WO2006042470A1

WO2006042470A1 - A method for performing flow fairness transmission in mpls ring network

Info

Publication number: WO2006042470A1
Application number: PCT/CN2005/001721
Authority: WO
Inventors: Xingyue Quan
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2004-10-20
Filing date: 2005-10-20
Publication date: 2006-04-27
Also published as: CN100490421C; CN1764148A

Abstract

A method for performing flow fairness transmission in MPLS ring network comprises the steps of: at first determining whether or not the packet is the best-effort service packet based on the information carried by the MPLS packet; then scheduling the best-effort service transmitted on each ring direction using the weight fairness scheduling algorithm according to the difference among the best-effort services. Consequently, the invention can firstly distinguish the corresponding best-effort service in the node of MPLS ring network, and then transmit the best-effort service using the setting fairness scheduling algorithm, so it effectively assure that each best-effort service in MPLS ring network can fairly employ the band resource remained by the higher priority service.

Description

Method for realizing fair transmission of traffic in MPLS ring network

The present invention relates to the field of multi-protocol label switching (MPLS) technology, and in particular, to a method for implementing fair delivery of traffic in an MPLS ring network. Background of the invention

The Multi-Service Transport Node (MSTP) based on the Synchronous Digital Sequence (SDH) system can well support Time Division Multiplexing (TDM) voice services and Digital Data Network (DDN) leased line services, but the support for IP packet services is poor. The uncertainty and unpredictability of IP traffic itself makes the use of traditional SDH equipment to provide IP packet transmission services with lack of bandwidth dynamic adjustment capability, low resource utilization, poor network scalability, complex equipment implementation, and weak topology management capabilities. And so on.

Ethernet technology can support IP packet services very well. It is characterized by simplicity, easy expansion, and low price. It has been widely used in LAN and metropolitan area networks. However, Ethernet technology cannot meet the reliability and scalability requirements of metropolitan area networks due to the lack of carrier-class quality of service (QoS), network fast protection, recovery and perfect operation and management (OAM). Correspondingly, the automatic discovery of the media access control (MAC) layer topology is slow and inefficient.

Resilient Packet Network (RPR) technology combines the advantages of Ethernet technology, Asynchronous Transfer Mode (ATM) technology, and SDH technology. Through the fair algorithm, the reuse problem of bandwidth between sites is well solved; the protection of loopback (Wrapping) and source routing (Steering) is provided, and the protection time is limited to 50ms; at the same time, high, medium and low are provided. A differentiated service with business priorities and a relatively complete OAM function is a more economical metro (MAN) solution. However, with the continuous development of information network technology and the rapid spread of the Internet, the concept of Next Generation Network (NGN) transport network has gradually formed, and the types, formats, and service requirements of network information flows have become increasingly rich, by SDH, asynchronous. The data transmission networks dominated by transmission mode (ATM), MSTP, and wavelength division multiplexing (WDM) technology are gradually becoming inadequate in handling the scheduling and exchange of transport layer services. NGN transport layer networks urgently need to be able to uniformly carry multiple services. A type of transport ring network technology that provides better QoS, is suitable for MAN and wide area network (WAN) applications, and is flexible and low-cost. To this end, the corresponding MPLS ring network technology has emerged.

Congestion is a common phenomenon in communication systems, but in the existing MPLS ring network technology, there is no control for congestion.

In the service node of the MPLS ring network, when the bandwidth of the high-priority service available in the link is as low as possible, the remaining bandwidth of the high-priority service is less than the total bandwidth of the best-effort service, and when congestion occurs, if multiple best-effort services are transmitted, Because the best efforts to transmit the traffic to preempt the bandwidth, it will cause some of the bandwidth that the best-effort service can occupy, while other best-effort services can only occupy the remaining bandwidth required by itself, resulting in the node trying to transmit the service. Unfair transmission. Further, in the case of congestion, due to unfair transmission, it is often the case that one or several of the best efforts to transmit the traffic cannot be transmitted. In the communication network, the general quality of service is not required for the best-effort service, but if a best-effort service fails to transmit at a certain node, it is unbearable for the user.

