KR20180039716A - Network systems and network nodes - Google Patents

Abstract

SUMMARY OF THE INVENTION An object of the present invention is to quickly erase MAC address information learned by each node constituting a network when configuration control of a ring network occurs. According to an aspect of the present invention, there is provided a ring network system configured by a plurality of nodes, each of the plurality of nodes comprising: a plurality of ports for transmitting and receiving communication frames; And a communication control unit for selecting the port to be used for transmission in accordance with a correspondence relationship stored in the MAC address learning unit, , And when a failure occurs in a part of the ring network, the transmission priority of the MAC address clear request frame is set higher than the normal communication frame and transmitted to another node.

Description

Network systems and network nodes

The present invention relates to a network system and a network node.

There is Ethernet (registered trademark) of Layer 2 specified in IEEE802.3 as one form of a network configured by learning MAC address information in a reception frame such as a switching hub and controlling a transmission destination of a frame .

In addition, STP (Spanning Tree Protocol) is described in Non-Patent Document 1 as a protocol for reducing the network configuration by Ethernet. In the STP, a control frame called a bridge protocol data unit (BPDU) is periodically exchanged. The STP has a function of detecting a change in state (topology) of a network due to a fault or the like, and switching a communication path. The communication path is switched, thereby causing inconsistency between the MAC address information that has been learned before the path change and the network topology. In the STP, a ring configuration or the like is used as a network configuration for redundancy in which communication is restored by transmitting a BPDU with a TC (Topology Change) bit set and erasing MAC address information.

Further, as a conventional technique of a network-specific redundancy protocol for a ring configuration, in the patent document 1, " the ring monitoring apparatus refers to a ring configuration apparatus that detects link recovery mounted on a link recovery notification frame, And transmits a flash request frame for instructing the ring device to be in the transmittable / receivable state. The ring constituent device that has received the frame clears the learned MAC address and changes the state of the ring port. &Quot;

Japanese Patent Application Laid-Open No. 2009-239767

ANSI / IEEE Std 802.1D, 1998 Edition: 8. The Spanning Tree Algorithm and Protocol

In the Ethernet, in the network node, a technique of relaying a received frame with priority by IEEE802.1p QoS is used. In the above-described method, a MAC address clear request for making a request to clear a MAC address to each node Since the request frame is not controlled first, each node constituting the ring network performs processing such as receiving and relaying the user communication frame and the MAC address clear request frame with the same priority. Therefore, if the frame for user communication is propagated on the network, the MAC address clear request frame stays in the transmission buffer of the node on the ring network until the relay of the user frame is completed, and the MAC address clear request frame A delay occurs until it reaches the node.

Particularly, when a specific user frame is relayed as a gull map, there is a problem that since the MAC address clear request frame is queued in the buffer by the user frame, delivery is delayed and communication recovery takes time.

SUMMARY OF THE INVENTION In view of the above problems, the present invention aims to quickly erase MAC address information learned by each node constituting a network when configuration control of a ring network occurs.

In order to solve the above problems, a representative network system of the present invention is a ring network system constituted by a plurality of nodes, each of the plurality of nodes includes a plurality of ports for transmitting and receiving communication frames, A MAC address learning unit that stores a correspondence relationship between a transmission source MAC address of the MAC address learning unit and the port that has received the communication frame in accordance with the correspondence relationship stored in the MAC address learning unit when the communication frame is transmitted And a relay processing unit for performing relay processing to other nodes in accordance with the transmission priority set in the received communication frame, wherein the plurality of nodes are connected to a part of the ring network When a failure occurs, a MAC address clear which clears the correspondence stored in the MAC address learning unit A degree of the transmission of the first nine frames above the normal frames of the communication will be characterized in that it comprises a first node for transmitting to the other nodes.

According to the present invention, when the configuration control of the ring network occurs, the MAC address information learned by each node constituting the network can be quickly erased.

