JPH02119451A - Continuous communication system for packet in token ring - Google Patents

Abstract

PURPOSE:To efficiently send numerous data at high speed by avoiding the release of a taken even if timeout takes place in the case of the absence of a transmission packet in other nodes. CONSTITUTION:A reception control section 144 at a sender node receives a packet sent from its own node and detects a change ('1' to '0') of the state of a transmission request bit 102 in the packet, then it is informed to a transmission control section 145, which generates a control output stopping the transmission when an output of timeout is generated from a timer 143. In this case, an effective token is sent from a node sending a packet and the transmission right is taken over to other node. When no transmission request comes from other node in the case of sending a packet continuously, the transmission control section 145 sends the information from a transmission buffer 13 continuously even after timeout. Thus, numerous data can be transmitted at high speed efficiently.

Description

[Detailed Description of the Invention] [Summary] Concerning a continuous packet communication method in Token Ring in which communication rights are granted by acquiring valid tokens, if there are no packets to be sent to other nodes, the current transmission continues even after timeout. The purpose is to provide a continuous communication method of packets in Token Ring that allows nodes to transmit continuously.A transmission request bit is provided at the end of the packet sent by a node that has obtained communication rights, and When requesting transmission, the other nodes on the ring that set the transmission request bit to one logical state, and which have packets to transmit,
The transmission request bit is set to the other logical state and the node that transmitted the information packet is notified, and the node that transmitted the packet sets a determined timer value when it detects that the transmission request bit of the packet is in one of the logical states. The configuration is such that a valid token is generated when the timer value is reached and the other logical state is detected by continuously transmitting packets beyond the threshold.

[Industrial Application Field] The present invention relates to a continuous packet communication system in a token ring in which communication rights are granted by acquiring valid tokens.

Token ring has been used as a control method for local area networks (LANs), but in recent years, LANs have been used mainly to provide high-speed transmission paths for computer data within a limited area. usage patterns are diversifying2, and attempts are being made to integrate various media6.
Jl: It became a sea urchin.

As one trend, it is desired to transmit large amounts of data such as high-definition still images and large files at high speed.

[Conventional technology] FIG. 4 shows an explanatory diagram of a conventional example.

In the token ring network configuration, as shown in A, each node is sequentially connected by a ring-shaped transmission path. Communication is controlled using data in the format shown in Figure 4B, called tokens, which circulate on the ring.

In FIG. 4B, the token is composed of a preamble indicated by P, a start delimiter indicated by SD, a frame control indicated by FC, and an end delimiter indicated by ED. The most significant bit of the FC of this token is a token display bit, and when this bit is "1", it indicates that it is a valid token, and when it is "0", it indicates that it is an invalid token. When the node that wants to transmit receives this valid token, it sets this display bit to "0", adds transmission information, etc., and transmits it.

The frame format of a packet when transmitting information is shown in FIG. 4 C1, in which the beginning of the token is used as the leading part, and includes a preamble P, a start delimiter SD,
It is followed by a frame control FC that includes a token indication bit (set to “0”), followed by control information such as destination address, source address, transmission information, frame check sequence (indicated by FCS), and finally ED. It is provided.

The procedure of communication using the conventional token ring will be explained with reference to FIG. 4 and an example of the operation of the ring network.

When node 1 wants to send information, if a valid token is received, it sets its token indication bit to 0'' and sends a packet according to the frame format shown in FIG. In the example above, the packet is received at node 2), passes through nodes 3 and 4, goes around the ring, returns to node 1, and is received and checked by the receiving section (not shown) of node 1. (not sent to the ring).The maximum length of the amount of information communicated in one packet is specified by the standard (for example, several kilobytes) based on the conditions of the node, transmission path, etc., so the amount of data transmitted If the number is large, divide it into multiple packets and send them consecutively.

However, in order to maintain the fairness of transmission opportunities, each node is provided with a timer, and in any case, packets cannot be continuously transmitted from one station beyond the timer value.

In other words, when the timer value is reached during communication, packet transmission is stopped and a valid token (token display bit is "1") is sent to the ring, and the valid token is detected to have returned unchanged. The interrupted data transmission can then be resumed.

[Problems to be solved by the invention] As mentioned above, in the conventional method, when transferring large-capacity data (several megabits or more) such as high-definition still images or large-capacity files, the packets to be sent to other nodes are Even without it, if the timer times out, you must release the token and wait until it goes around the ring again. Therefore, there is a problem in that the time required to transfer data that is desired to be transmitted continuously increases.

SUMMARY OF THE INVENTION An object of the present invention is to provide a continuous packet communication system in a token ring that allows a currently transmitting node to continue transmitting even after a timeout when there are no packets to transmit to other nodes.

[Means to solve the problem] A basic configuration diagram of the present invention is shown in FIG.

In FIG. 1, 10 represents a packet, 11 a terminal, 12 a reception buffer, 13 a transmission buffer, and 14 an access control unit.

The present invention provides an area for setting a transmission request bit after the information part of a packet, and when a transmitting node wants to transmit continuously, it sets this transmission request bit to one state and performs transmission, and the ring is It detects the state when it returns after completing one cycle, and if there is no change, it continues sending after the timeout, and if it changes and is in the other state, it stops sending at the timeout. be.

[Operation] The frame of the packet 10 of the present invention is provided with a token request bit 101 as in the conventional format, followed by a destination address, a source address, and information, but then a transmission request bit 102 is set to 1. bit provided. This transmission request bit 102 is used to control continuous communication of packets.

