Packet transfer method and packet transfer apparatus for multicast groups

0001The This invention relates to a multicast communication control apparatus.

0002As a packet transfer scheme within a network segment in which one or more physical media (eg cable) through a repeater, bridges and the like are connected, are NetBEUI (Net Extended User Interface), which is supported by a LAN Manager, and Windows NT or like available.

0003According to this Scheme network information (such as the address of each terminal and packet transfer control information) generally within a segment as a data link unit in Ethernet, Token Ring, or the like managed and centralized management in each terminal or a server subject.

0004In this case can the terminals that match with such a network protocol, together communicate with only a simple adjustment in a given segment, however, they do not communicate with terminals in other segments can, with which the given segment connected by routers, gateways and the like is.

0005TCP / IP according to the fourth and third layers of the OSI (Open System Interconnection) than the high-level protocol for each segment enables communication between terminals in a plurality of segments, the miteinande r are connected by routers, gateways and the like. TCP / IP allows terminals To communicate in all network segments together.

0006In this case are high and low-level layer addresses for information transfer managed in units of segments arranged server. These servers manage the addresses of the terminals is not consistent with the are connected to respective segments to each other by the high-level protocols are connected, but share the address space among themselves and use addresses in the address space, which the consistency of addresses is maintained.

0007On this way, the address management through distributed Offline processing between segments performed. Out Therefore, the following problem arises. For example, an Ip packet (Internet protocol packet) (to which an IP address as a high-level layer address and a MAC address are added as a low-level-layer address) from a terminal A in a given segment to a terminal B is to be transferred in another segment, the leads A routing server with respect to the corresponding segment in accordance with the IP address as a key by. In this case can the packet data is not transferred to the terminal B, due of non-coincidence between the low-level layer addresses or repeated Using the same low-level-layer address.

0008Each Network segment managed independently Network management information including the intra-segment address of Terminals in the segment, a high-level layer address, such as an IP address, communication control information over a Between Terminal communication scheme, such as 1: 1 communication or 1: N communication, and the like. For this reason, inter-segment communication between a Plurality of segments can not be performed readily.

0009Each Times when a terminal of a given network (sub-network) is isolated, which serves as a segment and with another subnetwork is connected, a new IP address must be set, which resulting in poor operability.

0010at a conventional Packet transfer system constituted by a plurality of network protocol layers is formed, checks when a packet is to be transferred, the high-level layer in the packet header written objective, which is administered by itself to the interpret aim and writes the destination information needed for low-level layer is to the packet to the destination in which the low-level layer managed to transfer header, whereby the package Transfers is.

0011It Assume that in a system in which the Ethernet protocol and the Internet Protocol (IP) to work as low- or high-level layers, to transfer a packet to all terminals in a network (sub-network) is serving as a segment (data link address management device). In this case, when the packet transferred according to an IP address is indicating a subnetwork as a destination, the package actually at the Ethernet transferred as the low-level layer with a multicast address, Intra-segment multicast indicates.

0012In this case, objects, passing through the two layers (ie, high- and low-level layers) are administered, generally managed independently. Specifically must if each terminal, the Ethernet protocol used to adjust an Ethernet address to an Netzwerkverbinmanure perform, and IP as the high-level layer is used, each terminal an IP address, and a subnetwork address (MAC address) set to. When a high-level multicast IP address in the above Fashion is determined by adjusting the IP address, can transfers the packet to all the terminals in the respective Ethernet segment will.

0013In However, this case, each time when a terminal from a given Subnetwork separately and connected with another subnetwork is, a new IP address to be set, resulting in poor Usability leads.

0014at the IP DHCP (Dynamic Host Configuration Protocol) is used, In order to solve the above problem. According to this Protocol, when a terminal of a given network to disconnect and another terminal group through a network is to be connected, necessary IP address information detected and in the own terminal merely by issuing a corresponding request be set to a DHCP server. Therefore must not be set each time a new IP address when performed the above operation is, thus, the operability is improved. In this case also allows multicasting by an IP address, only the transfer of Information to all terminals, a segment, such as the Ethernet form. For this reason, even when the low-level-layer multicasting forming with regard to specific terminals of the segment Terminals support multicasting are not performed with respect to these specific terminals. A one-to-one transfer must therefore be repeated as needed. This is because an IP address by Host and network portions is formed and a function for Transferring information to a designated segment including by using the information of the network section, for specifying terminals in the segment by using the Host section and for transferring the packet to the objectives includes.

0015at a conventional Multicast communication, every time when the transmission targets to be changed, the multicast address to be changed. For this reason, changes will carried out in an environment in which radio communication and an information communication device moves, the Multicast address frequently. For this reason, the communication procedure is complicated, which the communication efficiency is lowered, and a server is required, a multicast address set. Multicasting can not therefore performed without a server will.

0016Around To solve these problems, the following method is used. If there is no server to adjust is a multicast address, a plurality of terminals, to which the same information is transmitted when a group set on the basis of communication link information, decentralized by the respective terminals by management to get managed. Multicast communication is performed on the basis of the set group. at this method, a group set after is checked whether up communication links between a plurality of terminals can be, to be registered as a group. If a given communication link is separated, the separated terminal is omitted from the group. According to this Method, however, when the communication link between some Terminals of the plurality of terminals belonging to a group, is separated, a mismatch between the managed by the respective terminal group information caused.

0017If a new terminal appears in a network, the new terminal can not know the condition of an already adjusted group. Out Therefore, when a group set with the new terminal is, the new terminal will not be added to the set group but there must be a new group be set.

0018at a conventional Send data multicast communication when transmitted from the transmission side Data properly the receiving side is received, the respective receiving sites Response information (confirmation numbers) the proper reception at the transmission side specify. If the data correctly by a given receiving side be received, the receiving side sends response information the transmission side, the retransmission request. Upon receipt of the response information for requesting the retransmission transmits the transmission side the same data again.

0019This Operation specifies a one-to-n-way link, in which a device Transmitting data and a Plurality of devices receive the data. If any communication device a perform two-way communication should have Compounds constructed / are held equal in number which of the devices. However, this process contains, as response information for each transmission device produced and an acknowledgment packet transmitted for each transmission device is any acknowledgment packet inevitably only a piece of the answer information. Therefore decreases with an increase in the number of communication devices the number of acknowledgment packets to that in the network flow. This can increase the load on the network.

0020It Assume that a given device data received correctly has, however, another device receiving the data correctly has. In this case, the transmission side transmits the data again. In a conventional method, however, must both the device that received the data correctly has, as well as the device that received the data correctly has answer information with respect to the retransmitted data hand back. This means, the transmission side receives the acknowledgment packet with respect to the same data twice from the device, the receiving the first data and the retransmitted data correctly has. The unnecessary acknowledgment packet flows Therefore, in the network, overloading caused in the network.

0021Seiji Murate, inter alia, "A Network Architecture for Reliable Process Group Communication ", June 21, 1994 (1994-06-21) XP000489070 discloses a multicast communication control device according to the preamble sending of claim 1. The recipient a confirmation according to the number received messages.