Fig. 1 is a configuration diagram of this embodiment.
2 shows a format of a control frame used in the present embodiment.
Fig. 3 is a diagram showing distribution and transmission procedures of frames by priority. Fig.
Fig. 4 is a diagram showing a configuration control occurrence time. Fig.
5 is a diagram showing the motion of a high priority frame.
Fig. 6 is a diagram showing an example of a frame overtaking by priority.
7 is a diagram showing a flow up to MAC address misreport (address learning).
8 is a diagram showing a flow up to MAC address misrecognition (frame relay by address learning).
FIG. 9 is a diagram showing a flow up to MAC address misreporting (when an error occurs).
10 is a diagram showing a flow up to MAC address misreport (clear frame transmission).
11 is a diagram showing a flow up to MAC address misreport (overtaking due to priority).
12 is a diagram showing a flow up to the MAC address misreport (relay operation after the overtaking).
13 is a diagram showing a flow up to MAC address misrecognition (destination information mis-learning).
14 is a diagram showing a flow up to MAC address misreporting (frame discard by destination information misexcision).
Fig. 15 is a diagram showing a motion (resolution means) of the low priority frame.
16 is an internal block diagram of the node of this embodiment.

Hereinafter, in the ring network, in order to quickly recover the communication disconnection state due to the mismatch between the network configuration and the MAC address learning information of the apparatus constituting the ring network, Will be described.

Fig. 1 is a configuration diagram showing the present embodiment. As constitution contents, there are eight nodes (100-1 to 100-8) connected to the ring network by the communication lines 110-1 to 110-8, and branch lines of the nodes 100-1 to 100-8 A calculator not shown is connected. In addition, the node 4 (100-4) to the node 5 (100-5) are in a blocking state. The blocking state is a state of blocking communications other than the control frame for controlling the ring network. For example, by blocking the communication frame between the computers connected to the branch line of each node, the network necessarily exists in a predetermined section of the ring, . As an example of the control frame, a frame communicated between neighboring nodes to monitor a fault of the communication lines 110-1 to 110-8 or a fault occurred in the communication lines 110-1 to 110-8 has transitioned to a blocking node A frame for declaring a plurality of blocking nodes in a network, and a frame for adjusting them when a plurality of blocking nodes are contended in the network. It is also assumed that no abnormality occurs in all of the nodes 100-1 to 100-8 and the communication lines 110-1 to 110-8. 16 is a diagram showing an internal block diagram of the nodes 100-1 to 100-8 in Fig. In Fig. 16, the node 2 (100-2) will be described as a representative.

The node 2 100-2 is connected to the node 1 100-1 and the node 3 100-3 via the communication lines 110-1 and 110-2 and connected to the computer 1 800-1 through a branch line, , And the calculator 2 (800-2). In this example, two calculators are connected, but more than one calculator may be connected.

The node 2 100-2 includes a CPU 700, a memory 710, a transmission / reception control unit 720, and a plurality of ports 770 and 780 switch units. The switch unit includes a reception queue 750 for storing received frames, a priority queue 760 for classifying frames for each priority, a transmission queue 740 for storing transmitted frames, And an address learning unit 730.

The ports A and B 770 are ports for constituting a ring network, and two ports are provided in total for one node. The ports A and B 770 perform blocking / release according to an instruction from the CPU 700. [

Ports 1 and 2 (780) are ports for connecting a calculator or the like to a branch line. The number of ports is arbitrary, but two are shown in this example.

The reception queue 740 is a queue for storing frames received from the ports 770 and 780, and holds one for each port. It is also provided for storing frames received from the transmission / reception control unit 720. [ The reception queue 740 has a plurality of queues therein and changes the queue to be stored according to the priority of the reception frame. Details will be described later with reference to FIG.

The priority queue 760 has individual queues according to the priority (0 to 7 in the present embodiment), and a frame is transmitted from the reception queue 740 of each port to the queue corresponding to the priority . Then, based on the destination MAC address of the frame and the information in the address learning unit 730 of the switch unit, the frame in the priority queue is transmitted to the transmission queue of the destination port.

The transmission queue 750 is a queue for transmitting frames from a port in priority order, and holds one for each port. It is also provided for storing a frame to be transmitted to the transmission / reception control unit 720. Priority 7 is transmitted in priority to the highest priority frame, and low priority frames are queued until all frames of the high priority are completely transmitted.

