JPH09128314A - Communication controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication controller which efficiently transmits a large amount of continuous data packets such as video data onto a network. SOLUTION: A header generation means 110 generates addresses and sequentially generates respective packet lengths required for the generation of a header. A data transfer means 105 DMA-transfers transmission data from a main storage 103 in accordance with DMA setting which is set in the beginning. A protocol processing control means 107 selects header output or data output by controlling a selection means 11. A packet holding means 106 continuously generates the plural packets which are to be transmitted from the inputted header and data. Furthermore, a packet transmission control means 108 sequentially transmits the plural held packets on the network 113.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication control device used for connecting a computer system to a network and controlling transmission / reception of packet data between them.

[0002]

2. Description of the Related Art In recent years, with the development of network technology,
A server / client system in which data is centrally managed by a computer system called a server and data from the server is referred to via a network has been widely implemented in many computer systems called clients.

As a network to be used, generally, a LAN (Local Area Network) such as Ethernet (that is, a LAN created by IEEE (Institute of Electrical and Electronics Engineers) 802.3) is widely used. Has been done. In a LAN, n-to-n communication is performed using a transmission medium capable of broadcast communication.
The data from one server is sent to all clients, and each client takes in only the corresponding data addressed to itself by the destination information attached to the sent data.

Further, in such a communication mode, there is a risk that the respective data transmitted from the server or the client sharing the transmission path may collide with each other. Therefore, in order to avoid data collision, some methods of controlling the transmission right (access right) have been considered. CSMA / CD
(Carrier Sense Multiple Access with Collision Det
(abbreviation of section) is one of them. According to this method, the transmission medium forming the network is monitored before data transmission to check whether or not transmission from another terminal is performed. It is supposed to be confirmed. If the transmissions are unfortunate, the transmission is performed after waiting a random time.

In the field of Ethernet, existing 10BASE-T (10 is a transmission rate of 10 Mbps, B
ASE is a baseband transmission, and T indicates a twisted pair is used.) It is called Fast Ethernet that further develops 100 Mbps to realize a high transmission rate.
00BASE-T or 100VG-AnyLAN (Transmission speed is 100 Mbps, twisted pair of voice quality (voice grade) can be used, and token other than Ethernet can be used.
High-speed Ethernet such as ring frame can be used) has been commercialized. Under such circumstances, the data transfer capability on the server side is also desired to be improved so as to be able to cope with it.

By the way, in data transfer in Ethernet, data of up to 1.5 KB (kilobyte) is stored in one packet, and the data is transferred in units of the packet. However, regarding the transfer packet length, the maximum data transfer amount is 1.5K.
The variable length can be set as long as the upper limit of up to B is satisfied.

FIG. 8 is a schematic diagram showing a typical packet structure used in Ethernet. As shown in the figure,
One packet is a header (control information necessary for transmission and is added to the beginning of the packet) and subsequent transmission data up to 1.5 KB (however, FCS:
frame check sequence is included) and.
The header is composed of a destination address represented by 6 bytes, a source address also represented by 6 bytes, and a variable-length packet length represented by 2 bytes following the destination address. ing.

Next, in the server connected to the network, a communication control device is used in order to transmit data to many clients which are also connected to the network. The communication control device has a function of interposing between the computer system and the network and controlling transmission and reception of packet data between them. As described above, in order to speed up the transmission of data to be transmitted to the network, as described above, the data to be transmitted is DMA-transferred from the main memory provided in the computer system, and it is assembled and held in multiple packets. Aside
By executing the transmission control of the CSMA / CD method described above, each held packet is transmitted to the network.

FIG. 6 is a block diagram showing an example of the configuration of a conventional communication control device, and specifically, Japanese Patent Laid-Open No. 6-5399.
No. 4 discloses this. A communication control device 601 is configured as one functional device connected to the system bus 610 of the computer system 600. By interposing between the computer system 600 and the network 611, transmission / reception of packet data between them is controlled.

