JPH05260064A - Multimedia integrated lan system using token ring - Google Patents

Abstract

PURPOSE:To provide the LAN system integrating the transmission of periodic data and the transmission of non-periodic data and a system enabling communication with high transmission efficiency even concerning the burst data of still pictures or the like. CONSTITUTION:In the LAN system to transmit data by a node obtaining token while constituting the network with a token passing ring and plural nodes A, B, C..., a periodic data transmission mode for sounds and moving images or the like and a non-periodic data transmission mode for still pictures and text files or the like can be switched at all the nodes A, B, C... by the token, and the respective nodes A, B, C... can count time by a timer. The nodes A, B, C... obtaining the token execute prescribed transmission processings according to the mode of the token and the remaining time of the timer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multimedia integrated LAN using a talk ring, which enables efficient transmission of periodic data such as voice and moving images and aperiodic data such as still images and text files. Local area network) system.

[0002]

2. Description of the Related Art Conventionally, various methods such as a TDMA method, a CSMA / CD method, a token passing method, and an FDDI method are known as communication methods adopted in a LAN. In the LAN, an efficient method is adopted according to the characteristics of transmitted data.

That is, although a certain degree of communication error is allowed in voice data and moving image data, it is desirable to guarantee communication at regular intervals. Also, the still image data is
Similar to the text file data, some flexibility is allowed in terms of time, so it is not necessary to guarantee communication at regular intervals. For still image data, some error is allowed, such as voice data and moving image data. However, since the data size is large, once the communication right is obtained, it is desirable to acquire the communication right for as long as possible. In the text file data, it is desirable that no communication error is allowed and that the communication right can be acquired as long as possible like the still image data.

Among the various network systems mentioned above, FD
The DI (Fiber Distributed Data Interface) method has periodical data such as voice and moving image data that should be communicated at regular time intervals, and text files, still image data, and other time-sensitive constraints. It is a network method that skillfully integrates communication of aperiodic data.

This FDDI system uses an optical fiber ring, and has an information transfer rate of 100 M bits / sec.
The AN uses a token passing ring as a control method, and the distance between each node is up to 2 km and the number of stations is up to 1000.
It can handle stations and rings up to a total length of 200 km.

Each node has a timer, and controls the data transmission by measuring the token arrival interval. The data transmission is divided into two types: periodic data transmission and aperiodic data transmission. That is, the node that has obtained the token always first transmits the periodic data, and transmits the aperiodic data only when the arrival interval of the token is early (the transmission path is open and the aperiodic data can be transmitted). I do.

[0007]

In the FDDI method described above, when each node receives a token, it first transmits its own periodic data, and if the timer has enough space, it transmits aperiodic data (see FIG. 1). (See (b)). Therefore, when each node receives the token, it performs periodic data transmission if it has periodic data, and otherwise transmits aperiodic data according to the value of the timer. With this method,
When the token is received, the possessed data can be transmitted at that time, so the transmission delay can be small, but it is possible that the transmission time allowed for the transmission of non-periodic data may be divided into small pieces. However, the packet cannot be transmitted using a large size packet, and the efficiency of burst data transmission decreases. As shown in Fig. 2 (b), when several nodes (A, B, C, D) have large size data, the time to acquire the communication right once is short. However, the time it takes to complete the communication of the entire data becomes long as a whole. Therefore, as for the transmission time of the entire burst data, the transmission delay of the data is considered to be shorter if the communication can be performed at one time.

[0008]

SUMMARY OF THE INVENTION The present invention is a LAN system that integrates the transmission of periodic data and the transmission of aperiodic data, and is capable of communicating burst data such as still images with good transmission efficiency. It is intended to provide a multimedia integrated LAN system using the.

In the present invention, the concept of mode is used,
By setting a mode in the token, a packet having a size as large as possible can be used for transmitting aperiodic data.

That is, the multimedia integrated LAN system using the token ring of the present invention is a LAN system in which a network is composed of a token passing ring and a plurality of nodes, and the node which obtains the token transmits data. The token allows all nodes to perform mode switching between a periodic data transmission mode for voice, moving images, etc. and an aperiodic data transmission mode for still images, text files, etc., and each node is It is possible to measure time with a timer, and the node that got the token, according to the token mode and the remaining time of the timer,
It is characterized by performing a predetermined transmission process.

