JPH04257142A - Faulty node checking method for ring network - Google Patents

Abstract

PURPOSE:To reduce the number of bits in the check area of a check frame, which is used to detect trouble of nodes connected to a ring type network, independently of the number of nodes. CONSTITUTION:When contents of the check frame are the node number of a node one above its own node, this node judges the node one above its own node to be normal and rewrites contents of the check frame with the its own node number to send the check frame to a transmission line. If contents of the check frame are not the node number of the node one above its own node, its own node judges the node one above itself to be faulty and records the faulty node number or reports it to a master node and writes its own node number in a specific area.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for checking the health of nodes in a ring network constructed by connecting a plurality of nodes in a ring.

0002

[Background Art] There is a method of connecting multiple communication nodes and one multi-accessor using optical fibers to configure a network that is physically star-shaped but logically ring-shaped. . This method is described in IEICE Transactions, VOL. J73-B-I NO. 6,
“Study on the reliability and economic efficiency of optical ring LAN” published by Jun Sasaki, p. 537-545. In this method, as shown in FIG. 4, for example, if node n2 fails and stops sending signals, node n3 secures communication by receiving the signal that is always bypassed by the multi-accessor. be done. On the other hand, the master node (node number nM) needs to know the node number being bypassed. As an example of this method, as shown in FIG. 5, there is a method in which a test area is provided in a test frame sent from a master node.

[0003] In this method, an n-bit test data area is provided in the test frame corresponding to the total number of nodes n, and
A specific area is allocated to each node in advance so that the areas used by each node do not overlap with each other. When transmitting this inspection frame, the master node sets all inspection areas to "0" before transmitting it. Each time this test frame passes through each node on the ring, each node sets "1" in the bit position of the test area corresponding to its own node. On the other hand, the master node inspects the inspection area of the inspection frame every time the inspection frame goes around the ring. In this way, a normal node will be placed in the corresponding inspection area.
1” is written, but the bypassed node writes “1”
Therefore, the master node can detect the bypassed node number from the node number in the area where the inspection area of the inspection frame is "0".

0004

[Problems to be Solved by the Invention] As mentioned above, the conventional technology has the advantage of being able to detect multiple faulty nodes at the same time. This has the disadvantage that the same number of bits as the number of connected nodes is required, and as the number of connected nodes increases, a considerably larger number of bits is required. The present invention has been made in view of the above-mentioned problems, and its purpose is to reduce the number of bits required for the test area of a test frame for testing bypass nodes.

[0005]

[Means for Solving the Problems] The present invention is characterized by a network configuration in which a plurality of nodes are logically connected in a ring shape, and when a control means for accessing a transmission path from a node fails, the node is In a ring network equipped with a function to bypass the transmission path, a test frame having a specific area in which a node number is written is sent out to the transmission path, and each node checks the content of the specific area from the node one node upstream from its own node. When the node number is , the content of the specific area is rewritten to the node number of its own node and a test frame is sent. In this case, there is a faulty node inspection method in a ring network in which the faulty node number is recorded or notified to a specific node, and the own node number is written in the specific area, assuming that the node has been bypassed due to a fault.

[0006]

[Operation] Each time a test frame passes through its own node, each node checks the node number in the test area of the frame and writes its own node number in the test area. If a certain node fails and is bypassed, the nodes connected below that node will know that the previous node has been bypassed by detecting a node number that is different from the node number they received last time. The master node detects the bypassed node number by reporting this node number to the master node or by responding with this node number to the master node's information collection.

[0007]

[Embodiment] Fig. 1 is a configuration diagram of a communication system showing a first embodiment of the present invention when all nodes are operating normally, and Fig. 2 shows a case where the node number n2 in Fig. 1 has failed. The configuration diagram when the node is bypassed, Figure 3 is the same as Figure 1
FIG. 2 is a configuration diagram of a format of an inspection frame used in FIG. As shown in FIG. 1, the communication system according to the present invention is comprised of one ring-type transmission path, one multi-accessor, and a plurality of nodes. Multiple nodes are connected to a master node (nM) equipped with network management functions.
) and other nodes (n1, n2, n3). The master node (nM) has a function of generating frames, a function of accessing frames, a frame aligner function that adjusts the ring length to be an integral multiple of the frame length when it is not an integral multiple of the frame length, and a frame aligner function that adjusts the ring length to be an integral multiple of the frame length. It is equipped with a management function. On the other hand, general nodes have the ability to access frames and send and receive data.

