JP7142462B2 - COMMUNICATION DEVICE, COMMUNICATION DEVICE CONTROL METHOD, AND PROGRAM - Google Patents

Description

The present invention relates to a communication device, a communication device control method, and a program.

2. Description of the Related Art Conventionally, in packet communication, in order to guarantee the reliability of communication, a communication method is used in which a receiving side that receives a packet transmitted from a transmitting side uses an acknowledgment called ACK. For example, in TCP/IP (Transmission Control Protocol/Internet Protocol), which is widely used in Internet communication, the transmitting side chunks transmission data into segments, packetizes them, and transmits them. The receiving side manages the segments by sequence number in units of octets, and responds with the sequence number of the successfully received segment as ACK. Also, the transmitting side retransmits packets including segments for which ACK has not been received within a predetermined time.

In TCP/IP protocol processing, the transmitting side prepares a network buffer for packetization and retransmission processing of communication data. In recent years, TCP/IP protocol processing uses a packetization technique that can reduce processing by a CPU (Central Processing Unit) and achieve high-speed transmission. For example, for each socket API send() call, the specified user data is transferred to the network buffer and the checksum calculation is simultaneously processed by hardware offload, and the check calculated (pre-calculated) at the time of transfer This is a technique of packetizing by CPU processing using a sum value. In this technique, a data size of 1 MSS (Maximum Segment Size) or less, which is a predetermined transmission unit, is packetized one by one by CPU processing.

WO2010/073671

However, the prior art cannot utilize pre-calculated checksum values when performing packetization processing for transmission data having a larger size.

SUMMARY OF THE INVENTION An object of the present invention is to utilize a pre-calculated checksum value when packetizing transmission data having a larger size.

As one means for achieving the above object, the communication device of the present invention has the following configuration. That is, the communication device includes transfer means for transferring transmission data corresponding to a plurality of packets to a transmission buffer by DMA (Direct Memory Access); a first calculating means for calculating a first checksum value for ; a determining means for determining a transmission data size when transmitting to a communication partner device; and based on the transmission data size determined by the determining means, determining means for determining whether the first checksum value is available; and a packet for the transmission data transferred by the transferring means when the determining means determines that the first checksum value is available. a first generating means for generating a plurality of packets by performing the packetizing process using the first checksum value calculated by the first calculating means when performing the packetizing process; have.

According to the present invention, it is possible to utilize pre-calculated checksum values when performing packetization processing for transmission data having a larger size.

1 shows an example hardware configuration of a communication device according to an embodiment. 1 shows an example of software configuration of a communication device according to an embodiment. 4 is a flowchart for explaining data transmission processing according to the first embodiment; FIG. 10 is a flowchart for explaining data transmission processing in the second embodiment; FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail based on its embodiments with reference to the accompanying drawings. Note that the configurations shown in the following embodiments are merely examples, and the present invention is not limited to the illustrated configurations.

[Embodiment 1]
In the general process of TCP/IP packet generation on the sending side, user data specified by the socket API send( ) is first transferred to a network buffer and chunked into MTUs (maximum transmission units). A checksum of the chunked data and the pseudo-header is then calculated to generate a TCT/IP packet with the TCP header and IP header added. When the transmission path is Ethernet (registered trademark), in addition to these headers, an Ethernet frame with an Ethernet header added is generated and transmitted. The receiving side must manage segments by sequence number in octet units and respond with the sequence number of the received segment as ACK.

In TCP/IP protocol processing, window control using a predetermined transmission window size is performed in order to avoid a decrease in communication speed due to the receiving side sending an ACK every time the sending side sends a packet. In TCP/IP window control, the receiving side transmits ACK with the remaining size of the receiving buffer set to the transmission window size, and the transmitting side transmits transmission data without waiting for ACK until the transmission window size is reached. can be done. Furthermore, in TCP/IP window control, a sliding window is used to further improve the communication speed. In the sliding window, the receiving side sends an ACK each time it receives a packet, and the sending side slides the window when it receives the first ACK, and continuously sends data for the window size without waiting for an ACK. becomes possible.