In the above description, it is rational that the time set in the timer is half of the period in which the transmission quality of the periodic data can be guaranteed.

The transmission process performed by each node can be performed as follows. That is, the node that has obtained the token transmits the periodic data when the token mode is the periodic data transmission mode and owns the periodic data. In addition, when the token mode is aperiodic data transmission mode and you own aperiodic data, within the remaining time of the timer,
Transmit aperiodic data. The mode of the token switched by the node can be as follows. That is, the token mode is the aperiodic data transmission mode, and when the remaining time of the timer runs out, the token mode is changed to the periodic data transmission mode.

Further, when the node that has changed the token mode to the periodic data transmission mode obtains the circulating token, it changes the token mode to the aperiodic data transmission mode.

The multimedia integrated LAN system using the token ring of the present invention will be described in more detail with reference to FIG. (1) Basic configuration The form of the network is a token ring as shown in Fig. 3 (a). It is assumed that all the nodes A, B, C, and D hold voice, moving image, data, and still image data, and can transmit the respective data according to the mode when the token is received.

Media such as voices, data, moving images, still images, etc. are media (moving images, voices, etc .; these media are called periodic data) for which data must be transmitted at regular intervals as described above. ) And those with little time constraint (still images, texts, etc. These media are called aperiodic data). Therefore, in the present invention, two modes of a periodic data transmission mode and an aperiodic data transmission mode are provided so that the real-time property of the periodic data is surely maintained and efficient transmission is possible even for a large capacity such as a still image. Was added to the token.

Further, each node has a timer for guaranteeing the cycle, and the operation of this timer determines the transmission time of data to be transmitted and changes the mode. The timers of the nodes do not have to be synchronized, but it is possible to count the time accurately. The timer of each node sets the timer to a preset value when the transmission of the periodic data is first detected when the token ring is initialized.

When each node receives a token, it confirms the mode expected by the token. In that case, if the mode is periodic data transmission mode, if the node owns the periodic data, after transmitting the periodic data (voice, moving image) with certainty, the token is passed to the next node. (Fig. 3 (b)). If the mode receives a token of periodic data transmission mode, if the node does not have periodic data to be transmitted, transmission is not performed, and the token is passed to the next node without changing the mode.

When the token is received, if the mode is the aperiodic data transmission mode, the timer of the node is first referred to. At this time, if the timer has time remaining, as long as the timer expires, any amount of aperiodic data may be transmitted (Fig. (B)).
). (2) Mode change method Next, the change of the two modes set in the token will be described. First, the change from the aperiodic data transmission mode to the periodic data transmission mode is performed by any node according to the value of the timer of each node. As described above, each node has a timer and always counts down the timer. When this timer expires, the node whose mode holds the token for aperiodic data transmission is
After changing the mode from aperiodic data transmission to periodic data transmission, if the periodic data is held, transmission of the periodic data is started, and after the transmission is completed, the token is passed to the next node (Fig. 3 (b)). ..

At this time, the node that has changed the mode records that it has changed from the aperiodic data transmission mode to the periodic data transmission mode. The node receiving the token for transmitting the periodic data in the mode transmits the periodic data to be transmitted, if any, and if it does not have the periodic data, passes the token to the next node.

Next, the change from the periodic data transmission mode to the aperiodic data transmission mode will be described. A node that has changed the above mode from the aperiodic data transmission mode to the periodic data transmission mode, when the token of the periodic mode makes one round and returns (in this one round, all the nodes have the periodic data of this period). (Transmission has been completed), the mode is changed to aperiodic mode, and the token is passed to the next node (Fig. 3 (b)).
). At this time, the node whose mode is changed does not perform data transmission even if it has aperiodic data. this is,
In such a case, when the node whose mode has been changed holds a huge amount of aperiodic data, it is for preventing nodes other than this node from transmitting aperiodic data. In the LAN, it is premised that each node can fairly acquire the token, and it is necessary to guarantee this. Therefore, in the present invention, in order to maintain the fairness of the nodes, the node whose mode has been changed cannot perform aperiodic transmission there. The node receiving the token of the acyclic data transmission mode may transmit the aperiodic data, and each node may perform the transmission until there is no aperiodic data to be transmitted or the timer expires. When there are no more aperiodic data to transmit, the mode remains the same and the token is passed to the next node. When the timer expires, the mode is changed to cycle and the cycle data is transmitted as described above. (3) Timer settings Next, the timer settings for each node will be described. Set the timer to half the period you want to guarantee. (For example, if you want to transmit every 30ms, the timer is 15
set to ms).

