JPH01213047A - System for controlling double ring network communication - Google Patents

Abstract

PURPOSE:To prevent the collision of a packet and to realize the transmission of the packet of optional length without providing a special node by connecting a link for transmission and a link for returning to plural nodes and controlling the link with the aid of the switching part of each node. CONSTITUTION:A double ring network is constituted by connecting the nodes 3-1-3-(n) with the aid of the link 1 for transmitting the packet and the link 2 for returning an impact packet. The testing part 4 of each node has a function identifying the packet and controlling the switching part 7. When the testing part 4 identifies the packet for its own node, it fetches the packet to a reception part 5 and does not relay-transmit it to the node of a downstream side. As the packet is not transmitted to the link 1, the node of the downstream side can transmit the packet. As the node which transmits the packet switches and connects the receiving side of the link 1 to the link 2 and returns the packet which is transmitted from the node of an upstream side, it judges that the collision occurs when it receives the packet which its own transmits. Therefore, the packet of the optional length can be transmitted without taken or the like and the impact can be easily detected.

Description

[Detailed Description of the Invention] [Summary] This invention relates to a double ring network communication control method in which multiple nodes are connected by links for sending packets and for returning colliding packets, and prevents packet collisions without providing special nodes. , and to enable the transmission of packets of arbitrary length, a double ring network is constructed by connecting multiple nodes with links for transmitting packets and links for returning collision packets, and each The inspection unit of the node inspects whether the packet is being transmitted, is addressed to the own node, or is a packet returned from the own node, and packets destined for the own node are relayed to other nodes. The switching unit is controlled so that the packet is received by the receiving unit without being transmitted, and when transmitting a packet, it identifies that a packet from another node is not being transmitted, and sends the packet from the transmitting unit to the packet transmission link. The switching unit is controlled so as to switch and connect the receiving side of the link for packet transmission to the link for returning colliding packets, so that packets from other nodes are not collided with each other during packet transmission. Configure it to loop back to the link for returning packets.

[Industrial application field]

The present invention relates to a dual ring network communication control system in which a plurality of nodes are connected by links for packet transmission and collision bucket return.

Various systems have already been proposed as communication control systems in a ring network in which a plurality of nodes are connected in a ring shape. Ring networks with dual rings are also known. In such a ring network, it is desired to simplify packet transmission/reception control and collision control.

[Conventional technology]

As a communication control method in a ring network in which a plurality of nodes are connected in a ring shape, a slot/seven ring method, a token ring method, etc. are known.

In the throttling method, a plurality of slots that can accommodate fixed length data are circulated around a ring, and the control data section of each slot indicates whether or not that slot is in use.
The data transmitting node finds an empty slot, inserts data into it, and indicates that it is in use by the control data section of that slot. When data addressed to the own node is identified, the data is fetched, the control data section of the slot is updated, and an empty slot is displayed.

Therefore, multiple communications can be processed simultaneously.

In addition, in the token ring system, a token indicating the right to transmit is circulated on the ring, and the data transmitting node takes in the token and starts transmitting data instead. Upon completion of this data transmission, a token is transmitted. Therefore, other data transmitting nodes wait for transmission until they receive this token, thereby avoiding communication conflicts among multiple nodes. This method has the advantage of being able to transmit data of arbitrary length.

Furthermore, a contention ring system that is a mixture of the C3MA/CD system and the token ring system has been proposed. In this system, the network operates in two modes: contention mode and token ring mode, and the modes are switched depending on the communication load to take advantage of the advantages of both systems.

In this contention mode, when a transmitting node identifies that no other node's packets are being transmitted on the ring, it transmits its own packet and indicates that the packet has gone around the ring and returned. Confirm and end the sending operation. Also, when transmission starts at the same time as other nodes,
The packet that has gone around the ring and returned cannot be confirmed, and is judged to be a transmission collision. If another node is already transmitting a packet, the mode shifts to token ring mode. In this token ring mode, the transmitting node waits for the end of the packet transmitted by another node, and then transmits its own packet.

