JPH05252178A - Token ring data transmission system - Google Patents

Abstract

PURPOSE:To attain the leveling of throughput between each station considering the priority of each packet. CONSTITUTION:Mean transmission data length N at every station is calculated from the real polling period T assuming the data length of an X-th frame in a transmission data queue as M(X). A ratio J(X)/K of the mean value J(X) of priority of the packet of its own station to priority K of all packets in a network is found, and the maximum number of packets that can be stored in a value in which the ratio J(X)/K is multiplied by N is judged. The leveling of throughput between each station can be attained by sending out the packet from the forefront of the transmission data queue to the maximum number of packets successively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a token ring data transmission system, and more particularly to a token ring for transmitting data of arbitrary length as packet data having a frame structure between stations by sequentially passing tokens indicating transmission right among a plurality of stations. The present invention relates to a data transmission system.

[0002]

2. Description of the Related Art In a conventional token ring type data transmission system of this type, the number of transmission frames at the time of receiving a token is dynamically changed according to the system throughput of the entire network to equalize the throughput between stations. However, there is a drawback that the priority of each data packet cannot be included in the condition.

Here, the throughput means the amount of data that one station can transmit per unit time when each station mutually transmits data of arbitrary length.

Therefore, conventionally, there is a drawback in that, when leveling the variation in throughput among the stations, leveling cannot be performed in consideration of the priority of each data packet.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a token ring data transmission system capable of leveling the throughput among stations in consideration of the priority of each data packet.

[0006]

According to the present invention, a token ring data transmission system for transmitting data of arbitrary length as packet data having a frame structure between stations by sequentially passing tokens indicating a transmission right among a plurality of stations. There is a means for calculating the data length of the frame in the transmission waiting state, a means for observing the cycle in which the token circulates and calculating the token circulation time, and the entire network of data currently being transmitted by the local station. Means for determining the priority for the station, means for determining how long the current data is transmitted by each station on average from the token circulation time, transmission rate, and the number of stations, and these determinations Determine the number of frames that can be transmitted in response to the next token reception, depending on the average data length and priority that are the results That a means, token ring data transmission system being characterized in that each provided in each station is obtained.

[0007]

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

Referring first to FIG. 2, there is shown a schematic configuration of a system to which the present invention is applied. The plurality of stations 11 to 14 have a function of transmitting and receiving data to and from each other via the transmission line 15. Although not particularly shown, one node (station) in the network is called a monitor station and manages the entire network.

FIG. 3 is a block diagram of each station. A reception control unit 16 that performs reception control, a transmission control unit 17 that performs transmission control, a reception data queue 18 that stores reception data, and a transmission data queue 1 that stores transmission data.
9 and a CPU 20 that controls these units.

The transmission data to be sent to the transmission line 15 is sequentially accumulated in the transmission data queue 19, and every time a token frame is received from the transmission line 15, the head data of the queue 19 is framed and transmitted from the transmission control circuit 7. It is sent to the transmission line 15.

The frame sent out on the transmission line 15 is taken into the station by the reception control circuit 6 at the destination station and accumulated in the reception data queue 18.

When each station transmits data of arbitrary length to each other, the amount of data that one station can transmit per unit time is defined as the throughput of each station, and the variation in this throughput among the stations is leveled.

By receiving the token, each station has the right to frame the data and send it to the transmission path. Now, the number of stations in the network and the transmission speed are known (constant) if the system is determined. And now consider the traffic on this network.

Due to the characteristics of the token ring system, if the traffic in the network decreases, the token circulation time becomes shorter, and conversely, if the traffic increases, the token circulation time becomes longer. This actual token circulation time T can be calculated by measuring with a timer or the like at each station.

This value T is divided by the bit rate determined by the transmission rate (constant) of the network, and a value obtained by subtracting the time α corresponding to the protocol overhead from this is divided by the number of stations in the network to obtain the value. Assuming that N, N = {T ÷ (transmission rate) −α} ÷ (number of stations) (1)

N represented by the equation (1) is a value equivalent to the traffic amount indicating how much data each station currently transmits in the network on average, and is equal to the data length. It is the number expressed in the same dimension.

The value of N can be easily obtained by calculating the equation (1). However, instead of performing the operation of the equation (1) every time the token circulation time T changes, the average data length N is actually calculated. If the number of stations and the transmission rate are given as a parameter in the correspondence table between the token circulation time T and the token circulation time T, N at T in actual operation can be instantly determined.

If the value of N is averaged several times and updated with that value, a stable value N can be obtained.
Then, thereafter, the station uses the value of N until the value of N is determined and then N is updated.

As information necessary for equalizing the throughput among the stations, in addition to the value of N obtained in the above description, the priority information of the transmission data packet is necessary.

All packets have a priority represented by an integer value, and the definition of this priority is standardized within the network. For example, it is assumed that all stations know that the higher the numerical value of the priority is, the higher the priority is, and the maximum value of the integer indicating the priority is a system parameter.

Further, when a certain packet is generated, what priority is given to the packet depends on how much the deviation from the average value should be set and the importance of the data. It may be determined by the user after making a decision, and there is no particular limitation, and no mention is made.

