JP2005039312A - Real time communication warrant method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a real time communication warrant system for avoiding the effect on a packet transmission period caused by a transmission delay due to competition of packet transmission between nodes in a network wherein a prescribed of the nodes share a network band to carry out communication. <P>SOLUTION: The packet transmission processing is added with processing steps (1203, 1205) for deciding that the packet transmission is finished until occurrence of transmission of packets transmitted for a prescribed period on the basis of times Pmax, Pmin predicted by monitoring network communication so as to avoid the competition between the packet transmission and the transmission of packets which are periodically transmitted. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a packet communication network, and more particularly to a technique for guaranteeing communication quality of communication in which packets are transmitted at a constant cycle.
[0002]
[Prior art]
A communication network used in a home (hereinafter referred to as “network”) is required to be a low-cost network that can be easily constructed and managed. Examples of such networks include CSMA (Carrier Sense Multiple Access) networks using power lines and specific low power radio, or CSMA / CD (Carrier Sense Multiple Access) widely used in LAN (Local Area Network). There is a network of with Collision Detection).
[0003]
In a simple network typified by the CSMA method, a plurality of nodes perform communication while sharing the network bandwidth. Therefore, while a certain node communicates using the network, another node must wait for communication. . Therefore, when a node transmits a packet having a long data length, the waiting time until communication with another node becomes long. When it is required to transmit packets at regular intervals as in voice communication, adverse effects due to waiting time caused by communication of other nodes become a problem.
[0004]
As a solution to this problem, a method of shortening the packet length according to the network utilization rate (see, for example, Patent Document 1) or a method of reducing the amount of transmission data itself (see, for example, Patent Document 2) has been proposed. Yes.
[0005]
[Patent Document 1]
JP-A-9-116572
[Patent Document 2]
JP-A-3-270430
[0006]
[Problems to be solved by the invention]
In the above prior art, the probability of competing communication by a plurality of nodes is lowered by shortening the packet length or reducing the data amount, but it is not possible to reliably avoid competition between the nodes. Also, the waiting time due to contention of communication by multiple nodes in a situation where the network utilization rate is low, such as when the amount of data to be communicated is small but it is required to transmit packets at a fixed period, such as voice communication It has not been considered in the prior art to eliminate the above.
[0007]
An object of the present invention is to provide means for preventing data transmitted at a fixed period and other communication from competing on the network even when the amount of communication data on the network is small, and preventing the period from being disturbed. It is in.
[0008]
Another object of the present invention is to provide a network device in which, when there is a node that transmits data at a constant cycle, a node that communicates at a constant cycle and other nodes do not compete.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, in a network in which a band is shared by a plurality of nodes, when packets are transmitted at a constant time interval, packet transmission is performed for each node by monitoring the network. When the period is detected and the packet is transmitted to the network, the next packet transmission occurrence time is predicted, and the packet to be transmitted exceeds the packet length that can be completed before the next packet transmission occurrence prediction time The packet transmission is postponed until the predicted time of the next packet transmission.
[0010]
As another embodiment of the present invention, a period table in which one or a plurality of periods is registered in the network hub device is provided, and a time interval at which transmission is obtained by monitoring transmission of each connected node is represented in the period table. When the transmission interval and period of a node match, it is determined that the node is transmitting at a certain period, and at the next transmission occurrence time predicted from the period, A configuration is also conceivable in which transmission from a node is suppressed and contention with transmission of a node that is determined to be transmitting at a certain period is avoided.
[0011]
Furthermore, as another embodiment, when a communication with a fixed period is detected by monitoring the network and a packet from a network terminal is transmitted to the network, an algorithm for avoiding a conflict with the communication with a fixed period is implemented in the communication adapter. Also good.
[0012]
Further, as another embodiment, a configuration in which a network is configured by a terminal that performs communication at a fixed period and a terminal that has a function of detecting communication at a fixed period and preventing transmission from competing can be considered.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a diagram showing a first embodiment of a network system to which the present invention is applied.
The network system of this embodiment has a configuration in which various devices are connected to the home network 101. The home network 101 is a communication network in which the CSMA / CD method is used. Here, all the terminals connected to the home network 101 share the communication band of the home network 101. Specifically, the devices connected to the home network 101 include a gateway 103, a node management terminal 104, a data communication terminal 105, a plurality of nodes 106, a wireless access point 111, a plurality of VoIP phones 112, and entrance monitoring. A camera 113 or the like.
[0014]
The gateway 103 is a packet relay device that connects the home network 101 and the Internet 102. The data communication terminal 105 is a terminal that performs data communication with the Internet 102. In this embodiment, it is assumed that the data communication terminal 105 exchanges a packet having a long data length via the Internet 102 and the gateway 103.