This method uses the transmitted packet itself as a token without using a special token pattern.
There is no need for a special node to generate or manage tokens, and when the ring is not in use, communication can be performed without tokens in contention mode, making it possible to use the ring network due to the delay in token circulation. This has the advantage of preventing a decrease in efficiency.

[Problem to be solved by the invention]

In the above-mentioned throttling method, when the transmission data length is long, it is divided into slots and transmitted, and since a control data part is always added to each slot, it is difficult to control the data length to be transmitted. This has the disadvantage that the total length of the data section increases. For example, if 1000 bytes of data can be communicated in one packet, one control data section is sufficient, but if the data is divided into 100 bytes and communicated, 10 control data sections are also required. It turns out. In addition, it requires a special node with a slot generating function, and the number of slots varies depending on the scale of the ring network, so it is difficult to add or remove nodes, change the network length, etc.

In addition, the token ring method described above can transmit packets of arbitrary length, and by using multiple tokens,
Although it is possible to perform multiple communications at the same time, it has the drawback of requiring a special node to generate tokens, and also has the drawback of not being able to send packets until a token is acquired. The average time it takes for this token to reach the transmission requesting node is the time it takes to make a half-circle around the ring network, and the ring network cannot be used during this time, which also has the disadvantage of lower usage efficiency.

Furthermore, the contention ring method described above does not require a special node for generating and managing tokens.
In order to detect a packet collision in contention mode, the packet needs to go around the ring network, and since the packet round trip time increases in proportion to the ring length, the time required for collision detection also increases. However, there was a drawback that the efficiency of using the ring network was reduced.

An object of the present invention is to prevent packet collisions without providing a special node, and to enable transmission of packets of arbitrary length.

[Means to solve the problem]

The dual ring network communication control system of the present invention uses one of the dual rings for packet transmission and the other for collision detection, and will be described with reference to FIG.

Link 1 for transmitting packets and link 2 for returning collision packets connect a plurality of nodes 3-1 to 3-n to form a double ring network, and each node 3-1 to
3-n is provided with a received packet inspection section 4, a packet reception section 5, a packet transmission section 6, and a link switching section 7. The inspection unit 4 checks whether or not a packet from another node is being transmitted to the link 1 for packet transmission, whether or not a packet sent from the own node is looped back, and whether a received packet is addressed to the own node. When it is determined that the received packet is addressed to its own node, the receiving unit 5
The switching unit 7 is controlled to take in the received packet. When transmitting a packet, it is determined that a packet from another node is not being transmitted to the link 1 for packet transmission, and the switching unit 7 is controlled to switch link 1 for packet transmission.
At the same time, the receiving side of link 1 is switched and connected to link 2 for returning collision packets, and while packets are being sent from the own node, packets from other nodes are switched to link 2 for returning collision packets. This is a return to 2.

[Effect]

When a packet addressed to its own node is identified, the packet is received by the receiving unit 5 and is not relayed to the downstream side, so the downstream node does not transmit the packet to link 1 for packet transmission, so it does not transmit the packet. can do. In addition, the node that transmits the packet connects the receiving side of link 1 for packet transmission to link 2 for returning colliding packets.
Since the packet sent from the upstream node is returned to link 2 for returning the collision packet, when a packet sent by the own node is received and identified via link 2 for returning the collision packet, It can be determined that a collision has occurred. Therefore, packets of arbitrary length can be transmitted without requiring tokens and the like, and collision detection can be easily performed.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a block diagram of the main parts of the node according to the embodiment of the present invention, in which 11-1 and 11-2 are links for packet transmission;
11-1.12-2 is a link for returning collision packets, 1
3.14 is a buffer memory, 15 is a packet receiving circuit,
16 is a packet transmission circuit, 17.18 is a test circuit, 19
Reference numeral 20 and 21 represent a switch control circuit, and 20 and 21 are switch circuits constructed of transistors and the like, which can be switched and connected to contacts a and b and can also be turned off.

