JPS63240148A - Transmission control system in communication network - Google Patents

Abstract

PURPOSE:To reduce a token waiting time for each station by dividing one transmission frame into plural transmission areas, assigning a token to each transmission area to circulate plural tokes on a transmission line. CONSTITUTION:Plural stations 1a-1n are connected in a ring shape via a transmission line and one station la becomes a master station. A transmission frame 3 circulating on the transmission line in the direction of the arrow comprises a synchronizing pattern 10 placed at the head and n sets of transmission areas 11, 12 and 13 succeeding thereto. A token 4 is assigned to the areas 11, 12, 13 and plural tokens are circulated simultaneously on the ring. A station desiring to send a data monitors sequentially the areas 11, 12, 13 in the frame 3 passing through the stations and the token 4 detected at first is acquired. Thus, the toke waiting time for each station is decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a transmission control system for a communication network, and particularly to a transmission control system for token passing in a token passing ring type communication network.

[Conventional technology]

Conventionally, for token passing rings, for example, IEE Standard, 802.
5-1985. Token Ring Access Methods (1985) pp. 19-72 (IEEE S
td, 802.5-1985 Token Ring
Access Msthod, 1985 pp23-
25).

This technique is suitable for token passing rings (hereinafter referred to as token rings) with transmission speeds of about 4 to 16 megabits/second (hereinafter referred to as Mbpg).

[Problem that the invention seeks to solve]

One of the factors that characterizes the transmission characteristics of the Token Ring is the token latency, that is, the time from when a station is ready to send data until a token orbiting the ring reaches that station and is acquired. I have time. Token waiting time is one of the issues that is proportional to the network scale (total length).

Another important factor that indicates the transmission characteristics of Token Ring is the utilization rate of the transmission path.1 For example, "Local Networks", William Stirling, published by Macmillan Publishing Company, 1984 edition, 236-243.
Page w (Local NetworkssWilli
am Stallings, Acmi11. a
n Publishing Company 1984
) reports that the transmission path utilization rate in Token Ring is inversely proportional to the transmission speed, and the unfavorable result is that it decreases as the Token Ring transmission speed increases.

An object of the present invention is to provide a transmission control method that solves the problems of token waiting time and transmission path usage rate in the above-mentioned large-scale, high-speed token ring.

[Means for solving problems]

In order to achieve the above object, the present invention provides a communication network in which a plurality of stations are connected in a ring shape through a transmission path, in which a transmission frame divided into a plurality of transmission areas (sub-frames) circulates on the transmission path. , a token is assigned to each of the above transmission areas, and each station acquires one of the above tokens and outputs data to the transmission area, so that data from multiple stations can be transmitted in the same transmission frame. It is characterized by the following.

[Effect]

The transmission band of the entire token ring is defined as B (Mbps), and the transmission band of each transmission area divided into n is bi (Mbps).
ps) (where i=1 to n), B=Σbii=1. So, by assigning a token to each transmission area,
The whole token ring can orbit n tokens, increasing the probability that each station can get a token. According to this method.

Even if the token ring is scaled up, the token waiting time at each station can be significantly reduced compared to the conventional method in which one token circulates around the token ring.

On the other hand, even if the transmission speed of Token Ring is increased, the transmission band B of each divided transmission area is smaller than the transmission band B of the entire ring, so the transmission path usage rate of each transmission area is This is higher than the transmission path usage rate when one token is assigned to B. As a result, the transmission path usage rate of the entire token ring, which is the arithmetic average of the transmission path usage rates of each transmission area, is significantly improved over the transmission path usage rate of one undivided transmission area.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 schematically shows the configuration of a token ring according to the present invention. In FIG. 1, a plurality of stations 18 to 1n are connected in a ring shape via a transmission line 2, and one of them 1a serves as a mask station. Reference numeral 3 denotes a transmission frame that circulates on the transmission path in the direction shown by the arrow, and this transmission frame 3 includes a synchronization pattern 10 located at the beginning, and n transmission areas (sub-frames) that follow, 11, 12 . It consists of 13. Each transmission area 1
Tokens 1, 12, and 13 are each assigned one token 4, and perform multiple toe-and-tuck movements on the ring at the same time.