0022The <patcit><text>US-A-4725834</text></patcit> disclosed a system for broadcasting messages to a plurality of stations, primary the one receiver contemplating, which is adapted to receive information messages and store, which are transmitted from a source station to a broadcasting station group.

0023The Invention provides a multicast communication control apparatus claim 1 ready.

0024Preferred embodiments the invention provide a packet transfer method and a packet transfer system willing it all servers in a plurality of network segments enable network management information from other segments by exchanging network management information to use shared between the servers, so that a simple Packet transfer is realized to all terminals.

0025Preferred embodiments provide a packet transfer method and unit ready multicasting perform to specific terminals can, characterized by a low-level-layer address (for example, MAC address) are, on the basis of a high-level-layer address (for example IP address).

0026Preferred embodiments provide a communication control apparatus and a communication control method ready, wherein when a new terminal in a network when Executed by Multicast communication without any server for performing Multicast communications appears, the new terminal the state an already adjusted group notified by another terminal is to the addition the new terminal to the group set to allow, and even if a mismatch between managed by the respective terminal group information caused, each terminal of the consistency group operating data can maintain.

0027Preferred embodiments provide a multicast communication device prepared the answer information with respect to all devices other than its own device in an acknowledgment packet provide, to be transmitted from the device, and the Package multicast.

0028These Invention can be more fully from the following detailed Description understood in conjunction with the accompanying drawings be, in which:

0029<figref idrefs="S77">1</figref> on Block diagram showing the overall order of a packet transfer system according to one embodiment of the invention;

0030<figref idrefs="S78">2</figref> on Block diagram according to the first arrangement of an inter-segment exchange server embodiment of the invention;

0031<figref idrefs="S78">3</figref> on Block diagram in the assembly of the Inter-segment exchange server <figref idrefs="S78">2</figref> detailed shows;

0032<figref idrefs="S79">4</figref> on Block diagram for explaining a procedure for exchanging network management information between segments;

0033<figref idrefs="S80">5</figref> on Block diagram for explaining a procedure for exchanging information between network segments;

0034<figref idrefs="S81">6</figref> on Block diagram for explaining a procedure for exchanging network management information between segments;

0035<figref idrefs="S82">7</figref> on Block diagram according to the second arrangement of an inter-segment exchange server embodiment of the invention;

0036<figref idrefs="S83">8th</figref> on Block diagram according to the third arrangement of the Inter-segment exchange server Arrangement of the invention;

0037<figref idrefs="S83">9</figref> on Block diagram in accordance with the arrangement of an Inter-segment exchange server the fourth embodiment of the invention;

0038<figref idrefs="S84">10</figref> on Block diagram schematically showing the overall arrangement of a communication system with packet transfer units according to the fifth embodiment, of the invention;

0039<figref idrefs="S85">11</figref> a View showing a concrete example of a network to an inventive packet transfer method briefly explain

0040<figref idrefs="S85">12</figref> a View showing an example of how data in an address table are stored in the transfer controller of a packet transfer unit is set;

0041<figref idrefs="S86">13</figref> on Block diagram showing the arrangement of the main part of a packet transfer unit according to the fifth embodiment of the invention;

0042<figref idrefs="S87">14</figref> on Flowchart for explaining the Multicast settings at the packet transfer unit in <figref idrefs="S86">13</figref>;

0043<figref idrefs="S86">15</figref> on Flow chart for explaining the Multicast settings at the packet transfer unit in <figref idrefs="S86">13</figref>;

0044<figref idrefs="S88">16</figref> on Flow chart for explaining the Multicast packet transfers at the packet transfer unit in <figref idrefs="S86">13</figref>;

0045<figref idrefs="S88">17</figref> on Block diagram showing the arrangement of a main part of a packet transfer unit according to the sixth embodiment of the invention;

0046<figref idrefs="S89">18</figref> on Flow chart for explaining the Multicast packet transfers at the packet transfer unit in <figref idrefs="S88">17</figref>;

0047<figref idrefs="S89">19</figref> on Block diagram showing another arrangement of the main part of the packet transfer unit according to the sixth embodiment shows;

0048<figref idrefs="S90">20</figref> on Flow chart for explaining the Multicast settings at a packet transfer unit according to the seventh embodiment the invention;

0049<figref idrefs="S91">21</figref> on Block diagram for explaining the Relationship between the packet transfer unit according to the seventh embodiment and an address management server;

0050<figref idrefs="S92">22</figref> on Flow chart for explaining the Multicast settings at a packet transfer unit according to the eighth embodiment, the invention;

0051<figref idrefs="S91">23</figref> on Block diagram showing an example of arrangement of an address management server;

0052<figref idrefs="S91">24</figref> a View showing an example of how data stored in a table are needed to address management by the address management server in <figref idrefs="S91">23</figref> is used;

0053<figref idrefs="S93">25</figref> on Block diagram illustrating a communication control apparatus according to the ninth embodiment of the invention;

0054<figref idrefs="S94">26</figref> on Block diagram illustrating a communication control apparatus according to the tenth embodiment of the invention;

0055<figref idrefs="S95">27</figref> a View showing terminals in groups within communicable Regions are formed;

0056<figref idrefs="S95">28</figref> a View showing a table between the communicable states the respective terminals indicates;

0057<figref idrefs="S96">29</figref> a View showing a table at terminals communicable the ninth embodiment shows;

0058<figref idrefs="S96">30</figref> a View the format of group information in the ninth embodiment shows;

0059<figref idrefs="S96">31</figref> a View a group information management table in the ninth embodiment shows;

0060<figref idrefs="S97">32</figref> a View showing the positions of terminals inside and outside a communicable area in the ninth embodiment shows;

0061<figref idrefs="S97">33</figref> a View showing a table at terminals communicable the tenth embodiment the invention specifies;

0062<figref idrefs="S97">34</figref> a View in the format of periodic group information the tenth embodiment shows;

0063<figref idrefs="S98">35</figref> on Flowchart showing a procedure by which a terminal Cn forms a group together with terminals C1 and C2;

0064<figref idrefs="S99">36</figref> on Flowchart showing a procedure by which a terminal C4 participates in a set group G1;

0065<figref idrefs="S100">37</figref> a flowchart showing a process, of conduct is when a Gruppeninformations management device <figref>614</figref> a terminal Cx receiving,

0066<figref idrefs="S100">38</figref> a flowchart showing a procedure, by the terminal Cx a group together with the terminals Cx, C1, X2 and X6 forms;

0067<figref idrefs="S101">39</figref> a flowchart showing a process, of conduct is when the terminal Cx periodic group of information terminals C2 and C5 receives.

