CN112291161B

CN112291161B - Time-sensitive network mixed flow scheduling method

Info

Publication number: CN112291161B
Application number: CN202011076958.0A
Authority: CN
Inventors: 袁亚洲; 曹旭; 陈彩莲; 杨博; 关新平
Original assignee: Yanshan University
Current assignee: Yanshan University
Priority date: 2020-10-10
Filing date: 2020-10-10
Publication date: 2022-03-11
Anticipated expiration: 2040-10-10
Also published as: CN112291161A

Abstract

The invention discloses a mixed traffic scheduling method of a time-sensitive network, which belongs to the technical field of time-sensitive networks of industrial Internet of things. On the basis of the gate control list, AVB and BE flow adopts a fuzzy control-based restricted preemption scheduling method. The method ensures that TT flow with the highest priority on site completes the determined real-time transmission, reduces AVB flow delay, ensures audio and video transmission quality, reduces bandwidth waste caused by AVB preemption to a certain extent, improves scheduling performance, and solves the scheduling problem of mixed flow common transmission.

Description

Time-sensitive network mixed flow scheduling method

Technical Field

The invention relates to the technical field of time-sensitive networks of industrial Internet of things, in particular to a time-sensitive network mixed flow scheduling method.

Background

In recent years, the traditional field production and manufacturing mode is gradually changed by the industrial internet of things (IIoT), data exchange among industrial equipment is allowed, and the field environment is monitored in real time through a high-precision sensor, so that production informatization and intellectualization are realized. To meet the stringent requirements of industrial field applications to determine real-time transmission, the IEEE802.1 working group developed a universal real-time ethernet standard, i.e., the IEEE802.1 time-sensitive network (TSN) standard, seeking to provide deterministic ethernet functionality based on clock synchronization, traffic shaping, data frame preemption, centralized network configuration.

At present, TSN-related research work focuses on time-sensitive traffic (TT traffic), excessively sacrifices time delay of non-TT traffic, audio and video traffic (AVB traffic) with the same relatively harsh requirement on time delay cannot arrive within an expiration date, and best effort traffic (BE traffic) in a network has certain interference, so that the transmission effect of mixed traffic cannot reach an expected standard. Because the research field of the TSN is relatively novel, and few workers finish the mixed transmission of 3 different types of flow, a new mixed flow scheduling method is provided to finish high-quality end-to-end transmission in an industrial field with coexisting multi-type flow.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a method for scheduling mixed traffic of a time-sensitive network, which ensures that TT traffic with the highest priority on site completes the determination of real-time transmission, reduces AVB traffic delay, ensures audio and video transmission quality, reduces bandwidth waste caused by AVB preemption to a certain extent, improves scheduling performance, and solves the scheduling problem of mixed traffic co-transmission.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows:

a time-sensitive network mixed flow scheduling method comprises the following steps:

step 1, defining characteristic parameters of each data frame of a network topology, wherein the flow in a flow set is represented by a six-tuple less than S, D, p, D, q and l, S represents a source node, D represents a target node, p represents a transmission period, D represents deadline, q represents a transmission queue ID, and l represents the length of a data frame. Wherein, each flow satisfies p is less than or equal to d;

and 2, according to the IEEE802.1Qbv standard, a time-aware shaper is utilized to design a gate control list to distinguish and process TT traffic and non-TT traffic, wherein the non-TT traffic comprises AVB traffic and BE traffic. The time perception shaper is TAS, the gate control list is GCL, and TT flow is ensured to be determined and transmitted in real time by establishing a completely independent time window;

step 3, flow of each queue in the transmission process is according to a formula

Judging the priority degree and reordering the queue flow, and arranging the flow with the lower W value in front of the queue so as to be sent preferentially; t represents the time when the flow reaches the node, and d represents the cut-off time of each type of flow;

step 4, transmitting various flows in a specific time slot window opening period according to a gating mechanism; during the opening period of a non-TT flow time slot window, AVB flow and BE flow adopt a fuzzy control-based occupation limiting scheduling method, wherein the occupation limiting scheduling method is to allow the AVB flow to occupy the BE flow according to a difference value between a residual time proportion and a residual transmission proportion and a fuzzy criterion established by flow priority, reduce the delay of higher priority flow and reduce bandwidth waste caused by frequent occupation to a certain extent;

step 5, formulating fuzzy rule according to step 4

(1) The difference rule of the remaining time proportion and the remaining transmission proportion is as follows:

the remaining time ratio:

the remaining transmission ratio:

difference value: Δ ═ M-N

T_pmRepresenting the current time, d representing the cutoff time, T_tcRepresents the completed transmission time, T, corresponding to the position of the flow_nqRepresenting the transmission time required for traffic without queuing;

determining the emergency degree according to the difference value delta, wherein the smaller the difference value is, the higher the emergency degree is;

(2) and (3) queue rules:

the switch comprises 7 non-TT flow priority queues in total, the queue numbers are from 0 to 6, and the higher the number is, the higher the priority of the stored flow is; the queue 7 is used for transmitting TT flow, the queue 6 and the queue 5 are used for transmitting AVB flow, and the rest queue is used for transmitting BE flow;

step 6, accurately describing the fuzzy object according to the difference value delta and the membership degree corresponding to the priority, and acquiring a final grade corresponding to fuzzy output by using a fuzzy logic control table; if the AVB traffic fuzzy output level is higher than the BE traffic, then preemption events are allowed to occur, otherwise preemption is not allowed.

