WO2012071851A1

WO2012071851A1 - Method and apparatus for adjusting bidirectional forwarding detection transmission interval according to network jitter

Info

Publication number: WO2012071851A1
Application number: PCT/CN2011/073771
Authority: WO
Inventors: 王士鹏; 王宝玉; 张冰; 李晋
Original assignee: 中兴通讯股份有限公司
Priority date: 2010-12-01
Filing date: 2011-05-06
Publication date: 2012-06-07
Also published as: CN102487338B; CN102487338A

Abstract

The present invention provides a method and apparatus for adjusting a Bidirectional Forwarding Detection (BFD) transmission interval according to network jitter, both of the method and the apparatus can measure a network jitter value X by transmitting messages between a BFD session source end and destination end; the BFD transmission interval is adjusted according to a negotiation interval value Y when the current BFD message is transmitted, a value of a detection time accumulator and the network jitter value X. The method and apparatus of the present invention overcome the shortcoming in the prior art that the packet transmission interval varies in a wide range randomly caused by inability to adjust the message transmission interval dynamically according to an actual network state when the BFD transmits the control messages, and solve the problem in the prior art that the actual packet transmission interval does not conform with actual environment configuration parameters. The method and apparatus of the present invention perform a range control of the packet transmission time interval according to the network jitter, and thus packet transmission time is controlled more accurately and the accuracy and applicability of the BFD detection are improved.

Description

Method and device for adjusting BFD transmission interval according to network control

The present invention relates to the field of communication technologies, and in particular, to a method and a device for adjusting a BFD (Bidirectional Forwarding Detection) transmission interval according to network jitter in link detection. Background technique

In order to protect critical applications, redundant backup links are designed in the network. When the network fails, the network equipment is required to quickly detect the fault and switch the traffic to the backup link to speed up the network. At present, some links than POS (Packet over SONET) can implement fast fault detection through hardware detection mechanism. However, some links such as Ethernet links do not have such detection mechanism. At this time, the application needs to rely on the mechanism of the upper layer protocol to perform fault detection, and the detection time of the upper layer protocol is more than 1 second. Such fault detection time cannot meet the requirements of some applications. Routing protocols such as OSPF (Open Shortest Path First), IS-IS (Intermediate System to Intermediate System Routing Protocol), although there are Fast Hello functions to speed up detection. However, the detection time can only reach 1 second accuracy, and the Fast Hello function is only for this protocol, and cannot provide fast fault detection for other protocols. The BFD protocol is produced in this context, which provides a common, standardized, media-independent, protocol-independent fast fault detection mechanism.

When sending BFD control packets, BFD considers the impact of jitter in the transmission network environment on the detection result. The transmission cycle is as follows:

When sending BFD control packets periodically, you must consider the maximum 25% jitter based on each packet. That is, the packet interval must be randomly reduced by a value from 0 to 25%, in order to avoid the same The subnet is synchronized with other systems, and the average packet interval is approximately 12.5% smaller than the negotiated value. If the detection time accumulator is 1, the transmitted packet interval must be 90% of the negotiated transmission interval value and not less than 75% of the negotiation interval value. This is to ensure that the remote system calculates the detection timeout before receiving the next message.

The transmission interval has an important impact on the BFD detection result. For network jitter, the actual transmission interval is reduced by random values, and the average packet interval is reduced by 12.5%. However, the actual transmission interval of the packet is not known, and the random value cannot be It is truly random, and thus there may be cases where the jitter is large and the packet interval is not reduced, resulting in detection errors. Moreover, when the network environment is good, it is not necessary to shorten the packet interval; when the jitter exceeds the above 25% range, it indicates that the network environment is poor, and in order to cope with the jitter, it is not necessary to adjust only the packet interval. You can inform the control plane to take other measures in advance by reporting the police notification, without having to wait for the BFD to detect the link break and then take measures.

Therefore, when the BFD sends control packets in the prior art, the interval for sending packets cannot be dynamically adjusted according to actual network conditions. As a result, the packet sending interval varies randomly within a large range, and the packet sending time cannot be accurately controlled. Summary of the invention

The main object of the present invention is to provide a method and apparatus for adjusting a BFD transmission interval according to network jitter, which aims to improve the accuracy and applicability of BFD detection.

