JPS62266943A - Data transfer control system - Google Patents

Abstract

PURPOSE:To attain line switching in the network of a token ring system by providing a data buffer and a controller on each node to prevent underflow of the data buffer due to the variation of a token circulating time. CONSTITUTION:A node 4 consists of a ring transmission/reception control section 11 on a ring transmission line 3 controlling transmission/reception and recovery relay of a transmission data, a transmission/reception data buffer 12 storing a transfer data tentatively, a terminal interface control section 13 and a controller 14. In the data transfer control of the controller 14, as soon as the phase is transferred to the data transfer phase, a sent data from the terminal equipment 1 is started to input to a buffer 12. The transmission to the transmission line 3, however, is controlled to allow the start after a prescribed time elapses. Since the data transfer from the buffer 12 is started by the controller 14 with a prescribed delay time in such a way, the underflow of the buffer 12 is prevented and the line switching in the network of the token ring system is realized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a data transfer control system for realizing circuit switching using a token ring network, which is a local area network.

[Conventional technology]

Conventionally, token ring networks have been applied exclusively to packet switching, and there have been no examples of them being applied to circuit switching. Therefore, there is no prior art to compare with, so here we will outline the packet exchange using the token ring method.

FIG. 5 shows an example of the configuration of a token ring network system, and in the figure, la, lb.

1 such as 1o is a terminal; 2 such as 2a, 2b, 2o, etc. is a terminal interface line; 3 is a ring transmission line with directionality; 4a,
4b, 4o, etc. are nodes that have the function of reproducing and repeating the signals on the ring transmission line 3 and the data transfer function between each terminal 1 and the ring transmission line 3, and the data transfer with the terminal 1 is performed through each terminal interface line. This is done through 2. 5 is a ring control device that manages tokens, generates a system clock for system-wide synchronization, etc.
This control device 5 performs its functions on each node la.

It is also possible to make it unnecessary by allowing lb and lc to have it autonomously.

FIG. 6 is a diagram showing an overview of data transfer in the token ring network configured as shown in FIG. 5.

In the figure, a token arrives at the node 4a at time L0. At this time, the node 4a has data to transmit, and sends this as frame A to the ring transmission path 3.
The token is played immediately after frame A (time t1
). Next, the node 4b does not have any data to transmit and merely reproduces and relays the frame A and the token (time tz). However, if frame A is a frame addressed to node 4b, node 4b receives frame A at the same time as reproducing and relaying. At time t3, the node 4C transmits the frame C and reproduces the token, and the ring control device 5 is reproducing and relaying the frame A. At time t4, frame A has gone around the ring transmission path 3 and is no longer used, so node 4a discards it and sends it to 1.-
This shows that Kun has received a call again. This means that the token has completed one cycle, and in this example, the token cycle time seen from the node 4a is ta-1o.

[Problem that the invention seeks to solve]

By the way, the token-tour time in the token ring network as described above is the sum of the round-trip propagation delay time of the ring transmission path 3, including the regenerative relay delay within each node, and the length of the transmission frame, including the length of the token. , varies greatly depending on the scale of the system and the transmission status of each node. Because of this variation, token ring networks
It was used exclusively for packet switching, and no attempt was made to apply it to circuit switching.

That is, in line switching, it is necessary to maintain data transfer at a constant rate between terminals, but fluctuations in token-to-token time cause the following problems. Assuming that the data transmission rate between terminals is X bits/second (constant) and the token-to-token cycle time is L seconds (variable), the data buffer on the sending side is t.
New data of X and L bits is accumulated in seconds, and this data is transferred to the data buffer on the receiving side via the ring transmission line 3. Since the received data transferred to the data buffer on the receiving side is transferred to the receiving terminal at a rate of X bits/second, the transfer of X-1 bits of received data to the receiving terminal is completed in t seconds. Therefore, if the next data does not arrive within the above seconds, an underflow will occur in the data buffer on the receiving side, and data transfer to the terminal will be temporarily interrupted. In the token ring system, since the token travel time constantly fluctuates, if no countermeasures are taken, such underflows will frequently occur and circuit switching cannot be realized.

