JP2004064477A - Communication system, communication equipment, program, and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication system, communication equipment, a program and a recording medium for making it possible for a host layer to select a transfer mode to be used for transferring datagram when the host layer performs communication by using a communication medium equipped with a plurality of transfer modes, for example, an IEEE1394 serial bus. <P>SOLUTION: This system is provided with: a means for making a network layer recognize the plurality of transfer modes of a communication medium as different interfaces; and a means for imparting different network addresses to the interfaces. Preferably, IEEE1394 is adopted as the communication medium, and an internet protocol as a communication protocol. Thus, it is possible to divide one physical network into a plurality of virtual networks according to the transfer modes, and it is made possible for a host application to select a transfer mode to be used by selecting a network address of the transmission destination. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a communication method for enabling a higher layer to select a transfer mode used for transferring datagrams when performing communication using a communication medium having a plurality of transfer modes, for example, an IEEE1394 serial bus. The present invention relates to a communication device and a recording medium.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, when building a local area network (LAN) for connecting electronic devices having a communication function such as a computer and a printer in an office or home, it is common to use Ethernet (registered trademark) as a communication medium. Met.
[0003]
When a network is constructed by Ethernet, since there is only one Ethernet transfer mode, a datagram requested to be transmitted by an application on a communication device is always transmitted in the above-described transfer mode.
[0004]
However, recently, a communication medium which is physically one communication medium but can handle a plurality of transfer modes at the same time has appeared.
[0005]
For example, an IEEE 1394 serial bus (hereinafter, IEEE 1394) is a high-performance serial bus and has an isochronous transfer mode for real-time transfer suitable for transfer of multimedia information and an asynchronous transfer mode for normal asynchronous transfer. The area of adoption from audiovisual equipment to personal computers is expanding.
[0006]
Therefore, IEEE 1394 is expected as an infrastructure of a home network integrating not only the above-described computer-centered LAN but also audiovisual equipment.
[0007]
Thus, the Internet Engineering Task Force (IETF), which defines technical standards for the Internet, standardized IP over 1394 that performs Internet Protocol (IP) communication over IEEE 1394 as RFC 2734.
[0008]
FIG. 5 shows a protocol stack when IP over 1394 is adopted. The datagram requested to be transmitted from the applications 501 to 503 is converted at 504 into IEEE1394 according to the transfer mode for transmitting from the IP packet in accordance with RFC 2734, and transmitted.
[0009]
An asynchronous stream is a transfer mode that combines an asynchronous transfer mode and an isochronous transfer mode, and RFC 2734 recommends that it be used for transmitting broadcast packets.
[0010]
However, even when using a communication medium having such a plurality of transfer modes, an application on a communication device prepares data to be transmitted when transmitting a datagram, and then transmits the datagram to a layer immediately below. The request does not include control information related to the physical layer.
[0011]
Therefore, in a link layer that controls a communication medium having a plurality of transfer modes, it is difficult to determine which transfer mode to use when a packet (datagram) transmitted from an upper layer is received. there were. For example, in the above example using IEEE 1394, it is difficult to make a determination at 505 in FIG.
[0012]
To solve this problem, Japanese Patent Application Laid-Open No. 2000-134278 proposed a method of incorporating a channel matron mechanism in the layer of IP over 1394, investigating a tendency of data transmission, and selecting a transfer mode to be used. The items to be examined include a method of detecting a certain number or more of datagrams, a method of examining a higher-order protocol, and a method of examining a port number (FIG. 6). Similarly, Japanese Patent Laying-Open No. 2001-94582 discloses a method for checking the IP packet size in a channel matron.
[0013]
According to the above proposal, even when the higher-level applications 601 to 603 have no means for selecting the IEEE 1394 transfer mode, it is possible to select the transfer mode estimated to be more suitable for the channel matron (705), IEEE 1394 enables efficient IP communication.
[0014]
Japanese Patent Application Laid-Open No. 2001-168915 has proposed a method of observing an IP packet to be transmitted and selecting a transfer mode of a physical layer depending on whether the packet is a continuous data flow.
[0015]
According to the above proposal, as in JP-A-2000-134278 and JP-A-2000-94582, the present invention is suitable even in a case where the upper applications 601 to 603 have no means for selecting the IEEE 1394 transfer mode. Can be selected.
[0016]
[Problems to be solved by the invention]
However, in the methods disclosed in JP-A-2000-134278 and JP-A-2000-94582, the selection of the IEEE 1394 transfer mode is based on the channel matron, and no means is provided for the upper application.
[0017]
Therefore, it is undeniable that the selection of the IEEE 1394 transfer mode by the channel matron may be different from the transfer mode expected by the host application.