The technical scheme of the invention is further improved as follows: in step 2, each TAS has 8 queues for storing data frames waiting to be forwarded on the corresponding link, and each queue has a gate with two states, namely an open state and a closed state; frames waiting in the queue are eligible for forwarding only when the associated door is open, the frames in the queue being in a wait-to-forward state during the closing of the associated door; eliminating the worst-case delay overshoot by mandatory full isolation; only considering how GCL is generated during the first super-period, after the first super-period, the subsequent scheduling follows a periodic cyclic rule, the first super-period being the least common multiple of the period of each traffic.

The technical scheme of the invention is further improved as follows: in step 3, the queue traffic reordering mechanism allows the traffic which enters the queue later and has a higher urgency to be sent first, and the queue reordering is limited to the queue, and does not involve cross-queue reordering.

The technical scheme of the invention is further improved as follows: step 4-step 6, during the opening of the associated door of the TT queue, the determined high-quality transmission of the TT flow is completed; during the period that the AVB and BE queue association gate is opened, the AVB traffic allows the BE traffic to BE subjected to limitation preemption based on fuzzy control.

Due to the adoption of the technical scheme, the invention has the technical progress that:

the method ensures that TT flow with the highest priority on site completes the determined real-time transmission, reduces AVB flow delay, ensures audio and video transmission quality, reduces bandwidth waste caused by AVB preemption to a certain extent, improves scheduling performance, and solves the scheduling problem of mixed flow common transmission.

Drawings

Fig. 1 is a flow chart of a hybrid traffic scheduling method in the present invention;

FIG. 2 is a schematic diagram of a channel transmission mode according to the present invention;

FIG. 3 is a schematic diagram of a hybrid traffic scheduling mechanism according to the present invention;

FIG. 4 is a flow priority membership graph in accordance with the present invention;

fig. 5 is a membership graph of flow urgency according to the present invention.

Detailed Description

The present invention will be described in further detail with reference to the following examples:

fig. 1 is a flowchart of a hybrid traffic joint routing and scheduling method of the present invention, which can be applied to a field topology model, wherein a hybrid traffic transmission process follows the channel transmission mode of fig. 2, and a scheduling manner satisfies the hybrid traffic scheduling mechanism of fig. 3. The steps involved in the method are described in detail below.

Step 1, defining characteristic parameters of each data frame of a network topology, representing the flow in a flow set by a six-tuple less than S, D, p, D, q and l, and respectively representing a source node, a target node, a transmission period, a cut-off time, a transmission queue ID and a data frame length. Wherein, each flow satisfies p is less than or equal to d.

And 2, according to the IEEE802.1Qbv standard, a time perception shaper (TAS) design Gate Control List (GCL) is used for distinguishing and processing TT flow and non-TT flow, wherein the non-TT flow comprises AVB and BE flow, and the determined real-time transmission of the TT flow is ensured by establishing a completely independent time window.

And judging the priority degree, reordering the queue traffic, arranging the traffic with a lower W value in front of the queue so as to be sent preferentially, wherein the queue reordering is only limited to the queue, and does not relate to cross-queue reordering. t represents the time when the traffic reaches the node, and d represents the deadline of each type of traffic.

And 4, transmitting the various flows during the opening period of the specific time slot window according to the gating mechanism. During the period that a time slot window of non-TT flow is opened, AVB flow and BE flow adopt a fuzzy control-based limited preemption scheduling method, namely, a fuzzy rule established according to the difference value of the residual time proportion and the residual transmission proportion and the flow priority allows the AVB flow to preempt the BE flow, the time delay of the higher priority flow is reduced, and the bandwidth waste caused by frequent preemption is reduced to a certain extent.

Step 5, formulating fuzzy rule according to step 4

the remaining time ratio:

the remaining transmission ratio:

difference value: Δ ═ M-N

T_pmRepresenting the current time, d representing the cutoff time, T_tcRepresents the completed transmission time, T, corresponding to the position of the flow_nqRepresenting the required transmission time for traffic without queuing.

The degree of urgency is determined from the difference Δ, with smaller differences being more urgent.