As described above, in recent years, in order to reduce processing by the CPU and transmit at high speed, a technology is used in which data sizes of 1 MSS or less are packetized one by one by CPU processing using a pre-calculated checksum value. . Also, a technology is used in which hardware offloading of segment chunking processing of transmission data and IP packetization processing of the chunked segments is performed on a network I/F. Such technology is realized by a TSO (TCP Segmentation Offload) function (see Patent Document 1). The TSO function is generally implemented by hardware offload such as NIC (Network Interface Card). By using the TSO function, it is possible to request the hardware offload to send application data in data units larger than the conventional MSS unit, chunk it into MSS units by the hardware offload, and send it continuously to the network. becomes. On the other hand, even with the TSO function, it is not possible to perform multiple IP packetization processes utilizing checksum values calculated by hardware offloading in advance when transferring user data to a network buffer.

In the present embodiment, a communication device capable of performing a plurality of IP packet generation processes utilizing pre-calculated checksum values even for data exceeding MSS will be described.

(Configuration of communication device 10)
FIG. 1 shows a hardware configuration example of the communication device 10 according to the first embodiment. The communication device 10 has a RAM (Random Access Memory) 101, a ROM (Read Only Memory) 103, a CPU 102, and a communication section 110 as its hardware configuration. Although these components are the same as those of a normal communication device, the communication device 10 in this embodiment further has a data transfer section 105, a frame generation section 106, a packet generation section 107, and a checksum calculation section 111. FIG. Each component will be described below.

A RAM 101 is used to store various data and as a work memory. The RAM 101 has a transmission buffer 112 for storing and managing transmission data. The ROM 103 stores various programs and the like executed by the CPU 102 . The CPU 102 can use the RAM 101 as a work memory to execute various programs stored in the ROM 103 and a recording medium such as a hard disk (not shown) as a program storage unit.

The communication unit 110 has a MAC (Media Access Control) module 108 and a PHY (Physical Layer) module 109, and communicates with a communication partner device via a network such as Ethernet (registered trademark). Data transmission/reception is performed by executing a network driver by the CPU 102 and controlling the MAC module 108 accordingly. In this embodiment, the communication unit 110 performs communication via Ethernet (registered trademark). Communication is also possible.

The data transfer unit 105 is configured by, for example, DMA (Direct Memory Access), and transfers data inside the communication device 10 . For example, the data transfer unit 105 transfers data stored in the RAM 101 to the frame generation unit 106 and packet generation unit 107 . The data transfer unit 105 may be transfer-controlled by the CPU 102 . A checksum calculator 111 performs checksum calculation on data stored in the RAM 101 . The frame generation unit 106 determines the size of transmission data to be transmitted, and performs generation processing of header information for generating transmission data of the determined size and header information for the transmission data. Packet generator 107 segments the transmission data and generates a header based on the transmission data and header information generated by frame generator 106, and generates a transmission packet from the segment and header. A timer management unit 104 manages a predetermined time required for packet transmission. A (transmission) packet described below is a unit of data transmitted and received on IP communication. Since this packet assembling method is not the essence of this embodiment, its explanation is omitted.

FIG. 2 shows a functional configuration example of the communication device 10 in this embodiment. Application 201 refers to a user application. In this embodiment, the application 201 is an application that calls the socket API send( ), whereby application data to be sent (send data) of arbitrary size is input to the protocol stack 202 .

The protocol stack 202 comprises a network buffer management section 203 , a segment processing section 204 , a communication protocol processing section 205 , a connection management section 206 , a TCP window control section 207 and a congestion control section 208 . The network buffer management unit 203 stores and manages transmission data input from the application 201 in the transmission buffer 112 (FIG. 1) of the RAM 101 . Network buffer management unit 203 also manages the size of transmission data stored in transmission buffer 112 . The connection management unit 206 manages information regarding communication connections of the communication device 10 . For example, the connection management unit 206 manages connection information such as MSS (Maximum Segment Size) in communication connections. The TCP window control unit 207 acquires the transmission window size of the TCP connection from the ACK (acknowledgement) received from the communication partner device via the communication interface control unit 209 and manages it. The congestion control unit 208 manages congestion control in TCP connections. For example, the congestion control unit 208 manages congestion window sizes in communication connections to the application 201 . The send window size and congestion window size may be used to determine the send data size.

The segment processing unit 204 determines the transmission data size (the size of the total transmission data that can be transmitted) based on the information managed by the network buffer management unit 203, the connection management unit 206, the TCP window control unit 207, and the congestion control unit 208. size). That is, the transmission data size is determined based on the transmission data size, MSS, transmission window size, congestion window size, etc. stored in the transmission buffer 112 in the RAM 101 . The communication protocol processing unit 205 controls the packet generation unit 107 to generate the TCP header and IP header of the TCP segment, and performs processes such as checksum calculation associated therewith. Then, the communication protocol processing unit 205 performs packetization processing on the data obtained from these processes to generate a transmission packet.

