CN100391195C - A Method of Dynamically Adjusting Data Packet Length Based on Network Quality of Service - Google Patents

Abstract

The present invention provides a method for dynamically adjusting the length of a data packet, comprising the steps of: a source end sends a time stamp packet containing time stamp information to a destination end; after receiving the time stamp packet, the destination end judges whether the length of the data packet needs to be changed; If it is necessary to change the length of the data packet, the destination calculates a new data packet length, and sends a request packet requesting to change the length of the data packet to the source; The packet length is changed to a new data packet length or kept unchanged, and a response packet is sent to the destination; the destination performs corresponding processing on the data packet length according to the content of the response packet. According to the method of the invention, the change of the network service quality can be dynamically monitored, the length of the data packet can be dynamically adjusted, and the influence of the change of the network service quality on the service quality of the user can be minimized. In addition, the method of the invention improves the utilization rate of network bandwidth.

Description

A Method of Dynamically Adjusting Data Packet Length Based on Network Quality of Service

technical field

The invention relates to a packet switching network, in particular to a method for dynamically adjusting the length of a data packet according to network service quality when transmitting time division multiplexing services in the packet switching network.

Background technique

The traditional time-division multiplexing (TDM) circuit switching service has the characteristics of small transmission delay and high real-time response capability, and is suitable for transmitting real-time services such as voice and video. It plays an extremely important role and has a huge market share in modern telecommunication networks. However, the TDM switching service uses an exclusive channel, so the resource utilization rate is low. If the TDM business can be transmitted through the packet switching network, the line utilization can be greatly improved and the transmission cost can be reduced.

To transmit synchronous or quasi-synchronous TDM circuit emulation services in an asynchronous packet-switching network, two main problems need to be solved: one is how to solve the clock synchronization between the sending end and the receiving end, that is, the clock recovery problem; the other is how to minimize the Delay, to better guarantee business characteristics.

The main reason affecting the accuracy of clock recovery is the packet delay of data packets in the packet switching network. The so-called packet delay refers to the time required for a data packet to pass from the sender to the receiver. The packet delay includes the following aspects: the waiting delay of the sending end encapsulation; the transmission delay of the signal line; the delay jitter caused by network congestion and other reasons.

At present, the main method to eliminate delay jitter is to set a certain size jitter buffer at the receiving end to reduce the jitter by sacrificing the delay characteristics in exchange for improving the accuracy of the recovered clock. In order to facilitate processing, the existing solution is to encapsulate the bytes in the TDM stream into fixed-length data packets, and the number of TDM bytes encapsulated in a data packet is determined by the user according to the actual network conditions.

When the network bandwidth utilization rate is low and the user requires a small delay for TDM services, the data packet length can be set as small as possible, so that there will be no delay due to the need to wait for more TDM frames during encapsulation increase. On the contrary, if the user does not have strict requirements on the real-time performance of the service or the network environment is good, the length of the data packet encapsulating the TDM stream can be set larger to save bandwidth resources.

However, the above method is not only complicated for users to operate, but also because the network structure and traffic characteristics are constantly changing with the needs and development of users, it is impossible for users to monitor the actual network traffic and structure changes in real time and make changes to the packet length. Therefore, the operability of this method is not strong, and it cannot better provide quality assurance for TDM simulation services.

Contents of the invention

The purpose of the present invention is to provide a method that is convenient for operation and can dynamically adjust the length of data packets, so as to better provide quality assurance for time-division multiplexing services.

To achieve the above object, the present invention provides a method for dynamically adjusting the length of a data packet, which is characterized in that it comprises the following steps:

The source sends a timestamp packet containing timestamp information to the destination;

After the destination terminal receives the timestamp packet, it judges whether the length of the data packet needs to be changed;

If it is necessary to change the length of the data packet, the destination calculates a new length of the data packet, and sends a request packet requesting to change the length of the data packet to the source;

The source end performs corresponding processing on the length of the data packet according to the content of the request packet, and sends a response packet to the destination end.

The method of the present invention also includes a step: the destination terminal performs corresponding processing on the length of the data packet according to the content of the response packet.

According to the method of the present invention, the change of network service quality can be dynamically monitored, and the length of data packets can be dynamically adjusted, so that the length of data packets can be dynamically changed according to the real-time traffic conditions of the network and the requirements of the user's service quality, thereby reducing network service quality to the greatest extent. Impact of quality changes on user TDM service quality. In addition, the method of the present invention utilizes the network bandwidth more effectively.