In order to achieve the above object, the technical solution of the present invention is achieved as follows:

A method for adjusting the BFD transmission interval according to the network jitter adjustment, including: transmitting a packet by the source end and the destination end of the BFD session to measure the network jitter value X; and detecting the time according to the negotiation interval value Y when the current BFD packet is sent The value of the accumulator, and the network jitter value X, adjust the BFD transmission interval.

The process of measuring the network jitter value X by sending a packet to the source end and the destination end of the BFD session includes: Recording the interval T of the packet sent by the destination end to the source end, and collecting the time stamp t of each packet received by the source end;

Calculating the time difference Δ t of each of the two said _3⁄4 texts;

The network jitter value X is calculated based on the equal interval time T and the time difference A t .

The process of adjusting the BFD sending interval includes:

When the value of the detection time accumulator is greater than 1, if X/Y<25%, the negotiation interval value Y when the BFD packet is sent is decreased by the first predetermined threshold M, and the adjusted BFD transmission interval is obtained; Or,

If X/Y ≥ 25%, the negotiation interval value of the BFD packet transmission is reduced by 25%, and the adjusted BFD transmission interval is obtained.

The process of adjusting the BFD sending interval further includes:

When the value of the detection time accumulator is 1, if X/Y<25%, the negotiation interval value Y when the BFD message is sent is decreased by the first predetermined threshold M, and then the second is decreased. The threshold value N is predetermined, and the adjusted BFD transmission interval is obtained;

Or,

The first predetermined threshold M and the second predetermined threshold N are determined based on the network status.

A device for adjusting a BFD transmission interval according to network jitter, comprising:

The network jitter value measuring module is configured to measure the network jitter value X by sending a message to the source end and the destination end of the BFD session;

The sending interval adjustment module is configured to detect the value of the time accumulator and the network jitter value X according to the negotiation interval value Y when the current BFD packet is sent, and adjust the BFD sending interval.

The network jitter value measurement module includes:

The statistical unit is used to record the interval time T of the destination end sending the message to the source end, and counting The source end receives the time stamp t of each message;

a time difference calculation unit, configured to calculate a time difference A t of arrival of each of the two messages;

The network jitter value calculation unit is configured to calculate the network jitter value X according to the equal interval time T and the time difference A t .

The sending interval adjustment module is used to: when adjusting the BFD sending interval:

When the BFD sending interval is adjusted, the sending interval adjustment module is further configured to:

Or,

The method and device for adjusting the BFD transmission interval according to the network jitter, and measuring the network jitter value by sending packets at both ends of the BFD session, according to the network jitter value, the negotiation interval value and the detection time when the current BFD packet is sent. The value of the accumulator adjusts the BFD transmission interval. When the BFD transmission control packet is used in the prior art, the packet transmission interval cannot be dynamically adjusted according to the actual network condition, which causes the packet interval to be randomly changed within a large range. Solving the problem that the actual packet sending interval in the prior art does not match the actual environment configuration parameter, and performing range control on the packet sending time interval according to the network jitter, thereby more accurately controlling the sending time, Accuracy and applicability of high BFD detection. DRAWINGS

1 is a schematic flow chart of an embodiment of a method for adjusting a BFD transmission interval according to network jitter according to the present invention;

2 is a schematic flowchart of measuring a network jitter value X by transmitting a packet from a source end and a destination end in a BFD session according to an embodiment of the present invention;

3 is a schematic flowchart of adjusting a BFD transmission interval according to a network jitter value X, a negotiation interval value Y when a current BFD packet is sent, and a value of a detection time accumulator according to an embodiment of the present invention. ;

4 is a schematic structural view of an embodiment of an apparatus for adjusting a BFD transmission interval according to network jitter according to the present invention;

FIG. 5 is a schematic structural diagram of a network jitter value measurement module according to an embodiment of the present invention for adjusting a BFD transmission interval according to network jitter. detailed description

The solution of the embodiment of the present invention is to measure the network jitter value by sending packets at both ends of the BFD session, and adjust the BFD transmission interval according to the network jitter value, the negotiation interval value of the current BFD packet transmission, and the value of the detection time accumulator. To improve the accuracy and applicability of BFD detection.

As shown in FIG. 1, an embodiment of the present invention provides a method for adjusting a BFD transmission interval according to network jitter, including:

Step S101: The network jitter value X is measured by sending a packet to the source end and the destination end of the BFD session. In this embodiment, the network jitter value X is calculated by sending a packet between the destination end and the source end of the BFD session. . The BFD 4 艮 text can be used for measurement, or the packet other than the BFD packet can be sent for measurement. The UDP packet is used as an example. The UDP packet can be sent to the source at the interval T to calculate the network jitter. The source collects the timestamp t of the UDP packet and calculates the packet. The time difference A t of the arrival of the UDP packet is obtained by the formula I ^T_ .