The address learning unit 730 stores the source MAC address of the received frame in association with the number of the reception port. When transmitting a frame, address information for determining a transmission destination port of the frame is provided. For example, when receiving a frame having a source MAC address of "AA" from the port A 770, the MAC address "AA" and the port A 770 are stored in association with each other. In addition, when the destination transmits a frame with the MAC address "AA ", the frame is transmitted from the port A 770 by providing information of the port A 770 associated with the MAC address " AA ". The learning information of this MAC address is deleted when the frame is received from another node or when the frame is not received from the node for about 5 minutes. When the destination does not store a port corresponding to the MAC address, the frame is transmitted from both ports A and B (770).

The CPU 700 receives the frame for ring control and the MAC address information clear request frame. The blocking control of the port A / B 770, the erasing of the address learning unit 730, and the transmission of the control frame and the clear request frame are performed in accordance with the conditions.

The transmission / reception control unit 720 has a function of receiving frames from the switch unit and storing them in a memory. And has a function of transmitting frame information created on the memory as a frame to the switch unit in response to an instruction from the CPU 700. [ Also, it has a function of notifying the CPU of which port (port A, B, 1, 2, ...) the frame received from the switch unit is received. (Transmission from port A, transmission to both ports A and B, and the like) when transmitting frame information on the memory in response to an instruction from the CPU 700, The above-described frame for ring control or MAC address clear request frame or the like uses this function to recognize a received port or transmit a frame only to a specific port.

The memory 710 is a memory for storing information of a frame received by the CPU from the transmission / reception control unit or a frame transmitted from the CPU. It also stores programs for the CPU to operate.

2 is a diagram showing a frame format to be propagated in a network. This frame includes a MAC header, a VLAN tag, a LEN / TYPE, frame information, and a CRC. In the MAC header, a destination address DA and a source address SA are set. In addition, a priority value (PCP) indicating the priority of transmission of a frame is stored in the VLAN header section 200-1 using IEEE 802.1Q VLAN tagging. Priorities can be set from a minimum value of 0 to a maximum value of 7. The node that has received this frame relays the frame with the highest priority value in preference to IEEE802.1p QoS.

Fig. 3 shows the distribution and transmission procedure of frames by the priority given to the reception frame in the nodes 100-1 to 100-8. In this example, the frame 300-1 of the priority 7 and the frame 300-2 of the priority 0 are simultaneously received by the port # 1 310-1 and the port # 3 310-3, respectively Let's take a moment's movement. In this example, the port # 1 310-1, the port # 2 310-2 is a port connected to the ring network, the port # 3 310-3, the port # 4 is a port , And the two received frames are frames transmitted from the port # 2 (310-2). The frame received by the port # 1 310-1 and the port # 3 310-3 is stored in a reception buffer called reception queues 320-1 and 320-4 for each port, Respectively. Thereafter, the priority queue (in this example, the priority queue 320-2 of the priority 7 and the priority queue 320-5 of the priority 0) prepared for each priority value Each port number is stored. The received frame stored in the priority queue is stored in the transmission queue of the destination port (the transmission queue of port # 2, 320-5) among the transmission queues for each port. From the transmission queue 320-3 of the port # 2, the frame having the highest priority value is relayed to the transmission port # 2 (310-2) in order and transmitted to the outside. Therefore, in this example, after the transmission frame 300-4, which is the priority 7, is transmitted, the transmission frame 300-3 having the priority 0 is transmitted. In addition, when transmission frames with high priority are relayed consecutively, it is considered that transmission frames with low priority will stay for a long time, but in this embodiment, transmission frames staying for a predetermined time are deleted.

In Fig. 4, there is shown a case where a communication abnormality occurs in the communication line 110-8 for some reason, and a configuration control occurs. First, the node 1 (101-1) and the node 8 (101-8) detect a failure, and transition the abnormal detection port to the blocking state. Further, the blocking state is released between the node 4 (100-4) and the node 5 (100-5), and the communication becomes possible.