This is illustrated below by a specific example.

As shown in FIG. 1, the three nodes S1, S2, and S3 all transmit traffic to the node S4. Assume that the total bandwidth of the link is 10M. As shown in Figure 2, node S1 sends 6M service, node S2 sends 5M service, node S3 sends 2M service, and the service is trying to transmit service. Bandwidth characteristics, on the S2 node, the 5M service to be sent by the S2 node is only Can get 4M bandwidth. On the S3 node, since the total bandwidth of the link 10M has been completely preempted by the services sent by the S1 node and the S2 node, and no bandwidth is allocated to the 2M service to be sent by the node, the 2M service cannot be sent to the S4. It can be seen from the above example that the unfair transmission phenomenon of the best-effort transmission service occurs in the S2 and S3 nodes where congestion occurs, and the phenomenon that the traffic of the 2M service to be transmitted cannot be transmitted to the S4 at the S3 node. Summary of the invention

In view of the above problems in the prior art, an object of the present invention is to provide a method for implementing fair delivery of traffic in an MPLS ring network, which can implement fair transmission of best effort transmission services in an MPLS ring network.

The object of the invention is achieved by the following technical solutions:

The present invention provides a method for implementing fair delivery of traffic in an MPLS ring network, including:

A. Determine, according to the information carried in the MPLS packet, a packet that attempts to transmit the service;

B. The best-effort service packets sent to each ring direction are respectively scheduled according to the best-effort transmission service using a weighted fair scheduling algorithm.

The information carried in the MPLS packet may be: a service transmission value set in an EXP field of an experimental domain in an MPLS packet;

Then step A is:

When the service transmission value carried in the EXP field of the received packet is less than a preset threshold, it is determined that the packet is a packet that tries to transmit the service.

The information carried in the MPLS packet may also be: a best-effort service flag set in the best-effort service packet;

Then step A is:

When the received message carries the best effort service flag, it is determined that the message is exhausted. Force to transmit business messages.

Preferably, said best effort delivery service flag is set in a fixed bit of the message EXP field. The information carried in the MPLS packet may also be: an LSP label value;

Then step A is:

When the label exchange path LSP label value of the received packet is a pre-configured dedicated label value of the LSP transmitting the best effort transmission service, it is determined that the message is a best effort transmission service message.

The information carried in the MPLS packet may also be: an LSP label value and a service transmission value set in an EXP field of the packet;

Then step A is:

When the service transmission value carried in the EXP field of the received packet is smaller than a threshold corresponding to the LSP label value of the packet, it is determined that the packet is a packet that tries to transmit the service.

Preferably, the step B includes:

B1. Set the correspondence between the label value and the best-effort service queue with the weight set in the MPLS ring network node, and the MPLS ring network node sends the best-effort service report sent in each ring direction according to the label value of the best-effort service. The text is added to the corresponding best effort delivery service queue;

B2. The best effort transmission service in the ring direction is scheduled according to the weight of the best effort transmission service queue in each ring direction using a weighted fairness scheduling algorithm.

Preferably, the best effort delivery service queue includes:

A group of forwarding packets in the Transit direction corresponding to the packets sent by the upstream ring network node try to transmit the service queue and the packets in the ring-up direction corresponding to the packets entering the ring to transmit the service queue; and each ring direction of each node Each of the above two sets of queues is included.

The step B2 may include:

B21. When the number of packets in the queue in the best-effort transmission queue in the Transit direction exceeds the threshold set in advance for the queue, send the packet to the upstream ring network corresponding to the packet in the i-Hail queue. Controlling the information, requesting to reduce the traffic corresponding to the best effort delivery service;

B22. The upstream ring network node that receives the control information reduces the sending traffic corresponding to the best effort transmission service according to the control information.

