JP2564298B2 - Transmission control method in communication network - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a transmission control system for a communication network,
In particular, it relates to a token passing transmission control method in a token passing ring type communication network.

[Conventional technology]

Conventional token passing rings include, for example, IEE, Standard, 802.5-
1985, Token Ring Access Method (1985)
Page 19 to Page 72 (IEEE Std.802.5-1985 Token Rin
g Access Method, 1985 pp23-15).

This technique is suitable for a token passing ring (hereinafter referred to as a token ring) having a transmission rate of about 4 to 16 megabits / second (hereinafter referred to as Mbps).

[Problems to be solved by the invention]

One of the factors showing the transmission characteristics of the token ring is the token waiting time, that is, from the completion of preparation of transmission data at a certain station until the token circulating on the ring reaches the station and is acquired. I have time. Since the waiting time of the token is proportional to the network scale (total extension), the token waiting time is one of the important problems to be solved in a large-scale token ring with a total extension of several tens to several hundreds of kilometers.

Another important factor showing the transmission characteristics of the token ring is the transmission line usage rate. For example, "Local Net Works," William Sterling, Macramin Publishing Company, 1984, 236-243, (Local
Networks William Stallings.Macmillan Publishing C
Ompany 1984) reported the unfavorable result that the transmission line usage rate in token ring is inversely proportional to the transmission rate, and becomes lower as the transmission rate of token ring increases.

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

[Means for solving problems]

In order to achieve the above object, the present invention provides a plurality of transmission areas (sub-networks) on the transmission line in a communication network in which a plurality of stations are connected by a transmission line in a ring shape.
The transmission frame divided into frames is circulated, a token is assigned to each of the transmission areas, each station acquires one of the tokens, and outputs data to the transmission area. Is characterized in that data from a plurality of stations is transmitted.

[Action]

When the transmission band of the entire token ring is B (Mbps), and the transmission band of each transmission region divided into n is bi (Mbps) (where i = 1 to n), Becomes So if you assign a token to each transmission area,
The entire token ring can orbit n tokens, increasing the probability that each station can obtain a token. According to this method, even if the token ring becomes large in scale, the token waiting time at each station can be significantly reduced as compared with the conventional method in which one token goes around the token ring.

On the other hand, even if the transmission speed of the token ring is increased, the transmission band b ₁ of each divided transmission area is smaller than the transmission band B of the entire ring, so the transmission line usage rate of each transmission area is This is higher than the transmission line usage rate when one token is assigned to B. After all, the transmission path usage rate of the entire token ring obtained by arithmetically averaging the transmission path usage rates of the respective transmission areas is significantly improved as compared with the transmission path usage rate of one non-divided transmission area.

〔Example〕

 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 schematically shows the configuration of a token ring in the present invention. In FIG. 1, a plurality of stations 1a to 1n are connected in a ring shape via a transmission line 2, and one of them is a master station. Three
Is a transmission frame that circulates on the transmission path in the direction indicated by the arrow, and this transmission frame 3 has a synchronization pattern 10 located at the beginning, followed by n transmission areas (sub-frames), 11, 12, 13 Consists of. One token 4 is assigned to each of the transmission areas 11, 12 and 13, and a plurality of tokens circulate on the ring at the same time.

A station desiring to transmit data sequentially monitors each transmission area 11, 12, 13 in the transmission frame 3 passing through the station, and acquires the token 4 detected first. Some embodiments of the transmission frame 3 in FIG. 1 are shown in FIGS.

In the transmission frame 3 shown in FIG. 2, each transmission area (A _{1 to} A _n ) 11, 12, 13 is arranged following the synchronization pattern field 10 located at the head of the frame. When applying this type of transmission frame, it is necessary to inform the stations 1a to 1n of the lengths (bit numbers) of the transmission areas 11, 12, and 13 in advance. Each station that has detected the synchronization pattern 10 detects the boundary between the transmission areas 11, 12, and 13 by counting the number of bits from the next bit of the synchronization pattern 10. A maximum of one token 4 is placed in each of the transmission areas 11, 12, and 13.