It is necessary to clear the MAC address table of each node and re-learn the MAC address information of each node on the network in order to reach the correct destination node when the blocking point transits as described above have. In the present invention, the MAC address clear request frame is transmitted from the node that detected the configuration control, so that the node that has received the clear request frame clears the MAC address table. In this embodiment, the transmission priority of the MAC address clear request frame is increased by IEEE 802.1Q VLAN tagging or the like for the MAC address clear request frame, thereby eliminating the transmission delay caused by the frame for user communication. Fig. 5 shows the movement of the MAC address clear request frame according to the present invention. The blocking between the node 4 (100-4) to the node 5 (100-5) is released, whereby the node 5 (100-5) that was the terminating node at the time of blocking receives the MAC address clear request frame 1, 2 (420, 421). Each node that has received the MAC address clear request frame 1, 2 (420, 421) clears its own MAC address table and is relayed to the adjacent node on the opposite side of the port that received the MAC address clear request frame. By using the frame of priority 7, it is propagated to all the nodes, and rapid path change becomes possible. In addition, by transmitting the MAC address clear request frame, the node that releases the blocking can quickly request the other node to clear the MAC address from the start of the configuration control.

On the other hand, the MAC address clear request frame with the higher transmission priority overtakes the user frame transmitted prior to the configuration control staying in the transmission / reception buffer held by the constituent node, and the mis-learning of the MAC address information by the overtaken user frame May occur.

As an example, a case in which a stay frame 430 having a priority of two in the network is propagated is illustrated. When the MAC address clear request frame 1 420 having the priority 7 set to the maximum value 7 is propagated from the node 5 (100-5) to the node 8 (101-8), since the priority is 7, It propagates past the stay frame 430 and clears the MAC address table of the node 7 101-7 and the node 8 101-8. As a result, the stay frame 430 arrives at the node after the MAC address is cleared, and erroneous learning of the MAC address information may occur based on the network configuration before the occurrence of the failure.

Fig. 6 is an example of the motion of the frame to overtake by the priority. The clear frame 500-1 and the stay frame 500-2 received at the port 1 510-1 are allocated at the port # 1 reception queue 520-1 and thereafter allocated to each priority queue 520 -2, and 520-3, respectively. And from the priority queue to the transmission queue 520-4 of the port # 2 in a round-robin manner. Since the transmission queue 520-4 of the port # 2 relays the transmission from the frame having the highest priority value to the transmission port # 2 510-2 in order, the clear frame 500-4, which is the priority 7, The stay frame 500-3, which is the priority 2, is transmitted. Therefore, even if the priority 2 frame is received first, if a clear frame of the priority 7 is received after a clear frame, the clear frame of the priority 7 is transmitted first, and the priority frame 2 is overtaken. This causes erroneous learning of the MAC address.

As an example, FIG. 7 to FIG. 14 illustrate a network in which the nodes 610-1 to 610-6 are formed in a ring, and the flow from the MAC address errata / frame relay to the MAC address erroneous frame is sequentially shown. It is assumed that the nodes 610-6 to 610-1 are in a blocking state, and that no abnormality occurs in all nodes and all communication lines.

Fig. 7 shows an example of MAC address learning in the ring configuration. A 600-1 is transmitted from the PC-A 600-1, and each of the nodes 610-1 through 610-6 transmits the destination information of the PC-A 600-1 Learn.

As shown in Fig. 8, when a frame having the PC-A 600-1 as a destination is transmitted from the PC-C 600-3, each of the nodes 610-1 through 610-5 And relays the frame to the PC-A according to the destination MAC address information.

Fig. 9 shows the operation of the frame at the time of occurrence of the fault. A failure occurs between the nodes 610-1 to 610-2, and the blocking point moves to both ends of the failure point by the configuration control. At this time, the user frame (priority 2) of the destination B is relayed between the nodes 610-2 to 610-3.

In Fig. 10, a MAC address clear frame (priority 7) is transmitted from the blocking generating nodes 610-1 and 610-2 after the configuration control. At this time, the transmission source nodes 610-1 and 610-2 clear the MAC address and transmit the MAC address clear frame.

In Fig. 11, overtaking of frames due to primality occurs between nodes 610-3 to 610-4. The MAC address clear frame of priority 7 overtakes the priority 2 user frame and is relayed to the adjacent node with the highest priority.

In Fig. 12, although the destination information is cleared by the MAC address clear frame, the node 610-4 erroneously learns the destination information of the PC-A 600-1 in the user frame immediately thereafter.

In Fig. 13, the user frame arrives at the PC-B 600-2, but the nodes 610-5 and 610-6 relaying until that time learn the destination information of the destination A by mistake.

