CN103338158A - GOOSE message transmission delay jitter suppression method - Google Patents

Abstract

The invention belongs to the technical field of electric power system communication, and proposes a method for suppressing GOOSE message transmission delay and jitter. The method adopts a backup retransmission mechanism to back up ordinary frames being sent by a port to a buffer; if any GOOSE message is forwarded to the port, stop sending normal frames and start forwarding GOOSE messages, and resend the normal frames backed up in the buffer after the GOOSE message forwarding is completed. This method can ensure that the forwarding delay of the GOOSE message does not cause jitter due to the common frame occupying the port, and is compatible with various existing Ethernet standards, and does not require any software and hardware modification of the terminal equipment.

Description

A method for suppressing GOOSE message transmission delay jitter

technical field

The invention belongs to the technical field of power system communication, and in particular relates to a method for suppressing GOOSE message transmission time delay jitter.

Background technique

The smart substation adopts the IEC61850 unified communication protocol, which is usually divided into process layer, bay layer and station control layer. Bay layer and station control layer equipment, process layer and bay layer equipment are interconnected through the communication network, and are used to control the GOOSE switch tripping or closing. Messages are transmitted through this communication network, so the real-time communication of GOOSE messages is very critical.

At present, the priority of GOOSE messages can be set to the highest through QoS technology, or a dedicated queue for GOOSE messages with the highest priority can be designated separately, and GOOSE messages can be sent to this dedicated queue for forwarding by means of message identification. , these two methods guarantee the real-time performance of GOOSE messages to a certain extent; especially the latter method can ensure that the priority of GOOSE messages is higher than that of all ordinary frames, thereby reducing the transmission delay of GOOSE messages.

However, limited by the switch forwarding mechanism, if a normal frame is being sent on the switch port, even if the GOOSE message has the highest priority, it needs to wait for the normal frame to be sent before it can be sent. Therefore, when the GOOSE message is forwarded in the switch Latency creates jitter based on the frame length of the normal frames the port is sending. According to the standard of Ethernet, the common frame length is between 64 bytes and 1518 bytes. When the port rate is 100M bit/s, it can be calculated that the GOOSE message delay jitter ranges from 5.12 microseconds to 121.44 microseconds between. The delay jitter is far greater than the average transmission delay of the switch (about 10 microseconds), which seriously affects the real-time performance of GOOSE packets, and effective measures need to be taken to suppress it.

Contents of the invention

Aiming at the deficiencies of the prior art, the present invention proposes a GOOSE message transmission time delay jitter suppression method, which is used to suppress the GOOSE message transmission time delay jitter of an industrial Ethernet switch.

A kind of GOOSE message transmission delay jitter suppressing method provided by the present invention, its improvement is that, described method comprises the following steps:

(1) Set a 1518-byte ordinary frame buffer on the Ethernet port of the switch;

(2) Set a dedicated queue for GOOSE messages with the highest priority on the Ethernet port of the switch;

(3) After the Ethernet port of the switch receives a frame, it judges the destination MAC address and Ethernet type value of the received frame through the GOOSE message identification module. If it is a GOOSE message, it is sent to the dedicated GOOSE message of the corresponding port. queue;

(4) When the Ethernet port of the switch sends a normal frame, the normal frame is backed up to the buffer before sending;

(5) When there are GOOSE messages in the GOOSE message queue of the Ethernet port, if the Ethernet port is not sending ordinary frames, then forward the GOOSE messages; if the port is sending ordinary frames, then stop sending the ordinary frames. frame, forwarding the GOOSE message at the beginning of the next clock cycle, and forwarding the normal frame backed up in the buffer after the sending of the GOOSE message is completed.