0068<figref idrefs="S102">40</figref> is a block diagram showing a multicast communication control apparatus according to the eleventh embodiment of the invention;

0069<figref idrefs="S103">41</figref> is a block diagram showing a state, wherein the multicast communication control devices with an Multicast communication are connected;

0070<figref idrefs="S103">42</figref> a view showing a format that a Data packet and acknowledgment packets in the eleventh embodiment is common, and more specifically, a data packet from a Device A is transmitted to each element of the group 2;

0071<figref idrefs="S104">43</figref> a view receiving group table a for storing the maximum sequence numbers of the sequence numbers of data packets shows the continuously received from the respective devices are, and more precisely a table in the device A is set;

0072<figref idrefs="S105">44</figref> a view that the format of an acknowledgment packet and more specifically, one of the apparatus A to each element Group II transferred Package shows;

0073<figref idrefs="S106">45</figref> a view to a transfer group table Storing the maximum acknowledgment numbers, received from the respective devices, and more particularly said one set in the device A table shows;

0074<figref idrefs="S107">46</figref> a block diagram illustrating an arrangement of a multicast communication control apparatus according to the twelfth embodiment of the Invention; and

0075<figref idrefs="S108">47</figref> a view in a data packet format the twelfth embodiment and more particularly to a

0076data packet shows the transfer from a device A to each element of Group 2 is.

0077On Packet transfer system according to a embodiment the invention is related to <figref idrefs="S77">1</figref> described.

0078In <figref idrefs="S77">1</figref> is each of first to third segments a network or subnetwork when the network layer of the seven layer protocols OSI (Open System Interconnection) of view, in which one or a plurality of physical media (eg cable) through Repeater and bridges are connected. In other words, each segment is a network (Subnetwork) -Adressenversorgungseinheit and more specifically, an address management device on a Low-level layer.

0079If a packet transfer between connected to a segment terminal perform is a low-level layer address (For example, a MAC address (Media Access Control address)) is used, which is included in the header of a packet. When a packet transfer perform between terminals by a plurality of segments, introduces Router routing a packet with the high-level layer address (Eg an IP address in TCP / IP) by which one in the header is packet contain, and the packet is for the corresponding segment transferred.

0080In <figref idrefs="S77">1</figref> are an inter-segment exchange server <figref>1</figref>, A radio base station (BS) <figref>2</figref>Connecting a plurality of radio terminals, to enable them, to communicate with one another, and a router <figref>3</figref> with a Network X connected to the first segment as a Subnetzwerkadressen management device to form.

0081Of the Inter-segment exchange server (sometimes referred to as a Server referred) <figref>1</figref> has a function to manage the Subnetzwerkadressen the respective accommodated in the network terminal to X, and also has a function for communicating with a with another segment connected to server.

0082On Inter-segment exchange server <figref>5</figref> and an inter-segment exchange server <figref>6</figref>. which serve as a router, are connected to a network Y. The network Y is connected to the network through the router X <figref>3</figref> connected. The second segment as a further Subnetzwerkadressen management device by rout <figref>3</figref> and the servers <figref>5</figref> and <figref>6</figref>. which are connected to the network Y, together with a plurality of the servers <figref>5</figref> and <figref>6</figref> connected terminals educated.

0083Of the Inter-segment exchange server (sometimes referred to as a Server referred) <figref>5</figref> has a function to manage the Subnetzwerkadressen the respective accommodated in the network terminal to Y, and also has a function for communicating with a with another Segment connected to server.

0084A Radio base station <figref>7</figref>That a plurality of radio terminals houses, and a plurality of terminals are wired with the server <figref>6</figref> connected to the third segment as yet another Subnetzwerkadressen management device to form.

0085Of the router <figref>3</figref> and the server <figref>6</figref>, The routing function a have to be used to forward packets between the. first and third segments connected terminals to transfer.

0086<figref idrefs="S78">2</figref> shows schematically illustrates an example of the arrangement of an inter-segment exchange server (The Inter-segment exchange server <figref>1</figref> in <figref idrefs="S77">1</figref> becomes described as an example) according to the first embodiment.

0087In <figref idrefs="S78">2</figref> becomes the server <figref>1</figref> by a network information management section <figref>10</figref>. a network information processing section <figref>20</figref>and a communication interface section <figref>30</figref> educated.

0088at Receive information to control / manage the network, for example, the network configuration and the address, ie, a network management information containing tax package, passes the communication interface section <figref>30</figref> the contained in the control packet information to the network information processing section <figref>20</figref>, Of the Netzwerkinformations- processing section <figref>20</figref> leads a predetermined protocol processing for the information by and stores the network management information in the network information management section <figref>10</figref>,

0089If a request to transmit a control packet to another terminal, by a high-level processor, a user or the network information processing section <figref>20</figref> generated is, is necessary information from the network information management section <figref>10</figref> detected, and the request to transmit the control packet is supplied to the communication interface portion <figref>30</figref> output.

0090at are receiving the transfer request the communication interface portion <figref>30</figref> the tax package to the Network. In this case, when a target in must be the goal in the network information processing section <figref>20</figref> in and the communication interface section <figref>30</figref> transmits the packet with the added thereto Destination information based on the target marking.

0091If own segment network management information to a server has exchange in another segment, is necessary information of the network information management section <figref>10</figref> periodically or in response to a request from the high-level processor, the user or the network information processing section <figref>20</figref> detected. To the acquired information in accordance to transfer to an inter-segment packet transfer protocol, is a transfer based on the transfer protocol and destination information for one Packet transfer to a server in another segment or a Plurality of servers characterized in other segments, and resulting information is supplied to the communication interface portion <figref>30</figref> together conducted with the network management information.

0092at Reception of this information, generates the communication interface section <figref>30</figref> a Packet frame, based on the marked packet transfer protocol, stores the network management information in the payload and transmits the packet to the designated server or servers on one or a plurality of number of times in accordance with the number of marked locations.

0093<figref idrefs="S78">3</figref> shows an example of the detailed arrangement of the communication interface portion <figref>30</figref>, In <figref idrefs="S78">3</figref> includes the communication interface section <figref>30</figref> a Intra-segment communications processor <figref>301</figref>, An inter-segment communications processor <figref>302</figref>. a common communication interface <figref>301</figref>, An intra-segment communication interface <figref>312</figref> and an inter-segment communication interface <figref>313</figref>,

0094The Common Communication Interface <figref>311</figref> is used, if intra-segment communication and inter-segment communication with the same Communication device must be carried out. is example the common communication interface <figref>301</figref> an interface portion as a data link to the Ethernet equivalent is when the intra-segment packet transfer scheme on NetBEIU and Inter-segment packet transfer scheme on TCP / IP based.

0095If Intra- and inter-segment communications with different communication devices perform are, packet transfer is with the intra-segment communication interface <figref>312</figref> and Inter-segment communication interface <figref>313</figref> performed.

0096the Control packet containing the network management information and the common communication interface <figref>311</figref> or Intra-segment communication interface <figref>312</figref> Will be received, is a packet processing in the intra-Segment communication processor <figref>301</figref> subjected. The necessary information is then supplied to the network information processing section <figref>20</figref> passed, to be subjected to a protocol processing. As a result, the network management information is extracted and in the network information management section <figref>10</figref> stored. If network management information is transmitted is a packet generated and transmitted by a route, to the for is the above procedure reversed.

0097If exchange information with a server in another segment is a control packet containing network management information and the common communication interface <figref>311</figref> or Inter-segment communication interface <figref>312</figref> receive is, to the inter-segment communications processor <figref>302</figref> led to a packet processing subjected to be. The Inter-segment communications processor<figref>302</figref> passes the necessary information to the network information processing section <figref>20</figref>, The processing section <figref>20</figref> performs protocol processing for the received information through to the network management information to extract, and sends the information to the network information managing section <figref>10</figref>. to store it therein. If a network management information transferred to is, a packet is generated and by a reverse route to for the transferred above procedure.