14, when the user frame is transmitted from the PC-B 600-2 to the PC-A 600-1 in this state, the destination information of the nodes 610-4 to 610-6 The frame is relayed to the route that does not arrive at the PC-A 600-1 by learning, and at the time of arrival at the node 610-2 having the port in the blocking state, Is discarded.

Even if the above flow occurs, even if MAC addresses of all the nodes are cleared by using the highest priority frame immediately after the configuration control, erroneous learning of the MAC address table occurs due to the stay frame, leading to mis-transmission of the user frame . In general, the learning information of the MAC address is deleted when a frame is received from another node from another port, or when a frame from the node is not received for about five minutes. Therefore, when there is no frame transmission from the PC-A, communication for a maximum of 5 minutes becomes impossible. Particularly, in the industrial network, since recovery after only a few seconds is required after the occurrence of the fault, improvement of the delay time is required.

In Fig. 15, the means for preventing the above-mentioned case will be described. In the present invention, after occurrence of the configuration control, the MAC address clear request frame 3 440 having the lowest priority 0 is transmitted from the newly terminated node (node 1 (201-1) in this example). Thus, even if erroneous learning is caused by the user frame 430 staying in the network after the MAC address clear request frames 1 and 2 (420 and 421) whose priority is set to the maximum value 7 are propagated to all the nodes, The MAC address table of all the nodes in the network can be reliably cleared because the user frame is not passed. This MAC address clear request frame 3 440 is transmitted at a timing at which the path switching is completed by changing the network configuration after generation of the configuration control due to the occurrence of the fault. Here, the completion of the change of the network configuration means that the blocking node with the new end can detect the earliest, so that the second MAC address table can be transmitted quickly.

As described above, in this embodiment, the MAC address clear request frame to be transmitted when the network configuration control has occurred, the IEEE 802.1Q VLAN tagging or the like is used to transmit the frame having the highest priority and the frame having the lowest priority , And have two types of priorities. The highest priority frame is used only for ring network control such as a MAC address clear request frame, and can not be used as a user communication frame.

When configuration control occurs due to a network failure or the like, a MAC address clear request frame in which the transmission priority (priority) is first set to the highest value is transmitted to all the network nodes. Since it is the highest priority, it can be propagated to the entire node quickly, with almost no delay in the transmission / reception buffer of each node, and the MAC address learning information can be erased.

Normally, communication is restored by the above-mentioned MAC address clear request frame having the highest priority, and then a MAC address clear request frame in which the priority is set to the lowest value is transmitted to all the nodes. Since the frame with the lowest priority does not overtake the user communication frame, even if erroneous learning of the MAC address learning information occurs due to the frame transmitted before the configuration control and staying in the transmission / reception buffer of each network node, Since the MAC address learning information is erased again by the clear request frame, the MAC address table of the entire node is erased securely.

Thereby, it is possible to quickly provide the communication path change due to the mismatching of the MAC address learning information, and to prevent the communication path recovery delay due to the erroneous learning of the MAC address.

In addition, the present invention is not limited to the above-described embodiment, but includes various modifications. For example, the above-described embodiments have been described in detail in order to facilitate understanding of the present invention, and are not limited to those having all the configurations described above. The components, functions, processing units, processing means, and the like may be realized by hardware, for example, by designing a part or all of them with, for example, an integrated circuit. Further, each of the above-described configurations, functions, and the like may be realized by software by analyzing and executing a program that realizes the respective functions of the processor. Information such as a program, a table, and a file that realize each function can be stored in a recording device such as a memory, a hard disk, a solid state drive (SSD), or a recording medium such as an IC card, an SD card, or a DVD.