[0015]
The data communication terminal 105 is connected to the home network 101 via the communication adapter 110. The communication adapter 110 transmits data received from the data communication terminal 105 to the home network 101, and transmits data received from the home network 101 to the data communication terminal 105. In this embodiment, the data communication terminal 105 and the communication adapter 110 are described as separate devices, but may be a single device included in the same housing.
[0016]
The wireless access point 111 is connected to a plurality of wireless nodes 107 by wireless communication. The wireless access point 111 serves as a bridge that relays packets between the wireless node 107 and the home network 101.
[0017]
The VoIP telephone 112 is a terminal for voice communication by VoIP (Voice over IP). Hereinafter, it is assumed that the VoIP telephone 112 cannot perform a plurality of voice communications at the same time and basically does not perform communications for other purposes during the voice communications. As an exception, communication for control purposes such as address resolution may occur, but the frequency is assumed to be 1 packet at the maximum during 5 consecutive packet transmission periods in voice communication. A “packet” refers to a unit of data transmitted and received by communication, and has a variable length depending on the amount of data stored.
[0018]
The transmission cycle of packets used in voice communication is set to a fixed value that is determined independently of the network utilization rate and the processing load of the VoIP telephone 112. The VoIP telephone 112 manages the transmission cycle, which is the above-described constant value, using a timer that is not affected by the processing load of the VoIP telephone 112. Note that the actual packet transmission time may be delayed from the actual period due to transmission competition or the processing load of the VoIP telephone 112, but it is not earlier than the actual period. Further, it is assumed that the traffic volume of voice communication is generally 64 kbit / second or less, which is sufficiently lower than the bandwidth of the home network 101.
[0019]
The communication adapter 110 records the time when packets transmitted from various terminals are transmitted by observing communication on the home network 101. The communication adapter 110 detects periodic packet transmission / reception such as voice communication from the record.
[0020]
FIG. 10 is a diagram illustrating a configuration of the communication adapter 110. The communication adapter 110 includes an interface 301, a reception processing unit 302, a reception buffer 303, a transmission processing unit 304, a transmission buffer 305, a bus interface 306, a cycle detection processing unit 312, a timer 313, and a memory 314. Note that the reception processing unit 302, the transmission processing unit 304, and the like may be separate hardware or integrated in one LSI.
[0021]
The communication adapter 110 is connected to the home network 101 via the interface 301 and is connected to the data communication terminal 105 via the bus interface 306. The interface 301 receives all packets transmitted / received on the home network 101 and sends the packets to the reception processing unit 302 and the cycle detection processing unit 312.
[0022]
The reception processing unit 302 stores the packet in the reception buffer 303 only when the destination address included in the packet is an address indicating the data communication terminal 105. The cycle detection processing unit 312 detects the cycle of packets transmitted and received on the network. The cycle detection processing unit 312 is realized by either a general-purpose processor or a dedicated logic circuit. In the case of a general-purpose processor, a program for period detection is executed by the processor.
[0023]
The period detection processing unit 312 uses a traffic table in order to manage information about observed packets on the network. The traffic table is stored in the memory 314. The traffic table has a plurality of entries. One entry includes an entry number, a source address, a destination address, the number of samples, sample time 1, sample time 2, sample time 3, sample time 4, difference value 1, difference value 2, difference value 3, maximum difference value, Each field includes a minimum difference value, a period flag, and an invalid count. An entry is created individually for each pair of a source address and a destination address of a packet.
[0024]
The entry number is a number unique to each entry and is used to identify the entry. The transmission source address and the destination address represent the transmission source address and the destination address included in the packet that the entry is to be recorded. The number of samples represents the number of sample times recorded in the entry, and a value of 1 to 4 is registered in the field.
[0025]
In the field corresponding to sample time 1 to sample time 4, the time when the corresponding packet is transmitted on the network is recorded. A value acquired from the timer 313 is registered in the time field. One entry holds a maximum of four times from the latest time as sample times, and is managed so that the sample time 1 is the latest and the sample time 4 is the oldest.
[0026]
The difference value 1 to the difference value 3 field stores the difference in sample time. The difference value n is a value obtained by subtracting the sample time n + 1 from the sample time n. The maximum difference value and minimum difference value fields store the maximum and minimum values of the difference values recorded in the entry, and the stored values are updated as needed each time a new difference value is calculated. Is done.
[0027]
In the period flag field, 1 is stored when it is determined that the corresponding packet is periodically transmitted, and 0 is stored otherwise. In the invalid count field, information indicating the number of packet observations not recorded as the sample time of the entry is recorded, and is used when determining the periodicity.
[0028]
FIG. 3 is a diagram illustrating a procedure in which the communication adapter 110 observes a packet on the network and detects periodically transmitted traffic.