0098A Procedure for exchanging network management information for terminals, which are housed in the respective segments, between the Servers with the above arrangement, and for sharing the Network management information between the respective servers next described.

0099<figref idrefs="S79">4</figref> is a schematic view for explaining the procedure for exchanging of network management information between segments. The first Segment is represented by terminals A, B and C and a server <figref>100</figref>. which has a routing function, formed. The second segment is through terminals D, E and F, a server <figref>101</figref> and a router <figref>102</figref> educated. It is assumed that the respective terminals in the first segment including the server <figref>100</figref> and the respective terminals in the second segment including the server <figref>101</figref> a TCP / IP communication to perform.

0100In this case, a table T1 in <figref idrefs="S79">4</figref> in the Network information management section <figref>10</figref> each server stored. The table T1 stores the segment identifiers (for Identifying the segments in which the respective terminals housed are), intra-segment address (for example, MAC addresses) and high-level-layer addresses (eg IP addresses) of in the respective segments accommodated terminals.

0101Each Server has network management information in said through the Collect server management segment. In this case also ARP (Address Resolution Protocol) are used. ARP resolves a MAC address with an IP address as a key on.

0102It Assume that the terminal A in the first segment of an IP packet has to be transmitted to the terminal B in the same segment, and that the A terminal the IP address (High-level layer address) of the terminal B has in advance, but not the MAC address (intra-segment address) of the terminal B has. In this case, the terminal A sends an ARP request within the segment in order to detect the MAC address of the terminal B (Step S1).

0103The broadcast ARP request is from all terminals in the first segment including the server <figref>100</figref> receive. The IP address of the terminal B is written to the ARP request. The terminal B determines of the broadcast ARP request that the MAC address of the own terminal is requested, and outputs the MAC address of the own terminal an ARP reply back to the terminal A. to the same time transfers the terminal B, the ARP response to the server <figref>100</figref> (Step S2).

0104at Detecting the MAC address of the terminal B stores the server <figref>100</figref> they temporarily in the in the network information management section <figref>10</figref> set Table T1.

0105By Repeat the above procedure, the network management information the respective accommodated in the first segment terminals in Table T1 registered in the network information management section <figref>10</figref> of server <figref>100</figref> is set.

0106If the IP address of the terminal that generated the request, in the table T1 of the server <figref>100</figref> is registered, the server <figref>100</figref> the table T1 look and an ARP reply response back to the ARP response, the first in the Segment was broadcast.

0107at the second segment is also network management information the respective accommodated in the second segment terminals in the table T1 stored in the network information management section <figref>10</figref> of Server is set in the same manner as above describes registered.

0108It Note that the server <figref>100</figref> and <figref>101</figref> Network management information exchange and each server, the network management information of the terminal extract in another segment and in its own table can register to the table T1 in <figref idrefs="S79">4</figref> to create.

0109Then perform the server <figref>100</figref> in the first segment and the server <figref>101</figref> in the second segment has a TCP / IP communication by, extract the network management information of the terminal in the respective segments of the in the network information management section <figref>10</figref> saved Tables, convert the information in control packets to and exchange them. (step S3)

0110at Receiving control packets from the servers in the respective segments extract the Server <figref>100</figref> and <figref>101</figref> the network management information of the control packets and register them in the tables T1, the in the network information management sections <figref>10</figref> adjusted are.

0111As result can the servers <figref>100</figref> and <figref>101</figref> the network management information all accommodated in the network terminal, the first through the and second segments are formed by use of the servers <figref>100</figref> and <figref>101</figref> set tables T1 manage.

0112It Note that when the server <figref>100</figref> and <figref>101</figref> Network management information have to collect from terminals in the through the Server-managed segments are housed, each server a ARP request itself can generate.

0113A Another procedure for exchanging network management information between segments is next regarding <figref idrefs="S80">5</figref> described.

0114The in <figref idrefs="S80">5</figref> Procedure shown is applied to a system, in which a unique intra-segment address in each segment itself is produced.

0115The Network management information (for example, the segment identifiers and the Intra-segment address (eg, the MAC address)) in the segment of the <figref>1</figref> accommodated Terminals A, B and C are determined by the server <figref>100</figref> managed. The network information management section <figref>10</figref> the server <figref>100</figref> has one in <figref idrefs="S80">5</figref> shown on table T2, wherein the network management information of the terminals A, B and C is registered. It should be noted that the table T2 does not always a storage box High-level-layer addresses (such as IP addresses) must have and such a field can be added as needed.

0116The Network management information (for example, the segment identifiers and the Intra-segment address (eg, the MAC address)) of the second segment in accommodated terminals D and E are determined by the server <figref>101</figref> managed. More precisely, the network information managing section <figref>10</figref> of server <figref>101</figref> one in <figref idrefs="S80">5</figref> shown Table T3, in which the network management information of the terminals D and E are registered. It should be noted that the table T3 is not always a memory box High-level-layer addresses (such as IP addresses) must have and such a field can be added as needed.

0117It Assume that when the terminal F to the second segment is reconnected, the terminal F, a control packet to the server <figref>101</figref> transfers, and the allocation of "#BB" as an intra-segment address to request (step S5).

0118at Receipt of this tax package exchanges the server <figref>101</figref> the Network management information of the terminal in the self-managed Segments and another segment to the server in the other Segment (the server <figref>100</figref> in the first segment in this Case), and checks if the intra-segment address "#BB" is used (step S6).

0119There the server <figref>101</figref> may determine that the intra-segment address "#BB" in the first segment is used, the server transmits <figref>101</figref> to the Terminal F, a control packet indicating that the intra-segment address "#FF" is assigned, to the repeated use of the same intra-segment address as the one terminal a is assigned to a different segment to prevent (step S7). It should be noted that, if it can be determined that the through not Terminal F requested address "#BB" is used, the address "#BB" assigned to the Terminal F is.

0120If the servers <figref>100</figref> and <figref>101</figref> the above procedure each Times repeated when a new terminal is connected to the Server gather network management information of the terminal, housed in the managed by the respective server segments are.

0121As is described above, when the new terminal F intra-segment address has to be determined in the second segment, a unique intra-segment address by exchanging network management information between the servers <figref>100</figref> and <figref>101</figref> be determined, the first and second segments are considered to be one segment.

0122If the server in each segment an address a newly-connected terminal zuzuweisen has, the server can, for example, by an address generate random numbers, and other servers on the contact details. In this case, if this address does not in other segments is used, the address as a unique address anywhere in the segments considered and assigned to the new terminal.

0123It Assume that network management information between the exchanged and determined servers in a plurality of segments is that an intra-segment address, which is used in a given segment, in another Segment is used. In this case, the server can in the given Segment the appropriate server the appropriate information notified as a control packet. In this case, the server that transfer the tax package has repeatedly perform the following procedure: Replacing the repeated Address with a different address to the repeated use To prevent the same address, and replace the network management information with other servers.

