JP4890285B2 - Network relay device - Google Patents

Description

  The present invention relates to a network relay device that processes IP packets on an Ethernet (registered trademark) frame such as an IP router, a layer 3 switch, or a personal computer.

  When a device that transfers IP packets, such as a conventional IP router, receives traffic that exceeds the processing performance of its own transfer processing unit, it sends a pause frame from the flow control unit to the adjacent transmission source device. By sending a request to stop transmission for a specified period of time, the reception control unit prevents discarding, and the transmission control unit prevents priority transmission control from delaying or discarding high-priority frames. It was out.

  When network congestion is detected in an IP router or the like, the packet is discarded according to the packet transfer priority, and the source device is notified using the Source Quench packet that the packet has been discarded. There was something like that (see, for example, Patent Document 1).

JP-A-9-205461

  However, since the flow control by the pause frame is control in units of physical ports, transmission of the high priority frame from the adjacent device is stopped, and the system is delayed or discarded. Further, when the flow control by the pause frame is disabled, there is a problem that when the traffic exceeding the processing performance of the transfer processing unit of the own device is received, the reception control unit discards the traffic regardless of the priority.

  On the other hand, in the case of using the Source Quench packet to notify the transmission source device of the occurrence of packet discard, if the packet is frequently discarded, the Source Quench packet is also transmitted accordingly. When congestion frequently occurs, there is a problem that traffic between the transmission source device and the IP router increases.

  The present invention has been made to solve the above-described problems, and an object thereof is to obtain a network relay device capable of reducing delay and frame loss in the entire system including the device itself and the transmission source device. And

The network relay device according to the present invention, when IP packet congestion occurs, receives a congestion control information that outputs reception congestion control information, and receives data congestion control information from the transfer control unit. When a flow control unit that generates a pause frame for temporary suspension, a pause frame discard control unit that discards a pause frame and sends a non-priority frame discard signal, and an IP packet transmitted from a transmission source device are received , based on the information and the non-priority frame discard signal priority included in the received frame as the IP packet, in which a priority reception control unit to discard lower priority frames.

Since the network relay device of the present invention discards the pause frame to be transmitted to the transmission source device and discards the low priority frame among the IP packets received from the transmission source device. The delay and frame loss in the entire system including the above can be reduced.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a network relay device according to Embodiment 1 of the present invention.
The network relay device 100 is a device that terminates an IP packet from the transmission source device 200 and transmits the IP packet to the network 300. The priority reception control unit 101, reception control unit 102, transfer control unit 103, downlink transmission control unit 104, flow A control unit 105, an uplink transmission control unit 106, and a pause frame discard control unit 107 are provided.

Based on the non-priority frame discard signal from the pause frame discard control unit 107, the priority reception control unit 101 performs control to discard a frame with low priority according to the priority included in the frame received as the IP packet from the transmission source device 200. Part. The reception control unit 102 is a control unit that receives the IP packet transmitted from the priority reception control unit 101. The transfer control unit 103 includes a reception buffer 108, and is a control unit that performs termination processing on the IP packet received by the reception control unit 102 and performs output control to the downlink transmission control unit 104. The downlink transmission control unit 104 is a control unit that performs transmission control of the IP packet from the transfer control unit 103 to the network 300.

  The flow control unit 105 is a control unit that generates a pause frame for temporarily stopping data transmission from the transmission source device 200 based on the reception control congestion information output from the transfer control unit 103. The uplink transmission control unit 106 is a control unit that performs transmission control for transmitting the pause frame output from the flow control unit 105 to the transmission source device 200. The pause frame discard control unit 107 is a control unit that discards the pause frame and transmits a non-priority frame discard signal to the priority reception control unit 101 when a pause frame is transmitted from the uplink transmission control unit 106. .

  The transmission source device 200 generates an IP packet and transmits the packet to the network relay device 100, and the network 300 is an IP network.