The system bus 610 is generally speeded up to improve the data transfer rate between the peripheral device, the processor 102, and the main memory 103.
For example, in the above-mentioned high-speed Ethernet, PCI (peri
pheral component interconnect) Bus etc. are used. The PCI bus enables simultaneous transfer of a 32-bit signal string, and by operating at a clock frequency of 33 MHz, a maximum of 133 MB / sec (about 1 Gbit / sec.
Seconds) data transfer is also possible. In addition, conventionally, the upper limit of transfer rate is about 8 MB / sec (64 Mbit /
Second) ISA (industry standard architecture) bus and 33MB / s EISA (extended industry stan
dard architecture) bus, and a maximum of 40 MB / sec microchannel are also used.

Reference numeral 602 denotes a processor that controls the entire computer system 600, and reference numeral 603 is a main memory used when the processor 602 performs various control operations, both of which are configured as functional devices connected to the system bus 610. Has been done. The communication control device 601 has a bus interface unit 6 for connecting to the system bus 610.
04, a data transfer means 605 for DMA (direct memory access) transfer of the transmission data from the main memory 603 to the packet holding means 606, and a packet for temporarily storing the transmission data transferred and assembled into a packet. A holding unit 606, a local processor 607 that creates a header as a protocol process for the transmission data transferred to the packet holding unit 606, and a control for transmitting the packet held in the packet holding unit 606 to the network 611. The packet transmission control means 608 for performing the above and the receiving means 609 for receiving the data sent through the network 611. The receiving means 609 is not directly related to the contents of the present invention, so here,
The structure is omitted.

FIG. 7 is a time chart for explaining the control operation of each unit at the time of transmission of the communication control device 601 shown in FIG. A packet n to be transmitted (however, n is a numerical value indicating the transmission order of packets) is generated as follows. First, in the local processor 607, the main processor 60 is passed through the bus interface unit 604.
When receiving the data transmission request from No. 2, the condition setting for executing the DMA transfer is set to the data transfer unit 605 (the part shown as "DMA setting" in the figure). The setting contents are 1.5 in the main memory 603.
The start address of the data to be transmitted, which is stored in KB units (that is, the read start address of the corresponding data in the main memory 603 that is the data transfer source)
And the data write start address in the packet holding means 606 which is the transfer destination and the transfer size of how many bytes of data are transferred in total, which are information necessary for the data transfer means 605 to perform the DMA transfer. Has become. Then, according to this condition setting, the data transfer means 6
In 05, preparation for DMA transfer is performed.

Then, in the local processor 607,
Protocol processing for the data transfer means 605, that is,
The header of the packet is created (in the figure, this is the part indicated as "protocol processing"). Here, regarding the contents of the header to be created, when the network 611 is Ethernet, as shown in FIG. 8, the destination address (6 bytes), the source address (6 bytes), and the packet length (2 Byte). However, the packet length is set as a numerical value within a range that does not exceed the maximum amount of data that can be transmitted in one packet, based on the total amount of data to be transmitted.

The data transfer means 605 starts the DMA transfer of the data from the main memory 603 to the packet holding means 606 at the same time when the protocol processing by the local processor 607 is started according to the set DMA transfer conditions (see FIG. (This is the leftmost head part of the part indicated as "DMA"). Then, in the packet holding means 606, the packet n to be transmitted is generated in the form in which the DMA-transferred data follows the header generated by the local processor 607. This is because the main memory 603 is composed of DRAM and the packet holding means 606 is composed of SRAM, so that the local processor 6
This is because the protocol processing according to 07 is performed at a time sufficiently faster than the DMA transfer of data.

Further, in the packet transmission control means 608,
When the protocol processing in the local processor 607 is completed, the packet holding means 606 receives a packet transmission request from the local processor 607.
Transmission of the packet n held in the network 611 to the network 611 is started (in the figure, it is the leftmost head portion of the portion indicated as "transmission of packet n"). The packet transmission control means 608 is provided with a FIFO (first in first out) memory (not shown), and it is determined that packet transmission to the network 611 is possible by the CSMA / CD method described above. Then, the packet data first written to the FIFO is controlled to be sequentially transmitted to the network 611.

When transmitting a plurality of packets continuously, as shown in the figure, after the DMA transfer of the transmission data for the packet n by the data transfer means 605 is completed, the local processor 607 transfers the data. The next DMA is set in the means 605. That is, the next one packet is assembled by the same procedure.

