JP3628894B2 - Data relay apparatus, data relay method, and recording medium on which data relay program is recorded - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a data relay apparatus and a data relay method for transferring data at high speed between a plurality of networks, and a recording medium on which a data relay program for realizing the data relay method is recorded.
[0002]
[Prior art]
For example, a so-called router is known as a relay device for connecting a plurality of networks such as a LAN (Local Area Network), a MAN (Metropolitan Area Network), and a WAN (Wide Area Network). The router is provided with a route table for selecting a route for transferring data therein. When the router receives the data, the router transfers the data based on information in an IP (Internet Protocol) header attached to the data. Select a route.
[0003]
This IP header has a structure as shown in FIG. That is, vers (version) indicates the IP version, and information indicating version 4, for example, is recorded.
[0004]
hlen (header length) indicates the length of the IP header in units of 32 bits (4 octets).
[0005]
Tos (type of service) represents the quality of service such as data priority, low delay, high throughput, high reliability, and low cost, and is set according to user designation and application protocol characteristics.
[0006]
The length represents the total length of the IP header and subsequent data in octets.
[0007]
The id is assigned by the transmission source in order to identify the original IP datagram when the fragmented IP datagram is reconstructed.
[0008]
The offset is composed of a flag for controlling the fragmentation of the IP datagram and a fragment offset indicating the position of the fragment in the first data by an offset value in units of 8 octets.
[0009]
tl (time to live) is an 8-bit integer value indicating the maximum time that an IP datagram can exist in the Internet, and is subtracted every time a router is relayed.
[0010]
The protocol is for identifying an upper protocol of the IP such as TCP (Transmission Control Protocol) or UDP (User Datagram Protocol).
[0011]
check sum represents a checksum that guarantees the accuracy of the IP header.
[0012]
src IP address (source IP address) is an IP address indicating the source of the IP datagram, and dest IP address (destination IP address) is an IP address indicating the destination of the IP datagram.
[0013]
When transferring data between a plurality of networks, the router basically examines the dest IP address in the IP header having the above-described configuration for each packet sent, as shown in FIG. Search the routing table managed in the network layer based on Based on the search result, the router determines a destination interface and a next relay router (next hop gateway).
[0014]
[Problems to be solved by the invention]
By the way, in the conventional router described above, when searching a routing table managed in the network layer, it is necessary to perform a longest-match for obtaining an entry corresponding to the longest subnet mask.
[0015]
As shown in FIG. 15, the IP address including the above-described dest IP address is composed of 32 bits, and generally includes a network part, a host part, and a subnet part configured by further dividing the host part. It is divided. The subnet mask is information indicating which part of the 32-bit IP address is the network part and the subnet part. The router examines this IP address, searches for a network corresponding to a subnet mask to which a node to which data should be transferred belongs, and determines its route.
[0016]
However, in this IP address, the network part, the subnet part, and the host part have variable lengths in 32 bits, and the router is very long to search for a subnet mask to which data is to be transferred. There was a problem that processing time was required.
[0017]
Further, in the conventional router, it is necessary to perform the above-described process of subtracting the tl and replacing the check sum each time data is transferred.
[0018]
The present invention has been made in view of such circumstances, and performs high-speed data transfer by omitting the heavy load processing in the conventional router, which has been required by performing data transfer in the network layer. It is an object of the present invention to provide a data relay device and a data relay method that can be used. Another object of the present invention is to provide a recording medium on which a data relay program for realizing the data relay method is recorded.
[0019]
[Means for Solving the Problems]
The present invention stores a data transfer path table in which a correspondence relationship between data link layer information included in a header attached to data transferred between a plurality of networks and the data transfer path is stored. And relay means for relaying and transferring data between a plurality of networks having different types of data link layers, wherein the relay means includes a data link layer included in a header attached to data to be relayed. In the data relay device that searches the data transfer path table stored in the storage means based on the information and determines the transfer destination of the data, the plurality of networks are used to transmit the data, respectively. The relay means can occupy a data transmission band, and the relay means includes a plurality of networks having different types of data link layers. When transferring relaying data between the work, based on information in the data link layer included in the header added to the data to be relayed, and determines the data transmission band.