Next, the operation of the first embodiment will be described.
In normal times, the received frame from the transmission source device 200 is sent to the transfer control unit 103 via the priority reception control unit 101 and the reception control unit 102, and the transmission destination is determined based on the destination address of the IP header, and the header is attached. Implement replacement processing. Thereafter, it is sent to the downlink transmission control unit 104, and priority control is performed by priority flags such as a priority bit in the VLAN-TAG and a ToS (Type of Service) field in the IP header.

  When the rate of the received frame from the transmission source device 200 exceeds the processing performance of the transfer control unit 103, the received frame is accumulated in the reception buffer 108 of the transfer control unit 103, and when the set threshold is exceeded, an overrun of the reception buffer 108 occurs. In order to avoid this, the transfer control unit 103 sends the reception control congestion information 10 to the flow control unit 105. In response to the reception control congestion information 10, the flow control unit 105 generates a pause frame 20 that stops transmission of the transmission source device 200 for a specified period. The pause frame 20 is transmitted to the pause frame discard control unit 107 via the uplink transmission control unit 106. When the pause frame discard control unit 107 receives the pause frame 20, the pause frame discard control unit 107 discards the pause frame 20 and transmits a non-priority frame discard signal 30 to the priority reception control unit 101 for a period specified by the pause frame 20. As a result, the pause frame is not sent to the transmission source device 200, and the transmission of the transmission source device 200 is continued.

  The priority reception control unit 101 is in the priority bit in the VLAN-TAG or in the IP header during the period when the non-priority frame discard signal 30 of the pause frame discard control unit 107 is asserted. Only frames designated with high priority by priority flags such as the ToS field are received, and all low priority frames are discarded.

  Such control avoids the delay / discard of the priority frame in the network relay device 100 and also avoids the delay / discard of the priority frame in the transmission source device 200, and is used for, for example, broadcast-type video distribution. It can also be used for a broadband router or the like that cannot use flow control by a pause frame.

As described above, according to the network relay device of the first embodiment, when congestion of IP packets occurs in the network relay device that relays IP packets from the transmission source device to the network, the reception congestion control information is output. When the reception congestion control information is received from the transfer control unit, the flow control unit that generates a pause frame for temporarily stopping data transmission from the transmission source device, the pause frame is discarded, and the non-priority frame When receiving an IP packet transmitted from the pause frame discard control unit that transmits a discard signal and the transmission source device, based on the priority information included in the frame received as the IP packet and the non-priority frame discard signal , since a priority reception control unit to discard lower priority frames, the own apparatus and the source apparatus It is possible to reduce the delay and frame loss in the entire system including.

Embodiment 2. FIG.
FIG. 2 is a configuration diagram of a network relay device according to the second embodiment.
In the figure, the basic configuration of the network relay device 100a is the same as that of the network relay device 100 of the first embodiment, but the configuration of the pause frame discard control unit 107a is different. When the pause frame discard control unit 107a receives the pause frame from the uplink transmission control unit 106, the pause frame discard control unit 107a discards the pause frame and also receives the priority reception control unit, similar to the pause frame discard control unit 107 of the first embodiment. A non-priority frame discard signal 30 is sent to 101. If congestion continues and the priority frame attribute is low frame loss even though this processing is performed, the pause frame 40 is set. It is configured to send out. That is, even after the processing of the pause frame discard control unit 107 of the first embodiment is performed, the reception control congestion information 10 is transmitted from the transfer control unit 103, and the pause frame 20 generated by the flow control unit 105 is controlled to perform uplink transmission control. When input to the pause frame discard control unit 107a via the unit 106, the pause frame 40 is transmitted. Other configurations in the network relay device 100a, the transmission source device 200, and the network 300 are the same as those in the first embodiment, and thus the corresponding parts are denoted by the same reference numerals and description thereof is omitted.