Step S102: Adjust the BFD transmission interval according to the network jitter value X, the negotiation interval value Υ when the current BFD packet is sent, and the value of the detection time accumulator.

The adjustment of the BFD transmission interval is divided into two cases. The first case is when the value of the accumulator is greater than 1; the second case is when the value of the time accumulator is 1. Set the negotiation interval value of the current BFD packet to Υ. When the detection time accumulator is greater than 1, if Χ/Υ<25%, the negotiation interval value when the BFD packet is sent is decreased by the first predetermined threshold. M (such as the network jitter value X) is then used as the actual transmission interval. If X/Y ≥ 25%, the negotiation interval value Υ when transmitting BFD 4 艮 is reduced by 25%, which is the actual transmission interval.

When the detection time accumulator is 1, if Χ/Υ<25%, the negotiation interval value Y when the BFD message is sent is further reduced by the second predetermined threshold value N by decreasing the first predetermined threshold M. (For example, reduce the network jitter value X and then subtract 5ms) as the actual transmission interval. If X/Y ≥ 25%, the negotiation interval for BFD transmission is reduced by 25% as the actual transmission interval.

The second case described above is more strict with respect to the first case. The processing of the BFD transmission interval needs to be stricter, because in the second case, the timeout period has only one transmission time interval, and if the margin reserved for the interval is insufficient, In the case of unstable network conditions, false positives may occur. Therefore, in the case of Χ/Υ <25%, the second case is larger than the interval in which the first case is reduced. Therefore, in this embodiment, in two cases, the Χ/Υ ratio is compared with 25%, and the actual BFD packet interval is adjusted.

The first predetermined threshold Μ and the second predetermined threshold Ν are determined according to the actual state of the network (including jitter, delay, packet loss rate, etc.). The Μ value is directly related to the jitter value and can be dynamically set. When the network jitter is large, the value takes a larger value. When the network jitter is small, the value takes a smaller value; for example, the value can be directly set. Multiply the jitter value or the jitter value by a factor. Awkward The value is only used when the accumulator is 1 in the detection time. If the accumulator is greater than 1 in the detection time, in order to prevent the BFD false detection, the value of the BFD transmission interval is reduced by another value. When M and N are respectively taken as values, the N value can be set statically or dynamically. The static setting is used when the network environment is relatively stable, and the dynamic setting is used when the network environment is unstable. In the case where the network environment is unstable, the values of M and N can also be set by multiplying the jitter value by a certain coefficient. The principle of the value is such that when the detection accumulator is 1, the BFD packet is sent. The negotiation interval value Y at the time is smaller than the transmission negotiation interval value in the case where the detection accumulator is greater than 1.

As shown in FIG. 2, step S101 includes:

Step S1011: Recording the interval T between the destination end and the source end, and collecting the time stamp t of each message received by the source end;

Step S1012, calculating a time difference A t of arrival of each two packets;

Step S1013: Calculate the network jitter value X according to the equal interval time T and the time difference A t .

As shown in FIG. 3, step S102 includes:

Step S1021, determining that the value of the detection time accumulator is greater than 1 or equal to 1, if greater than 1, then proceeds to step S1022; if equal to 1, proceeds to step S1025;

Step S1022, determining whether X/Y is <25%, and if yes, proceeding to step S1023; otherwise, proceeding to step S1024;

Step S1023: The negotiation interval value Y when the BFD packet is sent is decreased by the first predetermined threshold M, and the adjusted BFD transmission interval is obtained.

Step S1024: The negotiation interval value Y when the BFD packet is sent is reduced by 25%, and the adjusted BFD transmission interval is obtained.

Step S1025, determining whether X/Y is <25%, and if yes, proceeding to step S1026; otherwise, proceeding to step S1024;

In step S1026, the negotiation interval value Y when the BFD packet is sent is decreased by the first predetermined threshold M. Then subtract the second predetermined threshold N to obtain the adjusted BFD transmission interval.

It should be noted that, in the above network jitter value testing process, the destination end sends the source end to the source end.

A UDP packet is a small packet with a sequence number and an identifier. The identifier distinguishes the BFD session. The sequence number can be used to view the retransmission and packet loss on the receiving end. Because the packet length is small and the traffic is small, the network does not cause any Great impact.

