JP4577670B2 - Communication apparatus and data transmission control method - Google Patents

Description

  The present invention relates to a communication device connected to an external network, and more particularly to a communication device having an internal communication speed different from the communication speed of the external network and a data transmission control method thereof.

  In general, in a packet data communication system, priority control of packets can be performed by providing a priority identification field in a packet header (see, for example, Patent Document 1). In particular, when priority control is performed in which packets are transmitted in descending order of priority, it is desirable to avoid as much as possible that the packet is discarded by the repeater or that the transmission order is disturbed due to retransmission processing. Hereinafter, priority control will be briefly described with reference to FIG.

  FIG. 8 is a block diagram showing a schematic configuration of a general communication apparatus having a layer 2 switch. The communication device is provided with a layer 2 switch 11, a control unit 12, and a transmission data storage unit 13. Here, the layer 2 switch 11 is connected to the networks 1 and 2, the layer 2 switch 11 and the control unit 12 are connected by the internal data bus 14, and the communication speed of the data bus 14 is higher than the communication speed of the network 2. Suppose there is.

  In such a communication apparatus, the priority control of data transmission performed by the control unit 12 is normally such that transmission data subject to priority control is stored in the transmission data storage unit 13 in the order of arrival, and the control unit 12 sets the communication bandwidth of the data bus 14 to In addition, it is executed by sequentially reading the transmission data, or it is executed while referring to the above-described packet priority determination flag.

JP 2000-358067 A

  However, in the above-described communication device, when the connection speed of the external network 2 is slower than the internal data bus 14, all data cannot be transmitted by the layer 2 switch 11, and packet retention or discard occurs, and the control unit Data cannot be transmitted in the intended priority order of 12. This will be specifically described below.

  9A to 9C are time charts for explaining data loss that occurs when transmission data is actually transmitted to the network. Here, T indicates the amount of data that can be transmitted by the interface per unit time. In order to simplify the description, the network 1 has four packets as shown in FIG. 9A and the dedicated data bus 14 has four packets as shown in FIG. Assume that two packets can be transmitted as shown in FIG. The priority control target transmission data stored in the transmission data storage unit 13 is transmitted in the order of A1, A2, A3,.

  As described above, since the dedicated data bus 14 can transmit four packets, the control unit 12 transmits four packets from the transmission data storage unit 13 in unit time T, but the network 2 can transmit only two packets. For this reason, as shown in FIG. 9B, the layer 2 switch 11 cannot send two packets (A3, A4, etc.), and is discarded or stays in the layer 2 switch 11. For this reason, as shown in FIG. 9C, the order of data to be transmitted is A5 after A2, and the priority control performed by the control unit 12 becomes invalid.

  Further, when priority control is performed using the packet priority control determination flag, there is a possibility that unintended processing of the control unit 12 may be performed due to the function of the layer 2 switch 11 in between.

  That is, if there is a mismatch in the connection speed between the data bus 14 and the external network 2, the packet is discarded or stayed at the repeater such as the layer 2 switch 11, so that the original priority control of the control unit 12 is performed. Is not implemented. Further, even if the transmitted packet is discarded by a repeater such as the layer 2 switch 11, the control unit 12 cannot grasp which packet is discarded. I can't judge.

  Further, in the priority control using the priority determination flag of the transmitted packet, the control unit 12 may not be able to control the actual transmission order of the packet.

  Therefore, an object of the present invention is to provide a communication device and a data transmission control method that enable priority control to function effectively.

A communication apparatus according to the present invention is a communication apparatus that transmits transmission data to be subject to priority control from one of at least one communication terminal connected to a first network, and sequentially transmits the transmission data to a second network . Storage means storing a table for managing the communication speed of the at least one communication terminal, and the communication possible speed of the second network is slower than the internal communication speed of the communication device, and the communication of the source communication terminal Control means for transmitting a control signal for lowering the transmission speed of the transmission data to be equal to or lower than the communicable speed of the second network when it is determined that the transmission data is slower than the transmission speed. And

  According to the present invention, it is possible to make priority control function effectively.