FIG. 3 shows an example in which the fields 21, 22 and 23 indicating the lengths of the respective transmission areas 11, 12 and 13 are dispersedly arranged on the transmission frame 3. After detecting the sync pattern 10, each station knows the length (number of bits) of the first transmission area 11 from the content of the length information field 21 located next to the sync pattern field. Next, the length of the second transmission area 12 is known from the value of the length information field 22 located next to the transmission area 11. Similarly, the boundaries of the respective transmission areas can be detected up to the final transmission area 13. It should be noted that one token 4 is placed for each transmission area 11, 12, 13,
This is the same as in the case of FIG.

FIG. 4 shows the length information fields 21 to 23 in FIG.
In the example shown in FIG. After detecting the synchronization pattern 10, each station knows the length (number of bits) of each transmission area 11 to 13 included in the transmission frame from the content of the integrated length information field 30 following the synchronization pattern field, and then , The boundary of each transmission area is detected by sequentially counting the number of bits from the first bit of the first transmission area 11.

FIG. 5 is a diagram showing an embodiment of a transmission control block which is a main part of the station 1 (1a to 1n), and the operation of the present invention will be described in detail below with reference to this. In FIG. 5, a frame memory 63, a frame reception control unit 62, a frame transmission control unit 64, a frame transmission clock generation circuit 65, a token loss control unit 66, and a selector 67, which are surrounded by a broken line A in FIG.
The portion consisting of is unique to the master station 1a, and the other stations 1b to 1n have the same configuration as that shown in FIG. 5 except this portion.

First, the operation of generating the transmission frame 3 will be described.
The transmission frame 3 is generated by the master station 1a,
The data is output to the main transmission circuit 60 connected to the transmission line 2, and thereafter, the transmission line 2 and the stations 1b to 1n are circulated to return to the master station 1a. The transmission frame 3 is generated by
The frame transmission controller 64 in the master station 1a controls the frame memory 63 in synchronization with the frame transmission clock 65, and the synchronization pattern 10 according to the cycle of the transmission frame 3,
And the rest of the frame is output from the frame memory 63. At this time, when the transmission frame 3 has the format shown in FIG. 3 or FIG. 4 described above, the length information fields 21 to 23 of the respective transmission areas and the integrated length information field 30 have appropriate values. Is set. Master station 1a through the transmission line
With respect to the transmission frame 3 that has returned to, the reception clock detection unit 61 and the frame reception control unit 62 determine the loop delay of the transmission frame 3 depending on the transmission delay time in the transmission line 2 and each of the stations 1b to 1n. It is adjusted and stored in the frame memory 63. By repeating the above-described operation performed by the master station 1a, the transmission frame 3 continues to orbit the token ring at a constant cycle. At the stage when the master station 1a initially generates the transmission frame 3, the transmission areas 11 to
There is no token 4 on 13.

Next, the transmission area 11-in each station 1 (1a-1n)
The boundary detection operation of 13 will be described. When the transmission frame 3 reaches the station 1, the synchronization detection circuit 69 detects the synchronization pattern 10. Reference numeral 70 denotes a transmission area detection circuit, which detects the synchronization signal 58 from the synchronization detection circuit 69, the transmission frame clock 59, and the transmission frame 3 from each transmission area 11
The boundary signals 57 to 13 and the length signal 56 of the transmission area are output.

When the frame 3 has, for example, the format shown in FIG. 3, a timing for acquiring the length information 21 is obtained by the synchronization signal 58, and after the length information 21 is detected, the boundary is detected at the beginning timing of the transmission area 11. The boundary pulse and the length information are output to the signal 57 and the length signal 56, respectively. Other transmission areas
The same applies to 12 and 13. The selector 68 selects the output of the frame memory 63 in the case of the master station and the received signal of the transmission circuit 60 in the case of other stations. Similarly, the selector 68 selects the output of the frame transmission clock in the master station and the output of the reception clock detection circuit 61 in the other stations.