100-1: node 1
100-2: Node 2
100-3: node 3
100-4: node 4
100-5: Node 5
100-6: node 6
100-7: Node 7
100-8: Node 8
110-1: communication line 1 (between nodes 1 and 2)
110-2: communication line 2 (between nodes 2 and 3)
110-3: communication line 3 (between nodes 3 and 4)
110-4: communication line 4 (between nodes 4 and 5)
110-5: communication line 5 (between nodes 5 and 6)
110-6: communication line 6 (between nodes 6 and 7)
110-7: communication line 7 (between nodes 7 and 8)
110-8: communication line 8 (between nodes 8 and 1)
200-1: VLAN header
300-1: Reception frame (priority 7)
300-2: Received frame (priority: 0)
300-3: Transmission frame (priority: 0)
300-4: Transmission frame (priority 7)
310-1: Receive port # 1
310-2: Transmission port # 2
320-1: Port # 1 receive queue
320-2: Priority 7 Queue
320-3: Port # 2 transmit queue
320-4: Port # 3 receive queue
320-5: Priority 0 Queue
420: MAC address clear request frame 1 (priority 7)
421: MAC address clear request frame 2 (priority 7)
430: Retention frame (priority: 2)
440: MAC address clear request frame 3 (priority: 1)
500-1: Receive clear frame (priority 7)
500-2: Reception frame (Priority: 2)
500-3: Transmission retention frame (Priority: 2)
500-4: Transmission clear frame (priority 7)
510-1: Receive port # 1
510-2: transmission port # 2
520-1: Port # 1 receive queue
520-2: Priority 7 queue
520-3: Priority 2 queue
520-4: Port # 2 receive queue
600-1: PC-A
600-2: PC-B
600-3: PC-C
610-1 to 610-6:
700: CPU
710: Memory
720: Transmitting /
730:
740: Receive queue
750: transmission queue
760: Priority queue
770: port (A, B)
780: port (1, 2)
800-1: Calculator 1
800-2: Calculator 2

Claims (10)

1. A ring network system configured by a plurality of nodes,
Each of the plurality of nodes comprising:
A plurality of ports for transmitting and receiving communication frames,
A MAC address learning unit that stores a correspondence relationship between a source MAC address of the received communication frame and the port that received the communication frame;
A communication control unit for selecting the port to be used for transmission according to a correspondence relationship stored in the MAC address learning unit when transmitting the communication frame;
And a relay processing unit for performing relay processing to another node in accordance with the transmission priority set in the received communication frame,
The plurality of nodes include:
The transmission priority of the MAC address clear request frame for clearing the corresponding relationship stored in the MAC address learning unit is set higher than the normal communication frame and transmitted to another node when a failure occurs in a part of the ring network And a first node. 2. The method of claim 1, wherein the first node is an end node that blocks transmission of the communication frame, and when a failure occurs in a part of the ring-shaped network, the first node releases blocking of the blocking port, And transmits a clear request frame to the other node. 2. The network system according to claim 1, wherein the first node sets the transmission priority of the MAC address clear request frame to the maximum, and transmits the MAC address clear request frame to another node. 2. The network communication system according to claim 1, wherein, after a failure occurs in a part of the ring network, the plurality of nodes transmit the MAC address clear request frame at a higher priority than the normal communication frame And a second node that is set to be low and transmits to another node. The method according to claim 4, wherein the second node is a node adjacent to the fault location occurring on the network, transits the port connected to the fault location to the blocking port, and transmits the MAC address clear request frame to the other node And the network system. 5. The network system according to claim 4, wherein the second node sets the transmission priority of the MAC address clear request frame to the lowest and transmits to the other node. 2. The network device according to claim 1, wherein each of the plurality of nodes receives the MAC address clear request frame from one of two ports connected to the ring network, and transmits the MAC address clear request frame to the other port And deletes the correspondence stored in the MAC address learning unit of the own node. 2. The communication system according to claim 1, wherein each of the plurality of nodes has a buffer in which the communication frame is stored according to the transmission priority, and among the communication frames stored in the buffer, To the network node. A plurality of ports for transmitting and receiving communication frames,
A MAC address learning unit that stores a correspondence relationship between a source MAC address of the received communication frame and the port that received the communication frame;
A communication control unit for selecting the port to be used for transmission according to a correspondence relationship stored in the MAC address learning unit when transmitting the communication frame;
And a relay processing unit for performing relay processing to another node in accordance with the transmission priority set in the received communication frame,
The communication control unit,
When a failure occurs in a part of the ring network including a plurality of nodes including the own node, the transmission priority of the MAC address clear request frame for clearing the correspondence stored in the MAC address learning unit A network node that is set high and sends to another node. 10. The communication system according to claim 9,
Wherein the transmission priority of the MAC address clear request frame is set lower than that of the normal communication frame and is transmitted to another node after completion of the rebuild of the network after a failure occurs in a part of the ring network.

Images