[0020]
The data relay apparatus according to the present invention configured as described above relays / transfers data to a transfer destination determined based on data link layer information.
[0021]
Further, the present invention stores a data transfer path table in which a correspondence relationship between data link path information included in a header attached to data transferred between a plurality of networks and the data transfer path is stored. When data is relayed and transferred between a plurality of networks having different types of data link layers stored in the means, based on data link layer information included in a header attached to the data to be relayed In the data relay method for searching the data transfer path table stored in the storage means and determining the transfer destination of the data, the plurality of networks each have a data transmission band used for transmitting the data. It can be occupied and relays and transfers data between multiple networks with different types of data link layers. When, based on the information of the data link layer included in the header added to the data to be relayed, and determines the data transmission band.
[0022]
The data relay method according to the present invention as described above relays and transfers data based on data link layer information.
[0023]
Further, the data link layer information included in the header attached to the data transferred between the plurality of networks is performed by relaying and transferring the data between the plurality of networks having different types of data link layers. The data transfer path table describing the correspondence relationship with the data transfer path is searched based on the data link layer information included in the header attached to the data to be relayed, and the data transfer destination is determined. A recording medium on which a data relay program is recorded, wherein each of the plurality of networks can occupy a data transmission band used for transmitting the data, and the data relay programs are different from each other. When relaying and transferring data between multiple networks with different types of data link layers Based on the information of the data link layer included in the granted header, the data relay program and determines the data transmission band is being recorded.
[0024]
The recording medium on which the data relay program according to the present invention configured as described above is recorded supplies a data relay program for relaying and transferring data to a transfer destination determined based on information in the data link layer To do.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings.
[0026]
In the embodiment to which the present invention is applied, for example, as shown in FIG. 1, a network (hereinafter referred to as an ATM network) corresponding to an asynchronous communication mode (hereinafter referred to as ATM (Asynchronous Transfer Mode)). IEEE Std. Approved by The Institute of Electrical and Electronics Engineers, Inc. (IEEE). 1394-1995 Layer 2 forwarding for transferring data to and from a network conforming to the IEEE Standard for a High Performance serial Bus standard (hereinafter abbreviated as the IEEE 1394 standard). Router 10. First, the ATM and the IEEE 1394 standard will be briefly described.
[0027]
In ATM, in order to enable the same information transfer processing regardless of the communication speed, routing information is assigned to a header portion called ATM cell header for each fixed-length transfer information called ATM cell, and based on this, information is transferred. This is a method for multiplexing and routing.
[0028]
The ATM cell header has a configuration as shown in FIG. GFC (General Flow Control) is used for flow control on a user / network interface.
[0029]
VPI (Virtual Path Identifier) and VCI (Virtual Channel Identifier) are used to identify ATM connections, and PT (Payload Type) is assigned to enable forward congestion notification at the cell level. Yes.
[0030]
CLP (Cell Loss Priority) displays the priority of cell loss control that may be performed when congestion or the like occurs.
[0031]
Further, HEC (Header Error Check) represents CRC (Cyclic Redundancy Check) check information having 1-bit error correction and multi-bit error detection capabilities for header error detection and correction.
[0032]
The ATM cell header having such a configuration is defined by the ATM layer belonging to the so-called data link layer among the basic reference models of OSI (Open Systems Interconnection) that defines the protocol hierarchy. It is.
[0033]
As shown in FIG. 3, the OSI is organized hierarchically into a physical layer, a data link layer, a network layer, a transport layer, a session layer, a presentation layer, and an application layer. Yes.
[0034]
The first physical layer defines physical standards such as the shape of the connector at the end of the cable used for connection and the number and type of pins, electrical signal standards, etc., and includes standards related to optical communications. It is what In the physical layer, a bit string consisting of 0 or 1 is transferred.
[0035]
The second data link layer serves to delimit transmission of bit strings in the physical layer as a unit of meaningful information called a packet or a frame. The data link layer packetizes data, performs data transfer between adjacent systems together with packet error detection codes and sequence information, and controls transmission errors.
