JPS60190049A - Packet communication equipment - Google Patents

Abstract

PURPOSE:To communicate efficiently a packet data by cancelling the transmission request of a packet according to a cancel request of packet transmission and abolishing the prescribed number of packet data stored in a buffer. CONSTITUTION:A communication equipment consists of a packet processing section 3, a transmission buffer 4a storing a packet data, a reception buffer 4b, and a controller 5 controlling the communication of the packet data. When a prescribed time is elapsed after the transmission request of the packet is generated, if a remarkable time for the packet is delayed in such cases as the transmission of the packet is not successful yet or packet data of prescribed number or over are stored in the transmission buffer 4a; the packet transmission cancelling request is generated. The transmission request of the packet is cancelled according to the cancelling request and the packet data of prescribed number stored in the transmission buffer 4a are abolished.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention effectively controls the sending of communication packets, suppresses unnecessary packet communication that has lost real-time characteristics, and provides efficient data transmission. The present invention relates to a highly practical bucket 1 to communication device capable of communicating.

[Technical background of the invention]

Recently, various packet communication networks, typified by Ethernet, have been developed. The above Ethernet uses bucket communication control called the C8MA/CD (Carrier Sense Multiple Access Rice Collision Detention) method.
In addition, various other packet communication methods have been proposed, such as the 1-kun passing method and the slotted ring method.

By the way, in the above C8MA/CD method, each station participating in the network accesses the transmission path independently, that is, in a distributed manner, and multiple stations participating in the network simultaneously use the transmission path to send buckets 1 to 1. When this happens, the above-mentioned packet collision is resolved by individually different back-off control of each station, which actively utilizes probabilities. Therefore, CS M A /
In the CD system, the transmission delay time from the start of a packet transmission attempt to the successful transmission of the packet is not constant for each cycle, and the transmission delay time depends on the so-called congestion on the transmission path. It can be considered to be given by a random variable with a distribution.

In addition, the above-mentioned token passing method and slotted
For various systems such as the ring system, network analysis is often performed on the assumption that the transmission delay time is usually fixed. However, in reality, the transmission delay time of each station follows a distribution with quite large variations. For example, two stations A.

If B tries to communicate bucket 1- to the same station C at the same time, the packet that station C receives is from either station A or station B, and the other station ends up being Bucket 1 - Since communication fails, packet transmission attempts are made for a certain period of time. ′? It is clear from the fact that it is necessary to

As described above, in the various packet communication systems that have been proposed in the past, there are large variations in the packet transmission delay time of each station.

[Problems with background technology]

By the way, when video data, audio data, etc. are sequentially converted into buckets and communicated via this type of network,
Since these data are required to be real-time, variations in the packet transmission delay time become a major problem. For example, if there is a coincidentally large transmission delay time for a transmission request for a certain bucket 1~, any new packets generated during the elapsed delay time will be sent only after the transmission of the previous packet is completed. It will be tried. For this reason, even if voice packet data is communicated after a certain period of time, the real-time nature of the data is lost, so it becomes worthless, and even if the packet data is successfully communicated, the receiving end It will be discarded. Moreover, the transmission of such worthless data not only leads to unnecessary occupation of the network and makes the network unnecessarily congested;
Interfering with the sending of subsequent packets and destroying the subsequent packets as well.
There is a risk that it will become an iiii value.

For example, in the above-mentioned Ethernet, the time from the generation of a request to send one audio packet to the time it becomes clear that the sending has failed is 190 Illsec on average, with a standard deviation of 38
It has distribution characteristics close to the normal distribution of m5ec. For this reason, for example, if audio data is set to be packetized every i and sent out in sequence, 20
Approximately 10 voice packets generated one after another every m5ec will stay in the transmission buffer within the average packet transmission delay time. The permissible packet transmission delay time for audio data is, for example, 100 m.
If it is 5ec, at least two packets including the first packet lose their real-time nature and become worthless at the time when it becomes clear that the packet has failed to be sent. In reality, once a bucket transmission failure occurs, it often takes time to transmit subsequent packets depending on the degree of congestion on the transmission path, and as a result, there is a risk that even more voice packets may become worthless. .

Even though the number of packets rendered worthless increases in this way, the brush 21 to the controller of the communication device generally repeats attempts to send each packet to the transmission path in turn, so that the degree of congestion on the transmission path increases. This also caused a problem in that communication interference with other packets increased.

[Purpose of the invention]

The present invention has been developed in consideration of these circumstances, and its purpose is to minimize the negative impact on subsequent packets and to maintain packet data even when a large bucket transmission delay occurs. suppressing the deterioration of
It is an object of the present invention to provide a highly practical bucket 1 communication device that can efficiently communicate baguette data that requires real-time performance.

