-case English letters plus A-F from 0 to 31, and 5 characters are taken as an example for the purpose of more simply explaining the specific implementation of Huffman coding. Assume five characters a, B, C, D, E, and the frequency of occurrence, i.e., the weight, of each is 5,4,3,2, 1. Then, in the first step, two minimum weights are first taken as left and right subtrees to construct a new tree, that is, 1 and 2 are taken to construct a new tree, and the node is 1+2 to 3, as shown in fig. 9:
the dotted line is the newly generated node, then the newly generated node with weight value of 3 is placed into the remaining set in the second step, so the set becomes {5,4,3,3}, then according to the second step, the two smallest weight values are taken to form a new tree, as shown in the figure, and so on, and finally a complete huffman tree is generated, as shown in the following figure 10:
replacing the corresponding character with each weight value in fig. 10 to obtain the corresponding code of each character as follows: a- >11, B- >10, C- >00, D- >011, E- > 010. The encoding mode enables the encoding of characters with high occurrence frequency to be shorter, and the encoding of characters with low occurrence frequency to be longer, so that the compression effect of the binary string is realized.
The specific method of the step (3) is as follows:
(3.1) the monitoring server cluster firstly extracts the protocol field in the SID so as to judge the measurement task at this time;
(3.2) if the protocol field is 011, the measurement task is congestion control, the data stored in the SID is key value pair, the link ID and the link maximum utilization rate, the server cluster extracts the maximum utilization rate according to the format and stores the maximum utilization rate according to the format, and then a congestion solution is provided for the network according to a congestion control algorithm (such as HPCC, RED and the like);
(3.3) if the protocol field is 010, the measurement task is delay detection of path telemetry, data stored in the SID is a key value pair, a node ID and a timestamp reaching the node, a server cluster extracts the timestamps reaching each node according to a format and calculates the delay between a point and the delay between a sending end and a receiving end, and because a user does not care about the delay of any time point, during storage, in order to reduce excessive redundant overhead, only average delay, maximum delay and minimum delay are stored.
The specific method of the step (4) is as follows:
(4.1) the datagram is transmitted according to the designated path, and each time one hop is passed, a timestamp is collected, link utilization is carried out, and an address is popped from the SID so as to continue transmission;
(4.2) after the datagram arrives at the monitoring server, the monitoring server stores the measurement information of the path, and calculates time delay, bandwidth and the like according to the method;
and (4.3) the monitoring server stores the measurement information of the path, and the monitoring server calculates a path state table according to the measurement information after multiple times of measurement, and can set selection metrics by a user for routing.
The specific implementation mode is as follows:
as shown in fig. 1, is a schematic diagram of SRV6 network telemetry architecture.
The first router of the sending end is an SRV6source router and is mainly responsible for receiving query tasks from a user interface, adding SRH to the arriving datagram and setting a protocol field in the SID; the terminal router of the receiving end is an SRV6 sink router, the monitoring server cluster directly obtains the telemetering information of the time from the terminal router, and the datagram is restored, so that the transparency to the user is realized; some routers which do not support SRv6 exist in the network, so that the SRH extension header cannot be processed, and the direct forwarding datagram only has the ordinary IPv6 forwarding capability; the user interface provides an interface for a user, receives a telemetering task issued by the user and informs the SRV6source router.
To better illustrate the steps of the SRv 6-based network telemetry method, the format of datagrams transmitted in a visual network is first introduced. As shown in fig. 2, the datagram is made up of three parts. The first part is an IPv6 message header, and the middle part represents a special SRH SRv6 and is used for storing a SID list in a 128-bit IPv6 address format; the last part is a message load, and user information is transmitted.