The object of the present invention is to prevent data buffer underflow due to token-to-cycle time fluctuations and to realize line switching in a token ring network.

[Means for solving problems]

The data transfer control method according to the present invention includes a data buffer for temporarily storing data transferred between a terminal and a ring transmission line in each node, and a call control and data transfer system that connects nodes subject to 14 circuit switching. The controller includes a controller that controls data transfer of the buffer, and the controller delays the data transfer from the data buffer by a predetermined amount of delay that is predetermined according to the network when the call control phase is completed and the transition is to the data transfer phase. It is designed so that it starts with

[Effect]

In this invention, under the control of the controller, data transfer from the data buffer is started after a predetermined amount of data has been accumulated in the data buffer or after a predetermined period of time has passed after transitioning to the data transfer phase. Underflow will no longer occur in the data buffer.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a block diagram showing an example of the configuration of a node for carrying out the present invention, and the node 4 includes a ring transmission/reception control section 11 which is located on the ring transmission path 3 and controls transmission and reception of transfer data, reproduction interruption, etc. , a transmission/reception data buffer 12 that temporarily stores transfer data, a terminal interface control unit 13 that interfaces with the terminal 1, and a controller 14 that centrally controls these. Note that the terminal 1 here is a transmission-only terminal, and is connected to the terminal interface control section 13 of the node 4 via the terminal interface line 2.

The present invention is a data transfer control method in the controller 14 shown in FIG. 1, and an embodiment of its control sequence will be described below with reference to a flowchart shown in FIG. 2.

FIG. 2 shows the initial operation of the controller 14 until it can start transmitting data from the terminal 1 onto the ring transmission path 3 in response to a call request from the terminal 1 or an incoming call from another node. ing. When the call control phase in steps 21 and 22 is completed, the transmission data from the terminal 1 starts to be input to the transmission/reception data buffer 12 of the node 4 at the same time as the transition to the data transfer phase. The start of transmission is only allowed after a predetermined time has elapsed in step 23. That is, if the above predetermined time is t8 and the terminal interface speed is X bits/second, the amount of data initially sent to the ring transmission path 3 is X·1 bits, and thereafter, each time a token arrives, The data accumulated in the transmit/receive data buffer 12 is sent to the ring transmission path 3. Note that since the amount of data accumulated in the transmission/reception data buffer 12 is proportional to the passage of time, the determination in step 23 can also be made based on whether or not the accumulation of data in the transmission/reception data buffer 12 has reached a predetermined amount fiX·tl,l. becomes. Further, the capacity of the transmitting/receiving data buffer 12 is the above-mentioned X-t.

It is necessary to secure at least one bit.

Next, a method of calculating the predetermined time 1,1 will be explained.

FIG. 3 shows the situation of data transfer from node A to node B. Data flows into node A from the terminal at X bits/second, and data flows from node B at X bits/second.
Data leaks to the terminal in seconds. Here, the delay time from node A to node B is tpt (i=1.2.3...
-), delay time from node B to node A tII,
(j=1.2°3-...). Note that i and j correspond to the number of cycles of the token after the start of ring transmission. Now,
After starting data inflow from the terminal 1. If the transmission on the ring transmission path starts after a second, X-t, , bits of data are transferred and received by the Node B. Node B is X-t
, starts outputting data to the terminal at a rate of X bits/second immediately after receiving the bits. Thereafter, node A continues transmitting to the ring transmission path while acquiring tokens each time. In this situation, the amount of data remaining in the receive data buffer just before node B receives new data from the ring transmission line for the nth time is:
lZ-tF3 '-'-'-'--t+nz-bn
-++bn-z+tgh-z-tsn-+-bJ bits, rearranged as
) bit. If this is negative, it means that an underflow has occurred in the data buffer, and 'w+5 LFn-bit tBn-bit tF, I〉0, that is, t, > (tv,,-++in-+)+( tr
a-tr+), underflow will not occur. jFn-1+tiM-1 and jF++-E
The maximum value of F+ is k tr (MAX) + tl
(MAX) and 5 (MAX)-b (old N),
The former corresponds to the maximum token-to-token delay time, and the latter corresponds to the maximum delay time on the outward path between nodes, but since there are cases where the corresponding nodes are adjacent in the opposite direction of transmission, even in the worst case, the predetermined amount It can be seen that it is sufficient to set the delay tW to twice the maximum time for one round of tokens.