As described above, the reason why the DMA setting is repeated is that the data to be transmitted in the packet holding means 606 is a regular packet pattern in order for the packet transmission control means 608 to send the packet to the network 611. Because it must be. That is, since only the data is stored in the main memory 603 and the header is not stored, when the DMA transfer of the transmission data is performed once,
This is because the header can no longer be inserted and the next packet cannot be assembled. Therefore, after the transmission of one packet n is completed, the next D
The conditions for MA transfer are set, and the header generated by the packet holding means 606 is controlled so that the transmission data of the next packet n + 1 follows.

[0018]

However, according to the above-mentioned conventional communication control device 601, when it is necessary to continuously transmit a large number of packets such as video data, one packet is transmitted. Since the DMA setting is always performed to generate the data, the data transfer from the main memory 603 to the packet holding unit 606 is not performed during the DMA setting (the portion indicated by ΔT in the figure). become. That is, the ΔT after the packet n is transmitted by the packet transmission control means 608.
For the period of, the next packet n + 1 is never sent to the network 611.

This means that even if the network 611 has a large data transfer capacity, the transfer capacity of the system bus 610 to be used cannot be used to the maximum extent, and as a result, the unit time per unit time is reduced. This causes a problem that the amount of data transmitted to the network 611 is greatly reduced. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a communication control device capable of efficiently transmitting a large amount of continuous data packets such as video data onto a network. There is.

[0020]

In order to solve this problem, the present invention relates to a communication control device for controlling transmission / reception of a data packet between a computer system and a network for each header generated in order. The DMA transfer is performed so that a predetermined amount of transmission data continues, and a plurality of data packets are continuously generated.

As a result, when transmitting a large amount of continuous data packets such as video data, the data packets can be continuously transmitted to the network without interruption.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is a communication control device for controlling transmission / reception of a data packet between a computer system and a network, following each header generated in order. , A plurality of data packets are continuously generated by controlling DMA transfer of a corresponding predetermined amount of transmission data, and continuous data packets can be transmitted to the network. It will be possible.

According to a second aspect of the present invention, a header generating means for sequentially generating headers of data packets to be transmitted is generated based on the header information given in advance from the computer system, and the header generating means. A data transfer means for DMA-transferring a predetermined amount of transmission data to be transmitted after the header from the main memory in the computer system, and a header generated by the header generation means,
Data fetch selecting means for fetching by selecting any of the transmission data transferred by the data forwarding means, control means for controlling the selecting operation of the data fetch selecting means, a header fetched by the data fetch selecting means, and The communication control according to claim 1, further comprising packet holding means for holding a data packet generated by the transmission data, and packet sending control means for controlling sending of the data packet held by the packet holding means to a network. The device constitutes the apparatus, and the control unit controls the selection operation of the data fetching and selecting unit, so that continuous packets are continuously generated in the packet holding unit.

According to a third aspect of the present invention, the header generation means further generates a header based on the information of the total data amount to be transmitted of the header information given in advance from the computer system. Is provided with a packet length generation means for calculating a packet length and generating a packet length. For the first packet length, a header address common to all packets is first generated, then successively generated, and so on. 3. The communication control device according to claim 2, wherein the packet length of the packet is generated by the data fetching and selecting means after the header that was previously generated is fetched and then successively generated. A variable-length packet length in each header required when generating is calculated, and is generated in advance before generating the corresponding packet.

According to a fourth aspect of the present invention, the data transfer means calculates each time based on information on the total amount of data to be transmitted and information on the amount of data that can be transmitted in one data packet. 4. The communication control device according to claim 3 is configured to obtain information about the amount of data to be sequentially transferred in the DMA transfer, and execute the DMA transfer of the data once. A large amount of data is DMA-transferred.

According to a fifth aspect of the present invention, the control means further comprises detection means for detecting whether or not the writing of the header or the transmission data in the packet holding means is completed, and the header is detected by the detection means. When it is detected that the writing of the transmission data has been completed, the acquisition of the transmission data that should follow the header is selected. When the writing of the transmission data is detected, the acquisition of the next header is performed. The communication control device according to claim 4 is configured to perform selection control, and the packet holding means successively generates a plurality of packets by performing such control by the control means. .

