CN115190132B

CN115190132B - L2TP load scheduling method, device and system

Info

Publication number: CN115190132B
Application number: CN202210770299.3A
Authority: CN
Inventors: 赵红伟; 陈刚; 高婷静
Original assignee: Shanghai Liangxun Iot Technology Co ltd
Current assignee: Shanghai Liangxun Iot Technology Co ltd
Priority date: 2022-06-30
Filing date: 2022-06-30
Publication date: 2024-01-19
Anticipated expiration: 2042-06-30
Also published as: CN115190132A

Abstract

The invention discloses a method, a device and a system for L2TP load scheduling, wherein the method comprises the following steps: after receiving the message, screening out the data packet of the L2TP control message, and discarding other packets; extracting LAC and LNS identity information and unique identification of connection relation thereof from an L2TP control message data packet; creating a storage table item for the unique identification mark, and distributing a storage space; storing the content of the control message after each identification, starting a message retransmission counter and a timer, and recording the retransmission times and interval duration; analyzing the timing of the timer, calculating the key data of the negotiation of the Tunnel l and the session when the timer expires, judging the event type according to the calculation result and sending the event type to the instruction module; collecting L2TP configuration of LAC and LNS and sending to a storage module for storage; the instruction module reads the L2TP configuration and event types of the LAC and the LNS, and judges whether to send out early warning and send out configuration modification instructions to the LAC and the LNS. The invention can reduce the break probability of the tunnel L and shorten the recovery time of the batch terminal disconnection under the L2TP NAS-I nit connected mode.

Description

L2TP load scheduling method, device and system

Technical Field

The invention belongs to the technical field of Internet of things and data communication, and particularly relates to an L2TP load scheduling method, device and system.

Background

The layer two tunneling protocol (L2 TP) is a mature VPDN technology, and there are two common tunneling (Tunnel) modes: NAS-Initiated mode and Client-Initiated mode. Wherein, the Tunnel negotiation of NAS-Initiated mode is Initiated by the L2TP access concentrator (LAC: L2TP Access Concentrator), the terminal does not need to support L2TP, only PPP (Point to Point Protocol). After the terminal dials into the LAC, the LAC initiates a Tunnel negotiation request to an L2TP network server (LNS: L2TP Network Server), and Session (Session) negotiation and ppp dialing are carried out after the Tunnel negotiation is completed, so as to support multi-Session sharing of the Tunnel. Establishment, keep-alive, tear-down of Tunnel Control Message (Control Message) queues and periodic keep-alive messages (Hello Message) in dependence on UDP format of the Tunnel (Tunnel) of the L2TP, each Control Message carries a pair of Message numbers (Nr: receive number, ns: send number) in addition to identification attribute information such as Tunnel id and Session id, and the LAC and the LNS maintain respective non-conflicting queues for each Tunnel and Session by controlling the elimination attribute and number values. The periodic keep-alive messages are respectively selected by the LAC and the LNS to be sent or not, the sending period, the overtime time and the retransmission times are set, and after the response of the opposite terminal is not received by the Hello message, the opposite terminal is considered to delete the tunnel, so that the tunnel of the local terminal is also deleted. The problems of the prior art are: UDP is a stateless transmission mode, where when message delivery is lost, the receiving and transmitting ends cannot perceive through the UDP protocol, so that the LAC and the LNS can only continuously decide whether to immediately process the message or continue waiting according to the message number received by each. In order to avoid that the received and transmitted control messages are too much to be processed or the numbers are out of order, the LAC and the LNS generally set respective receiving and transmitting windows as buffers processed by the upper module, and the windows need to occupy storage space. With the development of wireless cellular networks and mobile internet of things, when a large number of internet of things terminals are accessed through a NAS-Initiated mode, the number of concurrent tunnels and the number of concurrent sessions in a single Tunnel are far more than those of traditional non-internet of things scenes, more dialing and disconnection events are triggered when the wireless environment where the terminals are located changes and shifts, a large number of control messages triggered by the events need to be processed when LAC and LNS maintain tunnels, and for LAC and LNS, the message processing speed and the buffer space are always limited. In practical application, when the window is full, subsequent messages cannot be received and transmitted, so that a tunnel is interrupted, a large number of terminals are disconnected simultaneously, when a large number of terminals are redialed simultaneously, the LAC and the LNS need to clean old Session and process new Session, a large amount of hardware computing capacity and storage space need to be consumed in a short time, in this case, repeated redial of the terminals can be caused to be unable to be connected, and even the LAC and LNS system breakdown can be caused. Whereas an ISP's LAC will typically serve different clients, APNs, it is also possible for a client side LNS to interface with LACs of multiple ISPs. In the prior art, load sharing actions are executed by the LAC and the LNS based on the configuration of the LAC and the LNS, and cannot be adjusted in real time according to the opposite-end load state, so that the whole system is affected when the load states of one LAC and one LNS are severely oscillated. Chinese patent CN102752221B discloses a method and apparatus for sharing data packet load applied in L2TP networking, the method comprising: the LAC establishes L2TP sub-tunnels belonging to the L2TP main tunnel with the LNS according to the routing quantity of the destination IP addresses of the L2TP main tunnel, distributes tunnel source IP addresses and tunnel destination IP addresses for the L2TP sub-tunnels, and sequentially multiplexes L2TP Session sessions between the LAC and the LNS in the established L2TP sub-tunnels respectively; when the LAC receives a data message in any L2TP Session, determining an L2TP sub-tunnel multiplexed by the L2TP Session, packaging a public network IP header for the data message and forwarding so as to avoid congestion caused by overload of part of link loads, wherein the packaged public network IP header comprises a tunnel source IP address and a destination IP address of the L2TP sub-tunnel multiplexed by the L2TP Session. The invention has the following defects: load sharing scheduling on the LNS side is not involved, nor is load scheduling based on Tunnel control messages. In Chinese patent CN109257444B, namely a load sharing method, device and system, the inventor discloses a load sharing method, device and system, which relate to the field of data communication, realize mutual backup among L2TP network servers through a load sharing device, simultaneously have the function of load sharing, lighten the processing pressure of LNS and improve the utilization rate of equipment. The method comprises the following steps: after receiving a session request sent by the at least one LAC, the load sharing device sends the session request to one LNS according to a load strategy; after receiving the session response of one LNS, forwarding the session response to the other LNS; and the session response carries the session information to be backed up. The invention arranges the load sharing device on the communication intermediate link of the LAC and the LNS, thus becoming a fault point, and meanwhile, the invention does not relate to load sharing scheduling at the LAC side or load scheduling based on Tunnel control messages. Therefore, how to develop a novel L2TP load scheduling method to overcome the above-mentioned drawbacks in the prior art is a direction that a person skilled in the art needs to study.