[0036]
The third network layer performs relaying and routing control of data transmission between network systems. In a wide-area network, communication cannot be performed unless a data transmission path is established. Therefore, path control based on the network address is performed in the network layer.
[0037]
The transport layer in the fourth layer guarantees communication quality, for example, by performing retransmission control in order to recover errors that occur during communication, and aligning the order of packets that arrive intermittently. It realizes the function to do.
[0038]
The session layer of the fifth layer controls communication so as to maintain an order as a dialog (dialog), and performs, for example, regulation for transmission right control and synchronization establishment.
[0039]
The sixth presentation layer converts character sets, character codes, and data structures.
[0040]
The application layer of the seventh layer provides a service that can use an application program in a console such as a computer. For example, the application layer is used to provide functions such as e-mail, file transfer, and remote login.
[0041]
In the above-described ATM layer, a 53-octet ATM cell composed of an ATM cell header and data can be generated, and so-called cut-through transfer can be performed. Further, in the ATM layer, when performing data transfer via the Internet, as shown in FIG. 4, an LLC / SNAP (Logical Link Control / Sub-Network Access Protocol) header is added to the IP datagram. An AAL5 (ATM Adaptation Layer 5) trailer for recombination and padding as necessary is added to generate a packet consisting of multiples of 48 octets. In the ATM layer, this packet is divided into 48 octet cells, and an ATM cell header of 5 octets is added to each cell to form an ATM cell of 53 octets, and this ATM cell is transferred.
[0042]
On the other hand, the IEEE 1394 standard is an interface standard that supports high-speed data transfer and real-time transfer for the purpose of an interface for multimedia data transfer. In the IEEE 1394 standard, a transfer operation performed in a network is called a subaction, and the following two types of subactions are defined. That is, as two subactions, a synchronous transfer mode that guarantees a transfer band called “isochronous” is defined, and an asynchronous transfer mode called “asynchronous” is defined.
[0043]
The header portion of the packet in the IEEE 1394 standard is different between “isochronous” and “asynchronous”.
[0044]
The “isochronous” header part (hereinafter referred to as a 1394 synchronization header) has a configuration as shown in FIG. 5, and includes a data length indicating the size of a data block following the 1394 synchronization header, and a packet of the upper layer. It includes a tag (isochronous data format tag) representing classification, a channel (isochronous channel) representing a channel, a sy (synchronization code) representing a synchronization code, and header_CRC representing CRC of a 1394 synchronization header.
[0045]
Further, the header part in “asynchronous” (hereinafter referred to as 1394 asynchronous header) has a configuration as shown in FIG. 6, and includes a dest ID (destination ID) indicating the address on the receiving side and a tl ( (transaction label), rt (retry code) representing the type of processing to be requested again, tcode (transaction code) representing the transaction code, pri (priority) representing the priority of the packet, Src ID (source ID) representing an address and header_CRC representing CRC of the 1394 asynchronous header are provided. Furthermore, the 1394 asynchronous header includes, for example, dest offset (destination offset), data length, extended_tcode, and the like as information specific to the packet type.
[0046]
The 1394 synchronous header and the 1394 asynchronous header having such a configuration are those defined in the link layer belonging to the data link layer in the OSI basic reference model described above. In the link layer, a packet including a 1394 synchronous header or a 1394 asynchronous header and data is generated and transferred. In the link layer, when data is transferred via the Internet, as shown in FIG. 7, after a fragment header for recombination is added to the IP datagram, a 1394 synchronous header or 1394 asynchronous header is added. Is added to form a packet and transfer. In the link layer, when this packet is formed, the IP datagram is divided according to the bandwidth reserved for use at the transfer rate or data transmission, for example, so that the fragmented IP datagram is fragmented. A header and a 1394 synchronous header or a 1394 asynchronous header are added to form a plurality of packets.
[0047]
In the network in which the ATM network to which the above-described ATM is applied and the IEEE 1394 network conforming to the IEEE 1394 standard are connected, the layer 2-forwarding router 10 for transferring data is connected to the CPU 11 as a relay means as shown in FIG. The main memory 12 serving as storage means, a line unit 13, and a line unit 14 are provided, and in addition, a power supply unit that supplies power, various ports, and the like, which are not shown, are provided. These units are connected to each other by a bus 15.