According to a sixth aspect of the present invention, the control means further elapses a predetermined time from the time when the detection means detects that the writing of the first header to the packet holding means is completed. 6. The communication control device according to claim 5, further comprising packet transmission start requesting means for requesting the packet transmission control means to start transmission from the header of the packet held in the packet holding means. Since the packet transmission start request is issued after the writing of the header is completed, the influence of the time error on the packet generation due to the selection operation of the data capture selection means can be avoided.

According to a seventh aspect of the present invention, the network is in an unusable state when the packet transmission control means further receives a packet transmission start request from the packet transmission start request means. 7. The communication control device according to claim 6, wherein the communication control device is configured to temporarily store the data packet from the packet holding means when the communication control device is detected. Is waited for.

According to an eighth aspect of the present invention, in addition to the communication control apparatus according to the second aspect, network address holding means for holding a plurality of destination network addresses in association with their identification numbers, and the computer system are provided. And a network address providing means for searching the corresponding destination network address when the identification number is given and for giving the searched network address to the header generating means. The address information can be easily and quickly instructed to the header generating means.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. (Embodiment 1) FIG. 1 shows a configuration of a communication control device according to a first embodiment of the present invention, 101 is a communication control device, and a system bus 1 in a computer system 100.
It is one functional device connected to 12. Then, it is arranged between the computer system 100 and the network 113 to control transmission / reception of network data between them. Reference numeral 102 denotes a processor that controls the entire computer system 100,
Reference numeral 103 is a main memory used when the processor 102 performs various control operations.
It is one functional device connected to 12.

The communication control device 101 has a bus interface unit 10 for connecting to the system bus 112.
4, data transfer means 105 for DMA-transmitting the transmission data from the main memory 103 to the packet holding means 106 in accordance with a control signal from the protocol processing control means 104 (described later), and temporarily holding a packet to be transmitted. Packet holding means 106, and the packet holding means 10
6, packet transmission control means 108 for controlling the transmission of the packet held on the network 113 to the network 113, and reception means 109 for receiving the data transmitted through the network 113 (the above functional blocks are shown in FIG. (Has the same function as the corresponding functional block shown in FIG. 4), a protocol processing control means 107, a header generation means 110, and a selection means 111.

FIG. 2 is a flow chart showing the flow of control operation of the protocol processing control means 107 shown in FIG. When receiving a data transmission request from the processor 102 (Yes in S1), the data transfer unit 1
A DMA setting request is made to 05 (S2). In this case, in the protocol processing control unit 107, the read start address of the data to be transmitted, which is stored in the main memory 103, and the write start address of the read data to the packet holding unit 106, are stored in advance from the processor 102.
Since each piece of information about the total amount of data (the number of bytes) to be transmitted, that is, the information necessary when the data transfer means 105 executes the DMA transfer, these pieces of information are provided to the data transfer means 105. Given.

Then, the data transfer means 105 which has received the information prepares to transfer the transmission data.
In this case, if the total amount of data to be transmitted exceeds the maximum transferable data amount of one packet (for example, 1500 bytes when using Ethernet),
Since a plurality of packets will be transmitted from the communication control device 101, the transfer data amount of each packet is calculated for all the packets in that case.

Next, when it is confirmed that the transfer preparation of the data transfer means 105 is completed (Yes in S3).
In this case), the selecting unit 111 is instructed to output the header 1 already generated by the header generating unit 110 to the packet holding unit 106 (S4). Then, according to this instruction, the selection unit 111 selects the header output, and outputs the header 1 to the packet holding unit 106.

Further, when it is confirmed that the output of the header 1 is completed (in the case of Yes in S5 and the writing of the header 1 to the packet holding means 106 is completed), it is performed. After more than a predetermined time,
The packet transmission control means 108 starts a timer so that the transmission of the packet 1 to the network 113 is started (S6). Regarding the set time of the timer in this case, it is necessary to adjust at least the bit string of the header 1 previously written in the packet holding means 106 so that the bit string of the data to be transmitted continues within a predetermined error time. Make enough time. By doing so, the packet holding unit 106 holds the bit string in the form of a packet that can be transmitted. Then, the packets held here are continuously read by the packet transmission control means 108 and sent to the network 113.

