JPH08191323A - Network communication system - Google Patents

Abstract

PURPOSE: To enable priority transmission using the priority control function that the protocol of a MAC sublayer has even for a communication using general protocols of TCP, UDP, IP, etc., having no concept of priority by using a specific priority transmission protocol driver as the protocol driver of an LLC sublayer. CONSTITUTION: A token ring LAN which performs a TCP/IP communication has port numbers given priority in advance. The LLC sublayer and MAC sublayer have a data transfer function for a communication between adjacent nodes, and the protocol driver of the LLC sublayer forms and passes a data frame to the MAC sublayer. As the protocol of this LCC sublayer, the priority transmission protocol is used which reads a transmission source port number out of a TCP header or UDP header added in the transport layer in data received from the network layer, converts the transmission source port number into predetermined priority, and sets the priority in the AC field of the data frame.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to TCP / IP (Transm
The present invention relates to a network communication system using a general-purpose protocol such as ission Control Protocol / Internet Protocol (Communication)
Access control) The present invention relates to a network communication system using a protocol having a priority control function such as token ring in a sublayer.

[0002]

2. Description of the Related Art Today, OSI (Open Systems Inter
connection: Open system interconnection) When applied to the seven-layer structure of the reference model, the network layer (third layer)
A protocol called IP (Internet Protocol) is mainly used for the portion corresponding to the TCP, and TCP (Transmission) is mainly used for the portion corresponding to the transport layer (fourth layer).
Control Protocol) or UDP (User Datagram Proto)
The Internet environment is maintained by TCP / IP communication using a protocol called col).

As an example of the LAN using the TCP / IP communication, a token ring type protocol (more specifically, the IEEE802.5 protocol) is used in the data link layer of the second layer of the OSI reference model (more specifically, in the MAC sublayer). ), There is a token ring type local area network (LAN) in which terminals are sequentially connected in a ring shape with a shielded twisted pair.

In the above token ring LAN, a special frame called a token circulates on the transmission medium of the ring type topology so that a plurality of terminals do not transmit the frame at the same time. The terminal that receives the frame adds the frame to the token and transmits it.

In this case, since the access right cannot be acquired unless the free token is received, if the terminal which receives the transmission request from the upper layer application cannot immediately acquire the free token, the transmission request data is temporarily sent to the transmission buffer. It will be stored in the (transmission queue). Traffic overloads the network,
When it takes a long time to acquire a free token, the transmission buffer stores a plurality of data in time series in the order of transmission requests, and when the terminal acquires a free token, the protocol driver of the MAC sublayer transmits the data. The data is read and transmitted in the order in which the transmission requests are received from the buffer.

By the way, generally in the token ring,
It is possible to perform priority control in which the priority of a frame to be transmitted is determined, and a frame having a high priority has an opportunity of frame transmission with a short waiting time. This will be described with reference to the token ring frame structure of FIG. (A) in the figure, a token, (b) in the figure, an access control (AC: Access Control) field, (c) in the figure
Shows the structure of the data frame.

The token is composed of a start delimiter (SD), an access control (AC), and an end delimiter (ED). The data frame includes a start delimiter (SD), access control (AC), frame control (FC), destination address (DA), source address (SA), information, frame check sequence (FCS), end delimiter (ED), It is composed of a frame status (FS). Access control (AC) included in the token and data frame
The field has a 3-bit priority bit area for setting the priority, and priority control in 8 steps is possible.

Upon receiving the token on the ring, the protocol driver of the MAC sublayer recognizes the priority set in the AC field of the ring and recognizes the priority set in the AC field of the data frame to be transmitted and the above token. Compare with priority. At this time, if a data frame having a priority equal to or higher than the priority of the token exists in the communication buffer, the protocol driver can capture the token and preferentially transmit the data frame. . On the contrary, if the priority of the data frame is lower than the priority of the token, transmission using that token cannot be performed. Even in this case, the priority set in the priority reservation bit of the token is compared with the priority of the data frame, and if the latter is larger, the priority reservation bit can be changed to reserve the priority. Is.