Before the network jitter value X is determined, the actual initial transmission interval of the BFD packet may be determined according to the existing BFD processing method, that is, a time interval smaller than max (bfd.DMTI, bfd.RemoteMinRxInterval) in the sending direction. Send BFD control packets. bfd.DMTI indicates the minimum interval for the local end to send BFD packets. bfdRemoteMinRxInterval indicates the minimum interval at which the peer wants to receive packets. It also distinguishes between the detection time accumulators being 1 and greater than 1. For example, when the detection time accumulator is 1, the transmission interval is set to 90% of the negotiated value; when the detection accumulator is greater than 1, the transmission interval is set to 85% of the negotiated value.

When adjusting the time interval for sending BFD packets according to the network jitter value, you can also use different evaluation criteria or combine the evaluation criteria with the X/Y ratio. For example, if the jitter value exceeds 60ms, the network state is considered to be poor. When the BFD interval is set, you can use this value to adjust the BFD interval.

Because BFD is a bidirectional forwarding protocol, the method of this embodiment can be used separately in each BFD direction.

The method described in this embodiment solves the problem that the actual packet sending interval does not match the actual environment configuration parameter in the prior art, and performs range control on the packet sending time interval according to the network jitter, thereby more accurately controlling the packet sending time and improving the BFD. Accuracy of detection and applicability of BFD detection.

As shown in FIG. 4, an embodiment of the present invention provides an apparatus for adjusting a BFD transmission interval according to network jitter, including: a network jitter value measurement module 401 and a transmission interval adjustment module 402, where: The network jitter value measuring module 401 is configured to measure a network jitter value X by sending a message to the source end and the destination end of the BFD session;

In this embodiment, the network jitter value X can be calculated by sending packets between the two ends of the BFD session, that is, the destination end and the source end. The BFD 4 text can be used for measurement, or the packets other than BFD packets can be sent for measurement.

The UDP packet is used as an example. The UDP packet can be sent to the source at the interval T to calculate the network jitter. The source collects the timestamp t of the UDP packet and calculates the packet. The time difference A t of the arrival of the UDP packet is obtained by the formula I ^T_ .

The sending interval adjustment module 402 is configured to adjust the BFD sending interval according to the network jitter value X, the negotiation interval value 当前 when the current BFD packet is sent, and the value of the detection time accumulator.

The second case described above is more strict with respect to the first case. The processing of the BFD transmission interval needs to be stricter, because in the second case, the timeout period has only one transmission time interval, and if the margin reserved for the interval is insufficient, In the case of unstable network conditions, false positives may occur. So in the case of Χ/Υ<25%, the second case is more time-consuming than the first case. Therefore, in this embodiment, in both cases, the Χ/Υ ratio is compared with 25%, respectively. Make a distinction and adjust the actual BFD dispatch interval.

The first predetermined threshold M and the second predetermined threshold N are determined according to the actual state of the network (including jitter, delay, packet loss rate, etc.). The M value is directly related to the jitter value and can be dynamically set. When the network jitter is large, the value takes a larger value; when the network jitter is small, the value takes a smaller value; for example, the value can be directly set. Multiply the jitter value or the jitter value by a factor. The value of N is only used when the accumulator is 1 in the detection time. If the accumulator is greater than 1 in the detection time, in order to prevent the BFD false detection, the value of the BFD transmission interval is reduced. When the values of M and N are taken separately, the N value can be set statically or dynamically. The static setting is used when the network environment is relatively stable, and the dynamic setting is used when the network environment is unstable. under. In the case where the network environment is unstable, the values of M and N can also be set by multiplying the jitter value by a certain coefficient. The principle of the value is such that when the detection accumulator is 1, the BFD packet is sent. The negotiation interval value Y at the time is smaller than the transmission negotiation interval value in the case where the detection accumulator is greater than 1.

As shown in FIG. 5, the network jitter value measuring module 401 includes: a statistical unit 4011, a time difference calculating unit 4012, and a network jitter value calculating unit 4013, where:

The statistic unit 4011 is configured to send the interval time T of the ^^ message to the source end, and collect the time stamp t of each message received by the source end;

The time difference calculation unit 4012 is configured to calculate a time difference A t of the arrival of each of the two texts;

The network jitter value calculation unit 4013 is configured to calculate the network jitter value X according to the equal interval time T and the time difference A t .