[0048]
The main memory 12 includes, for example, a DRAM (Dynamic Random Access Memory), a nonvolatile flash memory, or the like. The main memory 12 stores a route table having route information for transferring an IP datagram received from a connected network to another network. The main memory 12 stores various information necessary for operating the layer 2-forwarding router 10 and a flow table described later.
[0049]
The line unit 13 has an interface for connecting to an IEEE 1394 network, and has a function as a connection unit with the network. A plurality of the line units 13 are provided so as to correspond to the number of networks to which the layer 2-forwarding router 10 is connected.
[0050]
The line unit 14 has an interface for connecting to the ATM network, and functions similarly to the line unit 13 as a connection unit with the network. The line unit 14 is a network to which the layer 2-forwarding router 10 is connected. A plurality are provided so as to correspond to the number.
[0051]
The CPU 11 controls each unit, and has a function of searching for desired route information from the above-described route table or searching for information of a flow table described later.
[0052]
As shown in FIG. 9, the layer 2-forwarding router 10 is used for data transfer by a normal IP datagram method, and has the same routing table as described above that is managed in the network layer. A flow table which is a data transfer route table in which information of an ATM cell header, a 1394 synchronous header, or a 1394 asynchronous header (hereinafter, appropriately referred to as a data link header) for each flow that is a flow of a group of packets to a destination is collected Are stored in the main memory 12 and managed. This flow table records protocol number and port number information such as TCP and UDP, and the layer 2-forwarding router 10 classifies flows based on this information. In addition, as the flow table, only the address to which data is to be transferred may be recorded, and the flow can be classified by simplified information.
[0053]
In the following description, information representing logical port numbers such as VPI and VCI in the ATM cell header and channel numbers and offsets in the 1394 synchronous header or 1394 asynchronous header will be referred to as channel identifiers.
[0054]
The flow table is configured as shown in FIG. 10, for example. That is, in the flow table, among the interfaces provided in the plurality of line units 13 or 14, the type of interface for inputting a flow, a unit number representing a physical port number, and a channel identifier are recorded. Also, in the flow table, as the flow relay destination information, as with the input side, among the interfaces provided in the plurality of line units 13 or 14, the type of interface that outputs the flow, the unit number, and the channel An identifier is recorded. In the case of a multicast flow in which a plurality of output destinations exist for one flow, the flow table has a plurality of pieces of information on the output side with respect to one piece of information on the input side. When a data transmission band used for transmission is reserved, information indicating the band is added to the flow table.
[0055]
The layer 2-forwarding router 10 checks the information of the data link header without checking the IP header which is the information of the network layer of the received packet. For example, when the layer 2-forwarding router 10 recognizes that the packet belongs to the flow input from the interface having the unit number 3 connected to the ATM network and the channel identifier 50, the layer 2-forwarding router 10 is based on the flow table. The interface having the unit number 2 connected to the IEEE 1394 network and the channel identifier 20 is obtained as the output destination of the packet, and the packet is transferred with a guaranteed bandwidth of 3 Mbps.
[0056]
Specifically, the layer 2-forwarding router 10 relays data by an operation as shown in FIG. That is, as shown in FIG. 11, when the layer 2-forwarding router 10 first receives a packet in step S1, a channel identifier for flow is added to the packet as information in the data link header in step S2. The CPU 11 determines whether or not it is.
[0057]
If the channel identifier for the flow is not recognized, the layer 2-forwarding router 10 proceeds to step S5 in order to perform a packet transfer process by a normal IP datagram method. In step S <b> 5, the layer 2-forwarding router 10 performs a longest-match based on the destination IP address that is the destination IP address, and the CPU 11 searches the route table held in the main memory 12. Then, the layer 2-forwarding router 10 determines the next hop gateway that is the next relay router to which the packet is to be transmitted and its interface from the search result of the routing table, and performs the packet transmission process in step S6.