The data transfer section 400 corresponds to the data transfer section 105 and the checksum calculation section 111 (FIG. 1), and is composed of a chunk section 401 and a checksum calculation section 402 . The chunk unit 401 chunks transmission data into predetermined units (for example, MSS units) for data transfer. The checksum calculation unit 402 performs checksum calculation on each piece of data chunked by the chunk unit 401 .

The packet generation unit 300 corresponds to the data transfer unit 105 , the packet generation unit 107 and the checksum calculation unit 111 ( FIG. 1 ), and is composed of the data transfer unit 301 , the header generation unit 302 and the packet generation unit 303 . The data transfer unit 301 chunks transmission data into predetermined units (for example, MSS units), and performs checksum calculation on each piece of chunked data. Header generator 302 generates a TCP/IP header and an Ethernet header based on the header information generated by frame generator 106 . The packet generation unit 303 performs packetization processing on the data output from the data transfer unit 301 and the header generation unit 302 to generate transmission packets.

In this embodiment, the communication protocol processing unit 205 or the packet generation unit 300 generates transmission packets according to the transmission data size determined by the segment processing unit 204 . A method of generating a transmission packet will be described later with reference to FIG.

A transmission packet generated by the communication protocol processing unit 205 or the packet generation unit 300 is input to the communication interface control unit 209 . A communication interface control unit 209 is in charge of exchanging data and information between the protocol stack 202 and the communication interface 210 . A communication interface 210 corresponds to the MAC module 108 and PHY module 109 in FIG. 1 and communicates with the network. The transmission of the transmission packet may be performed when the timer management unit 104 notifies that a certain period of time or more has elapsed.

(Processing flow)
Next, referring to FIG. 3, processing in this embodiment will be described. FIG. 3 is a flowchart for explaining data transmission processing in this embodiment. This flowchart assumes data transmission processing by socket API send( ) (hereinafter, send( )).

First, in step S<b>101 , the application 201 calls send( ) in response to the execution of a predetermined program stored in the ROM 103 by the CPU 102 . When send( ) is called, the data transfer unit 105 transfers the transmission data to the transmission buffer 114 in the RAM 101, which is the data transfer destination, in step S102. In parallel with this, the chunk unit 401 chunks the transmission data in units of MSS, and the checksum calculation unit 402 calculates the checksum for the chunked data. As described above, the data transfer section 400 (FIG. 2) including the chunk section 401 and the checksum calculation section 402 corresponds to the data transfer section 105 and the checksum calculation section 111 (FIG. 1).

In step S<b>103 , the network buffer management unit 203 associates the chunked data with the checksum value for the chunked data, and stores them in the transmission buffer 112 . In step S104, the segment processing unit 204 determines whether the size of the transmission data (a series of chunked data) stored in the transmission buffer 114 exceeds the transmission window size managed by the TCP window control unit 207. judge. If the size of the transmission data stored in the transmission buffer 114 does not exceed the transmission window size (No in step S104), the process proceeds to step S105. In step S105, the segment processing unit 204 determines the size of the transmission data stored in the transmission buffer 114 as the transmission data size. On the other hand, if the size of the transmission data stored in the transmission buffer 114 exceeds the transmission window size (Yes in step S104), the process proceeds to step S106. In step S106, the segment processing unit 204 determines the transmission window size as the transmission data size.

In step S<b>107 , communication protocol processing section 205 determines whether or not the transmission data size determined in step S<b>106 or S<b>105 exceeds the MSS managed by connection management section 206 . If the determined transmission data size does not exceed the MSS (No in step S107), the process proceeds to step S108. In step S108, the communication protocol processing unit 205 calculates a checksum for the transmission data to generate a TCP/IP header, concatenates the TCP/IP header and the transmission data (segment) into a packet, and converts the TCP/IP packet into a packet. Generate. The communication protocol processing unit 205 further generates an Ethernet header, converts the generated TCP/IP packet into an Ethernet frame using the generated Ethernet header, and proceeds to step S114.

On the other hand, if the determined transmission data size exceeds the MSS (Yes in step S107), the process proceeds to step S109. In step S109, the frame generator 106 generates header information as information for generating a TCP/IP header and an Ethernet header, and proceeds to step S110. The processing of steps S110 to S113 is performed by the packet generator 300. FIG. Note that, as described above, the packet generation unit 300 (FIG. 2) corresponds to the data transfer unit 105, the packet generation unit 107, and the checksum calculation unit 111 (FIG. 1).