Preferably, the control information includes stopping the sending time;

Then step B22 is:

The upstream ring network node that has received the control information stops the transmission of the corresponding best effort transmission service during the subsequent stop transmission time.

Preferably, the threshold set in advance for the queue is a first threshold; further, the method further includes setting a second threshold for each queue in the Transit direction, the second threshold being lower than the first set for the corresponding queue Threshold

Then, the step B21 further includes:

When the number of packets in the queue in the best-effort transmission queue in the Transit direction is lower than the second threshold set for the queue, the upstream ring network node sends a control request to resume transmission of the corresponding best-effort traffic.

The step B22 further includes:

Receiving the request to resume the transmission of the upstream ring network node corresponding to the control information of the best effort service traffic, and recovering the transmission of the corresponding best effort service according to the control information.

Preferably, the step B2 includes:

B23. When the number of packets in the queue in the best-effort transmission queue in the Add direction exceeds the threshold set in the Add direction queue in advance, the traffic corresponding to the best-effort transmission service is reduced.

The method for reducing the traffic corresponding to the best effort service described in step B23 may be: discarding the data packet that exceeds the fair rate portion of the corresponding best effort transmission service. The method for reducing the traffic of the best-effort transmission service described in the step B23 may be: sending the link layer flow control information to the service source direction, and adjusting the transmission traffic of the best-effort transmission service. The method for reducing the corresponding best-effort service traffic described in step B23 may also be: sending link layer flow control information to the service source direction, adjusting the transmission traffic of the best-effort transmission service; and discarding the fairness of the corresponding best-effort transmission service The packet of the rate part.

It can be seen from the technical solution provided by the present invention that the present invention can identify the best-effort transmission service according to the information carried in the packet on the node of the MPLS ring network, and then add the message to the corresponding transmission. In the bandwidth queue, the fair distribution of the bandwidth that the best-effort transmission service can occupy is realized, so that the best-effort transmission services transmitted by the network nodes in the MPLS ring network can effectively and reasonably occupy the remaining bandwidth resources of the high-priority service. The invention effectively solves the problem that the services of some nodes which may occur in the prior art cannot be sent at all. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic diagram of MPLS network service transmission;

2 is a schematic diagram of preempting bandwidth of each service in FIG. 1;

3 is a process flow diagram of a first embodiment of the present invention;

Figure 4 is a schematic diagram of the format of an MPLS packet;

FIG. 5 is a schematic diagram of scheduling a service according to a first embodiment of the present invention; FIG.

FIG. 6 is a format diagram of a flow control message according to a second embodiment of the present invention. Mode for carrying out the invention

The core idea of the present invention is to identify the best-effort transmission service in the MPLS ring network, and perform queue processing for the best-effort transmission service to ensure that each best-effort transmission service can fairly occupy the remaining bandwidth resources of the high-priority service.

The invention can be applied only in the case of congestion, or whether it occurs or not It is applied in the case of congestion. .

The invention will now be described in detail by way of specific examples.

The flow of the first embodiment of the method for implementing fair delivery of traffic according to the present invention is as shown in FIG. 3, and mainly includes the following steps:

Step 31: Determine, on the MPLS ring network node, the best-effort service according to the information carried in the received packet. That is, the packet of the corresponding best-effort service is determined from the packet received by the ring network node, so that the best-effort transmission service is processed according to the fair delivery of the traffic.

In this step, the experimental domain (EX) field reserved in the MPLS packet label Label can be used to identify the best-effort transmission service by carrying the service transmission value in the field. When identifying the best effort delivery service based on the service transmission value of the EXP field, it is necessary to manually configure a threshold in the MPLS ring node. In addition, when the value of the EXP field in the message label is set for the best effort transmission service, the value is set to be smaller than the threshold value, and when the value of the EXP field in the message label is set for the non-best effort transmission service, the value is set to be greater than or equal to the threshold value. Value. Then, when the service transmission value carried by the EXP field in the packet received by the MPLS ring network node is smaller than a preset threshold in the node, the packet is determined to be a packet for best effort transmission. The structure of the MPLS packet label is shown in Figure 4. It can be seen from the figure that the EXP field has 3 bits, and the field can take a value of 0 to 7.