As described above, since priority control is possible in token ring, for example, TMS380C16 / 2
If priority transmission is performed using a general token ring protocol driver such as 6 series (manufactured by Texas Instruments), transmission delay of urgent data can be minimized.

[0010]

However, in order to use the priority control function of the protocol driver of the MAC sublayer as described above, a logical link control (LLC: Logical Link Control) which is an upper layer of the MAC sublayer is used. ) In the sublayer, it is necessary to form a data frame in which a desired priority is set in the AC field. However, TCP /
When using a general-purpose protocol such as the IP protocol,
For the following reasons, it is not possible to form a data frame in which the AC field has a desired priority in the LLC sublayer.

That is, in TCP / IP communication, when a data transmission request is issued by an upper layer application, the transmission data from the upper layer application is TCP (or UDP) in the transport layer and I in the network layer.
Via P and to the LLC sublayer of the data link layer.
Since TCP and UDP do not have the concept of handling the priority of transmission data, the upper layer application cannot specify the priority for TCP, and even if the priority is specified, the priority information is not It is not transmitted to the lower LLC sublayer. Similarly, IP does not have the concept of handling the priority of transmission data.

As described above, the conventional TCP / IP communication cannot use the priority control function of the token ring. Therefore, in order to use the priority control function, a dedicated protocol capable of transmitting the priority information of the upper layer application to the LLC sublayer forming the data frame is required.

As described above, in the conventional token ring LAN using TCP / IP communication, since the priority control function of the token ring cannot be used, there is an urgent data transmission request from the upper layer application. However, the data is not transmitted until the data accumulated in the transmission buffer has been sent, and there is a problem that the transmission delay increases when the network is overloaded.

The present invention has been made in view of the above, and an object thereof is TCP, UD which does not have the concept of priority.
Even if communication using a general-purpose protocol such as P or IP is used, M
An object of the present invention is to provide a network communication system capable of priority transmission using the priority control function of the AC sublayer protocol.

[0015]

A network communication system according to the present invention uses an L protocol as a protocol of a MAC sublayer.
A protocol having a priority control function (for example, a token ring protocol) that performs priority transmission based on a priority that can be set in a predetermined field of a data frame formed in the LC sublayer is used, and a protocol higher than the LLC sublayer is used. An identifier for uniquely identifying a plurality of upper layer applications as a transport layer by using a protocol having no concept of priority (for example, IP in the network layer) in at least one of the network layer and the transport layer. A network communication system using a protocol (for example, TCP or UDP) in which a port number is defined as, and a header including a transmission source port number is added to transmission data received from an application and data is passed to a network layer. , The following measures have been taken to solve the above problems It is characterized in that there.

That is, the above port numbers have priorities set in advance, and are added in the transport layer in the data received from the network layer as a protocol driver (protocol executing entity) of the LLC sublayer. The source port number reading means for reading the source port number included in the header, the port number / priority conversion table for converting the port number into a predetermined priority, and the source port number reading means for reading Port number / priority converting means for converting a source port number into a priority based on the port number / priority conversion table, and a priority for setting the priority obtained by this conversion in a predetermined field of a data frame A priority transmission protocol driver having setting means is used.

[0017]

According to the above configuration, as the transport layer protocol, a protocol such as TCP or UDP that defines a port number as an identifier for uniquely identifying a plurality of upper layer applications is used. Each port number has a predetermined priority (for example, port numbers 2000 to 2999 have the highest priority level 1 and port numbers 3000 to 3999 have the second highest priority level 2). ,…like).

The transport layer of the OSI reference model is
It is a layer that is involved in communication between applications (processes) and realizes data transfer between applications (processes) by using the lower data transfer function. The transport layer is used for the transmission data generated by upper layer applications. receive. In this case, the transport layer protocol driver adds a header including the source port number to the received transmission data and passes the data to the lower network layer.

