JP3156141B2 - Multimedia integrated LAN system using token ring - Google Patents

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 is capable of efficiently transmitting periodic data such as voices and moving images and aperiodic data such as still images and text files. Local Area Network) method.

[0002]

2. Description of the Related Art Conventionally, various systems such as a TDMA system, a CSMA / CD system, a token passing system, and an FDDI system have been known as communication systems employed in a LAN. In a LAN, an efficient system is adopted according to the characteristics of data to be transmitted.

That is, although some communication errors are allowed in audio data and moving image data, it is desirable that communication be guaranteed at regular intervals. Still image data is
Like text file data, some flexibility is allowed in time, so that communication need not be guaranteed at regular intervals. Some errors are allowed for still image data, like audio data and moving image data. However, since the data size is large, it is desirable that once the communication right is obtained, the communication right be obtained as long as possible. In the text file data, it is desirable that a communication error is not allowed and that the communication right be acquired for as long as possible, like the still image data.

[0004] Among the above various network systems, FD
The DI (Fiber Distributed Data Interface) method uses periodic data that should be communicated at fixed time intervals, such as data of voice and moving images, and loose time constraints, such as data of text files and still images. This is a network system that skillfully integrates communication of aperiodic data.

In the FDDI system, an L signal having an information transfer rate of 100 Mbits / sec using an optical fiber ring is used.
In AN, a token passing ring is used as a control method, the distance between each node is up to 2 km, and the number of stations is up to 1000.
Bureaus and rings can handle up to a total length of 200 km.

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

[0007]

In the FDDI system, each node first transmits its own periodic data when receiving a token, and transmits aperiodic data if the timer has enough time (FIG. 1). (b)). Therefore, upon receiving the token, each node performs periodic data transmission if it has periodic data, and otherwise transmits aperiodic data according to the timer value. In this scheme,
When the token is received, the data owned at that time can be transmitted, so the transmission delay is small, but the transmission time allowed when transmitting non-periodic data may be finely divided, and burst data transmission such as still images Cannot be transmitted using a large-sized packet, and the efficiency of burst data transmission decreases. As shown in FIG. 2 (b), when several nodes (A, B, C, D) have large data, the time required to acquire the communication right once is short. However, the time required to complete the communication of the entire data becomes longer as a whole. Therefore, as for the transmission time of the entire burst data, it is considered that the data transmission delay is reduced when communication is performed at once.

[0008]

SUMMARY OF THE INVENTION The present invention is a LAN system which integrates the transmission of periodic data and the transmission of non-periodic data, and is capable of communicating burst data such as still images with high transmission efficiency. It is an object of the present invention to provide a multimedia integrated LAN system using the Internet.

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

That is, the multimedia integrated LAN system using a token ring according to the present invention is a LAN system in which a network is constituted by a token passing ring and a plurality of nodes, and a node that has obtained a token transmits data. The token enables switching of the mode between a periodic data transmission mode for voice, moving images, and the like, and an aperiodic data transmission mode for still images, text files, etc., by all nodes. The timer can measure the time, and the node that obtained the token, according to the mode of the token and the remaining time of the timer,
It is characterized in that predetermined transmission processing is performed.

In the above, it is reasonable that the time set in the timer is set to a 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 as follows. That is, the node that has obtained the token transmits the periodic data when the mode of the token is the periodic data transmission mode and possesses the periodic data. In addition, when the mode of the token is the aperiodic data transmission mode and owns the aperiodic data, when the remaining time of the timer is exceeded,
Transmit non-periodic data. The mode of the token switched by the node can be as follows. That is, when the mode of the token is the aperiodic data transmission mode and the remaining time of the timer runs out, the mode of the token is changed to the periodic data transmission mode.

When the node that has changed the mode of the token to the periodic data transmission mode obtains the circulated token, it changes the mode of the token to the aperiodic data transmission mode.

Referring to FIG. 3, the multimedia integrated LAN system using the token ring according to the present invention will be described in more detail. (1) Basic configuration The form of the network is a token ring as shown in Fig. 3 (a). All nodes A, B, C, and D have data of voice, moving image, data, and still image, and can transmit each data according to the mode at the time of receiving the token.

As described above, media such as audio, data, moving images, and still images need to be transmitted at regular intervals (moving images, audio, etc.). These media are called periodic data. ) And those with little time constraints (still images, text, etc. These media are called aperiodic data). Therefore, in the present invention, two modes, a periodic data transmission mode and an aperiodic data transmission mode, are used to ensure that the real-time property of the periodic data is ensured, and to efficiently transmit even large images such as still images. Was provided on the token.

Each node has a timer for guaranteeing a cycle. The timer operates to determine the transmission time of data to be transmitted and to change the mode. The timer of each node does not need to be synchronized, but can count the time accurately. The timer of each node sets the timer to a preset value when the transmission of periodic data is first detected at the time of token ring initialization.