[0029]
The interface 301 acquires a packet on the home network 101 and sends it to the cycle detection processing unit 312. The period detection processing unit 312 searches the traffic table and checks whether there is an entry that matches the destination address and the source address included in the packet (processing 701).
[0030]
If there is no corresponding entry, the period detection processing unit 312 creates a new entry in the traffic table and ends the process. In each field of the newly created entry, the entry number is a number that does not overlap with other entries, and the source address and destination address are the source address and destination address included in the packet received from the interface 301. The period flag and the invalid count are each set to 0, the sample number is registered as 1, and the current time is registered as the sample time 1 (process 702).
[0031]
If there is a corresponding entry in the process 701, the period detection processing unit 312 is registered in the field of the sample time 1 of the entry from the current time (specifically, the time when the packet was sampled by the interface 301). A value Td obtained by subtracting the calculated value is obtained (processing 703). Then, the period detection processing unit 312 compares the times Tmtu and Td necessary for transmitting the maximum length packet allowed by the home network 101 (processing 704).
[0032]
When Td is smaller than Tmtu, there is a possibility that the time of one cycle of the packet transmission period is shorter than Tmtu. In this case, since it is impossible to transmit a packet having the maximum length without competing with periodic communication, the present invention does not set it as a processing target. Therefore, the period detection processing unit 312 performs the process (A) described later in the description of FIG. 8 and ends the period detection process.
[0033]
When Td is larger than Tmtu, if the value registered in the sample number field of the traffic table entry is 1, the period detection processing unit 312 detects the current time, specifically, the time when the interface samples the packet. Is registered in the traffic table as the sample time. In this processing, the value of the sample number field is incremented by 1 to become 2, the current time becomes the sample time 1, and the time recorded in the sample time 1 field is registered in the sample time 2 field. Further, the cycle detection processing unit 312 records Td in the field of the difference value 1 and ends the processing (processing 706).
[0034]
When the sample number of the entry is larger than 1 in the process 705, the cycle detection processing unit 312 performs an entry update process (process 707), and then ends the process.
[0035]
FIG. 4 is a diagram showing the procedure of the entry update process executed in process 707.
First, the period detection processing unit 312 compares the Td calculated in the processing 703 with the values registered in the maximum difference value and minimum difference value fields of the entry (processing 801 and 804). If Td is between the maximum difference value and the minimum difference value, there is a high possibility that the extracted packet is involved in periodic communication, and the period detection processing unit 312 proceeds to the next process. When Td is larger than the maximum difference value or smaller than the minimum difference value, the cycle detection processing unit 312 updates the maximum difference value or the minimum difference value (processing 803 and 806).
[0036]
At this time, the cycle detection processing unit 312 checks whether or not the difference between the updated maximum difference value and the minimum difference value is less than Tmtu (processing 802, 805). When the difference between the maximum difference value and the minimum difference value is equal to or greater than Tmtu, the period tolerance becomes larger than the period disturbance due to transmission competition, and therefore the period detection processing unit 312 needs to make this communication a target of guarantee. Judge that there is no. If Td exceeds the maximum difference value and the difference between the maximum difference value and the minimum difference value is equal to or greater than Tmtu, the period detection processing unit 312 determines that the periodic communication is completed in process 802, and will be described with reference to FIG. The entry is initialized by the process (B) and the process is terminated. When Td is smaller than the minimum difference value and the difference between the maximum difference value and the minimum difference value is equal to or greater than Tmtu, the period detection processing unit 312 performs the process (A) and ends the process.
[0037]
When Td is between the maximum difference value and the minimum difference value, the period detection processing unit 312 confirms the number of sample times registered in the entry corresponding to the target packet (process 807). If the number of sample times is 3, the period detection processing unit 312 further determines whether or not the value registered in the invalid count field of the entry is 2 or more (process 810). When the invalid count value is 2 or more, the period detection processing unit 312 does not consider that the packet corresponding to the entry is periodically transmitted, performs the process (B), and ends the process. This is a condition derived from the premise that a packet other than voice communication in the VoIP telephone 112 is at most one packet during five consecutive voice communication cycles. Therefore, it goes without saying that the threshold of the invalid count changes if the premise is different.
[0038]
When the number of sample times is other than 3, the period detection processing unit 312 registers the current time (the time when the packet was sampled) in the entry. When the number of sample times is already 4, the period detection processing unit 312 discards the value registered in the oldest sample time 4 field and newly registers the values registered in the sample time 1 to sample time 3 fields. Sample time 2 to sample time 4, and the current time (time when the packet was sampled) is registered as sample time 1. When the number of samples is less than 4, the same processing is performed except that 1 is added to the number of samples (however, sample time 4 is not discarded). The difference value is processed in the same manner (process 808).