A plurality of nodes have the same configuration, and each node is connected in a ring shape by a link 11-1.11-2 for packet transmission and a link 12-1.12-2 for returning collision buckets and nodes. , a double ringne nodwork is constructed. In addition, the node connected to the packet transmission link 11-1 and the collision packet return link 12-2 is an upstream node, and the opposite side is the packet transmission link 11-2 and the collision packet return link 12. The node connected to -1 will be referred to as a downstream node.

In addition, when the switch circuits 20 and 21 do not transmit or receive packets, the switch circuits 20 and 21 are in the connection state shown in the figure, and the
3.14, the packet will be relayed and sent out. Further, the inspection circuit 17 inspects the destination of the received packet, and checks whether the packet is addressed to its own node.

When transmitting a packet, the inspection circuit 17 identifies that a packet from another node is not being transmitted through the link 11-1 for packet transmission, and the switch control circuit 19 controls the switch circuit 20 to transmit the packet. The reliable link 11-2 and the packet transmitting circuit 16 are connected, and packets are transmitted from the packet transmitting circuit 16. At the same time, the switch circuit 21 is controlled by the switch control circuit 19 to connect the buffer memory 13 and the collision packet return link 12-2, and when a packet is sent from an upstream node, the packet is sent to the collision packet. The packet is returned to the link 12-2 for returning the packet. The inspection circuit 18 also inspects whether the packet sent by the own node has been returned by another node.

Based on the test output signal and transmission request signal from the test circuits 17 and 18, the switch control circuit 19 determines that there is no communication state when it does not detect a packet addressed to its own node and there is no transmission request, or When a packet addressed to the own node is detected, it is in the receiving state, when there is a transmission request and no packet from another node is detected, it is in the sending state, and when receiving and sending are simultaneous, it is in the sending/receiving state. The switch circuits 20 and 21 are controlled in accordance with the
For example, as shown in Table 1, switch circuit 20.21
This is to control the switching connection state between contacts a and b and off (off).

Table 1, Figure 3 is an explanatory diagram of the formant of a packet, which includes a packet start pattern STX, a destination address section indicating the destination node, an originating address section indicating the originating node, and a data length section indicating the length of data to be transmitted. , a data part, and a packet end pattern ETX. Note that if the formant includes a destination address and a source address,
It is also possible to use other formats.

FIG. 4 is a block diagram of the main parts of the test circuit, showing the relationship between the buffer memory 30 and the test circuit 31. That is, the self-node address from the register 34 is compared with the destination address and originating address of the received packet stored in the buffer memory 30, respectively, by comparison circuits 32 and 33, and when a match signal is obtained from the comparison circuit 32, , it is possible to identify that the packet is addressed to the own node. Also, when a match signal is obtained from the comparison circuit 33, in the case of a link-side inspection circuit for packet transmission, it means that the packet sent by the own node has returned after a round, and the node at the destination address is at fault. It can be determined that Furthermore, in the case of a link-side inspection circuit for returning a collision packet, it can be determined that a collision has occurred. In the event of a collision, the switch circuit 20 is controlled by the switch control circuit 19, and packet transmission is stopped.

FIG. 5 is an explanatory diagram of a dual ring network according to an embodiment of the present invention, in which nodes Nj, Nk, and Ni.

Nx are connected in a ring shape by a link 41 for packet transmission and a link 42 for returning collision packets to form a double ring network, and each node Nj, Nk, N
i and Nx have the configuration shown in FIG. Reference numeral 43 denotes an inspection circuit, which is used to inspect packets on the link 41 for transmitting packets and the link 42 for returning conflicting packets. For example, when transmitting a packet from node Ni, it is identified that no packet from another node is being transmitted on the link 41 for packet transmission,
A packet is sent to a link 41 for packet transmission, and the receiving side of the link 41 for packet transmission is switched and connected to a link 42 for returning a collision packet.

Therefore, the packet sent from the node Ni is transmitted via the link 41 for packet transmission, and the designated node takes in the packet. Therefore, when a packet transmitted from the own node cannot be detected as being received from an upstream node via the link 41 for packet transmission, the packet communication is considered to have been successful.