To elaborate the SRv 6-based network telemetry method, the assignment of 128-bit SIDs during network telemetry is described next. As shown in the default SID format of FIG. 3, the SID is divided into three parts, a header, a trailer, and a data portion. In order to mark the beginning or the end of an SID, a specific 8-bit binary string 01111110 is used as the beginning and the end marks of the SID, in order to prevent the SID data part from having 01111110, the data part is scanned, if 5 continuous 1 s appear, a 0 is directly added, and the reverse operation is carried out on the receiving side, so that the transparent transmission is realized; the protocol part has 3 bits in total, and 8 functions are provided for a user, for example, 011 represents that the task of the measurement is congestion control; the SID data portion stores telemetry data for the node in the form of key-value pairs. At the time of storage, in the following order: a node ID of 4 bits; telemetry data compressed to less than 20 bits; and an end character. The main role of the padding bits is to pad the SID to 128 bits, thus achieving memory alignment; since there are multiple SIDs in one SRH, in order to facilitate the server cluster to directly intercept all SIDs, the EF flag bit is used to flag — when the SID is the last SID of the SRH, its EF is 1, and the EF bits of the rest SIDs are all 0.
The present invention will now be described with reference to specific examples and drawings. The invention comprises the following steps:
(1) the user determines the dimension of the measurement and informs the user interface, the user interface sends the dimension to the SRV6source router, the router sets the protocol bit in the SID according to the dimension, and the format of the SID is different if the protocol bit is different;
(2) the datagram is transmitted in the network, when arriving the router which supports SRv6, obtain and process the telemetering data according to the requirement of the agreement; when the router reaches the router which does not support SRv6, the router can directly forward the datagram because the SRH cannot be processed.
(3) When the datagram reaches the SRV6 sink router, the monitoring server cluster extracts all telemetering data in the datagram and restores the datagram for delivery to the receiving end so as to realize transparency to users.
(4) The SRV6 sink router may deliver the data measured in the previous step to the user interface after certain processing. When a new datagram is received by the user interface, a route can be determined for that datagram or flow according to the user's needs.
In order to specify the working steps of the Srv 6-based in-band network telemetry method, the following 5 use cases specifically describe different working modes of the method under different measurement degrees.
Specific example 1:
if the telemetry task is the average time delay in path telemetry, the protocol field is 010, and at this time, the workflow of the Srv 6-based in-band network telemetry method is as follows.
As shown in the SID for measuring network time delay in fig. 4, the data portion in the SID is the time stamp of when the datagram arrives at the node, and it is mandatory to reduce the overhead of the time stamp to 16 bits. This is because 32 bits are generally required if an exact time is to be expressed in 2. At this time, one SID can only store timestamps of 2 nodes, and this overhead is too large to be acceptable. In practical use cases, very accurate delay data may not be required. Conversely, excessive jitter and more abnormal values are of concern. Therefore, when storing the time stamp, the 32-bit time stamp data is compressed to 16 bits using the huffman coding method described above.
When the average time delay in path telemetry is measured by using the network telemetry method based on SRv6, the specific steps are as follows:
(1.1) the user issues the measurement task to a user interface, and the user interface sets a source router according to the measurement task, so that protocol bits in all SIDs are set to be 010;
(1.2) when the datagram j reaches the node i, acquiring an arrival time stamp and the node ID, compressing the 32-bit time stamp to 16 bits according to Huffman coding, and storing according to the format of the graph IV;
(1.3) when the datagram j reaches the sink router, the monitoring server cluster acquires all SIDs from the datagram j and extracts a data part. Because the data part comprises time stamps and node IDs of all the nodes, time delay between points and between a receiving end and a sending end can be calculated;
(1.4) when a plurality of datagrams arrive at the sink router, enough path delay samples exist in the monitoring server cluster, and the monitoring server can calculate according to the path delay samples to obtain the average time delay of the path telemetering.
Specific example 2:
if the telemetry task realizes congestion control based on SRv6 network telemetry, the protocol field is 011, and the working flow of the Srv 6-based in-band network telemetry method is as follows.