(2) And (3) queue rules:

the switch comprises 7 non-TT traffic priority queues in total, the queue numbers are from 0 to 6, and the higher the number is, the higher the priority of the stored traffic is. Queue 7 is used to transmit TT traffic, queue 6 and queue 5 are used to transmit AVB traffic, and the remaining queues are used to transmit BE traffic.

And 6, accurately describing the fuzzy object according to the difference value delta and the membership corresponding to the priority, and acquiring the final grade corresponding to the fuzzy output by utilizing the fuzzy logic control table in the table 1. The traffic table with the importance attribute of general and the urgency attribute of urgent in table 1 is ranked as G₇The importance attribute is urgency and the urgency attribute is general traffic lookup table level G₈The importance of the flow is more critical than the urgency in the parameter settings embodying table 1. And finally, the decision rule is that if the AVB flow fuzzy output level is higher than the BE flow, the preemption event is allowed to occur, otherwise, the preemption is not allowed.

TABLE 1 fuzzy logic control table

The above-mentioned embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solution of the present invention by those skilled in the art should fall within the protection scope defined by the claims of the present invention without departing from the spirit of the present invention.

Claims

1. a time-sensitive network mixed traffic scheduling method, is characterized in that comprising the following steps:

Step 1: Define the characteristic parameters of each data frame in the network topology. The traffic in the traffic set is represented by a six-tuple <S, D, p, d, q, l>, S represents the source node, D represents the target node, and p represents the transmission Period, d represents the deadline, q represents the ID of the transmission queue, and l represents the length of the data frame, where each traffic satisfies p≤d;

Step 2: According to the IEEE802.1Qbv standard, use the time-aware shaper to design a gate control list to distinguish between TT traffic and non-TT traffic, where the non-TT traffic includes AVB traffic and BE traffic, the time-aware shaper is TAS, and the gate control list is GCL , by establishing a completely independent time window to ensure the definite real-time transmission of TT traffic;

Step 3: During the transmission process, the traffic of each queue is based on the formula

Determine the priority and reorder the queue traffic, and arrange the traffic with a lower W value in front of the queue for priority sending; t represents the time when the traffic arrives at the node, and d represents the deadline for each type of traffic;

Step 4: According to the gating mechanism, various types of traffic are transmitted during the opening of a specific time slot window; among them, during the opening of the non-TT traffic time slot window, the AVB traffic and BE traffic adopt a limited preemption scheduling method based on fuzzy control to limit preemption. The scheduling method is to allow AVB traffic to preempt BE traffic, reduce the delay of higher priority traffic, and reduce frequent preemption to a certain extent. bandwidth waste;

Step 5, formulate fuzzy rules according to step 4

(1) The difference rule between the remaining time ratio and the remaining transmission ratio:

Ratio of remaining time:

Remaining transfer ratio:

Difference: Δ=M-N

T _pm represents the current time, d represents the deadline, T _tc represents the completed transmission time corresponding to the location of the traffic, and T _nq represents the transmission time required by the traffic when there is no queue;

Determine the degree of urgency according to the difference Δ, the smaller the difference, the higher the degree of urgency;

(2) Queue rules:

The switch contains a total of 7 non-TT traffic priority queues. The queue numbers are from 0 to 6. The higher the number, the higher the priority of the stored traffic. Queue 7 is used to transmit TT traffic, and queue 6 and queue 5 are used to transmit AVB traffic. The remaining queues are used to transmit BE traffic;

Step 6: Accurately describe the fuzzy object according to the membership degree corresponding to the difference Δ and the priority, and then use the fuzzy logic control table to obtain the final level corresponding to the fuzzy output; if the fuzzy output level of the AVB flow is higher than the BE flow, then Preemption events are allowed to occur, otherwise preemption is not allowed.

2. a kind of time-sensitive network mixed traffic scheduling method according to claim 1, is characterized in that: in described step 2, each TAS has 8 queues for storing and waiting to forward data frames on corresponding links, Each queue has a gate with two states, an open state and a closed state; frames waiting in the queue are only eligible for forwarding when the associated gate is open, and frames in the queue are in the waiting state for forwarding while the associated gate is closed ; Eliminate the worst-case high latency phenomenon through mandatory complete isolation; only consider how the GCL is generated in the first super cycle, after the first super cycle, the subsequent scheduling follows the periodic round-robin rule, the first Each superperiod is the least common multiple of the period of each flow.

3. A time-sensitive network hybrid traffic scheduling method according to claim 1, wherein: in the step 3, the queue traffic reordering mechanism is allowed to enter the queue and the traffic with higher urgency is sent first, and the queue is reordered. The queue is limited to this queue and does not involve reordering across queues.

4. a kind of time-sensitive network mixed traffic scheduling method according to claim 1, is characterized in that: in step 4-step 6, during the opening period of TT queue correlation gate, complete the determined high-quality transmission of TT traffic; During the opening of the BE queue association gate, AVB traffic is allowed to limit preemption of BE traffic based on fuzzy control.