At step S110, the data transfer unit 301 determines whether the checksum value calculated at step S102 is available. The checksum value calculated in step 102 is associated with the chunked data and stored in the transmission buffer 112 in step S103. However, through the processing from S104 to S105 or S106, the actual transmission data (actual transmission data) determined based on the transmission data size may change. For example, actual transmission data may span multiple chunks. Therefore, in step S110, the data transfer unit 301 determines whether or not the checksum value calculated in step S102 corresponds to the actual transmission data.

If the checksum value calculated in step S102 cannot be used as a result of the determination in step S110 (No in step S110), the process proceeds to step S111. In step S111, the data transfer unit 301 performs checksum calculation (recalculation) for each segment obtained by chunking actual transmission data in units of MSS. Subsequently, the header generation unit 302 uses the header information generated in step S109 to (automatically) generate a TCP/IP header and an Ethernet header for each segment. In step S113, the packet generation unit 303 concatenates the TCP/IP header generated in step S111 and each segment, forms a TCP/IP packet, adds an Ethernet header, and forms an Ethernet frame.

If the checksum value calculated in step S102 is available (Yes in step S110), the process proceeds to step S112. In step S112, the header generation unit 302 uses the checksum value calculated in step S102 and the header information generated in step S109 to (automatically) generate a TCP/IP header and an Ethernet header for each segment. Generate. In step S113, the packet generation unit 303 concatenates the TCP/IP header generated in step S112 and each segment, forms a TCP/IP packet, adds an Ethernet header, and forms an Ethernet frame. Note that the number of segments that can be concatenated at one time can be determined based on the congestion window size. At step S114, the communication protocol processing unit 205 transmits the Ethernet frame to the communication interface control unit 209, and ends the processing.

In this way, even if the transmission data size exceeds the MSS, IP packetization processing can be performed using the checksum value calculated in advance by hardware. In addition, even if a checksum value calculated in advance by hardware cannot be used, IP packetization processing can be performed using a checksum value recalculated by hardware. Note that the present embodiment can be applied even when the processing by hardware in steps S110 to S113 is executed by software. Also, in this embodiment, an example in which there is one communication interface has been given, but this embodiment can also be applied when there are a plurality of communication interfaces. Also, in the present embodiment, the TCP/IP protocol has been described as an example, but other protocols such as the UDP (User Datagram Protocol) protocol can also be applied.

[Embodiment 2]
Next, Embodiment 2 will be described. In addition, in this embodiment, the same code|symbol is attached|subjected about the structure similar to Embodiment 1, and the detailed description is abbreviate|omitted.

(Processing flow)
Processing in this embodiment will be described with reference to FIG. FIG. 4 is a flowchart for explaining data transmission processing in this embodiment. This flowchart assumes data transmission processing by the socket API send( ). Note that the processing of S201 to S210 is the same as the processing of steps S101 to S110 in FIG. 3 described in the first embodiment, so description thereof will be omitted.

At step S210, the data transfer unit 301 determines whether the checksum value calculated at step S202 is available. If the checksum value calculated in step S202 is not available (No in step S210), processing proceeds to step S211. In step S211, the data transfer unit 301 determines whether or not the actual transmission data is chunked in MSS units. Although the transmission data is chunked in step S202, the transmission data (actual transmission data) corresponding to the transmission data size may change through the processing from S104 to S105 or S106. Therefore, in S211, the data transfer unit 301 determines whether the actual transmission data is chunked in MSS units, ie, fragmented.

If the actual transmission data is not chunked by MSS (No in step S211), the process proceeds to step S212. In step S212, the data transfer unit 301 chunks the actual transmission data into segment sizes, and performs checksum calculation (recalculation) for each chunked transmission data (segment). Subsequently, the header generation unit 302 uses the header information generated in step S209 to (automatically) generate a TCP/IP header and an Ethernet header for each segment. In step S215, the packet generator 303 concatenates the TCP/IP header generated in S212 and the segment, forms a TCP/IP packet, adds an Ethernet header, and forms an Ethernet frame.

If the actual transmission data is chunked in units of MSS (Yes in step S211), the process proceeds to step S213. In step S213, the data transfer unit 301 performs checksum calculation of each chunked transmission data (segment). The header generation unit 302 also uses the header information generated in step S209 to (automatically) generate a TCP/IP header and an Ethernet header for each segment. In step S215, the packet generator 303 concatenates the TCP/IP header generated in S213 and the segment, forms a TCP/IP packet, adds an Ethernet header, and forms an Ethernet frame.