1. 1. First Embodiment 1.1) Configuration FIG. 1 is a block diagram showing a schematic configuration of a communication apparatus according to a first embodiment of the present invention. The communication apparatus 100 according to the present embodiment includes a communication unit 101, a control unit 102, a data storage unit 103, and a priority control information table 104.

The communication unit 101 can be connected to a plurality of networks, and can transmit and receive data to and from each network. Here, as an example, it is connected to the two networks 1 and 2, and the communication speed of the network 1 is R _EXT1 and the communication speed of the network 2 is R _EXT2 . The communication unit 101 and the control unit 102 are connected via an internal data bus 105, and the communication speed is R _INT . In the present embodiment, the communication speed _{R INT} of the internal data bus 105 is faster than the communication speed _{R EXT2} network 2, and the communication rate _{R EXT1} network 1 is assumed to be faster than the communication speed _{R EXT2} network 2 .

  The data storage unit 103 stores data received from the network 1 or 2 and data to be transmitted to the network 1 or 2 under the control of the control unit 102.

  The priority control information table 104 stores criteria for determining whether data to be transmitted requires priority control. If the data stored in the data storage unit 103 requires priority control, the control unit 102 checks the communication speed of the destination network and the internal data bus 105 or the communication status of the destination network as described below. Then, priority control according to the priority control information in the priority control information table 104 is executed. Hereinafter, priority control executed when data is transmitted to the network 2 that is slower than the internal data bus 105 will be described.

1.2) Priority Control FIG. 2 is a functional block diagram for explaining priority control in the communication apparatus shown in FIG. However, blocks having the same functions as those shown in FIG. Further, data A1, A2,... Indicate packet sequences to be subjected to priority control, and the number after A indicates the order to be transmitted set in the priority control information table 104.

  When the control unit 102 determines that the transmission data stored in the data storage unit 103 is a priority control target, the data packet has continuity, and therefore needs to be transmitted to the network 2 in the order of the packet. is there. For example, A2 must be transmitted after the data packet A1, and A3 must not be transmitted before A2. In this case, the control unit 102 receives information on the communicable speed of the network 2 from the communication unit 101, and controls packet transfer from the data storage unit 103 to the communication unit 101 according to the information.

If the communication rate R _EXT2 of the network 2 is faster than or the same as that of the internal data bus 105, the control unit 102 does not disturb the transmission packet order from the data storage unit 103 at the communication rate R _INT of the internal data bus 105 as it is. Can be sent to. That is, priority control is not hindered by the communication unit 101.

However, as assumed here, when it is determined that the communication possible speed _REXT2 of the network 2 is lower than the internal data bus 105, the control unit 102 stores data so as to match the communication speed of the network 2. Controls transfer of transmission packets from the unit 103 to the communication unit 101.

  For example, as shown in FIG. 2, the communication speed of the internal data bus 105 can transfer 4 packets per unit time T (A1A2A3A4 / A5A6A7A8 /...), Whereas the network 2 has 2 packets per unit time T. In the case where only the portion can be transmitted, the control unit 102 transfers the packet to the communication unit 101 at a rate of 2 packets (A1A2 / A3A4 /...) Every unit time T, and the communication unit 101 discards or retransmits the packet. Control so that processing does not occur. As a result, packets A1A2A3A4... Are sequentially transmitted from the communication unit 101 to the network 2 in the correct order, and the priority control according to the priority control information table 104 becomes valid.

  In order for the control unit 102 to obtain the communicable speed information of the network 2 from the communication unit 101, for example, the following method can be employed, and effective priority control can be performed.

・ MDIO
Control unit 102 can obtain a communicable speed information _{R EXT2} network 2 by MDIO (Management Data Input / output) interface management signals with the communication unit 101. If the communicable speed of the network 2 is slower than the internal data bus 105, the control unit 102 sets the packet transfer amount (transfer speed) per unit time T transferred from the data storage unit 103 to the communication unit 101, for example, It is possible to make priority control effective by reducing it to R _EXT2 / R _INT or less.