A station that wants to transmit data has to transmit data in each transmission area 11, 12,
#13 is monitored sequentially, and token #4, which is detected first in #1, is obtained. Several embodiments of the transmission frame 3 in FIG. 1 are shown in FIGS. 2-4.

In the transmission frame 3 shown in FIG. 2, each transmission area (A1''An) 11 , 12 follows the synchronization pattern field 10 located at the beginning of the frame.

13 are placed. When applying this type of transmission frame, it is necessary to inform each station 18 to 1n of the length and number of bits of each transmission area 11, 12, 13 in advance. Each station that has detected the synchronization pattern 10 counts the number of bits from the next bit of the synchronization pattern 10 to
Detect the boundaries of In each transmission area 11, 12.13,
Up to one token 4 can be placed on each.

FIG. 3 shows an example in which fields 21, 22, and 23 indicating the length of each transmission area 11, 12, and 13 are distributed and arranged on a transmission frame 3. After each station detects a synchronization pattern 10, , the length (number of bits) of the first transmission area 11 is known from the contents of the length information field 21 located next to the synchronization pattern field. Next, the transmission area 11
The length of the second transmission area 12 is known from the value of the length information field 22 located next to the . Similarly, the boundaries of each transmission area up to the final transmission area 13 can be detected.

In addition, for each transmission area 11, 12, 13, 1
The placement of individual tokens 4 is the same as in the case of FIG.

FIG. 4 shows the length information fields 21 to 2 in FIG.
3 are concentrated in one area 30 on the transmission frame 3.

After detecting the synchronization pattern 10, the length (number of bits) of each transmission area 11 to 13 included in the transmission frame is known from the content of the integrated length information field 30 following the synchronization pattern field, and then the first transmission By sequentially counting the numbers starting from the first bit of area 11,
Detect the boundaries of each transmission area.

FIG. 5 is a diagram showing an embodiment of the transmission control block which is the main part of station 1 (18-inch).
The operation of the present invention will be described in detail with reference to this. Incidentally, in FIG. 5, the frame memory 63. is surrounded by a broken line A. Frame reception control section 62° Frame transmission control section 64. Frame transmission clock generation circuit 65 and token disappearance control section 6
6. The part consisting of the controller 67 is unique to the master station 1a, and is used for other stations 1b to 1n.
has the same configuration as FIG. 5 except for this part.

First, the generation operation of transmission frame 3 will be explained. Transmission frame 3 is generated at master station 1a,
The signal is output to the main transmission circuit 60 connected to the transmission line 2, and thereafter circulates around the transmission line 2 and each station 1b to 1n and returns to the master station 1a. To generate the transmission frame 3, the frame transmission control unit 64 in the mask station la controls the frame memory 63 in synchronization with the frame transmission clock 65, and generates the synchronization pattern 10 according to the period of the transmission frame 3 and the frame in the frame. At this time, if the transmission frame 3 has the format shown in FIG. 3 or 4 described above, the length information field of each transmission area is outputted from the frame memory 63. Appropriate values are set in the fields 21 to 23 and the integrated length information field 30, respectively. Transmission frame 3 that has gone around the transmission path and returned to master station 1a
, the reception clock detection section 61 and the frame reception control section 62 adjust the circulation delay of the transmission frame 3 depending on the transmission delay time at the transmission path 2 and each station 1b to 1n, and store it in the frame memory 63. Store. By repeating the above operation performed at the master station 1a,
The transmission frame 3 continues to circulate around the token ring at a constant period.

Note that at the stage when the master station 1a initially generates the transmission frame 3, the token 4 does not exist on each of the transmission areas 11 to 13.

Next, the boundary detection operation of the transmission areas 11-13 at each station 1 (18-inch) will be described. When transmission frame 3 arrives at station 1, synchronization detection circuit 6
A synchronization pattern 10 is detected in step 9. 70 is a transmission area detection circuit, which receives the synchronization signal 58. from the synchronization detection circuit 69. From the transmission frame clock 59 and the transmission frame 3, a boundary signal 57 of each transmission area 11 to 13 and a length signal 56 of the transmission area are output.

For example, if frame 3 has the format shown in Figure 3,
The timing for acquiring the length information 21 is obtained by the synchronization signal 58, and after detecting the length information 21, the transmission area 1
At the beginning of number 1.