First, when SRv6 is used for congestion control, instead of proposing a new congestion control method, SRv6 is used to collect data needed by other congestion control methods, such as HPCC, RED, thereby reducing bit overhead. In order for SRv6 to support congestion control, only the highest utilization of the link needs to be maintained in the SID packet header, rather than the utilization per hop. As shown in fig. five, when performing congestion control, the protocol bit is defined as 011 as required, and the key value of the SID data portion is defined as (link ID, link maximum utilization rate), when performing congestion control using the network telemetry method based on SRv6, the specific steps are as follows:
(2.1) the user issues the measurement task to a user interface, and the user interface sets a source router according to the measurement task, so that protocol bits in all SIDs are set to be 011;
(2.2) when datagram j passes node i, the following calculation is performed within the packet:
Figure BDA0003349767700000091
wherein:
Figure BDA0003349767700000092
t represents base RTT, B represents link bandwidth, T, B is a constant, T represents time occupation of a new packet, byte is packet size, and qlen represents queue length when a data packet is listed.
The calculated link utilization U is written into the datagram in the format of fig. 5.
And (2.3) when the datagram j reaches the sink router, the monitoring server cluster acquires all SIDs from the datagram j and extracts a data part. As mentioned above, only the highest utilization rate of the link needs to be saved, so that the data in the server is updated only when the utilization rate of the new link is greater than the corresponding utilization rate in the current server cluster;
specific example 3:
if the telemetry task is based on SRv6 measurement path telemetry available bandwidth, the protocol field is 101, and at this time, the workflow of the Srv 6-based in-band network telemetry method is as follows.
First, when SRv6 is used to measure the available bandwidth of path telemetry, active measurement is adopted because the complexity of passive measurement is too high, the accuracy of passive measurement depends heavily on the performance of the packet capturer, and the passive measurement requires special authority and cooperation, which limits the effect of passive measurement to some extent. In this patent, a Packet Gap Model (PGM) is used, and the basic idea is to record the transmission time when the transmitting end transmits a datagram, and to calculate the transmission time interval and the reception time interval by analyzing the arrival time after the measured network with the capacity of C flows at the receiving end. The available bandwidth can be calculated according to the relation between the two. The method belongs to a direct detection method in active measurement, and can reduce the influence on the bandwidth caused by the conditions such as route change and the like to a certain extent. The method comprises the following specific steps:
(3.1) the user issues the measurement task to a user interface, and the user interface sets a source router according to the measurement task so as to set protocol bits in all SIDs to be 101;
(3.2) when datagram i passes through source router, use tijRepresenting the time when the datagram j arrives at the router i, the ID of the datagram is written in the SID of the datagram and the sending time t1iWhen the datagram i arrives at the sink router, the ID and arrival time t of the datagram are written in the SID of the datagram2i；
(3.3) the sending end continues to send the datagram, when the datagram j passes through the source router, the ID of the datagram and the sending time t are written in the SID of the datagram1jWhen the datagram j arrives at the sink router, the ID and arrival time t of the datagram are written in the SID of the datagram2j；
(3.4) calculating the sending time interval delta of the sending end according to the nth datagram when the nth datagram passes through the sink routerinAnd receiving end deltaoutThe acceptance time interval of (c):
Figure BDA0003349767700000101
Figure BDA0003349767700000102
(3.5) to this point, the available bandwidth A is calculated as:
Figure BDA0003349767700000111
specific example 4:
if the telemetry task performs path selection based on SRv6, the protocol field is 001, and the workflow of the in-band network telemetry method based on Srv6 is as follows.
(4.1) the user interface sets the SID protocol field in the arriving datagram to 00l and specifies the path for this datagram in the format of the following figure, which is put into the first SID as shown in fig. 7;
source address First hop address Second hop address Third hop address … Last hop address Destination address
(4.2) transmitting the datagram i according to a specified path, and collecting a timestamp and a link utilization rate according to the format of the graph 7 when one hop passes; popping an address from the SID after each hop so as to continue transmission;
and (4.3) in the transmission process, when each datagram i reaches one node, collecting or calculating according to the method to obtain information such as sending time, link utilization rate, time stamp and the like, and storing the information in the SID according to the format of the graph 7. During storage, if the condition of excessive overhead is met, the coding scheme is used for compression to reduce bit overhead.