[Summary of the Invention] The present invention is applicable to cases in which the sending of packet data is not successful even after a predetermined period of time has elapsed from the start of a request to send packet data, or when there is a predetermined number of packets in the buffer (where ＼When a request is made to send a kerato, the request to cancel the sending of the kerat is generated, and according to this cancellation request, the sending request to the bucket 1 is canceled and a predetermined number of bucket 1 data stored in the buffer are discarded. It was designed to do so.

〔Effect of the invention〕

In summary, according to the present invention, packet data whose real-time nature has been lost is sequentially discarded from buffer 1 in response to a request to cancel packet transmission, and a request to transmit subsequent packets is issued.
The above-mentioned real-time property is lost, and there is no need to go to the trouble of communicating bulk packet data. Furthermore, since communication of unnecessary packets is suppressed in this manner, there is no possibility that unnecessary packets will increase congestion on the transmission path. Moreover, as described above, since the data for packet 1 that has become worthless is discarded from the buffer, there is no possibility that subsequent packets will become worthless due to an attempt to send this worthless packet. Therefore, the loss of value of packet data that requires real-time performance, such as video data and audio data, is minimized, and the packet data that requires real-time performance can be effectively and efficiently processed. Great effects such as packet transmission becoming possible can be achieved.

[Embodiments of the invention]

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

FIG. 1 is a schematic diagram of a packet communication device (station) typified by Ethernet. This type of packet communication device is connected via a transceiver 2 to a transmission path 1 made of a coaxial cable or the like, and transmits audio data etc. in buckets between multiple communication devices via the transmission path 1. It is. (The L device includes a packet processing section 3 that converts voice data, etc. provided for communication into buckets, and restores the data that has been converted into buckets 1 to 1 and communicated based on the data, a transmission buffer 74a that stores packet data, and a reception buffer 74a that stores packet data. It is composed of a buffer 4b, and a controller 5 that performs communication of data from buckets 1 to 3.The packet processing unit 3 includes:
A/A/
The D converter 3a is provided with a packetization section 3b that converts the data digitized by the A/D converter 3a into buckets, for example, every 20 m5ec. This packetizer 31
) The packet data sequentially packetized is stored in the transmission buffer F4a in order and is used for transmission. Furthermore, the packet data communicated via the transmission path 1 and sequentially stored in the reception buffer 4b is guided to the debucketing section 3C of the packet processing section 3 and sequentially decomposed into buckets 1 to D. The signal is restored to its original signal form and outputted via the /A converter 3d.

The controller 5 issues a packet transmission request to the transmission line 1 to sequentially transmit the packet data stored in the transmission buffer 74a, and controls the transmission of buckets 1 to 1 to detect carrier detection, collision detection, etc. At the same time, the packet data communicated via the transmission path 1 is taken in and sequentially stored in the reception buffer 4b.

The above packet transmission control is performed, for example, on transmission line 1 ().
In other words, the well-known CS MA/
This is done by adopting the CD method, etc.

That is, in the apparatus configured as described above, for example, audio data that requires real-time performance is A/D conversion 19! The signal is sampled at predetermined time intervals via the device 3a and supplied to the packetizer 3b. In order to ensure the time-lance-balance (real-time nature) of the audio data, the packetizer 3b assigns a series of numbers to each bucketed data, and sequentially supplies the data to the transmission buffer 4a. . At this time, the bucket 1 conversion section 3b detects silence in the audio data and removes this silent packet from the communication target.

In other words, the above-mentioned Rro packet does not have a very important meaning with respect to voice data communication, and in fact, the transmission of the above-mentioned silent packet only increases the congestion degree of the transmission path 1, so it is removed from the communication target, Only voiced packets useful for voice data communication are selectively extracted and used as communication targets. Therefore, only the voiced data of the audio data is packetized, and the above-described packet transmission control is performed to sequentially transmit the packets.

In this way, the packet data sent out in order is transferred to the receiving buffer. 4b, and after correcting the temporal fluctuation between each packet due to the packet transmission control described above, the packets are supplied to the debucketing unit 3C.

Correction of temporal fluctuations in the received packet data stored in the receive buffer 4b involves rearranging each received packet data at equal intervals in time using a series of numbers assigned to each packet, and the above-mentioned packet data. This consists of discarding bucket i, which has lost real-time performance due to a packet transmission delay of 100 m5ec or more due to transmission control. Said depacketization! ;B3c inputs the packet data on which such temporal fluctuation has been corrected, and places the temporally missing packet data, for example, at the position M'r before it.
Bucket!・Receive bucket 1 by supplementing with data, etc.
The audio data is restored by sequentially disassembling the data into packets. The reputation data restored in this way is D.
/ Output via A converter 3d.

FIG. 2 shows the format of the audio packet data that is thus converted into buckets and sent out. This voice packet consists of, for example, a preamble, a destination address, a source address, a type field, a data field, and a frame check sequence. Furthermore, the above data
The field is variable in the range of 46 to 1500 octets, for example, depending on the communication packet data m.