The network layer is between systems (between terminals).
Having a communication data transfer function, the network layer protocol driver adds a header to the received data and passes the data to the lower LLC sublayer.

The LLC sublayer and the MAC sublayer (data link layer) have a data transfer function for communication between adjacent nodes,
The LLC sublayer protocol driver forms a data frame and passes it to the MAC sublayer. In the present invention, the priority transmission protocol driver is used as the protocol driver of the LLC sublayer.

In this priority transmission protocol driver, the source port number reading means reads the source port number contained in the header added in the transport layer in the data received from the network layer, and the source port number read by the means. On the basis of the port number / priority conversion table, the port number / priority converting means converts the priority into a priority, and the priority obtained by this conversion is set by the priority setting means in a predetermined field of the data frame.

As described above, by using the above-mentioned priority transmission protocol driver in the LLC sublayer, the upper layer application only specifies the port number according to the priority, and the priority is given without using the special priority information. You can specify the degree.

As a result, the layers located between the upper layer application and the data link layer are, for example, TCP, U
Even when a general-purpose protocol such as DP or IP that does not have the concept of priority is used, priority transmission using the priority control function of the MAC sublayer protocol is possible, and data requiring urgent Transmission delay can be minimized.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following will describe one embodiment of the present invention with reference to FIGS.

In the network communication system according to this embodiment, a token ring protocol (eg, IEEE80) is used in the MAC sublayer of the data link layer of the OSI reference model.
2.5 protocol), as shown in FIG. 2, a token ring LAN in which a plurality of terminals 1 ...

The protocol configuration used in the network communication system of this embodiment is shown in FIG. 1 in correspondence with the OSI reference model.

As shown in the figure, TCP and UDP are provided in the portion corresponding to the transport layer of the OSI reference model.
The part corresponding to the network layer uses IP, the part corresponding to the LLC sublayer of the data link layer uses a priority transmission protocol described later, and the part corresponding to the MAC sublayer of the data link layer uses the token ring protocol. That is,
This network communication system uses so-called TCP / IP.
It is a token ring LAN using communication.

In the figure, the session layer (fifth layer), the presentation layer (sixth layer), and the application layer (seventh layer) above the transport layer of the OSI reference model are collectively referred to as upper layers. It is assumed that each application is responsible for the function. Also,
Since the physical layer (first layer) is determined by the token ring, its description is omitted.

The priority transmission protocol used for the LLC sublayer is a general LLC sublayer that forms a data frame shown in (c) of FIG. 7 when receiving an IP datagram (packet) from an IP of the network layer. The layer protocol has a function, but further reads the source port number of the TCP header (or UDP header) included in the IP datagram, converts the number into 8 levels of priority, and It also has the function of setting the priority in the priority bit of the AC field. That is, the priority transmission protocol enables the use of the priority control function of the MAC sublayer protocol even in the case of TCP / IP communication.

FIG. 3 shows the configuration of the priority transmission protocol driver, which is the execution subject of the priority transmission protocol. As shown in the figure, the priority transmission protocol driver includes a data frame forming unit 2, an IP header length recognition unit 3, a transmission source port number recognition unit 4, and a port number / priority conversion unit 5.
And a port number / priority conversion table 6.

The data frame forming unit 2 is a functional module that forms the above-mentioned data frame when receiving an IP datagram from the IP of the network layer. The data frame forming unit 2 as the priority setting unit has a function of setting the priority obtained by the port number / priority converting unit 5 described later in the priority bit area included in the AC field of the data frame. .

The IP header length recognizing unit 3 has an Internet header length (IHL) included in the IP header added to the beginning of the IP datagram.
r Length) function module that recognizes the IP header length from the information in the field.

Here, the structure of the IP datagram formed by the IP of the network layer is shown below. An IP datagram is an IP header followed by data (TCP of upper layer).
Or data received from UDP). As shown in FIG. 4, the IP header has a 4-bit version (VER: Version), 4-bit IHL,
8-bit type of service, 16
Total length of bits (Total Length), 16-bit ID (Id
entification), 3-bit flags (FL: Flags), 1
3-bit fragment offset, 8-bit TT
L (Time To Live), 8-bit protocol, 16-bit header checksum, 32-bit source address, 32-bit destination address, variable length option, variable length padding (PAD) fields Composed of.