According to the present invention, since the mode is always changed every time the timer expires, the token of the periodic data transmission mode can be surely received before the timer expires once. However, in the case described below, assuming the worst case, a delay of two timers will occur, so a value of half the period to be guaranteed is set as the timer value. For example, as shown in FIG. 4, when periodic data is generated in the node (node A) at the moment when the periodic data transmission mode token is passed to the next node, the next periodic data transmission mode token is obtained. Once the timer expires, you will get somewhere until the timer of the next cycle expires. Therefore, in the worst case, it may be necessary to wait until the timer expires twice. Therefore, it is necessary to set the set value of the timer to half the value of the cycle that can guarantee the transmission quality of the cycle data.

[0022]

In the multimedia integrated LAN system using the token ring of the present invention, the concept of mode is used, and by changing the mode of the token, it is possible to make the packet of the largest size possible for the transmission of aperiodic data. .. This is shown in Fig. 1 (a). in this way,
When the mode is changed, data can be transmitted with the maximum packet size that can be used at that time, so that burst data such as still image data can be efficiently transmitted.

If a specific node changes the mode, a problem may occur when the specific node fails, and token idle is inevitable and efficiency is reduced. However, this can be avoided. it can.

[0024]

EXAMPLES The system of the present invention and the FDDI system were compared by simulation. (1) Simulation conditions The settings for the simulation are as follows.

Transmission capacity: 100 Mbits / sec Cable length: 50 Km, 100 Km Signal propagation speed: 2 × 10 ⁸ m / sec Total number of nodes: 250 nodes Periodic node number: 10 and 20 nodes Maximum packet length: 5 kbytes Periodic data period: 30ms, 20ms Aperiodic data size: Average 1 kbytes Burst data size: Average 100 kbytes Periodic data information amount: Average 4 Mbits / sec, 2 Mbits / s
ec Regarding the traffic transmitted by the data node, the throughput-delay time result does not calculate the delay time in each packet unit, but rather for each message generated by the data node (in the case of transmission by multiple packets, I decided to find the delay time until the last packet was sent. The data processing method in each node is limited, and any number of communications can be performed within the range until the timer expires. (2) Theoretical value in simulation Here, in order to describe the validity of the simulation result, comparison with the theoretical value at each set value of the simulation is performed. Lower limit of delay time for aperiodic data In the token ring method, throughput may be reduced due to token transfer. Since this depends on the propagation speed of the signal, the time required for the token to move around the ring depending on the ring size can be calculated.

When the ring size is 50 Km: 250 μs When the ring size is 100 Km: 500 μs Actually, an intra-node delay due to each node is added to this time.

First, the minimum value of the delay time values of non-periodic data is obtained.

Generally, the communication by the token passing system requires at least the following time.

Time required for first obtaining a free token Time from starting packet transmission to ending transmission of last packet Time from completion of packet transmission to reception of packet by the In the simulation, the time from the end of sending the packet to the receiving side receiving the packet is not added to the delay. That is, the delay is the time from when a transmission request is made to the node to when the node finishes transmitting the last packet. Here, the communication time of a packet is half the time required for one round of the ring on average, so it depends on the ring size and can be easily calculated.

First, the time taken to obtain a free token is calculated. When the throughput is low, tokens can be acquired on average in half the time it takes to complete one round of the ring, but what we must consider here is that there are two types of modes, periodic and aperiodic.