Transmission buffer status When the communication unit 101 is provided with a transmission buffer for temporarily storing transmission data packets, the control unit 102 constantly monitors the packet amount of the transmission buffer and obtains the packet amount as communication speed information. be able to. If the amount of packets stored in the transmission buffer continues to increase, it is determined that the communication speed of the network 2 is slower than the internal data bus 105. In this case, the control unit 102 can validate the priority control by reducing the packet transfer amount (transfer rate) per unit time T transferred from the data storage unit 103 to the communication unit 101. This method can be combined with the MDIO method described above.

When the communication unit 101 has a counter that counts the number of transmission data packets, the control unit 102 can obtain the number of packets transmitted from the communication unit 101 as communication speed information. If the number of packets transmitted from the communication unit 101 is smaller than the number of packets transferred from the control unit 102 to the communication unit 101, it is determined that the communication speed of the network 2 is slower than the internal data bus 105. In this case, the control unit 102 can validate the priority control by reducing the packet transfer amount (transfer rate) per unit time T transferred from the data storage unit 103 to the communication unit 101. This method can be combined with the MDIO method described above.

-Transmission speed of the communication unit When the communication unit 101 has a counter that displays the actual data transmission speed, the control unit 102 can obtain the transmission speed as communicable speed information. If the actual transmission rate of the communication unit 101 is slower than the transfer rate of the packet transferred by the control unit 102 to the communication unit 101, it is determined that the communication rate of the network 2 is slower than the internal data bus 105. In this case, the control unit 102 can validate the priority control by reducing the packet transfer amount (transfer rate) per unit time T transferred from the data storage unit 103 to the communication unit 101. This method can be combined with the MDIO method described above.

1.3) Effect As described above, according to the first embodiment of the present invention, the control unit 102 confirms the transmission speed information of the communication unit 101 and performs transfer control, so that predetermined priority control is effectively executed. can do. In particular, even when the communication speed of the network transmitted from the communication unit 101 is lower than that of the internal data bus 105, correct priority control can be executed. That is, it becomes possible to guarantee the priority control of the transmission packet regardless of the internal configuration of the packet.

2. First Embodiment Hereinafter, an embodiment of a communication apparatus using a method for acquiring communication-side speed information on a network side by a management signal of an MDIO interface will be described. The same applies to the case where the communication possible speed information of the network 2 is obtained by the above-described method other than the MDIO interface.

2.1) Configuration FIG. 3 is a block diagram showing a network configuration including a communication apparatus according to the first embodiment of the present invention. However, blocks having the same functions as those in FIG. In this embodiment, layer switch as the communication unit 101, a control unit such as a CPU, which is the program-controlled processor as the control unit 102, Ethernet communicable rate _{R EXT1} as a network 1 (R), can communicate as a network 2 Speed _{R EXT2} The routers 3 connected by Ethernet (registered trademark) are used. It is assumed that the network 2 is connected to the Internet 4 and a plurality of communication terminals 5 are connected to the network 1. The communication terminal 5 is a terminal having a communication function such as a personal computer PC.

  The communication apparatus 100 according to the present embodiment incorporates a layer 2 switch 101 that is a data repeater, and the layer 2 switch 101 can connect a plurality of networks (here, networks 1 and 2) having different communication speeds. For example, a plurality of networks such as 1000BASE-T / 100BASE-TX / 10BASE-T can be connected.

  The control unit 102 controls the overall operation of the communication apparatus 100, and the data storage unit 103 stores data received from one network and sent to another network. The priority control information table 104 stores priority settings for data transmitted by the control unit 102.

  Data transfer between the control unit 102 and the layer 2 switch 101 is executed through a dedicated data bus 105 defined by MII (Media Independent Interface) or GMII (Gigabit MII), and is transferred from the control unit 102 to the layer 2 switch 101. Transmission / reception of management signals used for control and status confirmation is performed through the MDIO interface 106.