A boundary pulse and length information are output as a boundary signal 57 and a length signal 56, respectively. The same applies to the other transmission areas 12 and 13. Note that the selector 68 selects the output of the frame memory 63 in the case of the master station, and selects the received signal of the transmission circuit 60 in the case of other stations. Similarly, the selector 68 selects the frame transmission clock at the master station and the output of the reception clock detection circuit 61 at the other stations.

The initial generation of token 4 is performed as follows. In the master station 1a, the token disappearance control unit 66 monitors the circulation time of the token 4 in each transmission area 11 to 13.

For example, in step 11, when it is detected that token 4 does not circulate for a certain period of time (consecutive frames), the initial generated token 4 is generated and sent to the corresponding transmission area 11. A token 4 is initially generated for each transmission area 11 to 13 on the transmission frame 3. The transmission timing control of these tokens 4 will be described in detail later.

Next, the data packet transmission operation at station 1 will be explained. FIG. 6 shows an example of a data packet format.

Station 1 ready with data packet to send
Then, the token acquisition control unit 76 sequentially checks the presence or absence of the token 4 in each of the transmission areas 11 to 13 of the transmission frame 3 passing through the station 1. If the token 4 is found, the token 4 is deleted and the data packet transmission permission signal 8 is sent to the data packet transmission control section 78 and the data packet transmission completion control section 77.
4 and the position (relative number) 85 occupied by the transmission area (for example, 11) containing the token 4 on the transmission frame. Thereafter, the data packet transmission control unit 78 transmits the data packet 90 onto the transmission path using the notified transmission area 11 over a plurality of temporally consecutive transmission frames 3.

During the period when data packet 9o is being transmitted.

The data packet transmission completion control unit 77 monitors the transmission area 11 notified from the token acquisition control unit 76, and when the transmission area 11 arrives, the RNR element indicator 91 in the data packet 90 included in the area is inspect. If the RNR indicator 91 is on, the data packet transmission completion control section 77 controls the data packet transmission control section 78.
to stop sending data packets. if,
If the RNR indicator 91 is off, the data packet transmission completion control unit 77 controls the ending/ending of the data packet.
The transmission area 11 is monitored until the delimiter 92 is detected, and when the ending delimiter 92 is detected, the response information 93 of the data packet following it is acquired. At this time, the data packet transmission completion control unit 77
The data packet transmission request source is notified of RNR occurrence or response information 93 as a transmission completion status.

It also notifies the token acquisition control unit 76 of a token sending request 86 . In response, the token acquisition control unit 76 sends the token 4 to the transmission area 11 that has been used up until now, and the data packet transmission operation at the station ends.

The transmission timing of the token 4 described above is controlled as follows. First, the token acquisition control unit 76 and the token loss control unit 66 select the target transmission area (for example, 11).
When transmitting token 4 in , if transmission of token 4 is started from an arbitrary position in transmission area 11, token 4 is divided into two frames j and j+1, as shown by reference numeral 41' in FIG. There is a risk. When such token division occurs, it becomes impossible for the token acquisition control unit 76 to detect the token 4 by sequentially searching the transmission areas 11 to 13. In order to avoid such a situation, each transmission area 11 to 13 (Ll) has a length of 4 tokens.
The length of the token acquisition control unit 76 and the token loss control unit 6
6 sends the token 4 to the target transmission area 11, timing control is performed according to the control flowchart shown in FIG.

That is, the token acquisition control unit 76 and the token loss control unit 66 that received the request to send the token 4 perform step 1.
In 00, as shown in FIG. 9, the total length is Ll bits, and some C bits have already passed 3Jfi.

For the target transmission area i (i=11, for example), the remaining information bit length (Ll-C) that can be transmitted is determined.

Next, it is determined whether the remaining information bit length is greater than or equal to the bit length of token 4 (step 101).

If rYESJ, token 4 is sent to the transmission area i (step 102). If rNOJ, token sending to transmission area i in the current j-th period transmission frame is postponed, and the transmission area i in the next period j+1 transmission frame is waited for arrival (step 103). Then, at the start of the transmission area i, step 10 is performed again.
Attempt to send 0 to 1-kun 4.