The IP header has a variable length (20 octets to 6 depending on the presence or absence of an option field and its length).
It is variable in multiples of 4 octets in the range of 0 octets), but from the information of the IHL field located at 4 to 7 bits from the beginning of the IP header, the length of the IP header,
In other words, the start position of the data as seen from the beginning of the IP header can be known. The IP header length recognition unit 3
Reads the information in this IHL field.

The transmission source port number recognition unit 4 receives the I
Based on the IP header length read by the P header length recognition unit 3, the source included in the TCP header or the UDP header added to the beginning of the data (data received from TCP or UDP) after the IP header -It is a functional module that recognizes the source port number from the information in the port (Source Port) field.

Here, the data after the IP header in the IP datagram, that is, the TCP of the transport layer
3 shows respective structures of a TCP segment formed by (1) and a user datagram formed by UDP.

First, the TCP segment is composed of a TCP header and data following it (continuous data (stream) received from an upper layer application is divided into segment sizes). As shown in FIG. 5, the TCP header has 16-bit source port, 16-bit destination port, 32-bit sequence number, 32-bit acknowledge number, 4-bit data offset, and 6-bit. Reserve, 6-bit control flag, 16-bit window, 16-bit checksum, 16-bit urgent pointer, variable-length option, variable-length Padding (PA
D).

The user datagram is composed of a UDP header and data following it (data received from the upper layer application). As shown in FIG. 6, the UDP header includes fields of 16-bit source port, 16-bit destination port, 16-bit LEN (Length), and 16-bit checksum.

As described above, in the 16-bit area from the beginning of the TCP header or UDP header added to the beginning of the data, there is a source port field indicating the source port number, and the source port number recognition unit 4 reads the information in this source port field to recognize the source port number.

The IP header length recognizing unit 3 and the source port number recognizing unit 4 constitute a source port number reading unit described in the claims.

The port number / priority conversion unit 5 is a functional module for converting the transmission source port number read by the transmission source port number recognition unit 4 into a priority based on the port number / priority conversion table 6. is there.

In TCP / IP communication, the concept of a port (port number) is used as an identifier by which TCP or UDP of the transport layer uniquely identifies a plurality of upper layer applications. The UDP header includes a source port number (source port field information) and a destination port number (destination port field information). In the present embodiment, each port number is stored in advance. The conversion from port numbers to priorities is defined by providing stepwise priorities (8 levels).

As an example, port numbers 2000 to
2999 is the highest priority level, port numbers 3000 to 3999 are the second highest priority levels, and so on, port numbers 4000 to 4999 are priority levels 3, and so on. Up to 8
Eight levels of port number / priority conversion are defined.

The table for port number / priority conversion defined as above is the port number / priority conversion table 6, and the port number / priority conversion unit 5 is used.
Uses this table to convert the source port number read by the source port number recognition unit 4 into a priority.

Each of the units 2 to 5 is a functional module realized by the CPU (Central Processing Unit) of each terminal 1 on the network executing a desired program stored in the memory. The port number / priority conversion table 6 is stored in a predetermined storage area of the memory.

The priority control in TCP / IP communication in the above configuration will be described below. Here, a case where TCP is used as the transport layer protocol will be described.

Each terminal 1 on the network has a plurality of applications, and each application has a level of urgency (ie,
8 levels of priority) are determined, and data transmission is performed using any one of the port numbers defined above according to the level.

A TCP driver (a TCP executing entity) that has received a data transmission request from a certain upper layer application
Uses the port number assigned by that application to establish a connection with a specific application (process specified by a pair (socket) of IP address and port number) of another terminal 1 on the network. Established to do so-called socket communication.