If the checksum value calculated in step S202 is available (Yes in step S210), processing proceeds to step S214. In step S214, the header generation unit 302 uses the checksum value calculated in step S202 and the header information generated in step S109 to (automatically) generate a TCP/IP header and an Ethernet header for each segment. Generate. In step S215, the packet generator 303 concatenates the TCP/IP header generated in S214 and the segment, forms a TCP/IP packet, adds an Ethernet header, and forms an Ethernet frame. Note that the number of segments that can be concatenated at one time can be determined based on the congestion window size. At step S216, the communication protocol processing unit 205 transmits the Ethernet frame to the communication interface control unit 209, and ends the processing.

In this way, even if the transmission data size exceeds the MSS, IP packetization processing can be performed using the checksum value calculated in advance by hardware. In addition, even if the checksum value calculated in advance by hardware cannot be used, or even if the actual transmission data is not chunked, the checksum value recalculated by hardware is used to generate IP packets. conversion processing can be performed. Note that the present embodiment can be applied even when the processing by hardware in steps S210 to S215 is executed by software. Also, in this embodiment, an example in which there is one communication interface has been given, but this embodiment can also be applied when there are a plurality of communication interfaces. Also, in the present embodiment, the TCP/IP protocol has been described as an example, but other protocols such as the UDP protocol can also be applied.

[Other embodiments]
The present invention supplies a program that implements one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and one or more processors in the computer of the system or device reads and executes the program. It can also be realized by processing to It can also be implemented by a circuit (for example, ASIC) that implements one or more functions.

101 RAM, 102 CPU, 103 ROM, 104 timer management unit, 105 data transfer unit, 106 frame generation unit, 107 packet generation unit, 108 MAC module, 109 PHY module, 110 communication unit, 111 checksum calculation unit

Claims (9)

A communication device,
transfer means for transferring transmission data corresponding to a plurality of packets to a transmission buffer by DMA (Direct Memory Access);
a first calculation means for calculating a first checksum value for the transmission data in parallel with the transfer of the transmission data by the transfer means;
determining means for determining a transmission data size when transmitting to a communication partner device;
determining means for determining whether the first checksum value is available based on the transmission data size determined by the determining means;
When the determining means determines that the first checksum value can be used, the above calculated by the first calculating means when packetizing the transmission data transferred by the transferring means a first generation means for generating a plurality of packets by performing packetization processing using the first checksum value;
A communication device comprising: 2. The communication apparatus according to claim 1 , wherein said determining means determines said transmission data size based on information received from said communication partner apparatus. a second calculation means for calculating a second checksum value when packetizing the transmission data transferred by the transfer means;
When performing the packetization process on the transmission data transferred by the transfer means, by performing the packetization process using the second checksum value calculated by the second calculation means, a plurality of a second generating means for generating packets;
further having
3. The communication device according to claim 1 , wherein said second generating means generates a plurality of packets when said determining means determines that said first checksum value is not available. further comprising chunking means for chunking the transmission data when the determining means determines that the first checksum value is not available;
4. The communication device according to claim 3 , wherein said second calculating means calculates said second checksum value for each segment chunked by said chunking means. further comprising management means for managing the first checksum value in a memory in association with the transmission data;
5. The communication apparatus according to any one of claims 1 to 4 , wherein said determining means determines whether said first checksum value is available by referring to said memory. 6. The communication apparatus according to any one of claims 1 to 5 , wherein the first checksum value is a checksum value for each segment forming the transmission data. The first generating means generates a header for each segment using the first checksum value, and generates a plurality of packets by concatenating the header and each segment. 7. A communication device according to claim 6 . A control method performed by a communication device, comprising:
a transfer step of transferring transmission data corresponding to a plurality of packets to a transmission buffer by DMA (Direct Memory Access);
a calculation step of calculating a first checksum value for the transmission data in parallel with the transmission of the transmission data in the transmission step;
a determination step of determining a transmission data size when transmitting to a communication partner device;
determining whether the first checksum value is available based on the transmission data size determined in the determining step;
If it is determined in the determining step that the first checksum value can be used, the first checksum value calculated in the calculating step is performed when packetizing the transmission data transferred in the transferring step. a generation step of generating a plurality of packets by performing packetization processing using the checksum value;
A control method characterized by having A program for causing a computer to function as the communication device according to any one of claims 1 to 7 .

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