In FIG. 1, in order to check whether the node is normal and connected to the ring, or whether it is bypassed, the master node sends the test frame shown in FIG. 3 with its own node number written in the test area. Send regularly or as needed. The test frame is received by each normal communication node, and the data in the test area is stored and rewritten to the node number of the communication node. By repeating the above process, each node learns the node number of its previous node and stores this as an initial value. FIG. 2 shows a case where communication node n2 fails and is bypassed. In this case, writing of the node number into the test area of the test frame sent from the master node is performed normally in the communication node n1. However, even when this test frame arrives at the next failed and blocked communication node n2, writing to the test area is not performed, and the test frame is passed to the communication node n3 with the area value unchanged. The communication node n3 inspects the inspection area of the inspection frame that has arrived, and determines that the communication node n2 is bypassed because the value is the node number n1 of the communication node n1, which is different from the number n2 of the communication node n2. Recognize that.

[0009] The communication node n3 issues an inspection frame indicating that the communication node n2 is being bypassed and notifies the master node, or responds to an inquiry from the master node and informs the master node that the communication node n2 is being bypassed. respond. From this, the master node can recognize the bypass of communication node n2. In the above explanation, the case where the number of communication nodes is 4 was shown, but it is clear that the above explanation also holds true when the number of nodes is a general integer value. Regarding the area value, if the node numbers of all nodes are unique, set the node number to 10.
It may be expressed in base or binary numbers, or it is also possible to use negative numbers.

[0010]Also, although it has been described that the test area used to test whether each node is bypassed is provided in the test frame issued by the master node periodically or as needed, It is clear that the same effect can be obtained even if this is provided in a communication frame used for normal communication. Furthermore, in the above explanation, a network using multi-accessors has been taken as an example. However, the use of multiple accessors only means that each node is bypassed at the optical level when it is bypassed, and is therefore not a requirement for forming the invention. Therefore, even if the configuration is such that, for example, if the function to access a communication frame fails, the communication frame is simply relayed.
It is clear that similar effects as explained above can be obtained.

[0011]

[Effects of the Invention] As explained above, according to the present invention,
In a ring type transmission line connecting multiple nodes, one multi-accessor, and these, the following effects can be achieved by circulating a test frame including a test area in which a node number is written on the ring type transmission line. . (1) Even if the number of connected nodes increases, it is possible to detect whether each node is bypassed using a small number of bits in an area. (2) At the time of system construction, by circulating the inspection frame, it is possible to confirm at the master node what number of general nodes are connected to the system and in what order.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a normal ring network according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram when a ring network fails in the embodiment of the present invention.

FIG. 3 is a diagram showing a data format of a test frame in the present invention.

FIG. 4 is an explanatory diagram of node bypass in a ring network according to the prior art.

FIG. 5 is an explanatory diagram of a data format of a test frame and a method of detecting a bypassed node number according to the prior art.

[Explanation of symbols]

n1, n2, n3, nM node

Claims (1)

[Claims] Claim 1: A network in which a plurality of nodes are logically connected in a ring, and which has a function of bypassing the node from the transmission path in the event that a control means for accessing the transmission path from a node fails. In a network, a test frame having a specific area in which a node number is written is sent out to the transmission path, and each node sends a test frame to the transmission path when the content of the specific area is the node number of a node one node upstream from its own node. Each node rewrites the contents to its own node's node number and sends out a test frame, and if the contents of the specific area are other than the node number of the node one node upstream from its own node, each node indicates that the node in question has been bypassed due to a failure. A method for inspecting a faulty node in a ring network, which is characterized by recording or notifying a faulty node number to a specific node and writing its own node number in the specific area.