In addition, in this step, a fixed bit in the EXP field may also be utilized, and the fixed bit is set to the best effort service flag for the best effort transmission service in the service transmission process to distinguish it from other services. For example, for the first bit of the EXP field, if the bit is set to 0 if it is a best effort service, then this 0 is the best effort service flag; if it is a non-best effort service, the bit is set to 1. In this way, the MPLS ring network node can judge whether the received service packet is a best-effort service according to the value of the bit.

The service packet discussed in the present invention is a service packet transmitted in an MPLS ring network. Therefore, the MPLS ring network node can also identify the best-effort service packet according to the label value of the LSP. To this end, each node in the MPLS ring network needs to set a dedicated label value of a group of LSPs that transmit the best-effort transmission service, and when transmitting the best-effort transmission service, the best-effort transmission service is transmitted by using the configuration-dedicated LSP, so that The ring network node can determine the best-effort service packet in the received service packet according to the label value.

Of course, in the present invention, whether the service packet received by the ring network node is a best-effort service packet is determined according to the combination of the label value and the EXP field value of the LSP. For example, for a service transmitted by an LSP corresponding to a preset set of LSP label values, a judgment threshold according to whether it is a best effort transmission service is 5; a service transmitted by an LSP corresponding to another set of LSP label values When judging whether it is trying to transmit the service, the judgment threshold is based on 3.

Step 32: After the packet is identified as a best-effort service packet, the service packet sent to each ring direction is enqueued according to the MPLS label in the packet, and each level of the best-effort transmission service is performed. Corresponding to a queue, that is, the best-effort service packets with the same weights correspond to the same queue, and the weights correspond to the importance of the best-effort service, that is, the amount of bandwidth resources that can be allocated for the service.

The queue in each ring direction includes a best-effort service message queue and a local upper ring sent by the upstream ring network node, that is, the best-effort service that is added to the ring by the node (that is, the node is connected to the ring) The queues are recorded as the transit direction queue and the add direction queue. When the packets in the queue are scheduled, the corresponding packets are sent to the corresponding ring for transmission. Because the MPLS ring has two directions, there are two sets of queues and two instances of the WRR weighted polling scheduling algorithm.

In a specific application process, the specific LSP label value of the best-effort service may be used to determine which queue to send the packet to the Transit direction or the Add direction queue. Take the Transit direction as an example. If the local node is configured as follows: The queue corresponding to the LSP label values 1 and 3 is 1, the weight of the queue is 3; the queue corresponding to the LSP label value 4 is 2, and the weight of the queue is 2. Tag value 5 The queue corresponding to 12 is queue 3, and the queue has a weight of 1. After receiving the best-effort service packet with the tag values of 1 and 3, the local node sends the packet to P column 1; after receiving the best-effort service packet with the tag value of 4, the packet is sent to the queue. 2; After receiving the best effort service ^ with a tag value of 5 to 12, the message is sent to queue 3.

Step 33: The WRR (weighted random discarding algorithm) weighted round-robin scheduling algorithm is used to perform scheduling processing on the packets in each queue, that is, sent to the MPLS ring network for transmission;

The WR weighted round robin algorithm is a weight-based scheduling algorithm, which is based on the weighting of each queue configuration by the user. For example, corresponding to the example in the foregoing step 32, the weight of the queue 1 is 3, the weight of the queue 2 is 2, and the weight of the queue 3 is 1, the speed of sending the packet in the queue 1 is the sending speed of the packet in the queue 3. 3 times, the speed of sending packets in queue 2 is twice the sending speed of packets in queue 3, and the sending speed of packets in the queue with the same weight is the same. For example, there is a queue 4 in the queue of Add direction. The weight of the packet is 3, and the packet transmission rate of the service in queue 4 and the queue 1 in the transit queue are the same.