Next, following the processing of step S6, the selection means 111 is instructed to output the data from the main memory 103 DMA-transferred by the data transfer means 105 to the packet holding means 106 (S7). . Upon receiving this instruction, the selection means 111 selects data output, switches the output of the header 1 to the output of data 1, and outputs the data to the packet holding means 106. In this way, the data transfer means 105 starts the DMA transfer of the data for the first packet. Then, the packet 1 is generated in a predetermined address area of the packet holding unit 106.

After that, when it is confirmed that the predetermined time has elapsed by the time counting operation of the timer (Y in S8)
In the case of es), the packet transmission control means 108 is requested to start transmission of the first packet 1 being generated in the packet holding means 106 to the network 113 (S9). Then, in the packet transmission control means 108 that has received this request, the packet holding means 106
The packet 1 held in 1 is taken out and transmission to the network 113 is started.

However, in transmitting the packet 1 to the network 113, as described above, the CSMA / CD
Since transmission control is performed according to the method, if the network 113 is being used by another computer system or the like at the time of transmission, it is not possible to immediately start packet transmission. In such a case,
The packet transmission control means 108 waits for the start of the transmission of the packet 1, but during that time, the packet holding means 10
In 6, data of the first packet 1 is continuously written. Further, when it takes some time before the network 113 can be used, the data packets extracted from the packet holding unit 106 are stored in the buffer provided in the packet transmission control unit 108 in the order of extraction. Go on.

Further, when it is confirmed by monitoring the packet holding means 106 that the first DMA transfer of the data 1 by the data transfer means 105 is completed (S1).
If YES in 0), it is determined whether or not there is a next data packet to be transmitted (S11).
Note that this judgment is made in advance by the computer system 10
It is performed based on the information of the total amount of data to be transmitted given from 0.

Then, when there is a next-order data packet to be transmitted (that is, when the total amount of data to be transmitted exceeds the maximum transferable data amount of one packet, the first data 1 is DMA-transferred). Has already been completed, and this flowchart is Yes in S11), the selecting unit 111 is instructed to output the next header 2 (S12). Therefore, the selecting unit 111 receiving this instruction selects the header output, and outputs the next header 2 already generated by the header generating unit 110 to the packet holding unit 106.

Next, when it is confirmed that the output of the header 2 is completed (Yes in S13),
The selection unit 111 is instructed to output the next data 2 (S14). After that, when the data transfer unit 105 confirms that the DMA transfer of the data 2 is completed (Yes in S15), the process proceeds to step S11. Then, when it is determined that there is no next data packet to be transmitted (No in S10), the process returns.

FIG. 3 is a time chart for explaining the control operation of each unit at the time of transmission of the communication control apparatus 101 shown in FIG. 1. The conventional communication control apparatus 60 shown in FIG.
This is compared with the control operation of No. 1. Here, FIG.
The time relationship between the control operation of the protocol processing control means 107 shown in and the respective control operations performed in other functional blocks is shown.

In advance, the processor 102 sends to the header generation means 110 the destination address in the network 113 to be used and the source address in the own network 113 given to the computer system 100. The total amount of data to be used (here, 40
Information will be given by taking 00 bytes as an example). And
The header generation means 110 that has received these pieces of information first generates an address in the packet header (the portion shown as "address generation" in the figure).

Then, the header generating means 102 receives the data transmission request from the processor 102, calculates and obtains the data amount of each packet to be transmitted, and generates the first packet length (in the figure, "" Packet length generation 1 "). For the packet length in this case,
When the total amount of data to be transmitted exceeds the maximum value of the transferable data amount in one packet, the maximum number of bytes is set. Specifically, in this example, since it is known that the transmission data amount is 4000 bytes, the initial packet length is 1514 bytes (that is, header 14 bytes + data 1500 bytes). To generate.

With respect to the timing of the packet length generation (the portions shown as "packet length generation 2" and "packet length generation 3" in the figure) in the header generation means 110 after that, the immediately preceding header output by the selection means 111 is performed. The generation is started from the time point (end), which is a portion indicated by t2 and t4 in the figure. in this case,
Regarding the packet length generated by “packet length generation 2”, the remaining transmission data amount is 4000-1500 and 250.
Since it is 0 bytes, the next packet length is 1514 bytes, and the packet length 1514 is generated. Further, regarding the packet length generated by "packet length generation 3", since the remaining transmission data amount is 4000-3000 and 1000 bytes, the next packet length is 1014 bytes, and the packet length 1014 is generated.