[0018]
Also, the technique disclosed in Japanese Patent Application Laid-Open No. 2001-168915 is similar in that a means for selecting a transfer mode is not provided to a higher-level application. The present invention has been made to solve the above problem, and has as its object to provide an upper application with an opportunity to select a transfer mode to be actually used for datagram transfer from a plurality of transfer modes of a communication medium. I do.
[0019]
[Means for Solving the Problems]
In order to achieve the above object, a first invention according to the present application is characterized in that a plurality of transfer modes of a communication medium are recognized as different interfaces by a network layer, and different network addresses are given.
[0020]
More preferably, the communication medium is IEEE1394, and the communication protocol is the Internet protocol.
[0021]
In the above configuration, one physical network can be divided into a plurality of virtual networks by a transfer mode, and the upper application can select a transfer mode to be used by selecting a destination network address. it can.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this embodiment, it is assumed that IEEE 1394 is used as a communication medium and an Internet protocol is used as a protocol.
[0023]
Those skilled in the art can easily infer from this embodiment the embodiment using other communication media and protocols.
[0024]
(First embodiment)
FIG. 2 shows an example of a network to which terminals to which the communication system of the present invention is applied are connected.
[0025]
The terminal 201 has an IEEE 1394 interface to which the communication system of the present invention is applied, and in the present embodiment, also has an Ethernet interface.
[0026]
The terminal 202 and the terminal 203 are communication devices provided with an IEEE 1394 interface and an IP over 1394 protocol stack conforming to RFC2734. It does not matter whether the communication system of the present invention is used. Also, here, the connection is made only to the IEEE 1394 network by the IEEE 1394 interface, but it may be connected to another network by another interface (such as Ethernet).
[0027]
The IEEE 1394 network 204 indicates that the terminals 201 to 203 are interconnected by IEEE 1394. The connection form, the number of connections, and the like are not limited to the example shown in this figure, but follow the restrictions in the IEEE 1394 standard.
[0028]
An asynchronous transfer mode 205 and an isochronous transfer mode 206 schematically indicate that the IEEE 1394 network 204 can communicate in an independent transfer mode. In fact, they are not physically separated.
[0029]
FIG. 3 shows an IP address assigned to each terminal in FIG. In the present invention, since the asynchronous transfer mode and the isochronous transfer mode are treated as independent interfaces, different IP addresses are respectively provided.
[0030]
From this figure, the network address of 192.168.1.0/255.255.255.0 is the network 205 of the asynchronous transfer mode, and the network address of 192.168.2.0/255.255.255.0 is the network address of 192.168.2.0/255.255.255.0. It can be seen that this corresponds to the network 206 in the isochronous transfer mode.
[0031]
FIG. 4 shows a routing table of the terminal 201. The routing table is path information for determining a transfer destination of an IP packet and an interface used for transmission.
[0032]
When transmitting an IP packet, the logical product of the destination IP address of the IP packet and Netmask is calculated, and the logical product is sequentially compared with the value of Destination from the first row of the routing table, and the first matching row becomes the path information to be applied. The Interface indicates an interface used for transmission. If the Gateway is 0.0.0.0, the IP packet is transmitted to the destination IP address of the IP packet. Otherwise, the IP packet is transmitted to the address indicated by the Gateway.
[0033]
FIG. 1 shows a protocol stack when the communication system of the present invention is applied.
[0034]
The applications 101 to 102 are applications that request transmission of datagrams. The datagram requested to be transmitted is passed to a protocol layer such as TCP or UDP, and a necessary header or the like is given. Then, the datagram is passed to an IP layer.
[0035]
In the IP layer, an IP header is added to the datagram from the upper layer to form an IP packet. With respect to the formed IP packet, an interface to be used for transmission is determined based on the destination IP address and the routing table (107), and the link layer of the interface is requested to transmit the IP packet.
[0036]
In this embodiment, the IP address 104 is 192.168.1.1, the IP address 105 is 192.168.2.1, and the IP address 106 is 192.168.3.1.
[0037]
If the interface (asynchronous transfer mode) of the IP address 104 is selected by referring to the routing table (107), the packet is converted into an asynchronous packet in the IP over 1394 layer, and is transmitted through the IEEE 1394 link layer and the IEEE 1394 physical layer. (108).
[0038]
Similarly, when the interface (isochronous transfer mode) of the IP address 105 is selected, the packet is converted into an isochronous packet in the IP over 1394 layer and transmitted in the isochronous transfer mode (109).
[0039]
When the interface (Ethernet) of the IP address 106 is selected, the transmission of the IP packet is requested to the link layer of the Ethernet as in the normal case (111).