Initial generation of the token 4 is performed as follows.
In the master station 1a, the token disappearance control unit 66
The orbiting time of the token 4 is monitored for each of the transmission areas 11 to 13, and when it is detected that the token 4 does not orbit for a certain time (successively for a plurality of frames) in a certain transmission area, for example, 11, Token 4 for the corresponding transmission area 11
Is generated and sent. By this operation, the token 4 is initially generated for each of the transmission areas 11 to 13 on the initially generated transmission frame 3. The transmission timing control of these tokens 4 will be described in detail later.

Next, the operation of transmitting the data packet in the station 1 will be described. FIG. 6 shows an example of the data packet format.

In the station 1 in which the data packet to be transmitted is prepared, the token acquisition control unit 76 causes the transmission areas 11 to 13 of the transmission frame 3 passing through the station 1 to
The presence or absence of token 4 is sequentially checked. If the token 4 is found, the token 4 is deleted, and the data packet transmission control signal 78 and the data packet transmission completion control signal 77 are transmitted to the data packet transmission permission signal 84 and the transmission area including the token 4 (for example, 11) notifies the position (relative number) 85 occupied on the transmission frame. After that, the data packet transmission control unit 78 transmits the data packet 90 on the transmission path using the notified transmission area 11 over the plurality of temporally continuous transmission frames 3.

During the period in which the data packet 90 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 1 arrives, the data packet 90 included in the area is transmitted. Examine the RNR prime 91 inside. If the RNR indicator 91 is turned on, the data packet transmission completion control unit 77 notifies the data packet transmission control unit 78 to stop the data packet transmission. If the RNR indicator 91 is off, the data packet transmission completion control unit 77 monitors the transmission area 11 until the ending delimiter 92 of the data packet is detected, and the ending delimiter 92 is detected. Subsequent response information 93 for the relevant data packet
To win. At this time, the data packet transmission completion control unit 77
Notifies the data packet transmission request source of RNR occurrence or response information 93 as the transmission completion status.
In addition, the token acquisition control unit 76 is notified of the token transmission request 86. In response to this, the token acquisition control unit
76 sends the token 4 to the transmission area 11 which has been used so far, and the data packet transmission operation at the station is completed.

The transmission timing of the token 4 described above is controlled as follows. First, when the token acquisition control unit 76 and the token disappearance control unit 66 send the token 4 to a target transmission area (for example, 11), when the transmission of the token 4 is started from an arbitrary position in the transmission area 11, Reference numeral 41 'in FIG.
As shown by, the token 4 may be divided into two frames j and j + 1. When such token division occurs, the token acquisition control unit 76 causes the transmission area 11 to
Token 4 cannot be detected by 13 sequential searches. To avoid this situation, each transmission area 11-13
The length (L _i ) of all tokens is equal to or greater than the length (L _T ) of the token 4, and the token acquisition control unit
When the 76 and the token loss control unit 66 send the token 4 to the target transmission area 11, the timing control is performed according to the control flow chart shown in FIG.

That is, the token acquisition control unit 76 and the token disappearance control unit 66 that have received the transmission request for the token 4 are
In, as shown in FIG. 9, the overall length is at L _i bits already 1
Destination transmission area i (i
= For example, 11), the remaining transmittable information bit length (L _i −C) is obtained.

Then, it is judged whether or not the remaining information bit length is equal to or longer than the bit length of the token 4 (step 101), and if "YES".
Then, the token 4 is sent to the transmission area i (step
102). If "NO", the token transmission to the transmission area i in the transmission frame of the j-th cycle this time is postponed, and the transmission area i in the transmission frame of the next cycle j + 1 is waited for (step 103). Then, the transmission area i
At the beginning of the step 1, the transmission of token 4 is again attempted from step 100.