Immediately after sending the packet from this node Ni, the upstream node Nx identifies that no packet from another node is being transmitted on the link 41 for packet transmission, and
When a packet is sent out, since a return circuit has already been formed at the downstream node Ni, the packet sent from the node Nx is returned via the collision packet return link 42, and the inspection circuit 43 detects the occurrence of a collision. If possible, immediately stop sending packets.

FIG. 6 is an explanatory diagram of the operation of a node, where (a) shows a node in a non-communication state, and the switching unit of the node is
This corresponds to the non-communication state of 1), and the upstream node and the downstream node are connected to each other with respect to the link 41 for transmitting packets and the link 42 for returning collision packets. Then, it is checked whether the packet transmitted to the packet transmission link 41 is addressed to the own node.

In addition, (b) shows a node in a receiving state, and the switching unit of that node corresponds to the receiving state in (2) of Table 1, and the link 41 for packet transmission is connected between an upstream node and a downstream node by the switching unit. Is it in a state where it is separated from the node and receives packets from the upstream node? Wholesale.

Further, (C1 indicates a node in a transmission state, the switching unit of that node corresponds to the transmission state in (3) of Table 1, and the link 41 for packet transmission and the link 42 for returning a collision packet are as follows. The switching unit disconnects the upstream node from the downstream node, and sends out the downstream node.Furthermore, the link 41 for packet transmission and the link 42 for returning the collision packet are connected back by the switching unit, and the upstream node A packet transmitted from a node via the packet transmission link 41 is looped back to the collision packet return link 42.The packet is also checked to see if it is addressed to the own node, and the collision packet is returned from the downstream node. It is checked whether the packet sent from the own node is returned via the return link 42.

Also, (d) shows a node in a transmitting/receiving state, and the switching unit of that node corresponds to the transmitting/receiving state in (4) of Table 1. This corresponds to the case where a packet is transmitted from an upstream node, and there is a link 41 for transmitting the packet and a link 4 for returning the collision packet.
2 is opened, and link 4 for packet transmission is opened.
1 receives packets transmitted from the upstream node via 1.

FIG. 7 is an explanatory diagram when transmitting from multiple nodes, (al is
This shows a case in which nodes Nj and Ni are in a transmitting state and packets are sent from node Nj to node Nk and from node Ni to node Nx through the link 41 for packet/node transmission, and packets from node Nj are sent to node Ni. Since the packet is looped back and sent back to the node Nj via the collision packet return link 42, the node Nj can identify the occurrence of a collision. Also, the packet from node Ni is looped back at node Nj and sent to link 4 for returning the collision packet.
2 is sent back to node Ni, so node Ni can also identify the occurrence of a collision. That is, if a node upstream from the destination node enters a transmitting state, the packet will be looped back.

In addition, (bl indicates the case where nodes Nj and Ni are in the sending state and send packets from node Nj to node Nk, and from node Ni to node Nk, and the packet sent from node Ni to link 41 for packet sending is ,
A link 41 for transmitting the packet received by the downstream node Nk and a link 4 for returning the collision packet to the node Nj.
Even if a loopback connection with No. 2 is made, the packet from Node Ni is not returned, so Node Ni can determine that the communication was successful. Further, as in the case described above, the packet from node Nj is looped back at node Ni and sent back through the collision packet return link 42, so that node Nj can identify the occurrence of a collision.

In addition, (C1 shows the case where nodes Nj and Ni are in the sending state and send packets from node Nj to node Nk, and from node Ni to node Nj, respectively, and the packet sent from node Ni to link 41 for packet sending is ,
Received by node Nj. Furthermore, since the packet sent from node Nj is looped back at node Ni upstream from destination node Nk and sent back to node Nj by the collision packet return link 42, node Nj can identify the occurrence of a collision. .

Also, (dl indicates the case where nodes Nj and Ni are in the transmitting state and send packets from node Nj to node Nx, and from node Ni to node Nx, respectively, and the packet from node Nj is received by node Nx, The packet from node Ni is looped back at node Nj, and node Ni can identify the occurrence of a collision.