Disclosure of Invention

The invention aims to provide an L2TP load scheduling method, which can reduce the Tunnel interruption probability and shorten the recovery time of batch terminal disconnection under an L2TP NAS-Initiated mode.

The technical scheme adopted by the method is as follows:

an L2TP load scheduling method, comprising the steps of:

step 1: screening the L2TP control message data packet from the original mirror image flow, and discarding other packets;

step 2: extracting control message type, LAC and LNS name from the L2TP control message data packet, and using the control message type, LAC and LNS name as unique identification for identifying the identity and relationship of LAC and LNS;

step 3: creating a storage table item for the unique identification mark, and distributing a storage space;

step 4: storing the content of the control message after each identification, and recording the retransmission times and the retransmission duration;

step 5: analyzing the timing of the timer, calculating Tunnel and Session negotiation key data when the timer expires, and judging the event type according to the calculation result;

step 6: collecting L2TP configuration of LAC and LNS;

step 7: and judging whether to send out early warning and a configuration modification instruction to the LAC and the LNS according to the L2TP configuration and the event type of the LAC and the LNS.

Preferably, in the L2TP load scheduling method,: in the step 1, the acquisition module screens out the L2TP control message data packet according to the following conditions: the protocol Type is UDP, the destination port is 1701, and Packet type=1 in the L2TP header.

Preferably, in the L2TP load scheduling method,: the unique identification in step 2 includes source IP, destination IP, control Message Type value of L2TP header, host Name value in the control message packet.

Preferably, in the L2TP load scheduling method,: step 3 further comprises: and starting an inactive aging timer while creating the storage table entry, deleting the storage table entry when the inactive aging timer expires, and recycling the storage space.

Preferably, in the L2TP load scheduling method,: and 4, storing the content of the control message after each identification, wherein the content comprises the values of Tunnel ID, session ID, ns, nr and Receive Window Size in the message.

Preferably, in the L2TP load scheduling method,: step 4 further comprises: analyzing load sharing weight of negotiation initiated to the LNS by the LAC based on the times of receiving the negotiation message and the maximum allowed Session number of the LNS; and analyzing the retransmission cycle and the maximum number of retransmissions based on the time stamp when the retransmission of the message occurs.