[0039]
If the number of samples in the entry is 4 as a result of the above processing, the period detection processing unit 312 considers that the packet is periodically transmitted (process 809), and adds the communication to the guarantee target. Process (C) is performed.
[0040]
FIG. 5 is a flowchart showing the procedure of the process (C).
The period detection processing unit 312 clears the value of the invalid count field of the entry and thereafter uses it to represent the number of invalid packets during one period (process 1101).
[0041]
When a plurality of VoIP telephones 112 are performing periodic communication simultaneously in the home network 101, in the present embodiment, communication that guarantees real-time performance, that is, communication that does not have a waiting time for using the network is simultaneously limited to three. Restrict. Thereby, the load of packet transmission processing, specifically, the load of the transmission control unit 304 can be reduced. In order to manage communication targeted for real-time guarantee, the communication adapter 110 stores a target entry array that stores the number of periodic traffic that represents the number of targeted communications and the entry number of the entry corresponding to the targeted communications. Within 314.
[0042]
When it is determined that an entry whose cycle flag is 0 is a new periodic communication (processing 1102), if the number of periodic traffics is already 3, the cycle detection processing unit 312 determines that the entry has real-time performance guarantee. It does not add to the object (processing 1103). If it is less than 3, the period detection processing unit 312 adds 1 to the number of periodic traffics, and adds the entry number of the communication subject to real-time property guarantee to the target entry array. Further, the period detection processing unit 312 changes the value 0 of the period flag field to 1 (process 1104).
[0043]
When the cycle flag is 1 in the processing 1102 and when the processing 1104 is finished, the cycle detection processing unit 312 sorts the elements of the target entry array in ascending order of the minimum difference value of the entries. Hereinafter, the target entry 1, the target entry 2, and the target entry 3 are described in ascending order of the minimum difference value (process 1105).
[0044]
When a plurality of periodic communications are targeted for real-time property guarantee, transmission of another periodic communication occurs during one period of one periodic communication. The packet interval is substantially shortened. When the time between packets when multiple periodic communications are combined is shorter than the time Tmtu for transmitting the maximum length packet, the maximum length packet is transmitted without competing with all the periodic communications at all. It is not possible.
[0045]
Therefore, the period detection processing unit 312 calculates a value X obtained by dividing the minimum difference value of the entries by the number of periodic traffics (process 1106). If it is smaller than Tmtu, it is determined that real-time property guarantee is impossible. The entry with the smallest minimum difference value (target entry 1) is excluded from the guarantee target (processing 1107 to processing 1109). By repeating this process until X becomes equal to or greater than Tmtu, the period detection processing unit 312 determines an entry that is a target of real-time property guarantee. The above is the period detection process by packet observation.
[0046]
Next, a process for detecting the end of periodic communication such as voice communication and deleting an entry whose period flag is 1, that is, an entry that is a target of real-time property guarantee will be described. If the end of the periodic communication is detected and the corresponding entry is not excluded from the guarantee, the transmission of the data communication terminal 105 is unnecessarily postponed in order to avoid contention with the nonexistent communication. For this reason, it is necessary to perform this processing for detecting the end of periodic communication and removing it from the guarantee target.
[0047]
In order to detect the end of periodic communication, there are the following three situations where the communication adapter 110 should observe and detect packets on the network.
The first situation is a case where the corresponding VoIP telephone 112 no longer communicates with the destination address of voice communication. In this case, the entry update process (process 707) based on the observation of the packet does not occur at all, so the periodicity is not judged and the entry remains. In order to delete entries in this situation, the cycle detection processing unit 312 checks all entries in the traffic table at regular intervals, and the current time (specifically, the cycle detection processing unit 312 starts checking all entries). And the difference between the sample time 1 and the sample time 1 exceeds the minimum difference value + Tmtu.
[0048]
The second situation is a case where the packet is observed after the minimum difference value + Tmtu or more has elapsed from the sample time 1. At this time, processing 707 occurs, and processing (B) is performed via processing 801 and processing 802.
[0049]
FIG. 7 is a diagram showing the process (B), that is, the procedure for initializing entries.
First, the period detection processing unit 312 initializes the value of the field of the number of samples of the entry to 1, and initializes the value of the field of the sample time 1 to the current time (process 901). Next, if the value of the field of the period flag is 1, the period detection processing unit 312 deletes the corresponding entry number from the entry array and subtracts 1 from the number of periodic traffic (process 902). Thereafter, the period detection processing unit 312 sets the value of the field of the period flag of the entry to 0 (process 903).