Step 34: After the WR-scheduled message, the priority scheduling (SP) is performed together with the non-best-effort transmission service, because the best-effort transmission service has the lowest priority, so it can only occupy the bandwidth other than the best-effort transmission service, as shown in the figure. 5 is shown.

It can be seen that in the present invention, all of the best effort transmission services achieve a fair occupancy of bandwidth over the MPLS loop, achieving the object of the present invention.

In the second embodiment provided by the present invention, the flow control feedback mechanism for each service traffic is further included on the basis of the first embodiment, and since the label value of the LSP is generally only valid on a segment of the LSP link, The flow control feedback mechanism should be a flow control feedback mechanism between two adjacent ring nodes in the MPLS ring network.

First, two thresholds are respectively set for each queue in step 32, one is a high threshold Ht and one is a low threshold Lt, and a variable S is also set for recording the current queue. State, S is initially in the L state;

The following describes the specific flow control feedback mechanism of the Transit direction queue and the Add direction queue of the ring network node:

(1) When the queue is a queue in the Transit direction, the corresponding flow control feedback mechanism can be:

When the number of packets in the queue exceeds the set high threshold Ht, and the variable S is in the L state, the variable S of the queue is set to the H state, indicating that the number of packets in the queue exceeds the setting. The high threshold value is sent to the ring network node of the ring network at the same time. The flow control message uses a special tag value, and the forwarding priority is the highest, and the content of the packet further includes the corresponding queue. The identifier of the service, and a time value, where the time value indicates how long the corresponding message stops transmitting; the flow control message includes a special label Label value, and the corresponding value can be adopted. As shown in Figure 6, the packet format includes: a tag value Lable field, an EXP field, a bottom layer identifier, and a TTL field. In addition, the Holding ID in the figure is the ID of the best effort service, and the Holding Time is the above time value. . The tag value field may be assigned by a tag assignment protocol or a fixed special tag value.

When the number of packets in the queue is lower than the set low threshold Lt and the variable S is in the H state, when the variable S of the queue is set to the L state, the number of packets in the queue is lower than the setting. The lower threshold, and the flow control packet sent to the upstream ring network node, the time value involved in the packet is 0.

After the upstream ring network node receives the traffic control packet, the WRR scheduling determines the corresponding packet queue according to the ID of the carried service, and stops scheduling the packet from the queue, and sets a timer and timer. The time is the time value carried in the packet. When the timer expires, the packet in the queue is rescheduled. Of course, when the packet with the time value of 0 is received, the packet in the queue is rescheduled immediately. Text.

(2) When the queue is a queue in the Add direction, the corresponding flow control feedback machine The system can be:

When the number of packets in the queue exceeds the set high threshold, you can select two modes. One is packet loss. For example, you can use the Weighted Random Early Detection (WRED) technology to discard packets. It is to notify the client side to stop sending the link layer flow control information in the direction of the service source. For example, the PAUSE frame technology in the IEEE 802.3 protocol can be used. In addition, when the number of packets in the queue exceeds the set high threshold, the above two methods can also be used at the same time.

Therefore, in the present invention, the message queue feedback mechanism is used, and the service transmission is blocked to the upstream ring network node step by step, and finally the access node to the ring on the ring is fed back to the client layer of the ring to reduce the service rate. To achieve business fairness. The specific needs of the physical situation. Therefore, it is to be understood that the specific embodiments of the present invention are not intended to limit the scope of the invention.