It should be noted that, in the network jitter value test process, the UDP packet sent by the destination end to the source end is a small packet with only a sequence number and an identifier. The identifier distinguishes the BFD session, and the sequence number can be viewed at the receiving end. Transmission and packet loss, because the message length is small, the traffic is small, so it will not have a big impact on the network.

Before determining the network jitter value X, determining the actual initial transmission interval of the BFD packet, It can be performed according to the existing BFD processing method, that is, the BFD control packet is sent at a time interval smaller than max (bfd.DMTI, bfd.RemoteMinRxInterval) in the transmission direction. bfd.DMTI indicates the minimum interval for the local end to send BFD packets. bfdRemoteMinRxInterval indicates the minimum interval at which the peer wants to receive packets, and distinguishes between the detection time accumulators being 1 and greater than 1. For example, when the detection time accumulator is 1, the transmission interval is set to 90% of the negotiation value; when the detection accumulator is greater than 1, the transmission interval is set to 85% of the negotiation value.

Because the BFD is a bidirectional forwarding protocol, the device in this embodiment can be separately used to adjust the BFD transmission interval in each BFD direction.

The method and device for adjusting the BFD transmission interval according to the network jitter, and measuring the network jitter value by sending the packet at both ends of the BFD session, according to the network jitter value, the negotiation interval value when the current BFD packet is sent, and the detection time accumulator The value of the BFD transmission interval is adjusted. When the BFD transmission control packet is used in the prior art, the packet transmission interval cannot be dynamically adjusted according to the actual network condition, thereby causing the packet interval to be randomly changed within a large range. In the prior art, the problem that the actual packet sending interval does not match the actual environment configuration parameter, the range control of the packet sending time interval is performed according to the network jitter, thereby more accurately controlling the packet sending time, and improving the accuracy and applicability of the BFD detection.

The above is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and equivalent structural or process changes made by the present specification and drawings may be directly or indirectly applied to other related technical fields. The same is included in the scope of patent protection of the present invention.

Claims

Claim

A method for adjusting a bidirectional forwarding detection BFD transmission interval according to network jitter, wherein the method includes:

The network jitter value X is measured by sending a packet to the source and destination of the BFD session.

According to the negotiation interval value Y when the current BFD packet is sent, the value of the time accumulator is detected, and the network jitter value X is adjusted to adjust the BFD transmission interval.

The method according to claim 1, wherein the process of measuring the network jitter value X by sending a message to the source end and the destination end of the BFD session includes:

Recording the interval T between the destination end and the source end, and collecting the time stamp t of each packet received by the source end;

Calculating the time difference Δ t of each of the two said _3⁄4 texts;

The method according to claim 1, wherein the adjusting the BFD transmission interval comprises:

The method according to any one of claims 1 to 3, wherein the process of adjusting the BFD transmission interval further includes:

or, If X/Y ≥ 25%, the negotiation interval value of the BFD packet transmission is reduced by 25%, and the adjusted BFD transmission interval is obtained.

The method according to claim 4, wherein the first predetermined threshold Μ and the second predetermined threshold 确定 are determined according to a network state.

A device for adjusting a BFD transmission interval according to network jitter, comprising: a network jitter value measurement module, configured to measure a network jitter value X by sending a message to a source end and a destination end of a BFD session;

The sending interval adjustment module is configured to detect the value of the time accumulator and the network jitter value X according to the negotiation interval value 当前 when the current BFD packet is sent, and adjust the BFD sending interval.

The device according to claim 6, wherein the network jitter value measurement module comprises:

The statistical unit is configured to record the interval time 发送 at which the destination end sends the 艮 message to the source end, and collect the time stamp t of each message received by the source end;

The device according to claim 6, wherein the transmission interval adjustment module is configured to: when adjusting a BFD transmission interval:

9. Apparatus according to any one of claims 6 to 8 wherein:

When the BFD sending interval is adjusted, the sending interval adjustment module is further configured to: When the value of the detection time accumulator is 1, if X/Y<25%, the negotiation interval value Υ when the BFD message is sent is decreased by the first predetermined threshold Μ, and then the second is decreased. After the predetermined threshold value Ν, the adjusted BFD transmission interval is obtained;

Or,

If Χ/Υ ≥ 25%, the negotiation interval value of the BFD packet transmission is reduced by 25%, and the adjusted BFD transmission interval is obtained.

10. Apparatus according to claim 9 wherein said first predetermined threshold M and a second predetermined threshold N are determined based on network status.