[0050]
Note that since the packet observed at the time of entry initialization may be a new voice communication start packet, unlike the first situation, the period detection processing unit 312 does not delete the entry and sets the current time. Record as sample time 1 and leave the entry.
[0051]
The third situation is a case where the communication adapter 110 observes packets at a time interval shorter than the predicted cycle. In this case, the communication adapter 110 starts the process (A) through the process 704 when the packet is observed at a time interval shorter than Tmtu, and through the process 804 and the process 805 when the time interval is longer than Tmtu.
[0052]
In this situation, a packet that is not related to voice communication is transmitted in the middle of the cycle, but the voice communication itself continues, and when voice communication ends and communication other than voice communication starts. There are two possibilities. The communication adapter 110 uses a value registered in the invalid count of the entry to identify both.
[0053]
FIG. 8 is a diagram illustrating a procedure of the process (A), that is, the process in which the communication adapter 110 confirms the invalid count of entries.
The period detection processing unit 312 first adds 1 to the value registered in the invalid count field of the entry (process 1001). As described above, when the period flag of the entry is 1, the invalid count represents the number of packets that are not considered to be periodic observed during one period. In the present embodiment, since it is assumed that the number of packets other than voice communication in the VoIP telephone 112 is 1 packet at the maximum during five consecutive voice communication cycles, it is acceptable if the invalid count is 1 or less. . Therefore, the cycle detection processing unit 312 determines whether or not the value of the cycle flag is 1 (processing 1002), and further determines whether or not the invalid count is 2 or more (processing 1002). When the invalid count value is 2 or more, the period detection processing unit 312 considers that the voice communication has ended, performs the process (B), and initializes the entry.
The above is the period detection process by the communication adapter 110 observing communication in the home network 101.
[0054]
Next, a method for controlling packet transmission so that communication adapter 110 does not compete with periodic communication when there is a packet transmission request from data communication terminal 105 will be described.
[0055]
FIG. 9 is a diagram illustrating a procedure for controlling packet transmission in the communication adapter. Packets transmitted by the data communication terminal 105 are written to the transmission buffer 305 via the bus interface 306. The transmission control unit 304 calculates a time TL necessary for transmitting the packet over the network from the length of the packet to be transmitted. The TL is calculated by dividing the packet length by the communication speed of the network (process 1201).
[0056]
Next, the transmission control unit 304 repeats the following processing 1202 to processing 1205 for the entry of each entry number registered in the target entry array.
[0057]
The transmission control unit 304 predicts the time at which the packet of the entry registered in the target entry array (initially entry 1 and then entries 2 and 3 are targets) will be transmitted next. Here, values obtained by adding the maximum difference value or the minimum difference value to the sample time 1 which is the latest sample time (Pmax and Pmin, respectively) are set as the predicted values (process 1202).
[0058]
Thereafter, the transmission control unit 304 sets the time acquired from the timer 313 at this time as Pcur, and determines whether or not the packet can be transmitted by the time Pmin (processing 1203). If transmission is possible, the transmission control unit 304 calculates a limit time Plimit at which packet transmission is completed by Pmin (processing 1204), and proceeds to processing of the next entry.
[0059]
If it is determined in process 1203 that transmission is not possible by the time Pmin, the time Pcur may have already passed the time Pmax at the time of the determination. Therefore, the transmission control unit 304 determines whether the time Pmax and the time Pcur are large or small (process 1205). If the time Pcur is greater than the time Pmax, there is no need to postpone transmission, so the transmission control unit 304 proceeds to the next entry process.
[0060]
When the conditions of the processes 1203 and 1205 are not satisfied, the transmission control unit 304 predicts that the transmission of the packet at this time will compete with the periodic communication, and postpones the transmission. When the transmission is postponed, the transmission control unit 304 postpones the transmission to Pmax of the entry that does not satisfy the conditions of the processes 1203 and 1205, and repeats the process for the target entry array again (process 1210).
[0061]
When the above processing is performed on all entries registered in the target entry array and it is predicted that transmission is possible without competing with communication that guarantees real-time performance, the transmission control unit 304 determines whether the CSMA standard is satisfied. Wait until the network is ready for use (process 1206). However, when the limit time Plimit has passed while waiting for transmission (process 1207), the transmission control unit 304 needs to repeat the process again to determine a new transmission time. If the limit time Plimit has not passed, normal transmission is performed (process 1208).
[0062]
Through the above processing, the communication adapter 110 avoids the conflict between the communication of the data communication terminal 105 to which it is connected and the voice communication of the VoIP phone 112. Here, it is assumed that the transmission cycle of the VoIP telephone 112 is t, and the actual packet transmission time is delayed by at most 0.5 Tmtu with respect to the time determined by the transmission cycle. Then, Pmax and Pmin obtained by the period detection algorithm in the present embodiment are t + 0.5 Tmtu and t−0.5 Tmtu, respectively, and the difference between Pmax and Pmin is Tmtu, so that it is recognized as a period. In this case, the actual packet transmission time is between Pmax and Pmin from the sample time 1, and the transmission time is correctly predicted. Therefore, contention can be avoided by postponing transmission between times Pmax and Pmin.