Next, the operation of the network relay device according to the second embodiment will be described.
First, the normal operation and the first operation when the accumulation amount of the reception buffer 108 exceeds the set threshold value are the same as those in the first embodiment. That is, when the reception control congestion information 10 is transmitted from the transfer control unit 103, the flow control unit 105 generates a pause frame 20, which is input to the pause frame discard control unit 107a via the uplink transmission control unit 106. As a result, the pause frame discard control unit 107a transmits the non-priority frame discard signal 30 to the priority reception control unit 101 and discards the pause frame 20 as in the first embodiment. Thereafter, when the received frame is accumulated in the reception buffer 108 of the transfer control unit 103 and exceeds the set threshold even though the non-priority frame is discarded by the priority reception control unit 101, the transfer control is performed. The unit 103 sends the reception control congestion information 10 to the flow control unit 105. Accordingly, the flow control unit 105 generates the pause frame 20 and transmits it to the uplink transmission control unit 106, and the uplink transmission control unit 106 outputs this to the pause frame discard control unit 107a.

  When the pause frame discard control unit 107a receives the pause frame 20 from the uplink transmission control unit 106 within a certain period of time after discarding the pause frame 20 as in the first embodiment, the ToS field of the IP header, etc. Thus, a request from the application of the priority frame received from the adjacent transmission source device 200 is determined, and when the low frame loss priority is given, the non-priority frame discard signal 30 is continuously transmitted and the pause frame 40 is transmitted from the transmission source device. 200 is transmitted. Thereby, transmission from the transmission source device 200 to the network relay device 100a is stopped during the designated period, and priority frame loss suppression is performed by a buffer (not shown) of the transmission source device 200. Note that the determination of the request from the priority frame application in the pause frame discard control unit 107 a is performed based on communication (not shown) with the transfer control unit 103.

As described above, according to the network relay device of the second embodiment, the pause frame discard control unit continues to receive the IP packet after the priority reception control unit discards the low priority frame and receives the packet. When the priority frame attribute is low frame loss, the pause frame discarding is stopped, so that it is possible to cope with the case where the congestion state is severe.

Embodiment 3 FIG.
FIG. 3 is a configuration diagram illustrating the network relay device according to the third embodiment.
In the figure, the basic configuration of the network relay device 100b is the same as that of the network relay device 100 of the first embodiment, but the configuration of the pause frame discard control unit 107b is different. When the pause frame discard control unit 107b receives a pause frame from the uplink transmission control unit 106, the pause frame discard control unit 107b discards the pause frame and also receives a priority reception control unit, similar to the pause frame discard control unit 107 of the first embodiment. A non-priority frame discard signal 30 is sent to 101. If congestion occurs and the priority frame attribute is low frame loss in spite of performing this processing, a priority TCP packet is sent. A non-priority frame discard signal 30 is transmitted to the priority reception control unit 101 so as to be discarded in bursts by a predetermined number of packets. The priority reception control unit 101 is configured to discard TCP packets in a burst manner when such a non-priority frame discard signal 30 is received. Other configurations in the network relay device 100b, the transmission source device 200, and the network 300 are the same as those in the first embodiment, and thus the corresponding parts are denoted by the same reference numerals and description thereof is omitted.

Next, the operation of the third embodiment will be described.
First, the normal operation and the first operation when the accumulation amount of the reception buffer 108 exceeds the set threshold value are the same as in the first and second embodiments. Next, despite the discarding of the non-priority frame by the priority reception control unit 101, the reception control congestion information 10 is sent from the transfer control unit 103, and the pause frame is transmitted from the flow control unit 105 within a certain time. The pause frame discard control unit 107b determines the request from the application of the priority frame received from the transmission source device 200 based on the ToS field of the IP header, and when the low frame loss priority is given. Then, instead of transferring the pause frame to the transmission source device 200, it is determined that the TCP packet of the priority frames is discarded with priority, and the non-priority frame discard signal 30 including this information is transmitted to the priority reception control unit 101.

  That is, the pause frame is continuously discarded, and among the frames received from the transmission source device 200, the priority reception control unit 101 continuously discards the TCP packets in a set number of frames and performs retransmission. Suppress frame loss at the application level. The retransmission of the TCP packet is performed by a retransmission control unit (not shown) in the network relay device 100b.