In this case, the TCP driver divides the transmission data (stream) from the upper layer application into a predetermined segment size, further adds the above-mentioned TCP header to each segment to form a TCP segment, and this segment is formed. It is passed to the IP driver of the network layer (executor of IP). In the 16-bit area from the beginning of the TCP header of this TCP segment, the port number assigned by the upper layer application is set as the source port number.

However, TCP itself does not have the concept of priority, it merely sets the source port number, and does not care about the relationship between port number and priority.

The IP driver, which has received the TCP segment from the TCP driver, adds the above-mentioned IP header to the TCP segment to form an IP datagram (so-called packet), which constitutes an upper part of the data link layer. Pass to the preferred transmission protocol driver of the LLC sublayer.

It should be noted that the IP itself does not have any concept of priority, but merely forms an IP datagram and passes it to a lower priority transmission protocol driver.

Upon receiving the IP datagram from the IP driver, the priority transmission protocol driver performs the following operation. First, the IP header length is recognized from the information of the IHL field included in the IP header added to the beginning of the IP datagram, and the start position of the data is known (the function of the IP header length recognition unit 3). Next, the transmission source port number is recognized from the information in the source port field of the TCP header added to the beginning of the data after the IP header (function of the transmission source port number recognition unit 4). Next, the source port number is converted into a priority based on the port number / priority conversion table 6 (function of the port number / priority conversion unit 5). Then, when forming the data frame shown in (c) of FIG. 7, the priority is set in the priority bit area included in the AC field of the data frame (function of the data frame forming unit 2), and the formed data frame Token ring protocol driver for the MAC sublayer (TMS manufactured by Texas Instruments)
380C16 / 26 series).

The token ring protocol driver performs the above-mentioned priority control based on the priority set in the AC field of the data frame.

Even when UDP is used instead of TCP, the priority transmission protocol driver recognizes the transmission source port number from the information of the 16-bit source port field from the beginning of the UDP header, and the data frame is the same as above. The priority can be set in the AC field of the.

As described above, the network communication system according to the present embodiment uses the L protocol as the MAC sublayer protocol.
Using a token ring protocol having a priority control function that performs priority transmission based on the priority that can be set in the AC field of the data frame formed in the LC sublayer,
Protocols (TCP, U) that do not have the concept of priority in the network layer and transport layer that are upper layers of the LC sublayer
(DP, IP), a port number is defined as an identifier for uniquely identifying a plurality of upper layer applications as a transport layer, and a header including a source port number is added to transmission data received from the application. It is a token ring LAN by TCP / IP communication using TCP and UDP, which are protocols for passing data to the network layer, and priorities are set in advance for port numbers, and the network layer is used as a protocol for the LLC sublayer. TCP header or UD added at the transport layer in the data received from
Configuration using a priority transmission protocol having a function of reading the source port number included in the P header, converting the source port number into a predetermined priority, and setting the priority in the AC field of the data frame Is.

As a result, even in TCP / IP communication using a general-purpose protocol that does not have the concept of priority such as TCP, UDP, and IP, the priority control function of the MAC sublayer protocol is used. The prioritized transmission can be performed, and even when the network is overloaded, the transmission delay of urgent data can be minimized.

By the way, in addition to the port number that the user can arbitrarily select, the well-known port number (Well
A well-known port number (0 to 255) called a known port number is widely disclosed (for example, port number 21 is FTP, port number 23 is TELNET).
Are fixedly assigned to each). It is desirable to provide priorities (8 levels) in advance for such well-known port numbers as well, and the priority set for each well-known port number serves as a priority standard.

In this embodiment, a protocol which does not have the concept of priority is used in neither the network layer nor the transport layer, but the priority is set in at least one of the network layer and the transport layer. The present invention can be applied even when a protocol having no concept is used. That is, even if the upper layer application specifies the priority (here, the priority information itself, not the port number specification), if either the network layer or the transport layer located in the middle does not have the concept of priority. , Its priority is not communicated to the LLC sublayer. Even in such a case, by using the priority transmission protocol of the present invention as the LLC sublayer, the priority can be set in the data frame as described above. Therefore, for example, a protocol other than IP may be used as the protocol of the network layer.