[0058]
On the other hand, if the flow channel identifier is recognized in step S2, the layer 2-forwarding router 10 proceeds to the process in step S3. In step S3, the layer 2-forwarding router 10 searches the flow table held in the main memory 12 by the CPU 11 based on the interface and channel identifier that received the packet, and the interface and channel identifier that should transmit the packet. And decide. In step S4, the CPU 11 determines whether or not the corresponding entry exists in the flow table.
[0059]
Here, if there is no corresponding entry, the layer 2-forwarding router 10 proceeds to the process in step S5 and performs a packet transfer process by a normal IP datagram method.
[0060]
If the layer 2-forwarding router 10 determines in step S4 that the corresponding entry exists, the layer 2-forwarding router 10 transmits a packet from the interface determined in step S3, and ends the series of processes.
[0061]
As described above, the layer 2-forwarding router 10 has a mechanism for allocating individual channels for each flow and notifying the correspondence between flows and channel identifiers between adjacent nodes. In addition, it is not necessary to check the dest IP address and the routing table in the IP header, and it is not necessary to perform processing such as longest-match, processing such as ttl subtraction, checksum replacement, and the like. Therefore, in the layer 2-forwarding router 10, the packet is transferred at high speed by obtaining the interface to output the packet and the channel identifier based on the information of the data link header added to each packet. can do.
[0062]
Note that the data relay program for realizing the series of processes in the data relay described above may be stored in advance in the main memory 12 of the layer 2-forwarding router 10 or the like, for example, a recording medium such as a CD-ROM May be provided in a recorded form. In the layer 2-forwarding router 10, the above-described series of processing can be performed by writing and storing the data relay program recorded in the recording medium in this manner in the main memory 12, for example.
[0063]
The layer 2-forwarding router 10 connecting the ATM network and the IEEE 1394 network described above can be applied to a system in media cruising proposed as a network architecture replacing the current Internet architecture.
[0064]
Media cruising overcomes the difficulty of high-speed transfer of large volumes of data on the existing Internet, and secures and guarantees the normal best effort mode and the bandwidth used to reliably guarantee communication quality. The mode can be switched. In this media cruising, it is assumed to support a wide network form from a wide area to a home.
[0065]
A system in which the above-described ATM network and IEEE 1394 network are applied to media cruising is as shown in FIG. 12, for example. That is, in media cruising, the backbone network 50 is constructed by an ATM network, and the home network 70 which is a home network is constructed by an IEEE 1394 network. These backbone network 50 and home network 70 are connected by a subscriber network 60.
[0066]
The backbone network 50 is very large and utilizes ATM high-speed communication technology. For example, the backbone router 51 that is connected to an ATM network that is made of a large-capacity optical fiber and that serves as a backbone uses, for example, an ATM switch that has an extended function such as high-speed signaling.
[0067]
The subscriber network 60 is located in the periphery of the backbone network 50. For example, the subscriber network 60 is a subscriber composed of an optical fiber by FTTH (Fiber To The Home) or an ADSL (Asymmetric Digital Subscriber Line) using copper wire. The lines are concentrated by the edge router 61 and connected to the backbone. In the same way as the backbone router 51, the edge router 61 is obtained by extending functions such as high-speed signaling to an ATM switch, for example.
[0068]
The home network 70 is an IEEE 1394 network in which computers, AV (Audio Visual) devices, and the like are connected by a serial bus compliant with the IEEE 1394 standard. A home router 71 is used for connection to the subscriber network 60. The home router 71 is small and inexpensive, and includes an interface compatible with ATM as an external network interface and an interface compatible with the IEEE 1394 standard and Ethernet as an internal network interface.
[0069]
The routers belonging to each of these networks are equivalent to the above-described layer 2-forwarding router 10 although there are differences in resources and capabilities depending on the networks to which they belong. Will continue to forward.
[0070]
For example, when transferring data from the home network 70 to another home network (not shown), the home router 71 sets the 1394 synchronous header or 1394 asynchronous of the packet having the configuration shown in FIG. Check the channel identifier for the flow in the header. Then, the home router 71 searches the stored flow table based on the interface that received the packet and the channel identifier, determines the interface and channel identifier that should transmit the packet, and transmits the packet. At this time, as shown in FIG. 4, the data link header of the packet is changed from the 1394 synchronous header or the 1394 asynchronous header to the ATM cell header.