  If the reception control congestion information 10 continues to be transmitted from the transfer control unit 103 after such processing, the pause frame discard control unit 107b sets the non-priority frame to extend the burst period. A discard signal 30 is transmitted. This suppresses an increase in traffic due to retransmission.

As described above, according to the network relay device of the third embodiment, when the priority reception control unit discards a low priority frame, congestion of the IP packet continues and a pause frame is received from the flow control unit. The pause frame discard control unit instructs the priority reception control unit to discard TCP packets in bursts continuously for a predetermined number of packets when the received priority frame attribute is low frame loss. Even in a congested state, discard at the application level can be suppressed.

  In addition, according to the network relay device of the third embodiment, the burst period is extended when congestion of IP packets continues even when the priority reception control unit discards TCP packets by a predetermined number of frames. Therefore, it is possible to cope even when the congestion state further advances.

Embodiment 4 FIG.
FIG. 4 is a configuration diagram illustrating a network relay device according to the fourth embodiment.
In the figure, the basic configuration of the network relay device 100c is the same as that of the network relay device 100 of the first embodiment, but the configuration of the pause frame discard control unit 107c is different. When the pause frame discard control unit 107c receives the pause frame from the uplink transmission control unit 106, the pause frame discard control unit 107c discards the pause frame and also receives the priority reception control unit in the same manner as the pause frame discard control unit 107 of the first embodiment. A non-priority frame discard signal 30 is sent to 101, but if this process is performed and congestion occurs and the attribute of the priority frame has a low delay, UDP packets are sent at regular intervals. The non-priority frame discard signal 30 is transmitted to the priority reception control unit 101 so as to be discarded one by one. The priority reception control unit 101 is configured to discard UDP packets one by one at regular intervals when such a non-priority frame discard signal 30 is received. Other configurations in the network relay device 100c, the transmission source device 200, and the network 300 are the same as those in the first embodiment, and thus the corresponding parts are denoted by the same reference numerals and description thereof is omitted.

Next, the operation of the fourth embodiment will be described.
First, the normal operation and the first operation when the accumulation amount of the reception buffer 108 exceeds the set threshold value are the same as in the first to third embodiments. Next, despite the discarding of the non-priority frame by the priority reception control unit 101, the reception control congestion information 10 is sent from the transfer control unit 103, and the pause frame is transmitted from the flow control unit 105 within a certain time. The pause frame discard control unit 107c determines a request from the application of the priority frame received from the transmission source device 200 based on the ToS field of the IP header. Instead of transferring the pause frame to the transmission source device 200, the priority frame is also discarded, but it is determined to discard one packet at a fixed interval so as not to cause bursty packet loss of the UDP packet. A non-priority frame discard signal 30 including information is transmitted to the priority reception control unit 101.

  That is, the priority reception control unit 101 discards all of the low priority frames and the priority UDP packets frame by frame at regular intervals from the frames received from the transmission source device 200. If the reception control congestion information 10 is continuously transmitted from the transfer control unit 103 thereafter, the pause frame discard control unit 107c transmits the non-priority frame discard signal 30 so as to narrow the discard interval. . This minimizes quality degradation of audio and video applications due to priority frames.

As described above, according to the network relay device of the fourth embodiment, when the priority reception control unit discards the low priority frame, the congestion of the IP packet continues and the pause frame is received from the flow control unit. When the attribute of the received priority frame has a low delay , the pause frame discard control unit instructs the priority reception control unit to discard the UDP packets one by one at regular intervals, so that the congestion state has advanced. Even in this case, it is possible to minimize the quality deterioration of the audio or video application due to the priority frame.

  Also, according to the network relay device of the fourth embodiment, if the congestion of IP packets continues even if the priority reception control unit discards UDP packets one by one at regular intervals, the discard interval is reduced. As a result, even when congestion further progresses, it is possible to cope with minimizing the quality degradation of the priority frame.