[0040]
For example, when the application of the terminal 201 is a video server and the application of the terminal 202 is video playback software for playing (streaming playback) while downloading video data from the video server, data transfer between the video server and the video playback software It is desirable that a transfer rate of at least a certain level is guaranteed. In such data transfer applications, the use of the asynchronous transfer mode in which the bandwidth is guaranteed is clearly suitable.
[0041]
Therefore, the application (video server) of the terminal 201 can perform communication in a desired isochronous transfer mode by specifying 192.168.2.2 as the destination IP address when transferring video data.
[0042]
On the other hand, when the application of the terminal 201 is a mail server and the application of the terminal 202 is a mail client that obtains mail from the mail server, the communication data generated between the two is intermittent, so that video data streaming is performed. A guaranteed band such as reproduction is not required, but rather, it is desired not to uselessly secure a band using the asynchronous transfer mode.
[0043]
In such a case, the application (mail server) of the terminal 201 performs communication in a desired asynchronous transfer mode by specifying 192.168.1.2 as a destination IP address when transmitting mail data. be able to.
[0044]
【The invention's effect】
As described above, according to the first aspect of the present application, since the transfer mode to be used can be determined based on the destination IP address, the application requesting the transmission of the datagram selects an appropriate destination IP address. This has the effect that the IEEE 1394 transfer mode to be used can be selected.
[Brief description of the drawings]
FIG. 1 is an example of a protocol stack when the communication system of the present invention is applied.
FIG. 2 is an example of a network including a terminal to which the communication system of the present invention is applied.
FIG. 3 is a list of IP addresses in FIG. 2;
FIG. 4 is a routing table of a terminal to which the communication system of the present invention has been applied.
FIG. 5 is an example of a general protocol stack when IP over 1394 is used.
FIG. 6 is an example of a protocol stack when the technique disclosed in Japanese Patent Application Laid-Open No. 2000-134278 is used.
[Explanation of symbols]
101 to 103: Application 104 for performing communication via a network 104: IP address 105 assigned to asynchronous transfer mode IP address assigned to asynchronous transfer mode 106: IP address 107 assigned to Ethernet interface 107: Transmission interface by routing Selection 108 transmission in the asynchronous transfer mode 109 transmission in the isochronous transfer mode 110 broadcast in an asynchronous stream 111 network 112 in Ethernet network 201 in IEEE 1394 terminals 202 to 203 to which the present invention is applied IP over 1394 is possible Terminal 204: Physical network 205 by IEEE 1394: Asynchronous Virtual network 206 by transmission mode Virtual network 207 by isochronous transfer mode Network 401 by Ethernet Network address 402 of destination 402 IP address 403 of gateway to transmit Network mask 404 Interfaces 501 used for transmission 503: An application for performing communication via a network 504: A layer for converting an IP packet into an IEEE 1394 packet 505: A transfer mode of IEEE 1394 cannot be selected 601 to 603: An application for performing communication via a network 604: An IP packet for IEEE 1394 packet Layer 605 for converting to a mechanism for dynamically controlling the transfer mode of IEEE 1394 according to JP-A-2000-134278

Claims (12)

A communication method for performing communication using a communication medium having a plurality of transfer modes, and means for causing a network layer to recognize the plurality of communication modes as different interfaces,
A communication system comprising means for giving a different network address to the interface. 2. The communication system according to claim 1, wherein said communication medium is an IEEE 1394 serial bus. 3. The communication system according to claim 1, wherein a protocol used for communication is an Internet protocol, said network layer is an Internet protocol layer, and said network address is an IP address. A communication device used when communicating using a communication medium having a plurality of transfer modes,
Means for causing the network layer to recognize the plurality of communication modes as different interfaces,
A communication device, comprising: means for giving a different network address to the interface. The communication device according to claim 4, wherein the communication medium is an IEEE 1394 serial bus. 6. The communication device according to claim 4, wherein a protocol used for communication is an Internet protocol, said network layer is an Internet protocol layer, and said network address is an IP address. A program for communicating using a communication medium having a plurality of transfer modes,
Causing the network layer to recognize the plurality of communication modes as different interfaces;
A program for providing a different network address to the interface. 8. The program according to claim 7, wherein the communication medium is an IEEE 1394 serial bus. 9. The program according to claim 7, wherein a protocol used for communication is an Internet protocol, said network layer is an Internet protocol layer, and said network address is an IP address. A recording medium recording a program when communicating using a communication medium having a plurality of transfer modes,
Causing the network layer to recognize the plurality of communication modes as different interfaces;
A computer-readable recording medium having recorded thereon a program having a step of giving a different network address to the interface. 9. The recording medium according to claim 8, wherein said communication medium is an IEEE 1394 serial bus. 13. The recording medium according to claim 11, wherein a protocol used for communication is an Internet protocol, said network layer is an Internet protocol layer, and said network address is an IP address.

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