Among them, in step (3), the processing process of the GOOSE message identification module to determine the destination MAC address and Ethernet type value of the received frame includes:

If the destination MAC address of the received frame is between 0x010CCD010000--0x010CCD0101FF, and the Ethernet type value is 0x88B8, then it is judged that the received frame is a GOOSE message, and it is sent to the dedicated queue for the GOOSE message of the corresponding port;

If the destination MAC address of the received frame does not belong between 0x010CCD010000——0x010CCD0101FF, then it is judged that the received frame is a common frame, and forwarded according to the forwarding mechanism;

If the destination MAC address of the received frame is between 0x010CCD010000-0x010CCD0101FF, and the Ethernet type value is not 0x88B8, it is judged that the received frame is a normal frame, and forwarded according to the forwarding mechanism.

Wherein, in step (4), after each normal frame in the buffer is completely sent out, the buffer is cleared.

Wherein, in step (3), the Ethernet port of the switch performs a frame length check when receiving an Ethernet frame, and discards an Ethernet frame with a wrong frame length.

Wherein, the manner of performing length check on the Ethernet frame includes:

1) Judging according to the frame length, if the frame length is less than 64 bytes, then keep the Ethernet frame, otherwise discard it;

2) Judging according to the definition of the frame length, if it does not meet the definition of the frame length, discard it, otherwise keep the Ethernet frame.

Compared with the prior art, the beneficial effects of the present invention are:

The invention sets a common frame buffer of 1518 bytes on the Ethernet port of the switch for storing backup common frames, prepares for processing when GOOSE messages appear, and ensures the accuracy of data.

The present invention sets a dedicated queue for GOOSE messages with the highest priority on the Ethernet port of the switch to ensure the accuracy and real-time performance of the GOOSE messages.

The present invention backs up the common frames to the buffer before sending them; after each common frame in the buffer is completely sent out, the buffer is cleared to ensure the integrity of common posts, and the operation process of clearing the buffer saves space resources .

In the present invention, when the port is sending ordinary frames, if the GOOSE message enters the dedicated queue, the sending of the ordinary frame will be stopped, and the GOOSE message will be forwarded at the beginning of the next clock cycle. After the GOOSE message is sent, it will be forwarded in the buffer This method can ensure that the forwarding of GOOSE messages will not be affected by ordinary frames, so that the transmission delay of GOOSE messages in the switch is a fixed value, and the delay jitter caused by ordinary frames occupying ports is suppressed.

The invention checks the frame length when the Ethernet port of the switch receives the Ethernet frame, discards the Ethernet frame with wrong frame length, ensures the correctness of information, saves time and improves efficiency.

The invention is compatible with various existing Ethernet standards, does not need any software and hardware modification of terminal equipment, and ensures the universality of the method.

Description of drawings

FIG. 1 is a flowchart of a method for judging GOOSE messages provided by the present invention.

Fig. 2 is a flow chart of the port sending a message provided by the present invention.

Detailed ways

The specific implementation manners of the present invention will be further described in detail below in conjunction with the accompanying drawings.

The present invention proposes a GOOSE message transmission delay jitter suppression method, comprising the following steps:

(1) Set a 1518-byte ordinary frame buffer on the Ethernet port of the switch; (the "ordinary frame" in this embodiment is used to distinguish GOOSE files, that is, frames other than GOOSE messages are ordinary frames)

(2) Set a dedicated queue for GOOSE messages with the highest priority on the Ethernet port of the switch;

(3) After the Ethernet port of the switch receives a frame, it judges the destination MAC address and Ethernet type value of the received frame through the GOOSE message identification module. If it is a GOOSE message, it is sent to the dedicated GOOSE message of the corresponding port. queue;

Wherein, the processing procedure of the GOOSE message recognition module judging the destination MAC address and the Ethernet type value of the received frame is as shown in Figure 1, including:

If the destination MAC address of the received frame is between 0x010CCD010000--0x010CCD0101FF, and the Ethernet type value is 0x88B8, then it is judged that the received frame is a GOOSE message, and it is sent to the dedicated queue for the GOOSE message of the corresponding port;

If the destination MAC address of the received frame does not belong between 0x010CCD010000——0x010CCD0101FF, then it is judged that the received frame is a common frame, and forwarded according to the forwarding mechanism;

If the destination MAC address of the received frame is between 0x010CCD010000-0x010CCD0101FF, and the Ethernet type value is not 0x88B8, it is judged that the received frame is a normal frame, and forwarded according to the forwarding mechanism.