Embodiment 5 FIG.
FIG. 5 is a configuration diagram illustrating the network relay device according to the fifth embodiment.
In the figure, the basic configuration of the network relay device 100d is the same as that of the network relay device 100c of the fourth embodiment, but the configuration of the pause frame discard control unit 107d is different. When the pause frame discard control unit 107d receives the pause frame from the uplink transmission control unit 106, the pause frame discard control unit 107d discards the pause frame and, like the pause frame discard control unit 107c of the fourth embodiment, A non-priority frame discard signal 30 is sent to 101. If congestion occurs despite this processing being performed, an MTU (Maximum) indicating the maximum value of data that can be transmitted in one transfer An ICMP (Internet Control Message Protocol) frame is generated so as to reduce the size of the transmission unit, and is transmitted to the transmission source device 200. Other configurations in the network relay device 100d and the transmission source device 200 and the network 300 are the same as those in the fourth embodiment, and therefore, the corresponding parts are denoted by the same reference numerals and description thereof is omitted.

Next, the operation of the fifth embodiment will be described.
In the fourth embodiment, when discarding priority frames with low delay priority, the pause frame discard control unit 107d generates an ICMP frame for instructing to shorten the MTU size and sends it to the transmission source device 200. As a result, the frame length of the received frame from the transmission source device 200 is shortened, and it is possible to further reduce the quality degradation of the audio and video applications due to the discard of the priority UDP packet.

  When the congestion state of the transfer control unit 103 is recovered by discarding the priority frame, the pause frame discard control unit 107d generates an ICMP frame instructing to return the MTU size to the original size, and transmits the ICMP frame to the transmission source device 200. . In this way, the transfer efficiency is improved by returning the frame length of the received frame from the transmission source device 200 to the original value.

  The set value of the MTU size may be a fixed value according to traffic, conditions, or the like, but may be set to be reduced according to the occurrence of congestion. That is, if the ICMP frame for instructing to reduce the MTU size is sent to the transmission source device 200 and the congestion state of the transfer control unit 103 is not improved, the ICMP frame is transmitted so as to further reduce the MTU size. Here, if the MTU size is made too small, the processing capacity of the transfer control unit 103 will be insufficient. If the number of priority frames discarded in a certain period does not exceed a predetermined threshold value, An instruction to shorten the MTU size is issued, and when the threshold value is exceeded, the original MTU size is restored.

As described above, according to the network relay device of the fifth embodiment, the pause frame discard control unit generates the ICMP frame instructing to reduce the MTU size and transmits it to the transmission source device. It is possible to further reduce the quality degradation of the audio and video applications due to the disposal.

Embodiment 6 FIG.
In the sixth embodiment, the priority of the third to fifth embodiments is set after setting the generation threshold of the reception control congestion information 10 to be sent to the transfer control unit 103 to the flow control unit 105 in any of the third to fifth embodiments. The frame discard control is applied to the low priority frame discard control. That is, in the third to fifth embodiments, all low priority frames are discarded, but in the sixth embodiment, all low priority frames are not discarded. Apply to

  For example, when applied to Embodiment 3, priority TCP packet discard control is applied to low priority frame discard control. That is, the threshold value for outputting the reception control congestion information 10 from the transfer control unit 103 is set low, and the pause frame discard control unit 107b gives the priority reception control unit 101 bursts of low priority frames by a predetermined number of frames. In the case where further congestion occurs, the non-priority frame discard signal 30 is transmitted so as to extend the burst period.

When applied to the fourth or fifth embodiment, discard control for priority UDP packets is applied to low priority frames. That is, the threshold value for outputting the reception control congestion information 10 from the transfer control unit 103 is set low, and the pause frame discard control unit 107c (107d) sends low priority frames to the priority reception control unit 101 at regular intervals. The frame is discarded frame by frame, and if congestion further occurs, a non-priority frame discard signal 30 is transmitted so as to reduce the discard interval.
Except for this operation, it is the same as any one of the third to fifth embodiments.