  In addition, since the hardware and connection function of Ethernet (registered trademark) defined in IEEE802.3 are well known, detailed description thereof will be omitted.

2.2) Operation FIG. 4 is a flowchart showing a data transmission operation of the communication apparatus shown in FIG. Here, in order to simplify the explanation, the dedicated data bus 105 is connected to GMII capable of communication at R _INT = 1000 Mbps, and the network 1 is connected to 1000BASE-T capable of communication at R _EXT1 = 1000 Mbps. 2 is a 100BASE-TX connection capable of communication at R _EXT2 = 100 Mbps. That is, it is assumed that the communication speed of the network 2 connected to the outside through the dedicated data bus 105 is low.

  First, it is assumed that the communication terminal 5 continuously sends a plurality of data packets that require priority control to the network 2 in a predetermined order. When the control unit 102 receives these data packets through the layer 2 switch 101 (step 201), the control unit 102 stores them in the data storage unit 103 via the dedicated data bus 105 (step 202).

Subsequently, the control unit 102 confirms the transmission destination of the packet stored in the data storage unit 103 and determines whether or not the priority control set in the priority control information table 104 is necessary (step 203). When the priority control is determined to be necessary (step 203: YES), the control unit 102 confirms the communication speed available _{R EXT2} network 2 through MDIO interface 106 (step 204), the communication speed _{R INT} of the dedicated data bus 105 Compare (step 205). Here, since R _EXT2 <R _INT (step 205: YES), the control unit 102 sequentially reads out the packets from the data storage unit 103 at a speed that matches the communication possible speed R _EXT2 of the network 2 and performs the layer 2 switch 101. (Step 206).

Thus, the packets are transmitted to the network 2 in the order of the transmission packets transferred by the control unit 102 (step 207). Also, if it is not necessary priority control (step 203: NO) or when the communication speed _{R EXT2} network 2 is a communication rate _{R INT} or more dedicated data bus 105 (step 205: NO), the control unit 102 priority control guarantees The data from the data storage unit 103 is sent to the network 2 as it is at the communication speed of the dedicated data bus 105 without performing the transfer control for (step 207).

2.3) Effect As described above, the communication apparatus according to this embodiment can prevent packet discard and retransmission processing from occurring in the layer 2 switch 101, and packet transmission in which priority control according to the priority control information table 104 is enabled. Is possible. In other words, priority control can be guaranteed regardless of the internal configuration of the packet.

3. Second Embodiment In the first embodiment described above, the difference in communication speed between communication terminals connected to the network 1 is not considered. However, in actual Ethernet (registered trademark), 1000BASE-T / 100BASE-TX / It supports multiple communication speeds such as 10BASE-T. In this case, the control unit of the communication device does not control the packet transfer rate of the internal data bus, but transmits the communication terminal when the transmission rate of the communication terminal that is the transmission source is higher than that of the network 2. By suppressing the speed, it is possible to obtain the same effect as in the first embodiment.

  Therefore, when the communication terminal transmits a packet at a higher speed than the communication speed of the network 2, the communication apparatus according to the second embodiment of the present invention instructs the communication terminal to limit the transmission speed.

  In the following, a second embodiment of a communication apparatus using a method of acquiring communication-side speed information on the network side by a management signal of the MDIO interface will be described. The same applies to the case where the communication possible speed information of the network 2 is obtained by the above-described method other than the MDIO interface.

4). Second Embodiment 4.1) Configuration FIG. 5A is a block diagram showing a network configuration including a communication apparatus according to a second embodiment of the present invention, and FIG. 5B shows a transmission rate management table of a communication terminal. It is the figure shown typically. 5A, blocks having the same functions as those in FIG. 3 are denoted by the same reference numerals, and detailed description thereof is omitted. However, the network 1 corresponds to 1000BASE-T / 100BASE-TX / 10BASE-T as an example, and the transmission speeds of communication terminals (herein referred to as PCs) connected to the network 1 are different. To do. For example, the transmission speed R _{5 of} PC5 = 1000 Mbps, the transmission speed R _{6 of} PC6 = 100 Mbps, and the like.