Preferably, in the L2TP load scheduling method,: the Tunnel and Session negotiation key data in step 5 includes: the method comprises the steps of an active LAC name, an active LNS name, an active LAC IP number, an active LNS IP number, a Tunnel duration, a number of sessions in a Tunnel, a Tunnel establishment success rate, a Tunnel negotiation completion average duration, a Session negotiation success rate, a Session negotiation completion average duration, a Session cut-off number, a message retransmission rate, a message discarding rate, a window overflow number and a message response time delay.

In order to implement the L2TP load scheduling method, the invention also discloses an L2TP load scheduling device, which includes: the device comprises an acquisition module, a storage module, an analysis module and an instruction module;

the acquisition module is used for screening an L2TP control message data packet from the original mirror image flow, extracting a source IP and a destination IP from the L2TP control message data packet, extracting a control message type, an LAC and an LNS name from an L2TP header, and sending the control message type, the LAC and the LNS name to the storage module as unique identification for identifying the identity and the relation of the LAC and the LNS; periodically acquiring L2TP configuration and other related configurations from LAC and LNS, and sending the configuration to a storage module;

the storage module is used for storing the received LAC and LNS identities and the unique identification of the relationship, storing detailed information of Tunnel and Session in the subsequent control message, and calculating and storing the retransmission times and duration of the message; the method comprises the steps of storing LAC and LNS configurations acquired by an acquisition module; the system also comprises a calling interface for providing various statistical data in the control message for the analysis module.

The analysis module is used for analyzing the statistical data in the acquired control message and outputting an analysis result to the instruction module;

the instruction module is used for carrying out combination processing on the obtained analysis results, judging whether to send configuration adjustment instructions to LAC and LNS equipment or not according to the stored LAC and LNS configuration, and editing the sent instruction content.

The invention further discloses an L2TP load scheduling system, which comprises: an L2TP load scheduler as described above, which is bypassed over the communication link between the LAC and the LNS by a forwarding device supporting traffic mirroring.

Compared with the prior art, the method and the device have the advantages that the L2TP Tunnel control message is acquired in real time through the data acquisition module of the scheduler; recording negotiation key data of the LAC and the LNS by a storage module; the analysis module of the scheduler is used for counting the loss quantity of control messages and queuing time waiting to be processed, so that more reasonable tunnel concurrency quantity and single tunnel session concurrency quantity are calculated; finally, the LAC and the LNS are instructed to dynamically adjust Tunnel configuration through a scheduler instruction module, and finally the functions of reducing the Tunnel interruption probability and shortening the fault recovery time when the batch terminals are disconnected in the L2TP NAS-Initiated mode are realized.

Drawings

FIG. 1 is a system block diagram of embodiment 1;

fig. 2 is a flowchart of the operation of example 1.

The names of the corresponding parts of the reference numerals are as follows:

1. an acquisition module; 2. a storage module; 3. an analysis module; 4. and an instruction module.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

Example 1 is shown in fig. 1-2:

an L2TP load scheduling device and system, the device comprises: the device comprises an acquisition module, a storage module, an analysis module and an instruction module;

The system comprises: an L2TP load scheduler as described above, which is bypassed over the communication link between the LAC and the LNS by a forwarding device supporting traffic mirroring. The forwarding device is a common network device, and the traffic mirroring is a published mature technology, which is not the core of the present application and will not be described herein. The scheduler establishes an additional communication link with each of the LAC and LNS via the forwarding device to provide a channel for configuration acquisition and instruction transmission.

The working process is as follows:

an L2TP load scheduling method, comprising the steps of:

step 1: the L2TP control message data packet is screened from the original mirror traffic based on the following conditions: "protocol Type is UDP, destination port is 1701, packet type=1 in L2TP header"; and discard other packets;

step 2: the acquisition module extracts the control message type, LAC and LNS name from the L2TP control message data packet, namely: the source IP, the target IP, the Control Message Type value of the L2TP header and the Host Name value in the control message data packet are used as unique identification identifiers for identifying the identities and the relations of the LAC and the LNS and are sent to the storage module;

step 3: the storage module creates a storage table entry for the unique identification mark, allocates a storage space, starts an inactive aging timer, deletes the storage table entry when the inactive aging timer expires, and recovers the storage space; the Tunnel negotiation start and disconnection time stamp is also sent to the analysis module;