(4.4) after the datagram i reaches the monitoring server, the monitoring server stores the measurement information of the path, and calculates time delay, bandwidth and the like according to the method;
(4.5) repeating (4.1) to (4.4), but in order to collect information for multiple links, the path assigned by the user interface to the arriving datagram is random each time. Information for all links is not collected in actual use for two reasons: 1. the feasible paths from the sending end to the receiving end are too many, which may include many redundant or redundant paths, and if each path is collected, the too large overhead is unacceptable. 2. In the actual path selection, a best path does not need to be found in all paths, and only a reachable path with relatively low cost needs to be found. So far, the information collected for many times can be gathered into different tables at the monitoring server, and the table model is as follows:
Figure BDA0003349767700000112
Figure BDA0003349767700000121
watch 1
Wherein, VijThe representative calculation results in the link metrics from node i to node j, which may be time delay, bandwidth, link utilization, and different metrics are stored in different tables.
And (4.5) the monitoring server shares the measurement information matrix to the user interface for routing. When certain data reports are accumulated, the user interface calculates according to the following formula on the basis of the measure matrix:
Figure BDA0003349767700000122
wherein, TimeijRepresenting the time delay, V, from node i to node jijRepresenting the link utilization from node i to node j. a and b are user-defined parameters which can be used for reflecting higher utilization rate or less time which is emphasized by a user, and different parameters are set according to actual use conditions. The user interface generates a routing table therefrom, as follows:
Figure BDA0003349767700000123
and the user interface selects the path with the minimum sigma cost as the optimal route according to the calculation result, and places the path into the SID for transmission.
Specific example 5:
if the packet loss rate and the throughput rate of the telemetry task are measured based on SRv6, the protocol field is 100, and at this time, the working flow of the Srv 6-based in-band network telemetry method is as follows.
Since the packet loss rate and throughput rate measurement methods are similar and the required overhead is small, the measurements can be performed together.
(5.1) the user interface sets the SID protocol field in the arriving datagram to be 100, which indicates that the measurement task is flow remote measurement, and the measurement to be measured is throughput rate and packet loss rate;
(5.2) the user interface writes information such as a sending address, a destination address, a datagram ID and the like into the SID for transmission according to the format of FIG. 8;
(5.3) the user interface does the same for the next 1000 messages. And the message selects a proper route to the destination address according to the route selection method in the step four, the monitoring server cluster replies a user interface after receiving the message, and the user interface calculates the packet loss rate and the throughput according to the number of the received replied datagrams and the consumed time.
Experiment 1: simulation environment simulation test
Purpose of the experiment:
test SRv6 accuracy of measurements taken while running in-band network telemetry
The experimental steps are as follows:
1. arranging an SRV6 simulation environment in the mininet;
2. performing point remote measurement, flow remote measurement, path remote measurement, and measurement of throughput rate, packet loss rate, average time delay and available bandwidth in a network according to the patent steps;
3. collecting and processing measured telemetry values
Experiment 2: SRv6 in-band telemetry contrast
Purpose of the experiment:
test SRv6 comparison of efficiency when running in-band network telemetry to when running INT alone
The experimental steps are as follows:
1. arranging an SRV6 simulation environment in the mininet;
2. performing point remote measurement, flow remote measurement and path remote measurement according to the patent steps, measuring throughput rate, packet loss rate, average time delay and available bandwidth in a network and using expenses;
3. arranging the same network topology in the mininet;
4. using point remote measurement, flow remote measurement, path remote measurement, measuring throughput rate, packet loss rate, average time delay and available bandwidth in a network and using cost;
5. the overhead and accuracy of the two measurement methods are compared.
It should be noted that the above-mentioned embodiments are only preferred embodiments of the present invention, and are not intended to limit the scope of the present invention, and all equivalent substitutions or substitutions made on the basis of the above-mentioned technical solutions belong to the scope of the present invention.

