JPH04286244A - Packet communication network - Google Patents

Abstract

PURPOSE:To improve the transmission efficiency of a packet communication network in respect of a packet communication system in which plural nodes (station) are connected by a ring-shaped transmission line or a bus type transmission line, etc., and the packet of fixed length is transmitted, especially, the invalidation (abolition) of the packet. CONSTITUTION:Every node is provided with a node address memory 13 in which the addresses of all the nodes are stored, a comparing part 14 to compare the receiving node address of the packet to pass through the node with the node address stored in the node address memory, and an invalidating part 15 to invalidate the packet when the node address of the packet to pass through the node does not match with the node address stored in the node address memory.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a packet communication system in which a plurality of nodes (stations) are connected by a ring-type transmission path, a bus-type transmission path, etc., and transmits fixed-length packets, and in particular, the invention relates to a packet communication system in which a plurality of nodes (stations) are connected by a ring-type transmission path, a bus-type transmission path, etc., and transmits fixed-length packets. Regarding.

0002

2. Description of the Related Art With the recent development of communication technology, a highly efficient communication network is required. For this reason, a packet communication network is provided, but an abnormal packet whose receiving station address becomes an address that does not exist within the network due to a bit error on the transmission path, etc., is not received by any station and continues to circulate within the network. Traffic on transmission lines increases.

[0003] Conventionally, the above-mentioned abnormal packets were invalidated (discarded).
In order to do this, the control station that manages the network detects an error in the receiving station address of the packet passing through the network.

0004

[Problem to be Solved by the Invention] However, according to the packet invalidation method described above, the abnormal packet is not discarded until it reaches the control station. There was a problem that it could not be used and the transmission efficiency decreased. Therefore, an object of the present invention is to improve the transmission efficiency of a packet communication network.

[0005]

Means for Solving the Problems A means for solving the above problems is shown in FIG. That is, there is a node address storage means for storing all addresses of a node, a comparison means for comparing a received node address of a packet passing through the node with a node address stored in the node address storage means, and a comparison means for comparing the received node address of a packet passing through the node with the node address stored in the node address storage means. Each node is provided with invalidation means for invalidating the packet when the received node address does not match the node address stored in the node address storage means.

[0006]

[Operation] According to the above-described means, each node performs the same function as a monitoring node regarding the invalidation of abnormal packets.

[0007]

[Embodiment] FIG. 2 shows a loop type LAN to which the present invention is applied, in which a plurality of nodes, for example 4 nodes, transmit and receive data.
nodes 1-1, 1-2, 1-3, 1-4, and LA
A monitoring node 2 that monitors N is connected by a loop-type transmission line. FIG. 3 is a diagram showing the format of a packet used in the loop-type LAN according to the present invention. In FIG. 3, one packet is a fixed-length frame with a total of 128 bytes, including an 8-byte header and a 120-byte data area. As shown in FIG. 3, the header consists of DA indicating the destination address of this packet, usage status bit USD indicating whether the packet is valid or invalid, and so on.

Next, details of each node according to the present invention will be explained with reference to FIG. In FIG. 4, 11 is a synchronization unit that performs network synchronization detection and protection, and 12 is a timing generation unit that receives a synchronization signal from the synchronization unit 11 and sends a timing signal to each unit. Reference numeral 13 denotes a node address memory unit that stores the addresses of all nodes distributed by the management station at the time of line setup; and 14, the address of the received packet is determined by the network address signal from the node address memory unit 13 and the timing signal from the timing generator 11. This is a comparison unit that detects whether the station matches any one of the stations. Comparison section 14
As a result of the comparison operation, if the destination DA of the received packet does not match the address of any node, the invalidating unit 15 regards the received packet as an abnormal packet and discards the received packet. Specifically, the usage status bit USD of the received packet is rewritten from "1" to "0".

Reference numeral 14 denotes a data management unit which generates a destination address DA indicating the destination of the packet in the header of the received packet according to the timing signal from the timing generation unit 12.
a detection unit that identifies packets addressed to its own node, and a source address SA that indicates the source of the header of the received packet.
A detection unit that identifies frames and detects frames sent from other nodes, and a usage status bit (USD) in the header of received packets.
A detection unit that identifies the control busy bit BSY in the header of the received packet and detects a valid packet, a busy bit detection unit that identifies the control busy bit BSY in the header of the received packet and detects the status of the receiving buffer of the other node, and It is configured to include a processing unit that receives packets, discards frames, repeats frames, etc.

A receiving buffer 17 stores received packets, and a transmitting buffer 23 stores packets to be transmitted. An example of the operation in FIG. 4 will be described with reference to FIG. As shown in FIG. 5(A), first, when setting up the line, the monitoring node 2 sends "1" to the nodes (stations) 1-1 to 1-4.
An address table in which addresses "" to "4" are written is distributed, and this address table is stored in the node address memory 13 of each node 1-1 to 1-4.

Next, as shown in FIG. 5(B), node 1
-1, when data to be sent to node 1-4 occurs, an empty packet P is selected from among the passing packets.
(USD = “0”), load the data, set the usage status bit USD indicating that it is in use, set the destination address to “4” (meaning nodes 1-4), and put it on the transmission path. Send.

Next, as shown in FIG. 5(C), node 1
An error occurs in the destination address DA of the packet sent at -1. In this case, nodes 1-4 will no longer be able to receive it. As shown in FIG. 5(D), a packet in which an error has occurred in the destination address DA is discarded by the next node 1-2 to pass through, and becomes an empty packet. In other words, the usage status bit USD is set to "0".

Next, as shown in FIG. 5(E), node 1
If -3 is waiting to send data, the packet discarded by node 1-2 is immediately used by node 1-3. In the example case, data transmission to station 3 is shown. Also,
If node 1-2 is waiting to send data, it can send data using packets discarded by itself. In the above embodiment, a ring-type LAN has been described, but the present invention can also be applied to a bus-type LAN.

[0014]

[Effects of the Invention] As explained above, according to the present invention, abnormal packets existing in a packet communication network can be discarded at all nodes (stations) in the network. It can be shortened, packets can be used efficiently, and it can therefore contribute to improving the transmission efficiency of packet communication networks.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram showing the basic configuration of the present invention.

FIG. 2 is a diagram showing a ring-type LAN to which the present invention is applied.

FIG. 3 is a diagram showing a packet format according to the present invention.

FIG. 4 is a block circuit diagram showing a node according to the present invention.

FIG. 5 is a diagram showing an example of the operation of the ring-type LAN according to the present invention.

[Explanation of symbols]

1-1, 1-2, 1-3, 1-4...Node 2...Monitoring node 11...Period detection section 12...Timing generation section 13...Node address memory 14...Comparison section 15...Invalidation section 16...Data management section 17 …Reception buffer 18…Transmission buffer

Claims (1)

[Claims] 1. In a packet communication network to which a plurality of nodes (1-1 to 1-4) are connected, each node comprises node address storage means (13) for storing all addresses of the nodes; Comparison means (14) for comparing the received node address of the packet passing through the node with the node address stored in the node address storage means.
and invalidation means (15) for invalidating the packet when the received node address of the packet passing through the node does not match the node address stored in the node address storage means. Communication network.