step 4: storing the content of the control message after each identification, wherein the content specifically comprises the following steps: the values of Tunnel ID, session ID, ns, nr and Receive Window Size in the message; and analyzing load sharing weight of the LAC for negotiating to the LNS and the maximum allowed Session number of the LNS based on the times of receiving the negotiation message; analyzing a retransmission period and the maximum retransmission times based on the time stamp when the message is retransmitted;

step 5: the analysis timer counts, and when the timer expires, the method calculates Tunnel and Session negotiation key data, which specifically includes: the method comprises the steps of an active LAC name, an active LNS name, an active LAC IP number, an active LNS IP number, a Tunnel duration, a number of sessions in a Tunnel, a Tunnel establishment success rate, a Tunnel negotiation completion average duration, a Session negotiation success rate, a Session negotiation completion average duration, a Session cut-off number, a message retransmission rate, a message discarding rate, a window overflow number and a message response time delay; judging event types according to the calculation result;

event0: the event is retained. The result after the last analysis process is completed does not reach the abnormal threshold, which means that the analysis module does not detect the abnormality and is also used for notifying the current working state of the analysis module;

event1: l2TP breaks the chain. The analysis module receives the expiration of the LAC or LNS inactivity aging timer sent by the storage module, and indicates that a certain pair of LAC IP and LNS IP no longer mutually send control messages;

event2: tunnel shut-off. The storage module receives a Stop-Control-Connection-Notification (Stop-Control-Connection Notification) message sent by either the LAC or the LNS, and the analysis module receives a time stamp of the message sent by the storage module, which indicates that one end actively cuts off the Tunnel Connection;

event3: tunnel imbalance. The relation between the number of tunnels established between the LAC and the LNS and the number of IP addresses is unbalanced, which means that the number of tunnels established between the LAC IP and the LNS IP address pairs is obviously higher or lower than other IP address pairs;

evnet4: tunnel rejection. The LNS refuses the LAC to establish a new Tunnel request, which indicates that the number of tunnels allowed by the LNS reaches an upper limit;

event5: session imbalance. Indicating that at least one of a plurality of tunnels established between a certain pair of LAC IP and LNS IP exists in one Tunnel, the number of sessions in the Tunnel is obviously higher or lower than that of other tunnels;

event6: session rejection. The LNS refuses the LAC to establish a new Session request in a certain Tunnel, which means that the LNS allows the number of sessions of the Tunnel to reach the upper limit;

event7: tunnel is unhealthy. The Tunnel negotiation success rate, the average time length of the Tunnel negotiation completion, the message retransmission rate, the message discarding rate, the window overflow times and the message response time delay, wherein at least one value is higher than a preset threshold, which indicates that the Tunnel state is unstable and the abnormal cutting possibility is higher;

event8: session is unhealthy. The success rate of Session negotiation, the average duration of Session negotiation completion and the cutting-off times of the Session are higher than a preset threshold, which indicates that the Session state in the belonging Tunnel is unstable and the terminal is frequently dropped;

step 6: the acquisition module starts a configuration acquisition timer, when the timer expires, the L2TP related configuration of the LAC and the LNS is acquired and sent to the storage module for storage, the acquisition method is not the core of the application, and the storage module is updated after receiving the configuration;

step 7: judging whether to send out early warning and send out configuration modification instructions to the LAC and the LNS according to the L2TP configuration and event types of the LAC and the LNS:

event0: no alarm is given, no instruction is sent, and the instruction module confirms the working state of the analysis module through the event;

event1: sending an alarm, and sending configuration checking instructions to the LAC and the LNS to check the routing and negotiation configuration related to the L2 TP;

event2: sending out an alarm, and simultaneously sending out an instruction for immediately deleting the Session to the LAC and the LNS, and not waiting for confirmation of the opposite terminal so as to shorten the cleaning time;

event3: issuing an alarm, comparing the configuration related to the number of tunnels established by each IP and the LNS obtained from the LAC, and determining whether to instruct the LAC to modify the load sharing configuration related to the IP address pair;

event4: an alarm is sent out, configuration related to the number of tunnels established by each IP and LAC acquired from the LNS is compared, whether the LNS is indicated to modify the upper limit of the number of tunnels allowed is determined, whether the LAC is indicated to modify the configuration is determined, and an invalid Tunnel negotiation request is not sent to the IP any more;

event5: sending out an alarm, comparing the Session number per Tunnel acquired from the LAC with the load sharing related configuration, and determining whether to instruct the LAC to modify the configuration;