Other features and advantages of the present invention will become more apparent after reading the detailed description of the embodiments of the present invention in conjunction with the accompanying drawings.

Description of drawings

Fig. 1 is the schematic flowchart of the method for dynamically adjusting data packet length according to the present invention;

Fig. 2 is a schematic flowchart of the method shown in Fig. 1 in the case of signaling data packet loss;

Fig. 3 is a schematic flow chart at the receiving end of the method for dynamically adjusting the length of a data packet according to the present invention.

Detailed ways

Specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings.

Fig. 1 is a schematic flowchart of a method for dynamically adjusting the length of a data packet according to the present invention. The processing procedure shown on the left side in FIG. 1 is performed on the source side (sending side), and the processing procedure shown on the right side is performed on the destination side (receiving side). The flow chart shown in FIG. 1 is actually a signaling information interaction process between the source end and the destination end for the purpose of dynamically adjusting the length of the data packet.

First, initialize the packet switching network including the source end and the destination end, and set the service quality requirement q and related system parameters of the business. The initialization process of a packet-switched network is not relevant to the essence of the present invention and is well known to those of ordinary skill in the art.

After initialization of the packet-switched network, the source periodically sends time-stamped packets. That is, in step 101, the source end regularly sends a time stamp packet T containing time stamp information to the destination end at a frequency f in an in-band or out-of-band manner.

After the destination end receives the timestamp packet T containing timestamp information, in step 102, it uses the timestamp information contained in the timestamp packet T and uses the timestamp corresponding to the arrival time of the timestamp packet T to calculate the timestamp packet T's transmission delay t, delay jitter d.

Then, in step 103, the destination end applies the control strategy f1(l, t, d, q) according to the transmission delay t, the delay jitter d, the original data packet length l and the service quality requirement q, and judges whether it is necessary to change the data packet length.

Transmission delay t and delay jitter d are high-frequency variable parameters, and the data packet length cannot be changed because of a large change in transmission delay or delay jitter during a certain data transmission process. On the contrary, the average transmission delay and average delay jitter within a predetermined period of time should be used as a reference, combined with other parameters to determine whether to change the length of the data packet. Otherwise, the length of the data packet may change frequently, which may affect the stability of the system.

The judgment in step 103 has two results.

The first judgment result is not to change the length of the data packet. In this case, no information is sent to the source end, and the state before step 102 is returned, and the destination end waits to receive new data packets from the source end.

The second judgment result is to change the data packet length. In this case, processing proceeds to step 104 .

In step 104 , that is, in the case of deciding to change the length of the data packet, the destination determines the optimal length lnew of the data packet, and then proceeds to step 105 .

In step 105, include the new data packet length in the data packet Req requesting to change the packet length, then send the data packet Req to the source end, and wait for a response from the source end.

In step 106, after the source end receives the data packet Req requesting to change the packet length from the destination end, it applies the local rule g(l, lnew) to judge whether to accept the request for changing the packet length. This judgment has two consequences.

The first judgment result is to reject the request to change the packet length. In this case, in step 107, the source sends a response packet Ack to the destination to reject the request.

The second judgment result is to accept the request to change the packet length. In this case, in step 107, the source end sends a response packet Ack for accepting the request to the destination end, and after the first predetermined time interval t1 from this moment, step 109 is executed. The reason why step 109 is executed after the first predetermined time interval t1 is to ensure that the destination end has enough time to receive the response packet Ack and perform corresponding processing according to the content of the response packet Ack. For example, prepare to receive data packets encapsulated with a new packet length.

If it is decided in step 106 to accept the request for changing the packet length, then in step 109, the source starts sending data packets encapsulated with the new packet length lnew. In the transmitted data packet, the packet length change flag is set.

On the other hand, in step 108, after receiving the response packet returned by the sender, the destination end performs corresponding processing according to the content of the response packet, such as setting the length of the data packet to a new length or keeping it unchanged. Specifically, if the response of the source end accepting the request is received, the destination end confirms that the packet length of the locally received data packet will be changed from receiving the first packet length change flag bit to the data packet (i.e. the data sent in step 109) Packet) time is set to the new data packet length lnew. If the response of the source end rejecting the request is received, the destination end confirms that the packet length of the locally received data packet remains unchanged at the original data packet length l.