The transmission timing control of the data packet 90 is also similar to the above-mentioned token transmission timing control, and if the transmission timing is incorrect, the head portion 94 of the data packet 90 will have cycles j and j + 1 as shown by reference numeral 94 'in FIG. Can be divided into two transmission frames. In this case, as will be described later, the transmission area 11 to
It becomes impossible to detect the data packet addressed to station 1 by the sequential search of 13. To avoid this situation,
All the lengths (L _i ) of the transmission areas 11 to 13 are restricted so as to be equal to or longer than the length (L _H ) of the header section 94 of the data packet, and the data packet transmission control section 78 causes the data packet transmission control section 78 to The target transmission area i (i = eg
When sending to 13), the timing control is performed according to the control procedure shown in FIG.

That is, when the transmission of the header section 94 is started, the data packet transmission control section 78 firstly transmits the information bit length (L _i − Calculate C). Next, it is determined whether or not the bit length (L _i -C) is greater than or equal to the length of the header portion L _H (step 111), and if "YES", a part of the data packet 90 that completely includes the header portion 94. Or the entire transmission area i
(Step 112). If "NO", the transmission of the data packet to the transmission area i in the current cycle j is skipped and the start of the transmission area i in the next transmission frame of cycle j + 1 is waited (step 11).
3) At that point, try control from step 110.

Finally, the data packet receiving operation in each station 1 will be described.

The data packet reception monitoring section 73 determines whether the station 1
In order to determine whether or not the data packet 90 addressed to the station 1 is present in the transmission areas 11 to 13 in the transmission frame 3 passing through, the destination address 95 of the data packet header section 94 included in each transmission area and Compare with the address of station 1. If it is a data packet addressed to your station
When 90 is detected, the data packet reception control unit 74 is instructed to receive the data packet 87 and the relative number indicating the position on the transmission frame 3 of the transmission area (for example, 13) including the header portion 94 of the data packet. Notify 88. The data packet reception control unit 74 notifies the data packet reception monitoring unit 73 of the reception condition signal 89. For example, if the capacity of the transmission buffer 72 is insufficient, or if one of the transmission areas 11-13 has already
When receiving an instruction to receive a new data packet from another transmission area from the data packet reception monitoring section 73 during reception of one transmission area data packet, the data packet reception monitoring section 73 uses the signal indicating reception failure as the reception condition signal 89.
Notify to The data packet reception monitor 73 sets the RNR indicator 91 of the data packet to the ON state if the reception condition signal 89 indicates that the reception is not possible, and sets it to the OFF state if the reception is not possible.

After that, if reception is possible, the data packet reception control unit
The 74 receives the above-notified data packet in the transmission area 13 to the reception buffer 72 via the writing circuit 71 in a plurality of time-sequential transmission frames 3. When the data packet ending delimiter 92 is received, the data packet reception control unit 74 performs an error check of the frame sequence and other checks, and sets the result in the response information 93 as the reception status of the data packet. At the same time, the data packet reception display is notified to the data packet reception request source, and the operation of receiving one data packet is completed.

Reference numeral 90 denotes a terminal device connected to the reception buffer 72 via an internal bus (microcomputer bus) 83. In response to a reception notification signal 92 from the reception control unit 74, the contents of the reception buffer 72 are taken into the memory 91. When this is completed, the 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,
The transmission request 94 is output to the data packet transmission control unit 78.
In response to this, the transmission controller 78 operates the read circuit 80 at a predetermined timing to send the data packet in the transmission buffer 81 to a predetermined transmission area in the transmission frame.

According to the above discussion by William Sterlings, for example, assuming that the length of the data packet transmitted by the station is 100 bits, the total length of the transmission line is 1 km, and the signal propagation delay on the transmission line is 2 × 10 ⁸ m / s. , Transmission speed is 1Mbps, 10
It can be derived that the transmission line usage rates at each speed of Mbps and 50 Mbps are 95.2%, 66.7%, and 28.6%, respectively. However, if the 50 Mbps transmission band is equally divided into, for example, five transmission regions according to the present invention, the transmission line utilization rate of each transmission band and the entire ring can be improved to about 67%. In this case, if attention is paid to the individual transmission areas, the transmission rate is 1 / n of the total transmission rate, but if the transmission rate of the entire token ring is made sufficiently large, the transmission area between the stations in each divided transmission area is also increased. It is possible to give a sufficient transmission speed that does not hinder data transmission.