In the configuration of the node shown in FIG. 1, when information to be sent from the terminal 11 to another node is stored in the transmission buffer 13,
In the access control unit 14, the token control unit 142 detects that the reception control unit 144 receives a valid token (the token display bit is “1”). When a valid token is detected, the token display bit is set to "0" and the transmission control unit 145 is driven to transmit a packet according to the frame structure of the packet IO shown in FIG. 1, which includes information from the transmission buffer 13. , timer 143 starts. When transmitting this packet, if there is information to be transmitted continuously, the transmission request bit is set to "0" and packets of the same format are successively transmitted to the ring.

When a continuous packet is being transmitted and you want to transmit it from another node, when the packet is received by the reception control unit 144 of the other node, the transmission request bit is extracted from the packet by the transmission request bit control unit 141. , "0" is set to "1", and the other contents of the packet (-/) are transferred to the lower node without being changed.

The reception control unit 144 of the source node receives the packet transmitted from its own node, and transmits the transmission request (Biff) 102 in the packet.
When it is detected that the state of has changed (1″→“O”),
The transmission control unit 145 is notified, and the transmission control unit 145 generates a control output to stop transmission when a timeout output is generated from the timer 143. In this case, the node that was transmitting the packet transmits a valid token and transfers communication rights to another node.

When a transmission request is not generated from another node while continuously transmitting packets (when the transmission request bit does not become "0"), the transmission control unit 145 continuously transmits information from the transmission buffer 13 even after timeout. Send.

[Embodiment] FIG. 2 is a block diagram of a node according to an embodiment, and FIG. 3 is a frame format of a packet according to an embodiment.

In FIG. 2, reference numeral 20 denotes a reception buffer that receives and receives packets for the own node extracted by the reception packet sorting unit 21;
When 21 detects a packet with its own node as the destination address, it takes out the packet in a copy format and outputs it to the reception buffer, and for other packets, it simply performs a relay operation, and 22 operates on the transmission request bit. A transmission request bit management unit; 23 is a token management unit that generates and detects tokens; 24 is a timer that starts at the start of transmission and generates a timeout output at a preset time; 25 is transmission information output from the terminal; A transmit buffer 26 is a transmit arbitrator that either transmits information from the transmit buffer (when acquiring a token) or relays frames from an upstream node and transmits them downstream. represents.

The frame format of the packet in the embodiment shown in FIG. 3 includes a preamble, a start delimiter, a frame
control, destination address, source address, information,
A frame check sequence and an end delimiter follow, followed by one transmission request bit according to the present invention, and finally a frame status.

The format of the token uses the same structure as the conventional one (see FIG. 4B), and the operation of the embodiment of the node using the transmission request bit of the frame format shown in FIG. 3 is as follows: 1)
The cases of a node requesting transmission and 2) a node currently transmitting will be explained separately below.

1) Node requesting transmission ■Normally, the flow of information from an upstream node is relayed as is to a downstream node, but when a transmission packet is input from a terminal to the transmission buffer 25, it enters a transmission request state and requests transmission. The bit management unit 22 is notified of the setting request.

■The transmission request bit management unit 22 receives this and then sets the transmission request bit of the packet to be relayed from “O” to “1”.
” and wait for the token to come around.

■When the token comes around, the token management section 23
and acquires a token (setting the token display bit to 1"). At the same time, it controls the transmission buffer 25 and sends the packet stored there to the transmission path. At this time, the timer 24 is started and the upstream It does not relay the flow of information from the nodes.

2) Transmitting node - After the operation in 1) above, the node that is in the transmitting state uses the transmission request bit management unit 22 to determine when the packet it transmitted has gone around the loop and returned. The transmission request bit of the packet is monitored, and it is set to “1”.
When detecting that the token is set, the token management unit 23 is notified.

■Also, the timer 24 started at the start of packet transmission.
will time out after a certain period of time, and will notify the token management unit 23 of this.

(2) When a timeout occurs and a transmission request bit detection notification is received, the token management unit 23 stops transmitting packets from its own node, releases tokens, and sends valid tokens to downstream nodes.

Unless this condition is met, the packets in the transmission buffer 25 will continue to be transmitted, and the token will be released when the transmission buffer becomes empty.

[Effects of the Invention] According to the present invention, if there is no packet to be sent to another node, the token will not be released even if a timeout occurs, so the overhead required for the token to circulate as in the past can be eliminated, and large amounts of data can be transmitted efficiently and at high speed. Moreover, at the same time, it is possible to guarantee the fairness of transmission opportunities for each node.

[Brief explanation of drawings]

FIG. 1 is a basic configuration diagram of the present invention, FIG. 2 is a configuration diagram of a node according to an embodiment, FIG. 3 is a frame format of a packet according to an embodiment, and FIG. 4 is an explanatory diagram of a conventional example. In FIG. 1, 10: Packet 11: Terminal 12: Reception buffer 13: Transmission buffer 14: Access control section 141: Transmission request bit control section 142 Nidokun control section 143: Timer 144: Reception control section 145: Transmission control section

Claims (1)

[Claims] In a token ring in which communication rights are granted by acquiring a valid token, a transmission request bit (102) is provided at the end of a packet (10) transmitted by a node that has acquired communication rights, and the packet is transmitted. When continuously requesting transmission, the transmission request bit is set to one logical state, and other nodes on the ring that have packets to transmit rewrite the transmission request bit to the other logical state and transmit the information. The node that sent the packet is notified, and when the node that sent the packet detects that the transmission request bit of the packet is in one of the logical states, it continuously transmits the packet beyond a predetermined timer value, and A continuous packet communication method in a token ring, characterized in that a valid token is generated when a timer value is detected and a timer value is detected.