0124Still another procedure for exchanging network management information between segments is next regarding <figref idrefs="S81">6</figref> described.

0125It Suppose; that the radio terminal A physically in the first Segment is connected by a radio communication network. In this Case receives, when a data link protocol starts to automatically remaining with the Terminals B and C communicate, to an intra-segment address and the like set, the server <figref>100</figref> a package, which is used with the remaining terminals in the first Segment to communicate (a conventional package for requesting an intra-segment address "#AA" that only in is used to segment, if the server <figref>100</figref> available is) (step S10), and transfers the received packet as a Control packet to the server (a server <figref>103</figref> in this case) in another segment (step S11).

0126Of the server <figref>103</figref> provides the received packet to the control terminal D, E and F (in the second segment) (step S12). In this case the server can control packet broadcast.

0127Subsequently an address assignment in the same manner performed.

0128As is described above, even when the first and second segments are separated from each other when their high-level layers together are connected, address setting and packet transfer with the two Segments are carried out, which are regarded as one segment.

0129If For example, the terminal A in the first segment a tax package outputs as an ARP request in an Internet environment, in of the respective segments are connected by routers, as above described (step S10), the server receives <figref>100</figref> the Control packet and transfers it to the server <figref>103</figref> in a another segment (step S11). The server<figref>103</figref> broadcasts then the control packet in the second segment (step S12). If the corresponding terminal responds to this packet, a control packet transferred as an ARP response to the server that sent the above control packet, ie the server <figref>100</figref>, registered Upon receipt of this ARP response, the server <figref>100</figref> the corresponding information in the in the network information management section <figref>10</figref> set Table.

0130With the above procedure for exchanging network management information between segments using the Server <figref>100</figref> and <figref>101</figref> the Network management information of all terminals together with are connected to the respective segments.

0131If each terminal a communication packet of general user data by using the intra-segment address transferred to has monitored the servers <figref>100</figref>. <figref>101</figref> and <figref>103</figref> in the Segments intra-segment address of transmitted by the respective segments communication packets.

0132at each server receiving the communication packet refers to the Table T1, T2 or T3, which in the network information management section <figref>10</figref> saved are to check, whether the intra-segment address of the communication packet to a terminal is addressed in another segment. When the intra-segment address is addressed to a terminal in another segment, the communication packet is to the server in the corresponding segment or the servers in all remaining segments transferred. Upon receipt of this transferred Communication packet, the server refers to the table T1, T2 or T3, which in the network information management section <figref>10</figref> saved are to the high-level-layer address of Inter-segment address regain, and transferred the Communication packet to the appropriate terminal.

0133As described above according to the first embodiment Inter-segment communications readily as intra-segment communication exchanging network management information by a Inter-segment protocol is managed, clotting by a simple procedure withger setting load can be realized to the user, between the servers in a plurality of segments are performed.

0134In addition, when the speed of the inter-segment communications higher than the intra-segment communication is, the protocol processing load can be reduced in a server, and an early Network Information coincidence can between all servers assigned by directly transferring a control packet rather than the processing of Inter-Segment Information in each server, and again to transfer the resulting information can be realized.

0135In addition, by transferring information packets through the same scheme as that for the control information sharing and downsizing the apparatus can be realized.

0136On Inter-segment exchange server according to the second embodiment will be described next, by the server in <figref idrefs="S77">1</figref> as an example with reference on <figref idrefs="S82">7</figref> is taken.

0137In <figref idrefs="S82">7</figref> extracted upon receipt of a control packet a communication interface section <figref>31</figref> necessary Information from the control packet and forwards the information to a Network information processor <figref>21</figref>, This information is arranged in order of arrival in a queue. When a request to transmit a control packet, by a high-level processor, a user or a network information processing section <figref>20</figref> With Relative to another terminal at the arrival of the control packet is generated, a request, a control packet to the network transferred to, to the communication interface portion <figref>31</figref> output. Upon receiving the transfer request are the communication interface section <figref>31</figref> the tax package to the Network. In this case, when a target in must be a target marking by the network information processor <figref>20</figref> reliant, and the communication interface section <figref>31</figref> transmits the packet with added thereto Destination information in accordance with the statement.

0138If Network management information is exchanged between servers, for example, packets in an inter-segment communications processor <figref>304</figref> in Units of target servers placed in a queue. If a request for transmission to another server through a high-level processor, User or network information processor <figref>21</figref> is produced, this information is formed in one or a plurality of packets. The packet or packets are then added to the identified Server or servers as the objectives of one or a plurality of number of Draw in accordance transmitted with the number of targets.

0139As is described above, according to the second embodiment, when the speed of the inter-segment communications lower than the the intra-segment communication is, within a segment exchanged packets directly to a other segment transferred. With this operation, a plurality transmitted packages together, to reduce the number of packets between the segments be transferred, whereby the transmission efficiency improves is.

0140<figref idrefs="S83">8th</figref> shows another arrangement of inter-segment exchange server according to the third embodiment. The same reference numerals in <figref idrefs="S83">8th</figref> describe the same parts as in <figref idrefs="S78">2</figref>And only a different section will be described below. at the in <figref idrefs="S83">8th</figref> shown arrangement is a compression compressor <figref>40</figref> at the output side of a communications interface section <figref>30</figref> arranged, transfer of the packets to the network will. With this arrangement, packets in data compression transmitted as needed. When receiving a packet from the network to the compression processor checks <figref>40</figref>. whether the packet is a compressed packet. If the packet is a compressed Package, decompresses the compression processor <figref>40</figref> the Packet and forwards the resulting data to the communication interface portion <figref>30</figref>,

0141As is described above, according to the third embodiment, when the speed of the inter-segment communications lower than the the intra-segment communication is transmitted packets in the data compression to reduce the packet length, whereby the transfer efficiency improved compared with the case is where exchanged within the segment packets transferred directly will.

0142<figref idrefs="S83">9</figref> shows yet another arrangement of the Inter-segment exchange server according to the fourth Embodiment. The same reference numerals in <figref idrefs="S83">9</figref> describe the same parts as in <figref idrefs="S78">2</figref>And only a different section will be described below. at the in <figref idrefs="S83">9</figref> shown arrangement is a Chiffrierprozessor <figref>50</figref> at the output side of a communications interface section <figref>30</figref> arranged, transfer of the packets to the network will. With this arrangement, packets are transmitted as needed, after they are encrypted. When receiving a packet from the network determines the Chiffrierprozessor <figref>50</figref>Whether the packet is a Chiffrierpaket is. If the packageis Chiffrierpaket, decodes the Chiffrierprozessor <figref>50</figref> the Packet and forwards the resulting data to the communication interface portion <figref>30</figref>,

0143As is described above, according to the fourth embodiment, if there is a possibility for tapping information at the inter-segment communications are, data encrypted and exchanged between servers to Mysteries to keep between the segments, which improves safety is.

0144According to the above embodiment of the invention there are provided a packet transfer method and system, the Inter-Network communication in the same manner as Intra-network communication when transferring packets between Terminals can achieve through a plurality of networks.

0145On Communications system having a packet transfer unit according to the fifth embodiment of the Invention is related to <figref idrefs="S84">10</figref> described.