When the aforementioned collision occurrence is identified, packet transmission is stopped, and retransmission is performed after confirming that no packet from another node is being transmitted on the link 41 for packet transmission. Various methods can be adopted for this retransmission control, and for example, it can also be performed using a random waiting time.

〔Effect of the invention〕

As explained above, the present invention configures a double ring network by connecting a plurality of nodes 3-1 to 3-n using link 1 for packet transmission and link 2 for returning collision packets, and transmits The requesting node identifies that it is not transmitting a packet from another node on Link 1 for packet transmission, and sends out a packet, and also connects the receiving side of Link 1 for packet transmission and Link 2 for returning colliding packets. The switching unit 7 switches and connects the two nodes, and when the inspection unit 4 detects a packet addressed to its own node, the switching unit 7 switches and connects the packet so that the packet is received by the receiving unit 5 without being relayed. , when packets from other nodes are not being transmitted, packets can be sent at any time, and
Can send packets of arbitrary length.

Therefore, since control data such as slots and tokens is not required, there is no need for a node to manage them, and there is no need for an increase in control data in the throttling method or the waiting time until token acquisition in the token ring method. This has the advantage of not causing losses such as

Also, whether or not packet communication was successful is checked by whether or not the packet sent by the own node is returned, including cases where there is a collision with another node's transmission and cases where the sent packet is not received. be able to. The time required for this collision detection is twice the distance between nodes transmitting data at the same time (
If two nodes transmit at the same time, it will take the average time to go around the ring network, but if three nodes transmit at the same time, it will take on average 2/3 of the time to go around the ring network. time is reduced. That is, when β nodes transmit simultaneously, the time required for collision detection is
- It is reduced to 2/β time of the time required for a round.

Furthermore, since the receiving node takes in the packet, if multiple nodes transmit at the same time and the destination is a node located upstream from other transmitting nodes, all packet communications can be completed. In other words, since the packet arrives at the destination node without being looped back, the sending node does not detect the collision.
Communication can be completed normally.

[Brief explanation of the drawing]

Fig. 1 is a diagram explaining the principle of the present invention, Fig. 2 is a block diagram of the main part of a node according to an embodiment of the invention, Fig. 3 is a diagram explaining the formant of a packet, and Fig. 4 is a block diagram of the main part of the inspection circuit. , FIG. 5 is an explanatory diagram of a dual ring network according to an embodiment of the present invention, FIG. 6 is an explanatory diagram of the operation of nodes according to an embodiment of the present invention, and FIG. This is an explanatory diagram at the time of transmission. 1 is a link for transmitting a packet, 2 is a link for returning a collision packet, 3-1 to 3-n are nodes, 4 is an inspection unit, 5 is a reception unit, 6 is a transmission unit, 7 is a switching unit, 11-1.11-2
is a link for packet transmission, 12-1.12-2 is a link for returning collision packets, 13.14 is a buffer memory, 15 is a packet reception circuit, 16 is a packet transmission circuit,
Reference numerals 17 and 18 are inspection circuits, 19 is a switch control circuit, and 2 degrees and 21 are switch circuits.

Claims (1)

[Claims] A plurality of nodes (3-1 to 3-
n) to form a double ring network, and each of the nodes (3-1 to 3-n) includes a received packet inspection unit (4), a packet reception unit (5), and a packet transmission unit. a link switching section (6) and a link switching section (7), and the inspection section (4) is arranged to
) whether packets from other nodes are being transmitted at
Identify whether the received packet is addressed to the own node or not, and whether the packet sent by the own node is a looped packet, and when it is determined that the received packet is addressed to the own node, relay it to another node. the switching unit (7) so that the receiving unit (5) captures the received packet without transmitting it;
When transmitting a packet, the link for transmitting the packet (1)
identify that a packet from another node is not being transmitted, and control the switching unit (7) to switch and connect the packet transmission link (1) to the transmitting unit (6); The receiving side of the link (1) is switched and connected to the link (2) for returning the collision packet, and the packet sent from another node while the packet is being sent from the own node is connected to the link (2) for returning the collision packet. ) is a dual ring network communication control method characterized by loopback.