[0063]
As described above, by using the network system according to the present embodiment, communication with a small amount of communication data, such as voice communication, that requires transmission at a fixed period, and communication with a large amount of communication data and long packets Even if the communication is performed on the same network, data communication that does not adversely affect voice communication due to competition on the network becomes possible.
[0064]
In particular, the present embodiment is effective in the case where the communication of a dedicated device for voice communication such as a VoIP phone and the file transfer communication such as firmware update and recovery of the operation status log coexist in the home network 101. In addition, since the period is predicted by monitoring the communication on the network, the present embodiment can be applied regardless of the upper layer protocol, and can cope with a change in the period or a change in the number of nodes.
[0065]
Furthermore, by using the communication adapter 110, it is not necessary to add a function to the data communication terminal 105 itself. Note that the above-described real-time communication guarantee method does not necessarily have to be executed by the communication adapter 110. For example, like the entrance monitoring camera 113, the above-described method is realized by the terminal itself that is intended to transmit image data in bursts, so that the voice communication of the VoIP telephone 112 is disturbed by the data transmitted by the entrance monitoring camera 113. It can also be prevented.
[0066]
Therefore, in the present embodiment, by configuring a network system in which the above-described real-time communication guarantee method is installed in each terminal that performs bursty communication connected to the home network 101, voice communication on the network system is configured. It is also possible to guarantee the period.
[0067]
Subsequently, a second embodiment of the network system will be described. The configuration of the second embodiment is the same as that of FIG. However, in this embodiment, the algorithm of packet observation, transmission time prediction, and packet transmission control in the first embodiment is implemented in the gateway 103, and the target of the packet observation is between the node management terminal 104 and each node. It becomes a communication packet.
[0068]
The node management terminal 104 is a terminal for controlling a plurality of nodes 106 in the home network 101. The node management terminal 104 performs polling at a constant cycle T in order to grasp the operation status of the plurality of nodes 106.
[0069]
FIG. 2 is a diagram showing a polling communication sequence between the node management terminal 104 and each node 106. The node management terminal 104 transmits the polling packet 201 in order to each different node 106 every fixed period T. After performing polling for all the nodes 106, the node management terminal 104 performs the second polling for all the nodes 106 starting from the node 106 that first transmitted the polling packet 201, and so on. Continue.
[0070]
The node 106 that has received the polling packet 201 transmits a response packet 202 to the node management terminal 104. The polling packet 201 and the response packet 202 are both short in packet length, and the relationship between the period T and the response time t is T> t.
[0071]
In the present embodiment, when a large amount of data is sent from the Internet 102 to the data communication terminal 105 via the gateway 103 in the home network 101, the gateway 103 guarantees the real-time communication described in the first embodiment. Using the method, contention with communication between the node management terminal 104 and each node 106 is avoided.
[0072]
In this embodiment, the address of the node management terminal 104 is set in the gateway 103 in advance, and only packets whose source address matches the address of the node management terminal 104 are extracted for packet observation. In this embodiment, the processing 701 in FIG. 3 is changed to a determination as to whether or not the transmission source address matches the address of the node management terminal 104, and all packets that do not match are ignored. Therefore, the traffic table entry used in this embodiment does not include the destination address field, and as a result, only one entry whose source address matches the address of the node management terminal 104 is managed.
[0073]
In addition, when the gateway 103 observes communication between the node management terminal 104 and the plurality of nodes 106 by applying the first embodiment as it is, the gateway 103 selects an entry whose cycle is T × number of nodes. A number equal to the number of nodes is managed. Therefore, in this embodiment, since communication is identified only by the source address, it is only necessary to manage one entry of the period T in the traffic table, and the management load and the size of the traffic table are reduced. The packet observation and transmission control algorithms are the same as in the first embodiment, and the resulting effects are also the same.
[0074]
As described above, by using the real-time communication guarantee method according to the present embodiment, communication that requires a small amount of communication data such as polling for device management and periodic transmission, and a packet that has a large communication data amount and a long length Even if communication using a network is performed on the same network, data communication that does not adversely affect periodic communication due to competition on the network is possible.
[0075]
Also, in this embodiment, compared to the first embodiment, since the prediction of the period when a specific terminal periodically communicates with a plurality of nodes is made more efficient, the operation status monitoring of home appliances in the home network This is effective for guaranteeing real-time communication. Furthermore, the gateway 103 manages the timing of data transmission, so that real-time performance can be guaranteed for all communications from the Internet 102. That is, even when a plurality of data communication terminals 105 browse WWW (World Wide Web) at the same time, there is a feature that the function only needs to be implemented in the gateway 103.