Here, the average value of the priorities of the packets currently flowing on the network is not necessarily an intermediate value between the maximum value and the minimum value of the priorities. For example, if a large amount of emergency data is flowing, the average priority value of the entire network temporarily becomes high. Therefore, it is necessary to judge the position of the priority of the packet of the own station with respect to the average value.

Therefore, as shown in FIG. 4, fields MP and AP for priority information are added in the frame. The MP field takes the average value of the values received by all stations from the transmission line and the own station's value in order for the monitor station to collect the average value of the packet priority of all stations. It is a field.

More specifically, each station starts from the monitor station and goes through a loop, and each station averages the priority of the data of its own station (the average of the priority from the head of the transmission data queue to a certain number X of packets). Value: J (X))
Is a field for calculating an average value of the MP received from the transmission line and obtaining the average estimated value of the current priority of the entire network when the value is received again at the monitor station.

The AP field is a field for circulating the average value of priorities collected using the MP field from the monitor station to all other stations. Accordingly, the average value (estimated value) of the current priorities of the entire network acquired by each station will be represented by K.

SD is a flag indicating the beginning of the frame, P
F is a token flag indicating whether it is a token state or a state of carrying data, DA is an address for specifying a destination station, SA is an address for specifying a source station, and FCS is the validity of data in the entire frame. The frame check sequence DATA for checking, DATA is a field in which packet data to be transmitted by this frame is inserted.

From the transmission average data length N for each station and the average value K of the current priorities of all networks obtained as described above, the CPU 20 controls the transmission of packet data according to the processing procedure shown in FIG. As a result, the throughput can be leveled.

When the data to be transmitted is accumulated in the transmission queue in step 1, the transmission data length M is calculated (detected) in step 2. At the same time, in step 3, the token circulation time T is calculated, and this T is calculated by using a timer and measuring at any time.

In step 4, the average data length N is determined by the calculated token circulation time T.
Is determined instantaneously by referring to the average data length table 5. That is, as described above, using the number of stations and the transmission rate as parameters, the average data length N obtained in advance corresponding to the token circulation time T is calculated according to the equation (1), and the correspondence table 5 is obtained. N is determined by giving it to the memory of the CPU of the station.

In step 6, the priority of the data currently transmitted by the local station to the entire network (the ratio of the priority J (X) of the data to be transmitted by the local station to the average value K of the priorities of the entire network). ) = J (X) / K
To calculate. Note that J (X) indicates the average value of the priorities from the first packet to the Xth packet of the local station transmission data queue, as described above.

Then, the length of the Xth packet (X is a natural number) from the head of the transmission data queue of the local station is M (X), and while waiting for the token, M (1) to M (X) The minimum value of X that satisfies the sum> N × J (X) / K (2) is obtained. A value obtained by subtracting 1 from the value of X satisfying this indicates the maximum number of packets that the local station can continuously transmit with one current token.

Therefore, in step 7, X = 1, Z
= 0 is initialized. Here, Z is the data length M of each packet from the head of the transmission data queue to the Xth.
It is the integrated value of (X). In the next step 8, X = 1, X
When = 0, it is determined whether or not the expression (2) is satisfied. If not satisfied, X is further incremented by 1 in step 9 and the determination in step 8 is performed again.

By these steps 8, 9 and 10, N
The maximum value of X that does not exceed × J (X) / K is found, but for convenience, by finding X once exceeding N × J (X) / K and subtracting 1 from it (step 1
0), the maximum number of packets (X-1) that can be continuously transmitted when the next token is received is obtained.

In the actual operation, some other parameter can be added to the equation (2) in order to further improve the accuracy. In that case, the traffic of the entire network (corresponding to N) is also considered. If the number of transmittable packets can be quantitatively calculated from the position of the current packet priority of the own station with respect to the entire network, it is included in the technical scope of the present invention.

[0035]

As described above, according to the present invention, a frame that can be transmitted is transmitted according to the current traffic (average length of transmission data N) and the priority of the data currently transmitted by the local station to the entire network. Since the number is determined, there is an effect that the throughput among the stations can be equalized by setting the packet priority as a condition.

[Brief description of drawings]

FIG. 1 is a flowchart showing a processing procedure according to an embodiment of the present invention.

FIG. 2 is a system block diagram of a token ring data transmission system to which the present invention is applied.

FIG. 3 is a block diagram showing a configuration of each station.

FIG. 4 is a frame format diagram exchanged between stations.

[Explanation of symbols]

 11 to 14 stations 15 transmission lines

Claims (1)

[Claims] 1. A token ring data transmission system for transmitting data of arbitrary length as packet data of a frame structure between stations by sequentially passing tokens indicating a transmission right among a plurality of stations, in a transmission waiting state. Means for calculating the data length of the frame, means for observing the cycle in which the token circulates and calculating the token circulation time, and determining the priority of the data currently transmitted by the local station to the entire network. Means, a means for judging how long the current data is transmitted from each station on the average based on the token circulation time, the transmission speed, and the number of stations, and an average data length as a result of these judgments. And a means for determining the number of frames that can be transmitted in response to the reception of the next token according to the priority and the priority. A token ring data transmission system, which is provided in each station.