The communication device 300 according to the present embodiment has a control unit 301 and a transmission rate management table 302, and the rest has the same configuration as the communication device 100 according to the first embodiment and operates in the same manner. In the transmission speed management table 302, as shown in FIG. 5B, the transmission speed of the PC connected to the network 1 is registered in advance. For example, the transmission speed R _{5 of} PC5 = 1000 Mbps, the transmission speed R _{6 of} PC6 = 100 Mbps, and the like.

  The data transmission operation of the second embodiment of the present invention will be described below with reference to FIGS.

4.2) Operation FIG. 6 is a flowchart showing a data transmission operation of the communication apparatus shown in FIG. 5, and FIG. 7 is a sequence diagram of the data transmission operation shown in FIG. However, in FIG. 6, steps having the same functions as those in the flowchart shown in FIG.

Consider a case where a communication terminal PCx having a transmission rate _Rx connected to the network 1 continuously sends a plurality of data packets that require priority control to the network 2 in a predetermined order. In this case, when the control unit 301 receives these data packets through the layer 2 switch 101 (step 201), the control unit 301 stores them in the data storage unit 103 via the dedicated data bus 105 (step 202).

Subsequently, the control unit 301 confirms the transmission destination of the packet stored in the data storage unit 103 and determines whether or not the priority control set in the priority control information table 104 is necessary (step 203). When the priority control is determined to be necessary (step 203: YES), the control unit 301 confirms the communication speed available _{R EXT2} network 2 through MDIO interface 106 (step 204), the communication speed _{R INT} of the dedicated data bus 105 Compare (step 205).

When R _EXT2 <R _INT (step 205: YES), the control unit 301 refers to the transmission rate management table 302 to confirm the transmission rate R _x of the communication terminal PCx (step 401), and performs communication on the network 2 It is determined whether the possible speed _REXT2 is lower than the transmission speed _Rx (step 402). If the transmission rate _{R x} of the communication terminal PCx is faster than the communication speed of the network 2 (Step 402: YES), the control unit 301, with respect to the communication terminal PCx, communicable rate R of the transmission speed network 2 _A control signal is transmitted so as to be limited to _EXT2 or less (step 403).

  Since the communication terminal PCx transmits data at the limited communication speed in this way, when the control unit 301 receives the transmission data and stores it in the data storage unit 103 (step 404), it passes through the layer 2 switch 101 at the same communication speed. It can be sent to the network 2 (step 405).

Incidentally, if it is not necessary priority control (step 203: NO), if the communication speed _{R EXT2} network 2 is a communication rate _{R INT} or more dedicated data bus 105 (step 205: NO), or the source of the communication terminal PCx If the transmission rate R _x in is slower than communication speed of the network 2 (step 402: NO), the control unit 301 without performing the transfer control for the priority control guarantees, only the data from the data storage unit 103 The data is sent to the network 2 as it is at the communication speed of the data bus 105 (step 405).

For example, when the communication terminal PC5 having the transmission speed R ₅ = 1000 Mbps transmits a packet, the transmission speed 1000 Mbps of the communication terminal PC5 is faster than the communication speed 100 Mbps of the network 2 (step 402: YES), the control unit 301 Then, a control signal is transmitted to the communication terminal PC5 so as to limit the communication speed to 100 Mbps (step 403). On the contrary, when the communication terminal PC6 having the transmission speed R ₆ = 100 Mbps transmits a packet, the transmission speed 100 Mbps of the communication terminal PC6 is the same as the communication speed 100 Mbps of the network 2 (step 402: NO). The unit 301 sends the data from the data storage unit 103 as it is to the network 2 at the communication speed of the dedicated data bus 105 without performing transfer control for guaranteeing priority control (step 405).