0146In <figref idrefs="S84">10</figref> are a packet transfer unit <figref>410</figref>, A radio base station (BS) <figref>411</figref>. an address management server <figref>412</figref> and a plurality of wired terminals <figref>413-1</figref> to <figref>413-n</figref> with a network <figref>401</figref> connected. A plurality of radio terminals<figref>414-1</figref> to <figref>414-n</figref> are communicatively coupled to the radio base station <figref>411</figref> connected.

0147The Packet transfer unit <figref>410</figref> is also connected to a network <figref>402</figref> connected.

0148A Plurality of wired terminals <figref>420-1</figref> to <figref>420-n</figref> and a packet transfer unit <figref>421</figref>Which also serves as an address management server, are connected to the network <figref>402</figref> connected. The packet transfer unit<figref>421</figref> is also with a network <figref>403</figref> connected.

0149A Plurality of wired terminals <figref>432-1</figref> to <figref>432-n</figref> is to the network <figref>403</figref> by a stroke <figref>431</figref> connected. A radio base station <figref>433</figref> is also connected to the network <figref>403</figref> connected. A plurality of radio terminals <figref>434-1</figref> to <figref>434-n</figref> communicatively with the radio base station <figref>433</figref> connected.

0150Each the networks <figref>401</figref>. <figref>402</figref> and <figref>403</figref> serves as a a network segment (hereinafter simply referred to as a segment hereinafter) as an address management device for a data link (low-level layer). Packets are transferred by use of addresses in manages the respective segments.

0151Even when the networks <figref>401</figref>. <figref>402</figref> and <figref>403</figref> different use low-level layer protocols, can the wired terminal <figref>4013-1</figref> to <figref>413-n</figref>. the wireless terminals <figref>414-1</figref> to <figref>414-n</figref>Who wired terminals <figref>420-1</figref> to <figref>420-n</figref>, The wired terminal <figref>432-1</figref> to <figref>432-n</figref> and the wireless terminals <figref>434-1</figref> to <figref>434-n</figref> together with a high-level protocol (TCP / IP according to the fourth and third layers of the OSI (Open System Interconnection)) communicate.

0152Each Radio base station serves as a wireless bridge. For example, is any Packet transfer unit as a router on the Internet.

0153On Packet transfer method of this embodiment is briefly next described.

0154It Assume that in a network, as a segment that the in <figref idrefs="S85">11</figref> An arrangement shown in the terminal X, A, D, C, D, E and F are housed, a multicast setting at a low-level layer with respect to the specific terminal x, A, B and C with the low-level layer (Data Link) multicast address is "123" performed. In this case, for example, a notification of completion the multicast setting to the terminal X through the high-level layer Posted. Upon receiving this notification, the terminal generates X is a high-level-layer address (such as a multicast address, or Unicast address of IP) or assigns it to and stores the resultant Data.

0155<figref idrefs="S85">12</figref> shows a detailed example of the data stored in the terminal X address table. In this address table high-level layer addresses are in are the high-level layer address field stored, and low-level layer addresses in the low-level layer address field in correspondence with the high-level layer addresses stored. is In the low-level layer address field additional Information, such as multicast / unicast type data and terminal ID data (X, A, B, C) is also saved.

0156The Terminals X, A, B and C control the packet transfer by reference to Such address tables.

0157It Assume that in an Internet environment "133. 198. 81. 3" as a high-level-layer address assigned to specific terminals x, A, B and C for multicasting is. In this case passes on receipt of a notification of the Transfers "133rd 198. 81. 3 "of a high-level layer over an Internet protocol, the terminal X a packet to a low-level layer, the transfer address "123" of the low-level layer added is. Upon receipt of this package, the low-level layer transferred the received packet to the Terminals A, B and C according to the Transfer address "123".

0158The settings multicasting are in the terminals A, B and C, and also in Terminal X performed. Each terminal then generates an address similar to the Table in <figref idrefs="S85">12</figref> shown and stores. In the low-level multicast setting , a single terminal (eg, the terminal X) inform the high-level multicast setting, a high-level layer address to create. In this case, the terminal X transfers the high-level multicast information (Address "133. 198th 81. 3 "and additional Information in this case) to the remaining terminals as the Objectives of the multicasting (Terminals A, B and C in this case). Upon receiving the high-level multicast information stores each the terminals A, B and C, the information in the address table a transfer controller <figref>501</figref>, Each of the terminals X, A, B and C controls the packet transfer by referring to the address table.

0159It Assume that none of the terminals has a function of generating having a high-level layer address. In this case, if sends the multicast setting is carried out with reference to the specific terminals X, A, B and C having the multicast address "123", the terminal X a notification of completion of the multicast setting to the high-level layer. generates Upon receiving this notification the high-level layer, a request to a multicast address to detect the high-level layer in the specific address management server or broadcasts a request to a multicast address of to capture high-level layer.

0160If a multicast address from a given address management server returned is, the terminal stores X it in the above table of addresses in correspondence with a low-level layer address. In this case is when the remaining terminals as the objectives of multicasting not the low-level multicast setting is informed that received High-level multicast information to these terminals as the targets multicasting transferred. Upon receiving the high-level multicast information stores each of the remaining terminals them in their own Address table.

0161The Assembly and operation of the packet transfer unit of the invention is next described.

0162<figref idrefs="S86">13</figref> shows shows schematically the arrangement of the main part of the packet transfer unit according to the fifth embodiment. This arrangement is in the packet transfer units <figref>410</figref> and <figref>421</figref>. the wired terminal <figref>413-1</figref> to <figref>413-n</figref>, the wireless terminals <figref>414-1</figref> to <figref>414-n</figref>Who wired terminals <figref>420-1</figref> to <figref>420-n</figref>, The wired terminal <figref>432-1</figref> to <figref>432-n</figref> and the wireless terminals <figref>434-1</figref> to <figref>434-n</figref> in <figref idrefs="S84">10</figref> applied. It should be noted that the arrangement does not wired to all and must be radio terminals applied.

0163In <figref idrefs="S86">13</figref> becomes the packet transfer unit mainly through the transfer controller <figref>501</figref>, A multicast communication interface <figref>502</figref> and an address management device <figref>503</figref> educated.

0164Of the transfer controller <figref>501</figref> includes an address table similar to the in <figref idrefs="S85">12</figref> shown. When receiving a high-level package of a user, a high-level application protocol or the like proposes the transfer controller <figref>501</figref> the address table gradually provides a low-level layer address by the data written to the high-level package High-level layer address restores adds the low-level layer address to the packet added and transfers the packet to the multicast communication interface <figref>502</figref>. when a multicast communication perform is. The low-level-layer address appropriate high-level layer address is the address management device <figref>503</figref> set. In contrast, the transfer controller <figref>501</figref> a Function of transferring a packet on which of the multicast communication interface <figref>502</figref> received and to own the user's terminal, the high-level application protocol or the like is addressed.