[0071]
Next, the edge router 61 of the subscriber network 60 searches the stored flow table based on the interface that received the packet and the channel identifier in the ATM cell header, and the interface and channel identifier that should transmit the packet. And decide.
[0072]
Further, the backbone router 51 in the backbone network 50 searches the stored flow table based on the interface that received the packet and the channel identifier in the ATM cell header. Then, the backbone router 51 determines an interface to which the packet is to be transmitted and a channel identifier, and transmits the packet.
[0073]
When the backbone network 50 is composed of a plurality of ATM networks, packets are sequentially transferred by cut-through transfer between the ATM networks by performing the same processing at each backbone router 51 in each ATM network. Is done.
[0074]
The packet is repeatedly transferred in this manner, so that the data link header is finally changed from the ATM cell header to the 1394 synchronous header or 1394 asynchronous header, and is sent to the receiving terminal of the target home network (not shown). To reach.
[0075]
As described above, the layer 2-forwarding router 10 described above can be applied as the backbone router 51, the edge router 61, and the home router 71 in media cruising, and information on the data link header of the packet for each flow. The packet can be transferred at high speed based on the above. Note that packet transfer in media cruising may be performed in a normal best effort mode or in a mode that guarantees a band to be used. When transfer is performed in a mode in which the bandwidth is guaranteed, information indicating the bandwidth to be used is recorded in the flow table.
[0076]
As described above, the layer 2-forwarding router 10 shown as the embodiment of the present invention does not transfer the packet based on the information on the network layer, but on the information on the data link layer. Thus, packet transfer can be performed at high speed.
[0077]
The present invention is not limited to the above-described embodiment. For example, it is possible to apply a network constituted by Ethernet instead of the IEEE 1394 network, and the types of networks are limited. However, it goes without saying that other modifications are possible without departing from the spirit of the present invention.
[0078]
【The invention's effect】
As described above in detail, in the data relay device according to the present invention, the correspondence between the data link layer information included in the header attached to the data transferred between the plurality of networks and the data transfer path And a relay unit that relays and transfers data between a plurality of networks having different types of data link layers, and the relay unit relays the data In the data relay device for searching the data transfer path table stored in the storage unit and determining the transfer destination of the data based on the information of the data link layer included in the header attached to the data, a plurality of networks Describes the correspondence between the data link layer information included in the header given to the data transferred between them and the data transfer path The data link included in the header attached to the data relayed by the relay means for storing the data transfer path table in the storage means and relaying and transferring the data between a plurality of networks having different types of data link layers Based on the layer information, the data transfer route table stored in the storage means is searched to determine the data transfer destination.
Thereby, the data relay apparatus according to the present invention can transfer data at high speed.
[0079]
In the data relay method according to the present invention, the data transfer in which the correspondence between the data link layer information included in the header added to the data transferred between the plurality of networks and the data transfer path is described. A data link layer included in a header assigned to data to be relayed when the routing table is stored in the storage means and relayed and transferred between a plurality of networks having different types of data link layers In the data relay method for searching the data transfer route table stored in the storage means based on the information of the storage means and determining the transfer destination of the data, the plurality of networks are respectively used for transmitting the data Between two or more networks having different types of data link layers. When transferring relaying data, based on information of the data link layer included in the header added to the data to be relayed to determine the data transmission band.
As a result, the data relay method according to the present invention can transfer data at high speed.
[0080]
Further, the recording medium on which the data relay program according to the present invention is recorded performs a process of relaying and transferring data between a plurality of networks having different types of data link layers, and is transferred between the plurality of networks. The data link layer information included in the header attached to the data to be relayed is a data transfer route table describing the correspondence between the data link layer information contained in the header attached to the data and the data transfer route. A recording medium in which a data relay program for searching based on information and determining a transfer destination of the data is recorded, wherein each of the plurality of networks occupies a data transmission band used for transmitting the data The data relay program can include a plurality of different types of data link layers. A data relay program for determining the data transmission band based on data link layer information included in a header attached to data to be relayed when relaying and transferring data between networks Has been.