In addition, in the above embodiment, the case where this method is implemented in the data buffer on the transmitting side is shown, but it may also be implemented in the data buffer on the receiving side, as shown in steps 31 to 34 of the flowchart in FIG. Furthermore, based on the flowcharts of FIGS. 2 and 4 above, even if the data buffers 1 on both the transmitting side and the receiving side are configured to ensure a total delay of a predetermined amount t8, the same effect as in the above embodiment can be obtained. is obtained.

〔Effect of the invention〕

As described above, according to the present invention, each node is provided with a data buffer for temporarily storing data transferred between a terminal and a ring transmission path, and also has a call control function that connects nodes subject to circuit switching. The controller includes a controller that controls the data transfer of the data buffer, and the controller controls the data transfer from the data buffer when the call control phase is completed and the transition is to the data transfer phase.
Since the start is made with a predetermined amount of delay that is predetermined depending on the network, it is possible to realize line switching in a token ring network without causing data buffer underflow.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of the configuration of a node for implementing the present invention, FIG. 2 is a flowchart showing an example of a control sequence of a controller according to the present invention, and FIG. FIG. 4 is a flowchart showing another embodiment of the present invention, FIG. 5 is a block diagram showing the configuration of a token ring network, and FIG. 6 shows data transfer in the token ring network. It is an explanatory diagram. 1 is a terminal, 2 is a terminal interface line, 3 is a ring transmission line, 4 is a node, 5 is a ring control device, 11 is a ring transmission/reception control unit, 12 is a transmission/reception data buffer, 13 is a terminal interface control unit, and 14 is a controller. be. In addition, in the figures, the same reference numerals indicate the same or corresponding parts. Agent: Masuo Oiwa (and 2 others) Figure 1: Each Snowy γ Sakae # Procedural Amendment (To the Commissioner of the Japan Patent Office, -1
,”, Gohe 1, Indication of the incident, Patent Application No. 110201/1988 2,
Name of Yumei, Ya data transfer control method 3, and relationship with the amended person case Patent applicant address 2-2-3 Marunouchi, Chiyoda-ku, Tokyo Name (601) Moriya Shiki, representative of Mitsubishi Electric Corporation 4 Agent 1-L Location: 2-2-3-5 Marunouchi, Chiyoda-ku, Tokyo Date of amendment July 29, 1985 6 Full text of the specification to be amended 7 Contents of amendment (1. (Meal meal + 41 wahin or more)

Claims (5)

[Claims] (1) A mechanism in which a terminal is connected to a node provided on a directional ring transmission path and the upper limit of the token round trip time during normal operation is set, and the terminal interface speed at each node is synchronized throughout the system. In a token ring network with The controller includes a controller that performs data transfer control, and upon completion of the call control phase and transition to the data transfer phase, the controller transfers data from the data buffer with a predetermined amount of delay that is predetermined according to the network. A data transfer control method characterized in that the data transfer is started. (2) The data transfer control method according to claim 1, wherein the predetermined amount of delay is twice the maximum time for a token to go around the ring. (3) The data transfer control method according to claim 1, wherein the data transfer from the data buffer on the transmitting side to the ring transmission line is started after a predetermined delay. (4) The data transfer control method according to claim 1, wherein the data transfer from the receiving side data buffer to the terminal is started after a predetermined delay. (5) Data transfer from the transmitter's data buffer to the ring transmission path and data transfer from the receiver's data buffer to the terminal are both started after a predetermined delay. A data transfer control system according to claim 1.