As described above, according to the network relay device of the sixth embodiment, the transfer control unit lowers the threshold for determining whether or not congestion has occurred, and the pause frame discard control unit Since the priority reception control unit is controlled so as to extend the burst period when congestion continues continuously in a burst for a predetermined number of frames, low priority frames during light congestion impact of the waste can be kept to a minimum.

In addition, according to the network relay device of the sixth embodiment, the transfer control unit lowers the threshold for determining whether congestion has occurred, and the pause frame discard control unit performs a fixed interval with respect to the low priority frame. When the congestion continues to occur after that , the priority reception control unit is controlled so as to reduce the discard interval, so that the low priority frame at the time of light congestion impact of the waste can be kept to a minimum.

It is a block diagram which shows the network relay apparatus by Embodiment 1 of this invention. It is a block diagram which shows the network relay apparatus by Embodiment 2 of this invention. It is a block diagram which shows the network relay apparatus by Embodiment 3 of this invention. It is a block diagram which shows the network relay apparatus by Embodiment 4 of this invention. It is a block diagram which shows the network relay apparatus by Embodiment 5 of this invention.

Explanation of symbols

  10 reception control congestion information, 20, 40 pause frame, 30 non-priority frame discard signal, 100, 100a, 100b, 100c, 100d network relay device, 101 priority reception control unit, 103 transfer control unit, 105 flow control unit, 107, 107a, 107b, 107c, 107d Pause frame discard control unit, 200 transmission source device, 300 network.

Claims (9)

In a network relay device that relays IP packets from a transmission source device to a network,
A transfer control unit that outputs reception congestion control information when congestion of the IP packet occurs ;
Upon receiving the reception congestion control information from the transfer control unit, a flow control unit that generates a pause frame for temporarily stopping data transmission from the transmission source device;
A pause frame discard control unit for discarding the pause frame and sending a non-priority frame discard signal;
When receiving an IP packet transmitted from the transmission source device, priority is given to discarding a frame with low priority based on the priority information included in the frame received as the IP packet and the non-priority frame discard signal. A network relay device comprising a reception control unit. The pause frame discard control unit discards the pause frame when the priority reception control unit discards the low priority frame and the IP packet congestion continues and the received priority frame attribute is low frame loss. The network relay device according to claim 1, wherein the network relay device is stopped. When the priority reception control unit discards a low priority frame and the IP packet congestion continues and a pause frame is received from the flow control unit, the pause frame discard control unit determines that the received priority frame attribute is a low frame. 2. The network relay device according to claim 1, wherein in the case of a loss, the priority reception control unit is instructed to discard TCP packets continuously in bursts by a predetermined number of packets.   4. The network relay device according to claim 3, wherein if the IP packet congestion continues even if the priority reception control unit discards a predetermined number of TCP packets, the burst period is extended. Even after the priority reception control unit discards the low priority frame, when the congestion of the IP packet continues and the pause frame is received from the flow control unit, the pause frame discard control unit has a low latency attribute of the received priority frame. 2. The network relay apparatus according to claim 1, wherein the priority reception control unit is instructed to discard UDP packets one by one at regular intervals.   6. The network relay device according to claim 5, wherein when the priority reception control unit discards UDP packets one by one at regular intervals, if the congestion of IP packets continues, the discard interval is decreased. The network relay device according to claim 5 or 6, wherein the pause frame discard control unit generates an ICMP frame for instructing to reduce the MTU size and transmits the ICMP frame to the transmission source device. The transfer control unit lowers the threshold value for determining whether or not congestion has occurred, and the pause frame discard control unit discards the low-priority frames continuously in a burst manner for a predetermined number of frames. 5. The network relay device according to claim 3 , wherein the priority reception control unit is controlled so as to extend the burst period when the message continues. The transfer control unit lowers the threshold for determining whether congestion has occurred, and the pause frame discard control unit discards the low-priority frames one frame at a fixed interval, and congestion continues thereafter. 7. The network relay device according to claim 5 , wherein the priority reception control unit is controlled so as to reduce the discard interval.

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