  As a result, the data sent from the control unit 301 to the network 2 can effectively execute the initial priority control without being discarded or staying in the layer 2 switch 101.

4.3) Effect As described above, the communication apparatus according to the present embodiment limits the communication speed when the transmission speed of the communication terminal of the data transmission source is higher than that of the transmission destination network. The priority control of the control unit 301 can be validated without limiting the amount of data transmitted from the control unit 301. Thus, packet discard and retransmission processing can be prevented in the layer 2 switch 101, and packet transmission with priority control according to the priority control information table 104 enabled becomes possible. In other words, priority control can be guaranteed regardless of the internal configuration of the packet.

  In this embodiment, the communication speed is limited for the communication terminal of the transmission source, but the same result can be obtained by changing the connection speed of the network 1.

  The present invention is applicable to a repeater equipped with a layer 2 switch.

It is a block diagram which shows schematic structure of the communication apparatus by 1st Embodiment of this invention. It is a functional block diagram for demonstrating the priority control in the communication apparatus shown in FIG. 1 is a block diagram showing a network configuration including a communication device according to a first embodiment of the present invention. It is a flowchart which shows the data transmission operation | movement of the communication apparatus shown in FIG. (A) is a block diagram showing a network configuration including a communication apparatus according to a second embodiment of the present invention, and (B) is a diagram schematically showing a transmission rate management table of a communication terminal. It is a flowchart which shows the data transmission operation | movement of the communication apparatus shown in FIG. FIG. 7 is a sequence diagram of the data transmission operation shown in FIG. 6. It is a block diagram which shows schematic structure of the common communication apparatus which has a layer 2 switch. (A) to (C) are time charts for explaining data loss that occurs when transmission data is actually transmitted to the network.

Explanation of symbols

1, 2 Network 3 Router 4 Internet 5 Communication terminal (PC)
100 communication device 101 communication unit (layer 2 switch)
102 Control unit (CPU)
103 Data storage unit 104 Priority control information table

Claims (5)

In a communication apparatus in which transmission data to be subject to priority control is transmitted from one of at least one communication terminal connected to the first network, and the transmission data is sequentially transmitted to the second network.
Storage means for storing a table for managing a communication speed of the at least one communication terminal;
If it is determined that the communicable speed of the second network is slower than the internal communication speed of the communication device and slower than the communication speed of the transmission source communication terminal, the transmission data is transmitted to the transmission source communication terminal. Control means for transmitting a control signal for reducing a transmission speed to be equal to or lower than a communicable speed of the second network ;
A communication apparatus comprising: The communication apparatus according to claim 1 , further comprising a layer 2 switch capable of connecting at least the first network and the second network. A data transmission control method in a communication apparatus in which transmission data to be subjected to priority control is transmitted from one of at least one communication terminal connected to a first network, and the transmission data is sequentially transmitted to a second network,
Storing a table for managing a communication speed of the at least one communication terminal in a storage means ;
If it is determined that the communicable speed of the second network is slower than the internal communication speed of the communication device and slower than the communication speed of the transmission source communication terminal, the transmission data is transmitted to the transmission source communication terminal. Transmitting a control signal for reducing a transmission speed to be equal to or lower than a communicable speed of the second network ;
And a data transmission control method. 4. The data transmission control method according to claim 3, wherein the communication device includes a layer 2 switch that can connect at least the first network and the second network . A program that causes transmission data to be subject to priority control from one of at least one communication terminal connected to the first network, and causes the computer to function as a communication device that sequentially transmits the transmission data to the second network,
Storing a table for managing a communication speed of the at least one communication terminal;
If it is determined that the communicable speed of the second network is slower than the internal communication speed of the communication device and slower than the communication speed of the transmission source communication terminal, the transmission data is transmitted to the transmission source communication terminal. Transmitting a control signal for reducing a transmission speed to be equal to or lower than a communicable speed of the second network ;
As described above, the program further causes the computer to function.

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