〔The invention's effect〕

According to the present invention, one transmission frame is plural (n)
It is divided into transmission areas, and tokens are assigned to each transmission area so that a total of n tokens circulate on the transmission path, so the token waiting time at each station can be greatly shortened, The usage rate of can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a basic structure of a communication network and a transmission frame according to the present invention, FIGS. 2 to 4 are respectively a format diagram showing an embodiment of a transmission frame used in the present invention, and FIG. FIG. 6 is a diagram showing an example of the configuration of the station, FIG. 6 is a diagram showing an embodiment of a data packet sent out on the transmission path, and FIG. 7 is a diagram showing a token and a data packet.
FIG. 8 is a diagram for explaining a state in which the transmission frame is divided into two transmission frames (j and j + 1), FIG. 8 is a flow chart showing a control procedure for transmitting a token, and FIG. 9 is a transmission frame at the time of transmitting the token. Figure 10 for explaining the state
The figure is a flow chart showing the control procedure for transmitting the header portion of the packet. 1a to 1n ... station, 2 ... transmission path, 3 ... transmission frame, 4 ... token, 10 ... sync pattern, 11 to 13
...... Transmission area, 21-23 …… Transmission area length information, 30 ……
Integrated length information, 56 ... Length signal, 57 ... Boundary signal, 58 ...
… Synchronization signal, 59 …… Transmission frame clock, 60 …… Main transmission circuit, 61 …… Reception clock detection unit, 62 …… Frame reception control unit, 63 …… Frame memory, 94 …… Frame transmission control unit, 65 ...... Frame transmission clock, 66 …… Token loss control block, 67,68 …… Selector, 69 …… Sync detection block, 7
0 …… Transmission area detection unit, 71 …… Writing circuit, 72 …… Reception buffer, 73 …… Data packet reception monitoring unit, 74 ……
Data packet reception control block, 75, 79, 82 ... Selector, 76
...... Token acquisition control unit, 77 ...... Data packet transmission completion control unit, 78 ...... Data packet transmission control unit, 80 ...... Read circuit, 81 ...... Transmission buffer, 83 ...... Microcomputer bus, 84 ...... Data packet transmission possible Traffic light, 8
5,88 …… Relative number signal, 86 …… Token transmission request signal,
87 …… Data packet reception instruction signal, 89 …… Reception condition signal.

Front page continuation (72) Inventor Yasuhiro Takahashi 1099 Ozenji, Aso-ku, Kawasaki City, Hitachi, Ltd. System Development Laboratory (56) References JP 61-156947 (JP, A) JP 61-263348 (JP) , A) JP-A-60-20661 (JP, A)

Claims (3)

(57) [Claims] 1. A transmission control method in a communication network in which a plurality of stations are connected in a ring shape by a transmission path, wherein a plurality of transmission areas are formed on the transmission path, and a token is assigned to each transmission area. A transmission frame having a field indicating the length of each transmission area is circulated, and each station having communication data acquires a token in any transmission area of the transmission frame being circulated, and over a plurality of circulated transmission frames, The transmission area corresponding to the token is continuously occupied while detecting the boundary of the transmission area by using the content of the field indicating the length, and data transmission is performed. After the data transmission is completed, the transmission frame is transmitted. A transmission control method in a communication network characterized by releasing a token of a region. 2. Whether or not each station transmitting data completely sends out a token in the transmission area for transmitting the last part of the transmission data is subtracted from the length of the transmission area by the passed area length. It is determined by comparing the remaining information bit length that can be transmitted by the length of the token with the length of the token.If it is determined that the token cannot be transmitted completely, the token release is suspended and the corresponding transmission area of the next transmission frame. The transmission control method in a communication network according to claim 1, characterized in that the token is released by. 3. At least one of the plurality of stations monitors a token circulation time for each transmission area of a transmission frame, and assigns a token to a transmission area where a token does not rotate for a predetermined time. What is claimed is: Claim 1
A transmission control method in the communication network according to item 2 or item 2.