The transmission timing control of the data packet 90 is similar to the above-mentioned token transmission timing control, and if the transmission timing is incorrect, as shown by reference numeral 94' in FIG.
The header part 94 of data buckets 1 to 90 has periods j and j+1
can be divided into two transmission frames. In this case, as will be described later, the data packet reception monitoring unit 73 sequentially searches the transmission areas 11 to 13 to
It becomes impossible to detect the destination data packet. In order to avoid this *mt, the length of each transmission area 11 to 13 is increased (LH) to the length of the header part 94 of the data packet.
The data packet transmission control unit 78 imposes the constraint conditions so that the
4 to the target transmission area i (i=13, for example), timing control is performed according to the control procedure shown in FIG.

That is, when starting the transmission of the header section 94, the data packet transmission control section 78 first determines the information bit length (Li- C) The 0th order to calculate
In step 111), it is determined whether the bit length (+-C) is greater than or equal to the header length LH. If rYESJ, part or all of the data packet 90 including the header part 94 is transferred to the transmission area i (step 112)
.

If rNOJ, the transmission of the data packet to the transmission area i in the currently passing period j is postponed, and the next period, j
Wait for the beginning of the transmission area i in the +1 transmission frame (step 113), and at that point step 1
Try controlling from 10.

Finally, the data packet receiving operation at each station 1 will be explained.

The data packet reception monitoring unit 73
In order to judge whether or not there is a data packet 90 addressed to the station 1 in the transmission areas 11 to 13 in the transmission frame 3 passing through the transmission area, the destination address 95 of the data packet header part 94 included in each transmission area Compare with the address of station 1. If a data packet 90 addressed to the own station is detected, a data packet reception instruction 87 is sent to the data packet reception control unit 74, and a transmission area (for example, 13) containing the header section 94 of the data packet is sent to the data packet reception control unit 74. A relative number 88 indicating the position on the transmission frame 3 is notified. The data packet reception control unit 74 notifies the data packet reception monitoring unit 73 of a reception condition signal 89. For example, when the capacity of the transmission buffer 72 is insufficient, or when a data packet has already been received in one transmission area among the transmission areas 11 to 13. During I3!, an instruction to receive a new data bucket 1- from another transmission area was received from the data packet reception monitoring unit 73! If so, a signal indicating that reception is not possible is notified to the data packet reception monitoring unit 73 as the reception condition signal 89. The data packet reception monitoring unit 73 sets the RNR indicator 91 of the data packet to the on state if the reception condition signal 89 indicates that the data packet is not receivable, and sets the RNR indicator 91 of the data packet to the off state if the data packet is not receivable.

Thereafter, if the data packet can be received, the data packet reception control unit 7
4 receives the notified data packets in the transmission area 13 into the reception buffer 72 via the write circuit 71 in a plurality of transmission frames 3 that are continuous in one hour.

Upon receiving the ending delimiter 92 of the data packet, the data packet reception control unit 74 performs a frame sequence error check and other checks, and sets the results in the response information 93 as the reception status of the data packet. At the same time, notify the data packet reception request source of the data packet reception indication.

The reception operation for one data packet is completed.

90 is a terminal device connected to the reception buffer 72 via an internal bus (microcomputer bus) 83;
In response to the reception notification signal 92 from 4, the reception buffer 7
2 is taken into the memory 91, and when this is completed, a reception request 93 is output.

When the terminal device 90 wants to send a data packet,
After storing the data packet in the transmission buffer 81, a transmission request 94 is output to the data packet transmission control section 78.

In response to this, the transmission control unit 78 operates the readout circuit 80 at a predetermined timing, and sends the data packet in the transmission buffer 81 to a predetermined transmission area in the transmission frame.

According to the discussion by William Starlinges mentioned above, for example, it is assumed that the length of a data packet sent by a station is 100 bits, the total length of the transmission path is 1km, and the signal propagation delay on the transmission path is 2 x 10'm/S. When the transmission speed is 1 Mbps or 10 Mbps.