When each node receives the token, it confirms the mode expected for the token. In this case, if the mode is the periodic data transmission mode, and if the node owns the periodic data, the token is transferred to the next node after the periodic data (audio, video) is securely transmitted. (FIG. 3 (b)). If the node receives the token of the periodic data transmission mode, if the node does not have the periodic data to be transmitted, the node does not transmit the data, and passes the token to the next node without changing the mode.

If the mode is the aperiodic data transmission mode when the token is received, the timer of the node is first referred to. At this time, if the timer has a remaining time, any transmission of aperiodic data may be performed until the timer expires (Fig. (B)
). (2) Mode change method Next, the change of the two modes set in the token will be described. First, a change from the non-periodic data transmission mode to the periodic data transmission mode is performed by an arbitrary 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 is holding the token for aperiodic data transmission,
After changing the mode from the non-periodic data transmission to the periodic data transmission, if the periodic data is held, the 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 whose mode has been changed records that the mode has been changed from the non-periodic data transmission mode to the periodic data transmission mode. The node that has received the token of the periodic data transmission mode transmits the periodic data to be transmitted, if any, and if not, 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. The node that has changed the mode from the non-periodic data transmission mode to the periodic data transmission mode, returns the token of the periodic mode after one round of return (during this one round, all the nodes have the periodic data of this cycle. Mode is changed to aperiodic mode and the token is passed to the next node (Fig. 3 (b)
). At this time, it is assumed that the node whose mode has been changed does not transmit data even if it has aperiodic data. this is,
In such a case, if the node whose mode has been changed has an enormous amount of aperiodic data, it is to prevent a node other than this node from being unable to transmit the aperiodic data. The LAN is based on the premise that each node can acquire a token fairly, and it is necessary to guarantee this. Therefore, in the present invention, in order to maintain fairness of the nodes, a node whose mode has been changed cannot perform aperiodic transmission there. The node receiving the token of the aperiodic data transmission mode transmits the aperiodic data, and each node may transmit until there is no more aperiodic data to be transmitted or the timer expires. When there is no aperiodic data to be transmitted, the mode is left as it is, and the token is passed to the next node. When the timer expires, the mode is changed to the cycle and the cycle data is transmitted as described above. (3) Timer setting Next, the timer setting value of each node is described. Set the timer to half the length of the period you want to guarantee. (For example, if you want to transmit every 30 ms,
ms).

According to the present invention, the mode is always changed each time the timer expires, so that the token in the periodic data transmission mode can be reliably received before the timer expires. However, in the following case, if the worst case is assumed, a delay of two timers is generated. Therefore, a value of a half of the period to be guaranteed is set as the timer value. For example, as shown in FIG. 4, at the moment when a token in the periodic data transmission mode is passed to the next node, and periodic data is generated in that node (node A), the token in the periodic data transmission mode is obtained next. Earn somewhere before the timer expires and the next cycle timer expires. Therefore, in the worst case, the user may wait until the timer expires twice. Therefore, the setting value of the timer needs to be set to a half value of the period that can guarantee the transmission quality of the period data.

[0022]

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

If the mode change is performed by a specific node, a problem occurs when the specific node fails, or the idle rotation of the token is unavoidable, and the efficiency is reduced. it can.

[0024]

EXAMPLES The method of the present invention and the FDDI method were compared by simulation. (1) Simulation conditions The settings in 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 Number of periodic nodes: 10, 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 4Mbits / sec, 2Mbits / s
ec Regarding the traffic transmitted by the data node, the result of the throughput-delay time does not calculate the delay time for each packet, but for each message generated by the data node (when transmitted by a plurality of packets, (Until the last packet is transmitted). The processing method of the data in each node is a restriction type, and any number of communications can be performed within the range until the timer expires. (2) Theoretical value in simulation Here, in order to state the validity of the simulation result, comparison is made with the theoretical value at the time of each set value of the simulation. Lower limit of delay time of aperiodic data In the token ring method, it is conceivable that the throughput will be reduced due to the transfer of tokens. Since this depends on the propagation speed of the signal, the time for the token to go around the ring according to the ring size can be obtained by calculation.

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 of the aperiodic data is determined.

Generally, at least the following time is required for communication by the token passing method.

The time required to acquire a free token for the first time The time from the start of sending a packet to the end of sending the last packet The time from the end of sending a packet to the receiving end receiving the packet In the simulation, the time from the end of transmitting the packet until the receiving side receives the packet is not added to the delay. That is, the delay is defined as the time from when a transmission request is issued to the node to when the node finishes transmitting the last packet. Here, the communication time of a packet is, on average, half of the time required to make one round of the ring, and therefore depends on the ring size and can be easily obtained.

First, the time required to acquire a free token is determined. When the throughput is low, tokens can be acquired in half the time required to go around the ring on average, but what needs to be considered here is that there are two types of modes: periodic and aperiodic.