On the other hand, the above-mentioned data transmission request from the processor 102 is simultaneously sent to the protocol processing control means 107.
Also given to. Then, the data transfer means 105 which has received the DMA setting request from the protocol processing control means 107 sets the DMA transfer conditions and prepares for data transfer. After that, the selection unit 111 which receives the header output instruction from the protocol processing control unit 107
Then, the changeover switch (not shown) is switched to the header output side (the operation at the time t1 in the figure), and the header 1 already generated by the header generation means 102 is output to the packet holding means 106. To execute.

When the selecting means 111 receives a data output instruction from the protocol processing control means 107,
Change the selector switch to the data output side (in the figure,
At time t2), the data transfer from the data transfer means 105 is accepted, and the input data 1 is output to the packet holding means 106. Then, the subsequent selection operations of the selection means 111 are all similarly controlled by the protocol processing control means 107.

Further, in the data transfer means 105, after the transfer preparation is completed, when switching to the data output side by the switching operation by the selection means 111, one packet of data 1 (from this example, in this example) , 150
The packet holding means 106 has a data amount of 0 bytes).
DMA transfer to. Then, regarding the data transfer operation of the data transfer means 105 thereafter, a predetermined amount of data (150 for data 2 in this example) from the time when the selection means 111 similarly switches to the data output side.
(0 bytes, 1000 bytes for data 3)
DMA transfer is executed.

In the packet transmission control means 108,
The first packet 1 from the protocol processing control means 107
Is received, the packet holding means 10
The packet being generated in 6 is taken out and transmission to the network 113 is started (this is the operation at time t2 ^'in the figure). In this case, as described above, C
Since the transmission control is performed by the SMA / CD method, when the data transmission cannot be started, the data packet extracted from the packet holding means 106 is stored in the buffer, and when the transmission becomes possible, The data packets stored in the buffer are taken out in the order of accumulation and transmission to the network 113 is started. After that, as shown in the figure, packet 1 (that is, header 1 + data 1) is transmitted, packet 2 (that is, header 2 + data 2) is transmitted, and packet 2 is transmitted, and then packet 3 is transmitted.
(That is, header 3 + data 3) is continuously transmitted.

After that, when the output of the data 3 from the selecting means 111 is completed (at the time t7 in the figure), the protocol processing control means 107 no longer has any data packet to be transmitted. Since it is confirmed, the next header output is not instructed to the selection means 111. According to the first embodiment of the present invention described above, the communication control device 101 is provided with the header generation means 110, and the address of the header part forming a packet is generated in advance, and a plurality of addresses are generated. In the case of transmitting consecutive packets of, the packet length is generated prior to the packet to be transmitted.

Further, since the protocol processing control means 107 instructs the selection means 111 to selectively control the header output from the header generation means 110 and the data output from the data transfer means 105, the packet holding means 106
A plurality of packets are continuously generated and held.
Therefore, when transmitting consecutive packets such as video data, it is only necessary to set the DMA once, and as in the conventional case, DM is generated every time one packet is generated.
Since it is not necessary to perform the A setting, the problem that the packet cannot be transmitted within the time required for the DMA setting is completely eliminated. As a result, when the data transfer capacity of the network 113 is high, it becomes possible to realize packet transmission to the network 113 at the maximum transfer rate possible on the system bus 112.

(Second Embodiment) FIG. 4 is a block diagram showing a configuration of a communication control apparatus according to a second embodiment of the present invention, which is the communication control apparatus according to the first embodiment of the present invention described above. Blocks having the same functions as the configuration of 101 are shown with the same numbers. 100 is a computer system, 101 is a communication control device, 102 is a processor, 1
Reference numeral 03 is a main memory, 104 is a bus interface unit, and 105
Is a data transfer means, 106 is a packet holding means, 107
Is a protocol processing control means, 108 is a packet transmission control means, 109 is a reception means, 110 is a header generation means, 1
Reference numeral 11 is a selection unit, 112 is a system bus, and 113 is a network. The above are the same functional blocks as shown in FIG. 1, but the communication control apparatus 101 further includes a network address holding unit 401. It is equipped.