event6: issuing an alarm, comparing the relevant configuration of the number of Session of each Tunnel acquired from the LNS, determining whether to instruct the LNS to modify the upper limit of the number of Session allowed by the Tunnel, and determining whether to support LAC modification configuration, and not issuing an invalid Session negotiation request to the Tunnel;

event7; sending out an alarm, comparing the Tunnel parameter configuration of the IP pair obtained from the LAC and the LNS, sending out corresponding configuration modification instructions to the LAC and the LNS, and relaxing the Tunnel priority, retransmission and timeout and window size configuration to reduce the abnormal cutting risk;

event8: sending out an alarm, comparing the Tunnel parameter configuration of the IP pair obtained from the LAC and the LNS, sending out corresponding configuration modification instructions to the LAC and the LNS, and inhibiting the number of sessions to reduce the message receiving and transmitting density;

further preferably, in order to avoid command collision, the command module sets a plurality of timers, and a plurality of events received before the timers time out are combined to form a set of completely non-collision commands to be sent to the LAC and the LNS.

By adopting the technical scheme: according to the invention, the L2TP load is scheduled according to the actual working state of the L2TP Nas-Initiated mode, the risk of tunnel interruption is reduced, the fault recovery time of mass terminal disconnection caused by tunnel interruption is shortened, and the stability of L2TP connection in a large-connection scene of the cellular Internet of things is improved. The system disclosed by the invention is independent of the existing LAC and LNS, can be deployed on the LAC side or the LNS side, and can work at a single point or in a distributed mode. The method disclosed by the invention does not conflict with the existing L2TP load sharing technology, and has the effects of realizing load scheduling based on the actual working state on the prior art and enhancing the rationality of the existing load sharing technology. Because the device does not participate in the forwarding of the specific L2TP messages, no fault risk point is added on the basis of the typical L2TP Nas-Initiated mode. The system realizes automatic collection, storage, analysis and scheduling without manual intervention, thereby reducing the workload of operation and maintenance and reducing the risk of manual misoperation. According to the performance requirements of the actual application scene on the device, the specifications of each module can be adjusted, and the input-output ratio is improved.

Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. An L2TP load scheduling method, comprising the steps of:

step 6: collecting L2TP configuration of LAC and LNS;

2. The L2TP load scheduling method of claim 1, wherein the acquisition module in step 1 screens out L2TP control message data packets according to the following conditions: the protocol Type is UDP, the destination port is 1701, and Packet type=1 in the L2TP header.

3. The L2TP load scheduling method of claim 1, wherein: the unique identification in step 2 includes source IP, destination IP, control Message Type value of L2TP header, host Name value in the control message packet.

4. The L2TP load scheduling method of claim 3, wherein: step 3 further comprises: and starting an inactive aging timer while creating the storage table entry, deleting the storage table entry when the inactive aging timer expires, and recycling the storage space.

5. The L2TP load scheduling method of claim 1, wherein: the content of the control message after each identification in step 4 includes the Tunnel ID, sessionID, ns, nr, receive Window Size values in the message.

6. The L2TP load scheduling method of claim 1, wherein: step 4 further comprises: analyzing load sharing weight of negotiation initiated to the LNS by the LAC based on the times of receiving the negotiation message and the maximum allowed Session number of the LNS; and analyzing the retransmission cycle and the maximum number of retransmissions based on the time stamp when the retransmission of the message occurs.

7. The L2TP load scheduling method of claim 1, wherein: the Tunnel and Session negotiation key data in step 5 includes: the method comprises the steps of an active LAC name, an active LNS name, an active LAC IP number, an active LNS IP number, a Tunnel duration, a number of sessions in a Tunnel, a Tunnel establishment success rate, a Tunnel negotiation completion average duration, a Session negotiation success rate, a Session negotiation completion average duration, a Session cut-off number, a message retransmission rate, a message discarding rate, a window overflow number and a message response time delay.

8. An L2TP load scheduling apparatus, comprising: the device comprises an acquisition module, a storage module, an analysis module and an instruction module;

the storage module is used for storing the received LAC and LNS identities and the unique identification of the relationship, storing detailed information of Tunnel and Session in the subsequent control message, and calculating and storing the retransmission times and duration of the message; the method comprises the steps of storing LAC and LNS configurations acquired by an acquisition module; the system also comprises a calling interface for providing various statistical data in the control message for the analysis module;

9. An L2TP load scheduling system, comprising: the L2TP load scheduler of claim 8, which is bypassed over a communication link between the LAC and the LNS by a forwarding device supporting traffic mirroring.