Therefore, in the recording medium on which the data relay program according to the present invention is recorded, it is possible to provide a data relay program that can transfer data at high speed, and a data relay device to which this data relay program is applied is provided. Data transfer can be performed at high speed.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of a network system to which a layer 2-forwarding router shown as an embodiment of the present invention is applied, and a diagram showing a network system in which an ATM network and an IEEE 1394 network are connected.
FIG. 2 is a diagram illustrating an example of the format of an ATM cell header.
FIG. 3 is a diagram showing a basic reference model of OSI.
FIG. 4 is a diagram showing a configuration of a packet in which an ATM cell header is added to an IP datagram.
FIG. 5 is a diagram illustrating an example of a format of a 1394 synchronization header.
FIG. 6 is a diagram illustrating an example of a format of a 1394 asynchronous header.
FIG. 7 is a diagram illustrating a configuration of a packet in which a 1394 synchronous header or a 1394 asynchronous header is added to an IP datagram.
FIG. 8 is a block diagram showing a configuration of the layer 2-forwarding router.
FIG. 9 is a conceptual diagram illustrating processing in the layer 2-forwarding router.
FIG. 10 is a diagram showing an example of a flow table stored in the layer 2-forwarding router.
FIG. 11 is a flowchart showing a series of processing steps in the layer 2-forwarding router.
FIG. 12 is a diagram illustrating an example of a system in which the layer 2-forwarding router is applied to media cruising.
FIG. 13 is a diagram illustrating an example of an IP header format.
FIG. 14 is a conceptual diagram illustrating processing in a conventional router.
FIG. 15 is a diagram illustrating an example of a configuration of an IP address.
[Explanation of symbols]
10 Layer 2-forwarding router, 11 CPU, 12 main memory, 13 line section, 14 line section

Claims (6)

A storage means storing a data transfer path table in which correspondence information between data link layer information included in headers attached to data transferred between a plurality of networks and the data transfer paths is stored, and Relay means for relaying and transferring data between a plurality of networks having different types of data link layers, and the relay means is based on data link layer information included in a header attached to data to be relayed In the data relay device that searches the data transfer path table stored in the storage means and determines the transfer destination of the data,
The plurality of networks can each occupy a data transmission band used for transmitting the data,
The relay means, when relaying and transferring data between a plurality of networks having different types of data link layers, based on the information of the data link layer included in the header attached to the data to be relayed, A data relay apparatus that determines a data transmission band. 2. The data relay apparatus according to claim 1, wherein at least one of the plurality of networks is an ATM-compatible network, and at least one of the other networks is a network conforming to the IEEE 1394 standard. A data transfer path table in which the correspondence between the data link layer information included in the header given to data transferred between a plurality of networks and the data transfer path is described in the storage means. When data is relayed and transferred between a plurality of networks having different types of data link layers, the data is stored in the storage means based on data link layer information included in a header attached to the data to be relayed In the data relay method of searching the data transfer route table and determining the transfer destination of the data,
Each of the plurality of networks can occupy a data transmission band used for transmitting the data, and relays and transfers data between a plurality of networks having different types of data link layers. In this case, the data transmission method is characterized in that the data transmission band is determined based on data link layer information included in a header added to data to be relayed. 4. The data relay method according to claim 3, wherein at least one of the plurality of networks is an ATM-compatible network, and at least one of the plurality of networks is a network conforming to the IEEE 1394 standard. The process of relaying and transferring data between a plurality of networks having different types of data link layers, and data link layer information included in a header attached to data transferred between the plurality of networks, Data relay that searches the data transfer path table describing the correspondence with the data transfer path based on data link layer information included in the header attached to the data to be relayed, and determines the data transfer destination A recording medium on which a program is recorded,
Each of the plurality of networks can occupy a data transmission band used for transmitting the data, and the data relay program can transmit data between a plurality of networks having different types of data link layers. Recording medium on which a data relay program is recorded, wherein the data transmission band is determined based on data link layer information included in a header attached to data to be relayed . The data relay program supports data transfer when at least one of the plurality of networks is an ATM compatible network and at least one of the other networks is a network conforming to the IEEE 1394 standard. Item 6. A recording medium on which the data relay program according to item 5 is recorded.

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