Here, the number of nodes transmitting periodic data is 1
When transmitting an average of 4 Mbits / sec data per node, if the total number of periodic nodes is 10, then 100
Of the transmission capacity of Mbits / sec, 40 Mbits / sec is used for transmitting periodic data. In this case, if the set value of the timer is set to 15 ms, the first 6 ms is used for transmission of periodic data according to the protocol of the present invention. Therefore, it is considered that if the aperiodic data occurs in the first 6 ms, it cannot be transmitted immediately, and if it occurs in the latter half of 9 ms, it can be transmitted immediately after acquiring the token. That is, 40% of aperiodic data is kept waiting for an average time of 3 ms.
Considering that this and the remaining 60% of data can be sent immediately, a delay time of 1.2 ms occurs on average from the time of occurrence to the time of sending. To this, 0.125ms (50Km), which is the time until the token is obtained (half the ring), was added, and data with an average length of 1Kbytes was generated.
If the transmission time of 0.08 ms is added, the transmission request for aperiodic data is very small (when the throughput is low).
However, it is considered that the delay time of aperiodic data does not fall below 1.405 ms.

Table 1 shows a comparison between the simulation result and the theoretical value.

[0033]

[Table 1]

Comparing these theoretical values with the simulation results, the lower limit of the delay time is very close to the theoretical value, and it is considered that the simulation results are close to the actual values. Upper limit of throughput of aperiodic data Next, the upper limit value of throughput is examined. In the method of the present invention, since the mode is provided, the token is set to the cyclic mode while the timer expires,
It is considered that the ring makes one round as a round or aperiodic mode. Therefore, the maximum throughput of aperiodic data is when the ring size is 50 km and the timer setting value is 15
Assuming ms, there is a loss of 0.033, which is obtained by dividing the above-mentioned delay of making one round in the ring by the value of the timer. Therefore, 4M
When 10 nodes are transmitting periodic data of bits / sec, the maximum theoretical throughput of aperiodic data is 0.567, assuming that 40% of the periodic data is transmitted.

Similarly, when the ring size is 100 km, it takes time for the token to circulate, so the theoretical maximum throughput of aperiodic data is 0.533.

Table 2 shows a comparison between simulation results and theoretical values.

[0037]

[Table 2]

Comparing these theoretical values with the simulation results, the upper limit of the throughput is very close to the theoretical value, and the simulation result shows that
It is considered that the one close to the actual one was obtained. (3) Evaluation The method of the present invention is a method capable of efficiently transmitting a large amount of data such as a still image which is expected to have an increasing demand in the future, while the periodicity of the periodic data is surely guaranteed.

In order to show this, a comparison was made with the FDDI method, which is based on the token ring method like the present method and which also guarantees the cycle of the cycle data.

First, the transmission capacity is 100 Mbps, the cable length is 50 km, the total number of nodes is 250, and the number of periodic nodes is 1.
The results in the case of 0 node, the period data period of 30 ms, and the average amount of periodic data information of 4 Mbits / sec are shown in FIG. 5 for periodic data, in FIG. 6 for aperiodic data, and in FIG. 7 for burst data. In the figure, DPC is the system of the present invention.

First, consider FIG. Looking at this figure, while the throughput of aperiodic data is low,
It is considered that the FDDI method can perform transmission with less delay. This is because in the FDDI method, the periodic data is always transmitted when the token is acquired, so that the token can be acquired immediately after the periodic data is generated while the throughput is low.

On the other hand, in the method of the present invention, the delay time (about 6 ms) was constant from beginning to end regardless of whether the throughput of the aperiodic data was low or high. This is because, in the method of the present invention, since the communication is performed using the mode, the token circulates as the periodic mode only for the first one cycle of each cycle (15 ms) and the other cycles as the non-cyclic mode even when the throughput is low. Therefore, even if the periodic data is generated, it cannot be immediately transmitted.

From the results shown in FIG. 5, the cycle (30 ms) of the cycle data is surely guaranteed in any of the systems, and there is no problem.

Next, let us look at the result of transmission of aperiodic data. First, looking at the results in FIG. 6, when the throughput increases,
It can be seen that FDDI is transmitted more efficiently than the method of the present invention. However, looking at FIG. 7 here, while the throughput of the aperiodic data is low, no great difference is seen between both formulas, but when the throughput of the aperiodic data exceeds 0.4, the system of the present invention is used. It can be seen that the transmission delay is smaller and the transmission is obviously efficient.