0165at the multicast communication interface <figref>502</figref> is a Low-level multicast or unicast setting by the user or the high-level application protocol, ie the own terminal, or with a control packet from the multicast communication interface another terminal performed. This means, if the multicast setting is performed such that the multicast communication interface <figref>502</figref> a Low-level multicast address and additional Information to the address management device <figref>503</figref> transferred. If the multicast communication interface <figref>502</figref> an information packet, to which the self-managed low-level layer address is added, from the transfer controller <figref>501</figref> receives, sends the interface <figref>502</figref> the Packet to the network. In contrast, transferred when a addresses received from the network information packet to the own terminal is the multicast communication interface <figref>502</figref> the Packet to the transfer controller <figref>501</figref>,

0166at Receiving a low-level multicast Einstellbenachrichtigung and the low-level multicast address of the multicast communication interface <figref>502</figref> generated the address management device <figref>503</figref> a correspondingly High-Level-layer address and transfers the address and additional information about the transfer controller <figref>501</figref>, The address management device<figref>503</figref> transferred the high-level multicast address information to the specific terminal as the objectives of multicasting as needed.

0167Of the Operation of the packet transfer unit in <figref idrefs="S86">13</figref> becomes next with reference to the flowcharts of <figref idrefs="S87">14</figref> to <figref idrefs="S88">16</figref> described.

0168In <figref idrefs="S87">14</figref> becomes, when a multicast communication setting at the low-level layer with respect to a plurality of specific Terminals by users of a specific or any type of terminal by the multicast communication interface <figref>502</figref> marked is, the address management device <figref>503</figref> the set information including a low-level multicast address notified (step A1).

0169at Receiving the set of information of multicast communication on the low-level layer and the multicast communication interface <figref>502</figref> generated the address management device <figref>503</figref> according to a high-level layer address the low-level multicast address, and transfers high-level multicast information including the generated high-level multicast address to the transfer controller <figref>501</figref> together with the low-level multicast information including the low-level multicast address (Step A2).

0170at Receiving the high-level multicast information and the low-level multicast information stores they transfer controller <figref>501</figref> similarly in an address table of in <figref idrefs="S85">12</figref> shown (step A3).

0171If it is determined that the high-level multicast information and the low-level multicast information transferred to the remaining terminals as targets of multicasting must be forwarded the transfer controller, this information on the multicast communications interface <figref>502</figref>. to transfer it (step A4).

0172<figref idrefs="S86">15</figref> shows the operation of each of the terminals A, B and C as the objectives of the multicasting in <figref idrefs="S85">11</figref> in a case where, for example, the low-level multicast information and the high-level multicast information by the terminal X in <figref idrefs="S85">11</figref> are set, made in packages and of the multicast communication interface <figref>502</figref> to the Terminals A, B and C in accordance with the flow chart of <figref idrefs="S87">14</figref> transferred will.

0173In <figref idrefs="S86">15</figref> extracted, when each of the terminals A, B and C in <figref idrefs="S85">11</figref> on Multicast Einstellbenachrichtigungspaket with the low-level multicast information and the high-level multicast information from the terminal X receives (Step B1), each terminal high- and low-level multicast addresses of the packet and forwards the address to the transfer controller <figref>501</figref>, Upon receipt of the address information it stores the Transfer Controller in the in <figref idrefs="S85">12</figref> shown Address Table (Step B2).

0174With the in the flow charts of <figref idrefs="S87">14</figref> and <figref idrefs="S86">15</figref> shown operations are the high-level layer address, the corresponding low-level layer address, the additional information and the like, in the address table of each of the terminals as the Objectives of the multicasting registered (for example, the terminals X, A, B and C in <figref idrefs="S85">11</figref>).

0175Of the Operation of each terminal (for example, the terminals X, A and B, and C in <figref idrefs="S85">11</figref>) to be performed, if an actual Data user packet is multicast, is on next with reference <figref idrefs="S88">16</figref> described.

0176In <figref idrefs="S88">16</figref> on receiving a by a high-level multicast address addressed user information packet (step C1) of the Transfer Controller <figref>501</figref> a Low-level multicast address corresponding to the high-level-layer address (Step C2), and transfers a packet to the multicast communication interface <figref>502</figref> after add Transfer of information, including the low-level multicast address to the header of the packet, or transferred the package itself and the transfer of information, including the low-level multicast address to the multicast communication interface <figref>502</figref> as answer in different directions, whereby the above data to the be transferred destinations (step C3).

0177In <figref idrefs="S85">11</figref> passes For example, in an Internet environment, in an Internet Protocol at the high-level layer operates when the transfer controller <figref>501</figref> the terminal X a at "133rd 198.81. 3 "addressed Transfer notification from the high-level layer in the Internet protocol receives the transfer controller <figref>501</figref> the received data to the low-level layer by adding the low-level multicast address "123" to the data. at Receiving these data transfers the low-level layer, the corresponding Packets to the terminals A, B and C in accordance with the address "123".

0178at the above multicast setting, for example, the terminals X, A, B and C as the objectives of the multicasting in the network as a segment in <figref idrefs="S85">11</figref> a terminal that configured is to have only the in <figref idrefs="S87">14</figref> shown perform operation, a terminal that is configured to only the in <figref idrefs="S86">15</figref> shown perform operation, and a terminal that is configured to both the processes in <figref idrefs="S87">14</figref> as also <figref idrefs="S86">15</figref> perform, exhibit.

0179<figref idrefs="S88">17</figref> shows shows schematically the arrangement of the main part of a packet transfer unit according to the sixth embodiment, for example, the packet transfer units <figref>410</figref> and <figref>421</figref> in <figref idrefs="S84">10</figref> applied is.

0180In <figref idrefs="S88">17</figref> becomes the packet transfer unit mainly by transfer controller <figref>501</figref>A multicast communication interface <figref>502</figref>. an address management device <figref>503</figref> and a network interface <figref>504</figref> educated.

0181Of the transfer controller <figref>501</figref>, The multicast communication interface <figref>502</figref> and the address management device <figref>503</figref> are identical to the transfer controller <figref>501</figref>, The multicast communication interface <figref>502</figref> and the address management device <figref>503</figref> in the fifth embodiment and thus the description thereof is omitted.

0182The Network interface <figref>504</figref> performs communication processing equivalent the same layer as that of the multicast communication interface <figref>502</figref> by. Specifically transferred the network interface <figref>504</figref> on from the transfer controller <figref>501</figref> , transferred to to package a network with β a protocol that differs from that used by a network α is, in contrast to the multicast communication interface <figref>502</figref>. which transfers the packet to the network α.

0183If For example, the transfer controller <figref>501</figref> a network layer is, on the Internet a protocol operates is the multicast communication interface <figref>502</figref> a Data Link Layer equivalent the MAC of a wireless LAN, and the network interface <figref>504</figref> is a data link layer equivalent the MAC of the Internet.

0184Data, in the low-level layer address of the file in the transfer controller <figref>501</figref> set Address table to be stored, are not on the actual Low-level layer addresses limited, and can Identification data for identifying each terminal and a Network (segment) may be in which each terminal is housed. In the following description, these data are referred to as target data designated. If any Transfer Controller<figref>501</figref> identification data restoring for identifying each terminal requires the Multicast communication interface <figref>502</figref> and the network interface <figref>504</figref> a table for restoring a actual Low-level layer address by the identification information of terminals.