This network address holding means 401
Holds a table (see FIG. 5) in which network addresses (6 bytes) of a plurality of destinations are associated with their identification numbers (1 byte).
When an identification number is designated by 02, the table is referred to and the corresponding network address is output to the header generation means 110.

FIG. 5 is a schematic diagram showing an example of the destination address table held by the network address holding means 401 shown in FIG. In this table, 0, 1, 2, 3, 4, ... 25 represented by 1 byte
For each of the maximum 256 identification numbers of 5, the transmission destination address represented by 6 bytes is "00: 01: A2: 0".
3:04:05 "," 00: 01: E2: 03: 00:
70 ", ..., Are stored in a one-to-one correspondence.

The control operation of the communication control apparatus 101 shown in FIG. 4 will be described below using this transmission destination address table. In the processor 102, a plurality of network addresses (6 bytes) of destinations (up to 256) and their identification numbers (1 byte) as shown in FIG. Give and keep information about. Further, in the processor 102, the transmission source address in the network 113 of the computer system 100 is set in the header generation means 110 before transmitting the data. Then, when actually transmitting the data, the processor 102
Then, the identification number (1 byte) of the transmission destination is output to the network address holding unit 401. Receiving this, the network address holding unit 401 refers to the destination address table, generates a network address corresponding to the input identification number (1 byte), and outputs it to the header generation unit 110. In response to this, the header generation means 110 generates the address portion (the first 12 bytes) in the header (14 bytes). The subsequent operation is exactly the same as in the case of the first embodiment. Also, the network address holding means 40
If it is necessary to send to a network address other than the network address held in 1, the information may be reset in the network address holding unit 401.

According to the second embodiment of the present invention described above, by providing the network address holding means 401, the processor 102 transmits the network address (6) of the transmission destination as in the first embodiment. If the destination is fixed by specifying the identification number (1 byte) instead of specifying (byte), the amount of information that the processor 102 sets to the communication control device 101 at the start of transmission. Can be reduced. Therefore, the usage rate of the system bus 112 of the processor 102 can be reduced.

In the above description of the first and second embodiments, the DMA setting condition of the data transfer means 105 is given from the processor 102 to the protocol processing control means 107 in advance. At the time of transmission request, it may be given from the processor 102 to the protocol processing control means 107, or may be given directly from the processor 102 to the data transfer means 105.

Further, the data transfer means 105 itself judges the data amount of one packet to be transmitted, and the data D
Although the MA transfer is performed, the protocol processing control unit 107 may make a determination and instruct the data transfer unit 105. Further, regarding the switching timing of the header or data output by the selection means 111, the protocol processing control means 107 causes the packet holding means 106 to
Although the end (writing end) of the output of the header or the data to or from the device is confirmed and instructed, the selecting unit 111 itself may manage the time and determine the switching time.

Although the data transfer start timing of the data transfer means 105 is set to the time of switching to the data output by the selection means 111, the protocol processing control means 107 may instruct the time. In addition, the header generation means 11 from the processor 102 in advance.
Although the total amount of data to be transmitted is given to 0, it may be given from the protocol processing control means 107.

Although the header generated by the header generating means 110 has been described as only one type, two or more types of headers corresponding to the protocols of a plurality of layers are generated and inserted at the required data positions. I don't care. For example, a combination of the layer 2 Ethernet header and the layer 3 IP address may be generated as a new header.

Further, the protocol processing control means 107 is not limited to the case of supporting only one type of protocol, but one of the protocols is selected by an instruction from the processor 102 as a protocol corresponding to a plurality of protocols. Then, the header may be inserted according to the protocol.

[0062]

As described above, according to the present invention, when continuous packet data such as video data is transferred,
The DMA setting only needs to be done first. For this reason, conventionally, it was necessary to perform the DMA setting for each packet, and it was unavoidable that the packet transmission to the network would be interrupted, but this problem is completely eliminated. Therefore, when the packet transfer function of the network is large, it is possible to continuously transmit packets onto the network at the maximum transfer rate of the system bus without degrading the function. As a result, the amount of data transmitted to the network per unit time increases, and the network utilization efficiency is greatly improved.