Claims (5)

1. An SRv 6-based in-band network telemetry method, the method comprising the steps of:
(1) the user determines the dimension of the measurement and informs the user interface, the user interface sends the dimension of the query to the SRV6source router, and the router sets the protocol bit in the SID according to the dimension of the query;
(2) the datagram is transmitted in the network, when arriving the router which supports SRv6, obtain and process the telemetering data according to the requirement of the agreement; when the router does not support SRv6, the router directly forwards the datagram because the SRH cannot be processed;
(3) when the datagram reaches the SRV6 sink router, the monitoring server cluster extracts all telemetering data in the datagram, restores the datagram and delivers the datagram to a receiving end, and therefore transparency of a user is achieved;
(4) the SRV6 sink router may process the data obtained from the above steps and deliver the processed data to the user interface, and when the user interface receives a new datagram, determine a route for the datagram or flow according to the user's needs.
2. SRv 6-based network telemetry method according to claim 1, wherein the specific method of step (1) is as follows:
(1.1) the user determines the measurement of the network remote measurement, wherein the measurement comprises point remote measurement, the throughput rate packet loss rate in stream remote measurement, the average time delay of path remote measurement and the available bandwidth;
(1.2) the user issues the measure task to the user interface;
(1.3) adding an SRH part to each arrived datagram by the user interface according to a task of a user, and setting a corresponding protocol bit, so that when a subsequent node receives the datagram, measurement information is directly written according to the protocol bit;
(1.4) the user interface forwards the processed datagram to the next hop according to the SR.
3. SRv 6-based network telemetry method according to claim 1, wherein the nodes in step (2) are designed to process and write telemetry information as follows:
(2.1) SRv6, the network telemetry method uses key-value pair mode to store data, the primary key has two forms, one is node ID, and the other is link ID; when the primary key is the node ID, the node attribute column family comprises a timestamp of reaching the node and the node utilization rate; when the primary key is a link identification serial number, the link attribute column family comprises a link utilization rate and a link bandwidth;
(2.2) based on the understanding that the approximate value of the telemetry data is usually enough to satisfy most application programs, when the node writes the key-value pair into the datagram, the approximate value is used instead of the precise value, and the key-value pair is subjected to Huffman compression at the cost of certain error, that is, the following processing is carried out:
suppose the ID of the jth node is pjThe corresponding measured value is a character string sjThe original binary string sjThe 5 bits are divided into groups, and the groups from 0 to 31 correspond to 26 lowercase English letters plus A-F respectively.
4. SRv 6-based network telemetry method according to claim 1, wherein the specific method of step (3) is as follows:
(3.1) the monitoring server cluster firstly extracts the protocol field in the SID so as to judge the measurement task at this time;
(3.2) if the protocol field is 011, the measurement task is congestion control, the data stored in the SID is key value pair, the link ID and the link maximum utilization rate, the server cluster extracts the maximum utilization rate according to the format and stores the maximum utilization rate according to the format, and then a congestion solution is provided for the network according to a congestion control algorithm;
(3.3) if the protocol field is 010, the measurement task is delay detection of path telemetry, data stored in the SID is a key value pair, a node ID and a timestamp reaching the node, a server cluster extracts the timestamps reaching each node according to a format and calculates the delay between a point and the delay between a sending end and a receiving end, and because a user does not care about the delay of any time point, during storage, in order to reduce excessive redundant overhead, only average delay, maximum delay and minimum delay are stored.
5. SRv 6-based network telemetry method according to claim 1, wherein the specific method of step (4) is as follows:
(4.1) the datagram is transmitted according to the designated path, and each time one hop is passed, a timestamp is collected, link utilization is carried out, and an address is popped from the SID so as to continue transmission;
(4.2) after the datagram arrives at the monitoring server, the monitoring server stores the measurement information of the path, and calculates the time delay and the bandwidth according to the method;
and (4.3) the monitoring server stores the measurement information of the path, the monitoring server calculates a path state table according to the measurement information after multiple times of measurement, and the user sets selection metrics for routing.
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