It can be derived that the transmission path usage rates at each speed of 50 Mbps are 95.2%, 66.7%, and 28.6%, respectively. However, according to the present invention, the above 50M
If the bps transmission band is equally divided into, for example, five transmission areas, the transmission line usage rate of each transmission band and the entire ring can be improved to about 67%. In this case, if we focus on each individual transmission area, the transmission speed will be 1/n of the overall transmission speed, but if the overall transmission speed of the token ring is made sufficiently large,
It is possible to provide each transmission area after division with a sufficient transmission speed that does not impede data transmission between stations.

〔Effect of the invention〕

According to the present invention, one transmission frame is divided into a plurality of (n) transmission areas, and a token is assigned to each transmission area, so that a total of n tokens circulate on the transmission path. , the token waiting time at each station can be significantly reduced, and the utilization rate of the transmission path can also be improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the basic configuration of a communication network and transmission frame according to the present invention, FIGS. 2 to 4 are format diagrams showing embodiments of the transmission frame used in the present invention, and FIG. FIG. 6 is a diagram showing an example of a data packet sent out on a transmission path, and FIG. 7 is a diagram showing an example of the configuration of a
Figure 8 is a flowchart showing the control procedure for transmitting tokens, and Figure 9 is a diagram showing the state of the transmission frame at the time of transmitting the token. Diagram for explanation, No. 10
The figure is a flowchart showing a control procedure for transmitting the header part of a packet. 1a to 1n...station, 2...transmission line, 3.
...Transmission frame, 4...Token, 10...Synchronization pattern, 11-13 transmission area, 21-23...Transmission area length information, 30...Integrated length information, 56...
Length (i number, 57... Boundary signal, 58... Synchronization signal, 59... Transmission frame clock, 60... Main transmission circuit, 61... Reception clock detection section, 62... Frame Reception control unit. 63... Frame memory, 94... Frame transmission control unit, 65... Frame transmission clock, 66... Token erasure control unit, 67. 68... Selector, 69...
...Synchronization detection section, 70...Transmission area detection section, 71...
・Writing circuit, 72...Reception buffer, 73...
Data packet reception monitoring unit, 74...Data packet reception control unit, 75, 79, 82...Selector, 76.
... Token acquisition control unit, 77... Data packet transmission completion control unit, 78... Data packet transmission control unit,
80...Reading circuit, 81...Transmission buffer, 8
3... Microcomputer bus, 84... Data packet transmission enable signal, 85.88... Relative number signal, 86... Token transmission request signal, 87... Data packet reception instruction signal, 89. ...Reception condition signal. Agent: Katsuma Ogawa: ・ Arithmetic 2 diagram ￥ 6 Figure v′′7 Figure 3 Figure 9 Figure 1Q country

Claims (1)

[Claims] 1. In a communication network in which a plurality of stations are connected in a ring shape by a transmission path, a transmission frame divided into a plurality of transmission areas is circulated on the transmission path, and a token is assigned to each transmission area. and each station acquires one of the tokens and outputs data to the transmission area, thereby transmitting data from multiple stations in the same transmission frame. Transmission control method in networks. 2. The communication according to item 1, wherein each station that has acquired the token continuously occupies the transmission area over a plurality of transmission frames circulating on the transmission path and performs a data sending operation. Transmission control method in networks. 3. Determine whether each station that has acquired the token and completed data transmission can complete sending the entire token to the relevant transmission area in the transmission frame that is being received;
3. The transmission control system in a communication network according to claim 2, wherein if the entire token cannot be sent to the transmission area, the token sending operation is canceled and the determination is made again when receiving the next transmission frame. 4. Each station that has acquired the token sends data to the relevant transmission area of each transmission frame by attaching header information including at least the station address of the data destination to the sending data, and transmits the entire header information. 3. The transmission control system in a communication network according to claim 2, wherein when it is determined that the data cannot be transmitted to the transmission area, the data transmission operation is canceled and the data transmission operation is carried over to the next received frame. 5. A first feature characterized in that each station relays the transmission frame with information indicating whether or not the data addressed to the station has been successfully received or not attached to the transmission area in which the data is included. Transmission control method in the communication network described in . 6. At least one of the plurality of stations monitors the status of each transmission area in the transmission frame circulating on the transmission path, detects a transmission area in which a predetermined time has elapsed without a token or data, and terminates the transmission. 6. The transmission control system in a communication network according to any one of items 1 to 5, characterized in that a token is assigned to an area.