In step 110 corresponding to step 109, the destination end receives the data packet whose packet length change flag bit is set and encapsulated with the new data packet length lnew, then the data packet length used when the local legally received data packet is set to the new Data packet length lnew.

Fig. 2 is a schematic flowchart of the method shown in Fig. 1 in the case of signaling data packet loss. The steps in Fig. 2 are roughly the same as those in Fig. 1, except that in Fig. 2 the case of signaling data packet loss is considered. For example, after the request packet Req requesting to change the packet length is sent in step 105, the request packet Req may be lost, as shown in FIG. 2 . In addition, after the source end sends the response packet Ack in step 107, the response packet Ack may also be lost, as shown in FIG. 2 . In both cases, the destination end cannot get a response after sending the request packet Req requesting to change the packet length, thus failing to achieve the purpose of dynamically adjusting the length of the data packet.

To this end, after step 105, the destination monitors a second predetermined time interval t2. If no response packet Ack is received within the second predetermined time interval t2, then at step 1052 the request packet Req requesting to change the packet length is resent.

After the source end receives the request packet Req for the first time, it starts processing from step 106 . The request packet Req received by the source end for the first time may be the request packet Req sent by the destination end in step 105 , or the request packet Req resent by the destination end in step 1052 . Those skilled in the art can easily understand that the step of resending the request packet Req may not be limited to one time.

The processing of steps 106 and 107 is the same as that in FIG. 1 .

If within the first predetermined time interval t1, the source end receives the request packet Req from the destination end again (this situation shows that the response packet Ack is lost, and the destination end has executed step 1052), then the source end resends the response packet in step 1072 Ack. Those skilled in the art can easily understand that the step of resending the response packet Ack may not be limited to one time.

Subsequent steps 108 , 109 , 110 are the same as in FIG. 1 .

It is required in FIG. 2 that the first predetermined time interval t1 is greater than the second predetermined time interval t2. This requirement not only ensures that the destination has enough time to receive the response packet Ack and do corresponding processing according to the content of the response packet Ack (for example, to prepare for receiving the data packet encapsulated according to the new packet length), but also ensures that the source end The length of the data packet will not be changed before receiving the request packet Req resent by the destination end due to the loss of the response packet Ack.

Fig. 3 is a schematic flow chart at the receiving end of the method for dynamically adjusting the length of a data packet according to the present invention. As shown in FIG. 3, at step 301, the process starts. In step 302, system parameters are set, including service quality requirement q and other parameters. Then in step 303 it is judged whether a timestamp packet T containing timestamp information is received. If the judgment result of step 303 is "yes", then the process proceeds to step 304; otherwise, it waits at step 303 until receiving a timestamp packet T containing timestamp information.

In step 304, the transmission delay t and delay jitter d of the timestamp packet T are calculated. This step may also include calculating an average transmission delay and an average delay jitter of time-stamped packets received within a predetermined time period.

In step 305, according to the control strategy f1(l, t, d, q), it is judged whether to change the length of the data packet. Judgment criteria are the same as in Figure 1. If the judgment result of step 305 is “No”, then the processing procedure returns to step 303 and waits to receive the next timestamp packet T containing timestamp information, otherwise the processing procedure proceeds to step 306 .

In step 306, a new data packet length lnew is calculated according to the above control strategy.

In step 307, a request packet Req containing a new data packet length lnew is sent to the source.

In step 308, it is judged whether the response packet Ack is received. If the judgment result of step 308 is "Yes", then the process proceeds to step 310; otherwise, it proceeds to step 309.

In step 309, it is judged whether a predetermined period of time has elapsed, such as the second predetermined time interval t2 shown in FIG. 2 . If the judging result of step 309 is "yes", the process returns to step 307; otherwise, it returns to step 308.

In step 310, according to the content of the response packet Ack, the destination end judges whether the source end accepts the request, if the judgment result is "no", the source end rejects the request, then the process proceeds to 311; otherwise, it proceeds to step 312.

In step 311 , the destination keeps the length of the data packet unchanged, and then returns to step 303 .

In step 312, the destination end changes the data packet length to lnew, or confirms that the packet length of the locally received data packet will be set as a new data packet from the moment of receiving the first data packet whose packet length change flag bit is set length lnew. After that, the process returns to step 303 .