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

Table 1 shows a comparison between simulation results and theoretical values.

[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 actual ones. Upper Limit of Throughput of Aperiodic Data Next, the upper limit of the throughput will be considered. In the method of the present invention, since the mode is provided, while the timer expires once, the token sets the ring as a periodic mode for one cycle.
It is considered that the ring makes one round as a non-periodic mode. Therefore, the maximum throughput of the non-periodic 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 by dividing the delay of one round of the ring by the value of the timer. Therefore, 4M
In a state where 10 nodes transmit the periodic data of bits / sec, the theoretical maximum value of the aperiodic data is 0.567 assuming that the transmission of the periodic data for the entirety is performed.

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

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

[0037]

[Table 2]

Comparing these theoretical values with the simulation results, the results of the simulation show that the upper limit of the throughput is very close to the theoretical value.
It is considered that something close to the actual one was obtained. (3) Evaluation The method of the present invention is a method capable of efficiently transmitting large-capacity data such as still images, which is expected to increase in demand in the future, while ensuring periodic transmission of periodic data.

To illustrate this, a comparison was made with the FDDI system, which is based on the token ring system as in the present system and also guarantees the period of the periodic 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 nodes, a periodic data period of 30 ms, and a periodic data information amount average 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 drawing, DPC is the method of the present invention.

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

On the other hand, in the method of the present invention, a constant delay time (approximately 6 ms) was obtained throughout the period when the throughput of aperiodic data was low and 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 in the first round of each cycle (15 ms) even while the throughput is low, and the token circulates as the non-periodic mode in other cases. Therefore, even if periodic data occurs, it cannot be transmitted immediately.

From the results shown in FIG. 5, there is no problem in any of the methods in which the period of the periodic data (30 ms) is reliably guaranteed.

Next, the transmission result of the aperiodic data will be examined. 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, when looking at FIG. 7 here, while the throughput of the aperiodic data is low, there is no significant difference in both methods, but when the throughput of the aperiodic data exceeds 0.4, the method of the present invention is used. It can be seen that the transmission delay is smaller and that transmission is clearly efficient.

Similarly, the transmission capacity is 100 Mbps, the cable length is 100 km, the total number of nodes is 250, and the number of periodic nodes is 1.
The results in the case of 0 nodes, a periodic data cycle of 30 ms, and an average periodic data information amount of 4 Mbits / sec are shown in FIG. 8 for the periodic data and in FIG. 9 for the 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 the future computer communication, there are many opportunities to transmit burst data typified by still images. Therefore, by using the method of the present invention, it is possible to reliably guarantee the period of the periodic data and to transmit large-capacity data. It was also shown that data could be transmitted efficiently.

Next, FIG. 10 shows the efficiency of the system of the present invention with respect to distance.

FIG. 10 shows that the efficiency decreases as the ring size increases. This is because the time required for token passing depends on the ring size due to the nature of the token ring.

As shown in Table 2, the limit values of the throughput were 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 close to those.

[0051]

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

[Brief description of the 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 the FDDI system.

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

3A and 3B are diagrams showing an outline of the present invention, wherein FIG. 3A is a configuration diagram of a network, and FIG. 3B is a time chart.

FIG. 4 is a time chart for explaining a set time of a timer.

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

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

FIG. 7 is a graph comparing transmission efficiency of burst data.

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

FIG. 9 is a graph 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

Continuation of the front page (56) References Special Tables 63-502551 (JP, A) Sunil Joshi, Benkatraman Yell, "New Standards for High-speed Local Networks", Nikkei Mabrowhill, NIKK EI COMPUTER, September 1984. 17, p. 151-163 (58) Field surveyed (Int. Cl. ⁷ , DB name) H04L 12/42

Claims (4)

(57) [Claims] [Claim 1] constitute a network the token passing ring and a plurality of nodes, in a LAN system obtained node to perform transmission of data tokens, the
A plurality of nodes, respectively, with thereby enabling <br/> time measured by the timer, the node that obtained the token, the token
Is the non-periodic data transmission mode and the timer
When the remaining time runs out, the token mode is
Data transmission mode and change the token mode to cycle data
The node that changes to the transmission mode obtains the circulated token.
The token mode to aperiodic data transmission mode.
By changing the token , the token switches the mode between a periodic data transmission mode for voice, moving images, etc., and an aperiodic data transmission mode for still images, text files, etc.
A multimedia integrated LAN system using a token ring, which is enabled by all nodes, and wherein a node that has obtained a token performs predetermined transmission processing according to the mode of the token and the remaining time of the timer. 2. A multimedia integrated LAN system using a token ring according to claim 1, wherein the time set in the timer is a half of a period capable of guaranteeing the transmission quality of the periodic data. 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 mode of the token is the periodic data transmission mode and possesses the periodic data. LAN method. 4. The node that has obtained 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 the node owns the aperiodic data. A multimedia integrated LAN system using the described token ring.