[0076]
Next, a network system according to a third embodiment will be described.
FIG. 6 is a diagram illustrating a configuration of a network system according to the third embodiment. The network configuration of this embodiment is a star-type CSMA / CD network in which a plurality of nodes 106 are connected to a hub 601.
[0077]
The hub 601 includes a plurality of ports 602, a JAM signal transmission unit 603, a bus 604, a cycle management unit 606, a timer 313, a memory 314, a cycle detection processing unit 312, and a cycle table 607. The node 106 is connected to each port 602 of the hub 601 via a cable. The packet transmitted by the node 106 is electrically relayed to all the ports 602 through the bus 604, and the packet is observed by the cycle detection processing unit 312.
[0078]
The period detection processing unit 312 executes the same packet observation and period prediction algorithm as in the first embodiment. However, an entry registered in the traffic table does not correspond to a specific source address / destination address pair, but corresponds to one port 602. That is, all the packets transmitted from the node 106 connected to the port 602 become the observation target of the entry. Since the timer 313 and the memory 314 are the same as those in the first embodiment, description thereof is omitted.
[0079]
In the cycle table 607, transmission cycle information generally used in real-time communication such as voice and moving images is registered. If the period detection processing unit 312 determines that the communication of a certain entry is periodic, between the processes 1101 and 1102, which of the periods registered in the period table 607 corresponds to the period of the entry. Determine.
[0080]
Specifically, the determination is made based on whether or not the value registered in the period table 607 is in the range of the minimum difference value and the maximum difference value of the entry. If the corresponding cycle is not in the cycle table 607, it is determined that the communication of the entry is not periodic, and the cycle detection processing unit 312 performs the process (B).
[0081]
The period management unit 606 sends a JAM signal to all ports 602 other than the port 602 corresponding to the entry at a time when a certain node 106 predicts transmission based on the traffic table stored in the memory 314. The transmitter 603 transmits a JAM signal. The transmission period of the jam signal is between time Pmin and Pmax.
[0082]
In the CSMA / CD network, the node 106 that detects the JAM signal does not perform packet transmission. Therefore, the transmission of the node 106 at the port 602 that is predicted to transmit may compete with the transmission of other nodes 106. Disappears.
[0083]
As described above, by using the real-time communication guarantee method according to the present embodiment, even if communication that performs transmission at a constant cycle and communication that uses a long packet with a large amount of communication data are performed in a star-type network, it is constant. Data communication can be performed without delaying the transmission of the cycle.
[0084]
It should be noted that this embodiment is applied to a case where a fixed period communication such as voice communication and burst communication such as terminal firmware update and operation log collection are simultaneously performed in a home network. The fluctuation of the voice communication delay due to the competition of the voice is reduced, and the effect of improving the voice quality can be expected.
[0085]
In addition, since the hub 601 predicts the cycle by monitoring communication, the node 106 does not need to reserve a bandwidth in advance or notify the hub 601 and can use a normal terminal as it is. . In addition, by registering a typical transmission cycle of voice and images to be transmitted at a constant cycle in advance in the cycle table 607, the guarantee target is limited to the case where the transmission from the node 106 is voice or image communication. This makes it possible to prevent a non-periodic communication from being added as a guarantee target.
[0086]
Next, a fourth embodiment will be described. The network configuration of this embodiment is the same as that shown in FIG. In the present embodiment, a packet filter is provided between the interface 301 of the communication adapter 110 and the cycle detection processing unit 312. Then, addresses of a plurality of VoIP telephones 112 that perform voice communication are registered in advance in the packet filter.
[0087]
The packet filter checks whether the source address or destination address of the packet matches the registered address of the VoIP phone 112. If the source address and destination address of the packet do not match the address of the registered VoIP telephone 112, the packet filter discards the packet.
[0088]
As a result, in this embodiment, communication packets that are not voice communications can be excluded from the period detection processing target in the period detection processing unit 312, and as a result, the detection processing load and the number of entries in the traffic table are reduced. can do.
[0089]
As described above, in this embodiment, by limiting the address of the packet to be observed to the address of the VoIP telephone 112 that performs voice communication registered in advance, the traffic table is reduced in size and communication that is not voice communication is performed. Prevents accidental recognition of periodic communication.