Further, instead of designating the network address of the transmission destination, by designating an identification number composed of a smaller number of bits than the network address,
Since the system bus usage rate of the processor in the computer system can be effectively reduced, the bus load is lightened and the reliability of system bus operation is improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a communication control device according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing the flow of control operation of protocol processing control means 107 shown in FIG.

3 is a time chart for explaining the operation of each unit during transmission of the communication control apparatus 101 shown in FIG.

FIG. 4 is a block diagram showing a configuration of a communication control device according to a second embodiment of the present invention.

FIG. 5 is a network address holding unit 40 shown in FIG.
3 is a schematic diagram showing an example of a destination address table held by 1.

FIG. 6 is a block diagram showing a configuration example of a conventional communication control device.

7 is a time chart for explaining a control operation of each unit during transmission of the communication control device 601 shown in FIG.

FIG. 8 is a schematic diagram showing a typical packet configuration used in Ethernet.

[Explanation of symbols]

 101 communication control device 102 processor 103 main memory 104 bus interface unit 105 data transfer means 106 packet holding means 107 protocol processing control means 108 packet transmission control means 109 receiving means 110 header generating means 111 selecting means 112 system bus 113 network 401 network address holding means

Claims (8)

[Claims] 1. A communication control device for controlling transmission / reception of a data packet between a computer system and a network, wherein a predetermined predetermined amount of transmission data is DMA-transferred following each header generated in order. A communication control device configured to generate a plurality of data packets continuously by controlling. 2. A header generation unit that sequentially generates a header of a data packet to be transmitted based on header information given in advance by the computer system, and a place that should follow the header generated by the header generation unit. A data transfer means for DMA-transferring a fixed amount of transmission data from the main memory in the computer system, a header generated by the header generation means, and transmission data transferred by the data transfer means are selected and fetched. Data fetching and selecting means, control means for controlling the selecting operation of the data fetching and selecting means, packet holding means for holding the data packet generated by the header and the transmission data fetched by the data fetching and selecting means, and the packet The data packets held by the holding means are The communication control apparatus according to claim 1, further comprising a packet transmission control means for controlling the delivery of the workpiece, the. 3. The header generation means further calculates a packet length forming a header to be generated, based on information of the total amount of data to be transmitted in the header information given in advance from the computer system. And a packet length generation means for generating a packet length. For the first packet length, a header address common to all packets is first generated and then successively generated. 3. The communication control device according to claim 2, wherein the data fetching and selecting means fetches the header that was generated immediately before and successively generates it. 4. The data transfer means transfers the data sequentially in a DMA transfer calculated once on the basis of information on the total amount of data to be transmitted and information on the amount of data that can be transmitted in one data packet. Get information about the amount of data that should be
4. The communication control device according to claim 3, wherein the communication control device is configured to execute the DMA transfer of the data once. 5. The control means further comprises a detecting means for detecting whether or not the writing of the header or the transmission data in the packet holding means is completed, and the writing of the header is completed by the detecting means. When it is detected, control is performed to select the acquisition of the transmission data that should follow the header, and when it is detected that the writing of the transmission data is completed, select the acquisition of the next header. The communication control device according to claim 4. 6. The packet transmission control means after the control means further passes a predetermined time from the time when the detection means detects that the writing of the first header to the packet holding means is completed. 6. The communication control device according to claim 5, further comprising packet transmission start requesting means for requesting to start transmission from the header of the packet held in said packet holding means. 7. The packet transmission control means, when the packet transmission start request is further received from the packet transmission start request means, if it is detected that the network is in an unusable state, the packet transmission control means 7. The communication control device according to claim 6, further comprising packet storage means for temporarily storing the data packet from the holding means. 8. The communication control device according to claim 2, wherein
Furthermore, a network address holding unit that holds a plurality of destination network addresses in association with their identification numbers, and, when the identification numbers are given from the computer system, searches for the corresponding destination network addresses,
And a network address providing unit that gives the retrieved network address to the header generating unit.