The flow shown in FIG. 3 , especially steps 307 to 309 , effectively handles the loss of the signaling data packet (ie, the request packet Req or the response packet Ack) as shown in FIG. 2 .

Corresponding to the flow shown in FIG. 3 , a relatively simple processing procedure is performed at the source end, that is, step 101 shown in FIG. 1 is executed first and waits. If a request packet Req requesting to change the packet length is received, steps 106 and 107 in FIG. 1 are executed, and in case of a decision to accept the request to change the packet length in step 106, step 109 is executed after the first predetermined time interval t1 . Step 101 is performed periodically with frequency f. The execution of steps 106 and 107 depends on many factors such as the request of the destination, whether the request packet Req is lost, whether the response packet Ack is lost, or whether it times out. In the case that the request packet Req is received again within the first predetermined time interval t1, step 1072 shown in FIG. 2 may also be executed.

Although the embodiments of the present invention have been described with reference to the accompanying drawings, various variations or modifications may be made by those skilled in the art within the scope of the appended claims.

Claims (12)

1. the method for a dynamic adjusting data block length is characterized in that may further comprise the steps:

The source end sends the timestamp grouping that contains timestamp information to destination;

After destination is received described timestamp grouping, judge whether to need to change data packet length;

Change data packet length if desired, then described destination calculates new data packet length, and sends the request grouping that request changes data packet length to described source end;

Described source end is done respective handling according to the content of described request grouping to the data block length.

2. according to the method for claim 1, it is characterized in that the described step of needs change data packet length that judges whether may further comprise the steps:

Calculate described timestamp transmission packets time delay and delay variation;

At least according to QoS requirement, described propagation delay time, described delay variation, judge whether to need to change data packet length.

3. according to the method for claim 1, it is characterized in that the step that described transmission contains the timestamp grouping of timestamp information undertaken by described source end with preset frequency.

4. according to the method for claim 3, it is characterized in that the described step of needs change data packet length that judges whether may further comprise the steps:

Calculate described timestamp transmission packets time delay and delay variation;

Calculate the mean transit delay and the average delay variation of the timestamp grouping of receiving in the predetermined amount of time;

At least according to QoS requirement, described mean transit delay, the shake of described average delay, judge whether to need to change data packet length.

5. according to the method for claim 1, it is characterized in that in the described step that described new data packet length is added in the described request grouping that before described source end sends the step of request grouping that request changes data packet length, comprises.

6. according to the method for claim 1, it is characterized in that the described step that the data block length is done respective handling may further comprise the steps:

At least according to former data packet length, described new data packet length, judge whether to accept the described request grouping;

If accept the described request grouping, then send and accept the described request response packet to described destination; And

Behind first predetermined time interval, the data packet length that this locality sends is set to described new data packet length.

7. according to the method for claim 6, it is characterized in that further comprising the steps of:

Described destination receive described accept described request response packet grouping after, the length of the legal packet of local reception is set to described new data packet length.

8. according to the method for claim 6, it is characterized in that further comprising the steps of:

In second predetermined time interval of described destination after the request that the request that sends to described source end changes data packet length is divided into groups, monitor whether receive the described respond packet of sending from described source end; And

Do not receive under the situation of described respond packet that in described second predetermined time interval described destination resends the request grouping that described request changes data packet length to described source end.

9. method according to Claim 8 is characterized in that described first predetermined time interval is greater than described second predetermined time interval.

10. according to the method for claim 1, it is characterized in that the described step that the data block length is done respective handling may further comprise the steps:

At least according to former data packet length, described new data packet length, judge whether to accept the described request grouping;

If the rejecting said request grouping then sends the grouping of rejecting said request response packet to described destination.

11., it is characterized in that further comprising the steps of according to the method for claim 10:

Described destination remains unchanged the length of the packet of local reception after receiving described rejecting said request response packet grouping.

12., it is characterized in that further comprising the steps of according to the method for claim 10:

In second predetermined time interval of described destination after the request that the request that sends to described source end changes data packet length is divided into groups, monitor whether receive the described respond packet of sending from described source end; And

Do not receive under the situation of described respond packet that in described second predetermined time interval described destination resends the request grouping that described request changes data packet length to described source end.

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