By the way, the device of this embodiment is basically characterized in that it packetizes audio data and sends it out as described above, as shown in FIG. When the predetermined time has elapsed, a significant time delay in packet transmission is expected, such as when the above-mentioned packet has not yet been successfully transmitted, or when more than a predetermined number of packet data have been accumulated in the transmission buffer r4a. Bucket in case!・A transmission cancellation request is generated. In accordance with this cancellation request, the packet transmission request is canceled and a predetermined number of packet data stored in the transmission buffer 4a are discarded.

That is, if the packet exit control is performed as described above and the packet sending delay time is, for example, 100 m5ec or more, even if the packet is sent, the temporal fluctuation of the receiving buffer 4b of the receiving side device will not be affected. Correction control simply discards that packet data. Therefore, the configuration is such that the data in buckets 1 to 1 to be discarded are discarded in advance on the transmitting side, and the packet transmission is controlled so as not to be transmitted.

This packet sending control algorithm clears the sending buffer 14a when the next packet enters the sending buffer y4a when there is one word or a certain number of voice packets in the sending buffer 4a. At the same time, the CSMA/CD ill Ill is initialized, for example, without returning the back-off cycle r1 to zero. Alternatively, if there is a forwarding (iN bucket 1-),
When the number of back-offs reaches a predetermined value, the transmission buffer 74a is cleared and the C8MΔ/CD control is initialized. Note that the time from when an audio packet is input to the transmission buffer 4a until the packet data is sent out is measured, and if the bucket 1~ data has not been successfully sent after a certain period of time, the above transmission is performed. Clearing buffer 4a and CSMA/CD i
ll10 may also be initialized.

According to this device, which performs the sending of buckets 1 to 3 in this manner, the packet sending delay FfI becomes large and its real-time nature is lost, and the data in bucket 1 is discarded and no longer sent. Therefore, unnecessary occupation of the transmission path 1 due to communication of valueless packets is eliminated. As a result, the degree of congestion on the transmission path 1 is greatly reduced, and communication failures for the subsequent packets are reduced, so that the delay in sending packets to the subsequent bucket 1- is suppressed. Therefore, even if a large transmission delay occurs for one packet, the transmission delay of the subsequent bucket i will not increase in a chain reaction and each of these packets will become worthless. Communication becomes possible.

In other words, it is possible to alleviate congestion on the transmission path 1, minimize packet delay and packet data loss due to packet discard, and perform effective packet communication 3.

Note that the present invention is not limited to the embodiments described above. For example, when three or more buckets 1- are stored in the transmission buffer 4a, a transmission cancellation request may be generated, and transmission may be canceled depending on the number of bits or bytes of data in the transmission buffer 4a. A cancellation request may also be generated. Furthermore, for example, a host computer or the like may issue a cancellation request to the packet communication device without the communication device detecting the state of the transmitted packet and issuing a cancellation request. The criteria for generating this transmission cancellation request can be determined according to the network specifications.Also, here, audio data is cited as data that requires real-time performance, but video data and Other data may be used, and optical communication may be performed by connecting the transmission path 1 with an optical fiber.Furthermore, here, as a method with large variations in bucket 1-sending delay time, the C8MA/CD method is used. Although the examples have been given, it goes without saying that it is equally applicable to the 1~-kun passing method and the slotted ring method. It can be implemented by

[Brief explanation of drawings]

The figures show an embodiment of the present invention; Fig. 1 is a schematic configuration diagram of a packet communication device, and Fig. 2 is a diagram of a packet 1-data.
FIG. 3 is a diagram showing the main part of the packet transmission control of the apparatus of this embodiment. DESCRIPTION OF SYMBOLS 1... Transmission path, 2... Transceiver, 3... Packet processing unit, 4a... Transmission buffer, 4b... Reception buffer, 5... Controller l-0-ra. Applicant's agent Patent attorney Takehiko Suzue Figure 2 Figure 3

Claims (4)

[Claims] (1) Means for converting the sending data into buckets 1 and 1 and storing them in the buffer. When packet data is stored in the buffer, a packet sending request is issued, a packet is attempted to be sent to the transmission path, and the data is stored in the buffer 1. When a packet transmission cancellation request is issued, the means for sequentially transmitting the packet data stored in the buffer 1 cancels the packet transmission request for the packets 1 to 1, and cancels the packet transmission request for the packet data stored in the buffer 1. 1. A packet communication device comprising: means for discarding a packet. (2) A patent claim in which the packet transmission cancellation request is issued when the packet data has not been successfully transmitted after a predetermined period of time has elapsed from the start of generation of a transmission request for the packet data stored in the buffer. The packet communication device according to item 1. (3) The packet transmission cancellation request is issued when a predetermined number or more than a predetermined number of packet data are stored in the buffer. The packet communication device according to claim 1. (4) The bucket communication device according to claim 1, wherein the packet data discarded from the buffer 1 consists of moving image data or audio data.