[0090]
This embodiment is particularly effective for application to an environment where the number of voice communication dedicated devices and addresses hardly change, such as a home network. Further, the information registered in the packet filter may be not the address of the VoIP telephone 112 but information on the priority and traffic characteristics in the packet, for example, the value of the DS (Differentiated Services) field in the IP (Internet Protocol) header. Next, a fifth embodiment will be described. The network configuration of this embodiment is the same as that shown in FIG. In this embodiment, the wireless access point 111 executes the above-described real-time communication guarantee method.
[0091]
The wireless access point 111 observes communication in the home network 101 and detects periodic communication and its cycle by the same method as in the first embodiment. The wireless access point 111 controls the packet transmission so as not to compete with the periodic communication as in the first embodiment when the packet transmitted by the wireless node 107 is received wirelessly and relayed to the home network 101. .
[0092]
Therefore, in this embodiment, it is possible to prevent the periodic communication cycle in the home network 101 from being disturbed when the wireless node 107 performs burst communication.
[0093]
As described above, in this embodiment, the wireless access point 111 executes the real-time communication guarantee method according to the present invention, so that periodic communication and burst communication can be performed even in an environment where a wired network and a wireless network are mixed. When they occur at the same time, it is possible to avoid contention and not disturb the periodic communication cycle. Further, by implementing the function in the wireless access point 111, the real-time communication guarantee according to the present invention can be applied to the communication of all the wireless nodes 107.
[0094]
In addition, the structure which combined each embodiment is also possible. Furthermore, the present invention can be realized not only in the home network but also in other networks.
[0095]
【The invention's effect】
According to the present invention, it is possible to avoid the occurrence of transmission competition when there is a high possibility of periodic communication and packet transmission competing, and data communication without adversely affecting communication that requires transmission at a fixed period. There is an effect that can be. In addition, there is an effect that communication contention can be avoided even when the amount of communication on the network is small.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a network according to the present invention.
FIG. 2 is a diagram showing a communication sequence between a node management terminal 104 and a node 106;
FIG. 3 is a diagram illustrating a procedure of packet observation processing.
FIG. 4 is a diagram illustrating a procedure of entry update processing.
FIG. 5 is a diagram illustrating a processing procedure when it is determined that an entry is periodic communication.
FIG. 6 is a block diagram of a network hub device.
FIG. 7 is a diagram illustrating a processing procedure when it is determined that an entry is not periodic communication.
FIG. 8 is a diagram illustrating a processing procedure when a packet is observed at a time interval shorter than a cycle.
FIG. 9 is a diagram illustrating a procedure of transmission processing.
10 is a block diagram of the communication adapter 110. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 101 ... Home network, 103 ... Gateway, 104 ... Node management terminal, 105 ... Data communication terminal, 106 ... Node, 107 ... Wireless node, 110 ... Communication adapter, 111 ... Wireless access point, 112 ... VoIP telephone.

Claims (10)

A method of transmitting data over a network,
A device connected to the network acquires a packet of another device transmitted on the network,
Calculating the periodicity of the acquired packets;
According to the calculated periodicity, the apparatus transmits data to the network so that the apparatus does not compete with a packet transmitted by the other apparatus. 2. The data according to claim 1, wherein there are a plurality of the other devices, and the device calculates the periodicity of a packet transmitted by a predetermined number of other devices among the plurality of other devices. Transmission method. The data communication method according to claim 1, wherein the device is a communication adapter that connects the network and an arbitrary communication terminal. The data communication method according to claim 1, wherein the device is a gateway that connects the network and a second network. The data communication method according to claim 1, wherein the device is an access point connected to the network and performing wireless communication with an arbitrary communication terminal. There are a plurality of the devices, the first device is a communication adapter that connects the network and an arbitrary communication terminal, and the second device is a wireless connection between the network and the arbitrary communication terminal. 2. The data communication method according to claim 1, wherein the data communication method is an access point to be connected. 2. The data communication method according to claim 1, wherein the packet to be observed is limited to a packet that matches a value set in advance in a specific field in the packet. The data communication method according to claim 1, wherein the device is a hub device connected to the other device via the network. In a network where a band is shared by a plurality of nodes, when one or a plurality of the nodes transmit a packet based on a certain period, a node that does not perform transmission based on a certain period monitors the network to When transmitting the packet to the network by detecting the packet transmission period of each node that performs transmission based on the period, predicting the next packet transmission time of the node performing transmission based on a certain period A method for guaranteeing real-time communication, comprising: deferring packet transmission until after the predicted transmission occurrence time when the packet length cannot be completed by the predicted transmission occurrence time. A device connected to a network,
A connection unit connected to the network;
A cycle detection processing unit,
The connection unit acquires a packet of another device transmitted through the network,
The detection processing unit calculates the periodicity of the acquired packet,
The said connection part transmits data to the said network so that it may not compete with the packet which said other apparatus transmits according to the said calculated periodicity.

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