Similarly, transmission capacity 100 Mbps, cable length 100 km, total number of nodes 250, periodic node number 1
The results in the case of 0 node, the period data period of 30 ms, and the average amount of periodic data information of 4 Mbits / sec are shown in FIG. 8 for periodic data and in FIG. 9 for burst data.

From these results, it can be seen that the method of the present invention is a method capable of efficiently transmitting burst data while ensuring the periodicity of the periodic data.

In future computer communications, burst data typified by still images will be transmitted more often. Therefore, when the method of the present invention is used, the period of the periodic data can be surely guaranteed and the data having a large capacity can be ensured. It has been shown that can also be transmitted efficiently.

Next, the efficiency with respect to distance of the system of the present invention is shown in FIG.

It can be seen from FIG. 10 that the efficiency decreases as the ring size increases. This is because due to the nature of the token ring, the time required to pass the token depends on the ring size.

As shown in Table 2, the throughput limit values are 0.593 at 10 km and 0.56 at 50 km, respectively.
The values are 0.533 at 7,100 km and 0.467 at 200 km, and the results are similar to those obtained.

[0051]

As described above, according to the present invention, the periodic data transmission mode and the aperiodic data transmission mode can be set in the token, and each node can measure the time by the timer, and the aperiodic data transmission mode can be set. In the transmission mode, since the aperiodic data can be transmitted with the maximum allowable packet size, the aperiodic data can be efficiently transmitted while guaranteeing the transmission quality of the periodic data.

[Brief description of drawings]

FIG. 1A is a diagram showing an example of a time chart of the present invention, and FIG. 1B is a diagram showing an example of a time chart of an FDDI system.

FIG. 2 is a conceptual diagram when transmitting burst data,
(a) is a figure in the case of this invention, (b) is a figure in the case of FDDI system.

FIG. 3 is a diagram showing an outline of the present invention, (a) is a network configuration diagram, and (b) is a time chart diagram.

FIG. 4 is a time chart illustrating a set time of a timer.

FIG. 5 is a graph comparing transmission efficiency of periodic data when the token ring is 50 km.

FIG. 6 is a graph similarly comparing the transmission efficiency of aperiodic data.

FIG. 7 is a graph comparing transmission efficiencies of burst data similarly.

FIG. 8 is a graph comparing the transmission efficiency of periodic data when the token ring is 100 km.

FIG. 9 is a graph for similarly comparing transmission efficiency of burst data.

FIG. 10 is a graph showing a change in transmission efficiency depending on the size of a token ring.

[Explanation of symbols]

 A, B, C, D nodes

Claims (6)

[Claims] 1. In a LAN system in which a token passing ring and a plurality of nodes form a network, and the node that obtains the token transmits data, the token is periodic data for voice, moving images, etc. All nodes can switch the transmission mode and the non-periodic data transmission mode for still images, text files, etc., and each node can measure the time with a timer. Is a multimedia integrated LAN system using a token ring, which performs a predetermined transmission process according to the token mode and the remaining time of the timer. 2. The multimedia integrated LAN system using token ring according to claim 1, wherein the time set in the timer is half of the period in which the transmission quality of the periodic data can be guaranteed. 3. The multimedia integration using token ring according to claim 1, wherein the node that has obtained the token transmits the periodic data when the token mode is the periodic data transmission mode and owns the periodic data. LAN method. 4. The node which obtains the token transmits the aperiodic data within the remaining time of the timer when the mode of the token is the aperiodic data transmission mode and owns the aperiodic data. A multimedia integrated LAN system using the described token ring. 5. The token according to claim 1, wherein the node that has obtained the token changes the token mode to the periodic data transmission mode when the token mode is the aperiodic data transmission mode and the remaining time of the timer runs out. A multimedia integrated LAN system using a ring. 6. The multi-ring using token ring according to claim 1, wherein the node, which has changed the token mode to the periodic data transmission mode, changes the token mode to the aperiodic data transmission mode when it obtains the cyclic token. Media integrated LAN method.