Claims

Claim

A multi-protocol label switching method for implementing fair delivery of traffic in an MPLS ring network, characterized in that the method comprises:

A. determining, according to the information carried in the MPLS packet, that the packet is a packet that tries to transmit the service;

B. The best-effort service packets sent to each ring direction are respectively scheduled according to different weighted fair scheduling algorithms corresponding to the best-effort transmission service.

The method for implementing fair delivery of traffic in an MPLS ring network according to claim 1, wherein the information carried in the MPLS packet is: a service transmission value set in an EXP field of an experimental domain in an MPLS packet. ;

Then step A is:

When the service transmission value carried in the EXP field of the packet received by the MPLS ring network node is smaller than the pre-set threshold, the packet is determined to be the best-effort service packet.

The method for implementing fair delivery of traffic in an MPLS ring network according to claim 1, wherein the information carried in the MPLS packet is: a best effort service flag set in a best effort service packet;

Then step A is:

When the received message carries the best-effort service flag, it is determined that the message is a message that tries to transmit the service.

The method for implementing fair delivery of traffic in an MPLS ring network according to claim 3, wherein the best effort transmission service flag is set in a fixed bit of a message EXP field.

The method for implementing the fair delivery of the traffic in the MPLS ring network according to claim 1, wherein the information carried in the MPLS packet is: a label switched path LSP label value; Then the step A is:

The method for implementing the fair delivery of the traffic in the MPLS ring network according to claim 1, wherein the information carried in the MPLS packet is: an LSP label value and a service transmission set in an EXP field of the packet. Value

Then step A is:

The method for implementing fair delivery of traffic in an MPLS ring network according to claim 1, wherein the step B includes:

B2. Use the weighted fairness algorithm to schedule the best effort service message according to the weight of the best effort service queue in each ring direction.

The method for implementing fair delivery of traffic in an MPLS ring network according to claim 7, wherein the best-effort transmission service queue includes:

The method for implementing the fair delivery of the traffic in the MPLS ring network according to claim 8, wherein the step B2 includes: When the threshold is set in advance for the queue, the upstream ring network node corresponding to the packet in the queue sends control information, requesting to reduce the traffic corresponding to the best-effort service;

The method according to claim 9, wherein the control information includes stopping transmission time;

Then step B22 is:

The method according to claim 9, wherein the threshold set in advance for the queue is a first threshold; further, the method further includes setting a second threshold for each queue in the Transit direction, the first The second threshold is lower than the first threshold of the queue;

Then, the step B21 further includes:

When the number of packets in the queue in the best-effort transmission queue in the Transit direction is lower than the second threshold corresponding to the queue, the upstream ring network node sends a request to resume the transmission of the control information corresponding to the best-effort traffic.

The step B22 further includes:

Receiving the request to resume the transmission of the upstream ring network node corresponding to the control information of the best effort transmission service traffic, and recovering the transmission corresponding to the best effort transmission service according to the control information.

The method for implementing fair delivery of traffic in an MPLS ring network according to claim 8, wherein the step B2 includes:

B23. When the number of packets in the queue in the best-effort transmission queue in the Add direction exceeds the threshold set in the queue for the Add direction, the traffic corresponding to the best-effort transmission service is reduced.

The method for implementing fair delivery of traffic in an MPLS ring network according to claim 12, wherein the method for reducing traffic corresponding to best effort transmission in step B23 is: And discarding the data packet in the corresponding best effort transmission service that exceeds the fair rate portion.

The method for implementing the fair delivery of the traffic in the MPLS ring network according to claim 12, wherein the method for reducing the traffic corresponding to the best effort transmission in the step B23 is: sending the link layer flow control to the service source direction. Information, adjust the sending traffic of the best-effort delivery service.

The method for implementing the fair delivery of the traffic in the MPLS ring network according to claim 12, wherein the method for reducing the traffic corresponding to the best effort transmission in the step B23 is: sending the link layer flow control to the service source direction. And adjusting the sending traffic of the best effort transmission service; and discarding the data packet in the corresponding best effort transmission service that exceeds the fair rate portion.