Further, in this embodiment, the token ring LA is used.
Although N has been described, the present invention is not limited to this, and the present invention is also applicable to other network communication systems using a protocol having a priority control function in the MAC sublayer. Another example of a MAC sublayer protocol having a priority control function is a token bus protocol (for example, IEEE802.4 protocol), and the present invention is also applicable to a token bus LAN.

The above-mentioned embodiments are merely for clarifying the technical contents of the present invention, and should not be construed in a narrow sense by limiting to such specific examples. Various modifications can be made within the scope of the claims.

[0062]

According to the network communication system of the present invention,
As described above, as a transport layer, a port number is defined as an identifier for uniquely identifying multiple upper layer applications, and a header containing the source port number is added to the transmission data received from the application A network communication system using a protocol for passing data to a layer, wherein the port number has a priority set in advance, and as a protocol driver for the LLC sublayer, in the data received from the network layer, Source port number reading means for reading the source port number included in the header added in the transport layer, a port number / priority conversion table for converting the port number into a predetermined priority, and the above-mentioned source The source port number read by the port number reading means It has a port number / priority conversion means for converting the priority into a priority based on the port number / priority conversion table, and a priority setting means for setting the priority obtained by this conversion in a predetermined field of the data frame. This is a configuration using a priority transmission protocol driver.

Therefore, the upper layer application only needs to specify the port number according to the priority, and the priority can be specified without using special priority information.
Even when a general-purpose protocol having no concept of priority such as TCP, UDP, and IP is used for the layer located between the upper layer application and the data link layer, the protocol of the MAC sublayer It is possible to perform priority transmission using the priority control function of the device, and it is possible to minimize the transmission delay of urgent data even when the network is overloaded.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention, in which a protocol configuration used in a network communication system
It is an explanatory view shown corresponding to an I reference model.

FIG. 2 is a block diagram showing an overall schematic configuration of the network communication system.

FIG. 3 is a functional block diagram showing a configuration of a protocol driver of a priority transmission protocol used in the network communication system.

FIG. 4 I in an IP datagram formed by IP
It is explanatory drawing which shows the format of P header.

FIG. 5 is an explanatory diagram showing a format of a TCP header in a TCP segment formed by TCP.

FIG. 6 is an explanatory diagram showing a format of a UDP header in a user datagram formed by UDP.

FIG. 7 is an explanatory diagram showing a configuration of a token, a data frame, and an access control field included in the token or the data frame used in the token ring.

[Explanation of symbols]

1 Terminal 2 Data Frame Forming Unit (Priority Setting Unit) 3 IP Header Length Recognition Unit (Source Port Number Reading Unit) 4 Source Port Number Recognition Unit (Source Port Number Reading Unit) 5 Port Number / Priority Conversion Unit (Port number / priority conversion means) 6 Port number / priority conversion table

Claims (1)

[Claims] 1. A protocol having a priority control function as a protocol of a medium access control sublayer, which performs priority transmission based on a priority that can be set in a predetermined field of a data frame formed in a logical link control sublayer. By using a protocol that does not have the concept of priority in at least one of the network layer and the transport layer above the logical link control sublayer, multiple applications in the upper layer are uniquely identified as the transport layer. In a network communication system that uses a protocol that defines a port number as an identifier and adds a header containing the source port number to the transmission data received from the application and passes the data to the network layer, add the above port number The priority is set in advance, and the logical link control sublayer As a protocol driver of, the source port number reading means for reading the source port number included in the header added at the transport layer in the data received from the network layer, and the port number is converted into a specified priority. Port number / priority conversion table for converting the transmission source port number read by the transmission source port number reading means into priority based on the port number / priority conversion table A network communication system characterized by using a priority transmission protocol driver having priority setting means for setting the priority obtained by this conversion in a predetermined field of a data frame.