Among them, the Ethernet port of the switch performs frame length check when receiving Ethernet frames (including GOOSE messages and ordinary frames), and discards Ethernet frames with wrong frame lengths. Ways to check the length of Ethernet frames include:

Judging according to the frame length, if the frame length is less than 64 bytes, then retain the Ethernet frame, otherwise discard; or

Judging according to the definition of the frame length, if it does not meet the definition of the frame length, discard it, otherwise keep the Ethernet frame.

(4) When the Ethernet port of the switch sends ordinary frames, the ordinary frames are backed up to the buffer before sending; after each ordinary frame in the buffer is completely sent out, the buffer is cleared;

(5) When there are GOOSE messages in the GOOSE message queue of the Ethernet port, if the Ethernet port is not sending ordinary frames, it will forward the GOOSE messages normally; if the port is sending ordinary frames, it will stop sending the said frame. Ordinary frame forwards the GOOSE message when the next clock cycle begins, and retransmits the ordinary frame backed up in the buffer after the GOOSE message is sent. The process is as shown in Figure 2.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: the present invention can still be Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention shall be covered by the scope of the claims of the present invention.

Claims (5)

1. a GOOSE message transmissions delay variation inhibition method is characterized in that described method comprises the steps:

(1) sets the normal frames buffering area of 1518 bytes at the ethernet port of switch;

(2) set the GOOSE message private queue of a limit priority at the ethernet port of switch;

(3) after the ethernet port of switch receives a frame, by target MAC (Media Access Control) address and the ethernet type value of GOOSE message identification module judgement received frame, if the GOOSE message is sent it into the GOOSE message private queue of corresponding port;

When (4) ethernet port of switch sends normal frames, send again after described normal frames backed up to buffering area;

(5) when in the GOOSE of the ethernet port message private queue GOOSE message being arranged, if this ethernet port is then transmitted the GOOSE message not sending normal frames; If this port sending normal frames, then stop to send described normal frames, when the next clock cycle begins, transmit described GOOSE message, treat that described GOOSE message is sent completely after, the described normal frames that backs up again in intransit buffering the district in.

2. the method for claim 1 is characterized in that, in the step (3), GOOSE message identification module judges that the target MAC (Media Access Control) address of received frame and the processing procedure of ethernet type value comprise:

If the target MAC (Media Access Control) address of received frame is between 0x010CCD010000---between the 0x010CCD0101FF, and the ethernet type value is 0x88B8, judges that then described received frame is the GOOSE message, and it is sent into the GOOSE message private queue of corresponding port;

If the target MAC (Media Access Control) address of received frame does not belong to 0x010CCD010000---between the 0x010CCD0101FF, judge that then described received frame is normal frames, transmits according to forwarding mechanism;

If the target MAC (Media Access Control) address of received frame is between 0x010CCD010000---between the 0x010CCD0101FF, the ethernet type value is not 0x88B8, judges that then described received frame is normal frames, transmits according to forwarding mechanism.

3. the method for claim 1 is characterized in that, in the step (4), after complete the sending of every frame normal frames, empties described buffering area in buffering area.

4. the method for claim 1 is characterized in that, in the step (3), the ethernet port of described switch carries out the frame length inspection when receiving ethernet frame, abandons the ethernet frame of frame length mistake.

5. method as claimed in claim 4 is characterized in that, the mode of ethernet frame being carried out length check comprises:

1) judges according to frame length, if frame length less than 64 bytes, then keeps described ethernet frame, otherwise abandons;

2) judge according to the definition of frame length, if do not meet the frame length definition, then abandon, otherwise keep described ethernet frame.

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