0185It Note that the radio base station <figref>411</figref> in <figref idrefs="S84">10</figref> the Packet transfer unit with the in <figref idrefs="S88">17</figref> shown may comprise arrangement.

0186Of the Operation of the packet transfer unit in <figref idrefs="S88">17</figref> becomes next described. A multicast setting is the same way and manner as with respect to <figref idrefs="S87">14</figref> and <figref idrefs="S86">15</figref> described performed.

0187<figref idrefs="S89">18</figref> is a flow chart for explaining an operation that perform is when a high-level multicast packet Will be received.

0188at Receiving a high-level multicast packet through the own Terminal generated and transferred by a high-level protocol (step D1) proposes, the transfer controller <figref>501</figref> the address table for that in the transfer controller <figref>501</figref> is set, and in <figref idrefs="S85">12</figref> shown is to low-level destination information by the high-level address (multicast restore or unicast address) written in the packet is. If the recovered low-level objective information to the addressed network β is, the packet to the network interface <figref>504</figref> transferred. Upon receipt of this package is the network interface <figref>504</figref> the transferred packet to the network in accordance β from the low-level layer address, by the network interface <figref>504</figref> is managed (Steps D2 and D3).

0189at Receiving a packet from the network β by the multicast communication interface <figref>502</figref> (Step D1) proposes the transfer controller <figref>501</figref> the address table according to Low-level target information through the spelled in the packet destination address restore. If the recovered low-level destination information addressed α to the network is, the packet to the multicast communication interface <figref>502</figref> transferred. Upon reception of the transferred packet is the multicast communication interface <figref>502</figref> the Packet to the network in accordance α with by the multicast communication interface <figref>502</figref> managed Low-level layer address out. When a plurality of destination addresses from the address table is restored, that is, a multicasting should be carried out, is the multicast communication interface <figref>502</figref> the Packet to the network in accordance α from the low-level multicast address to the package of at any to transfer corresponding terminals (steps D2 and D3).

0190at Receiving a packet from the network β by the network interface <figref>504</figref> (Step D1) refers to the transfer controller <figref>501</figref> to the address table, to the low-level target information by restore the spelled in the packet destination address. If the recovered addressed low-level target information to the network α is, the packet to the multicast communication interface <figref>502</figref> transferred. Upon reception of the transferred packet is the multicast communication interface <figref>502</figref> the Packet to the network in accordance α with by the multicast communication interface <figref>502</figref> managed Low-level layer address out. When a plurality of destination addresses from the address table is restored, that is, a multicasting should be carried out, is the multicast communication interface <figref>502</figref> the package to the network in accordance α from the low-level multicast address to the package of at any to transfer corresponding terminals (steps D2 and D3).

0191<figref idrefs="S89">19</figref> shows an example of an arrangement of a packet transfer unit including a Plurality of network interfaces <figref>504</figref>, Each with the in <figref idrefs="S88">17</figref> are shown identical. When the packet transfer unit α with different networks, β and γ in this Fashion is connected, can the network interface <figref>504</figref> in correspondence with the respective networks are arranged. More specifically, the Multicast communication interface <figref>502</figref> With the transfer controller <figref>501</figref> connected, so that the received Information first to the transfer controller <figref>501</figref> transferred is. The transfer controller<figref>501</figref> then refers to similarly an address table the in <figref idrefs="S85">12</figref> shown to the information to the network interface <figref>504</figref> and the multicast communication interface <figref>502</figref>, the the respective high-level destination addresses corresponding to transfer. These interfaces provide the information to the respective networks in accordance with managed by the respective interfaces for low-level layer addresses out.

0192In this case can the networks α, β and γ different use protocols or the same protocol. If the networks use the same protocol, it is sufficient if the networks are physically separated, for example, physically different cable.

0193A Packet transfer unit according to the seventh embodiment is next described. Since the circuit arrangement of this embodiment, same as that in <figref idrefs="S88">17</figref> is shown, this packet transfer unit regarding <figref idrefs="S88">17</figref> described.

0194For example is this embodiment has the packet transfer unit <figref>410</figref>, The wired terminal <figref>413-1</figref> to <figref>413-n</figref>. the wireless terminals <figref>414-1</figref> to <figref>414-n</figref>Who wired terminals <figref>420-1</figref> to <figref>420-n</figref>, The wired terminal <figref>432-1</figref> to <figref>432-n</figref> and the wireless terminals <figref>434-1</figref> to <figref>434-n</figref> in <figref idrefs="S84">10</figref> applied. It should be noted that the embodiment not applied to all wired terminals and wireless terminals must become.

0195In <figref idrefs="S88">17</figref> becomes the packet transfer unit mainly by transfer controller <figref>501</figref>A multicast communication interface <figref>502</figref>. an address management device <figref>503</figref> and a network interface <figref>504</figref> educated.

0196Of the transfer controller <figref>501</figref> similarly has an address table of in <figref idrefs="S85">12</figref> shown on. When receiving a packet from a user, a high-level application protocol or the network interface <figref>504</figref> refers to the transfer controller <figref>501</figref> on the address table and provides a low-level layer address corresponding the written in the package high-level layer address restores adds the low-level layer address to the package, and transfers the packet to the multicast communication interface <figref>502</figref> and the network interface <figref>504</figref>, In contrast, the transfer controller <figref>501</figref> a function for transferring a package on which of the multicast communication interface <figref>502</figref> receive and addressed to the own terminal, to the user, the high-level application protocol or the like.

0197at the multicast communication interface <figref>502</figref> will the Low-level multicast or unicast setting by the user or the high-level application protocol, ie the own terminal, or with a control packet of the multicast communication interface another terminal performed. More specifically, transferred, when a multicast adjustment is performed, the Multicast communication interface <figref>502</figref> a low-level multicast address, and additional Information about the address management device <figref>503</figref>, If the multicast communication interface <figref>502</figref> on Information packet to the self-managed low-level layer address added is, from the transfer controller <figref>501</figref> receives is the interface <figref>502</figref> it to the Network. In contrast to transferred when a signal received from the network information packet is addressed to the own terminal, the multicast communication interface <figref>502</figref> the Packet to the transfer controller <figref>501</figref>,

0198at Receiving a low-level multicast Einstellbenachrichtigung of the multicast communication interface <figref>502</figref> adds the address management device <figref>503</figref> the High-level layer address a specific device (eg the address management server <figref>412</figref> in <figref idrefs="S84">10</figref>) added to a multicast address acquisition request, attached to the specific device is addressed, and transfers the resulting Request to the Transfer Controller <figref>501</figref>To a high-level multicast address produce. When the transfer controller<figref>501</figref> results Address acquisition request from the multicast communication interface <figref>502</figref> and the Network interface <figref>504</figref> receives the results are transferred. The pair of high-level layer address in the Results is written, and low-level layer address of the corresponding Terminals, in the address management apparatus <figref>503</figref> saved is, will the transfer controller <figref>501</figref> along with additional Information transferred. The high-level multicast address information is according to specific terminals as the objectives of multicasting transferred needs.

0199The Network interface <figref>504</figref> performs communication processing by which the same layer as that of the multicast communication interface <figref>502</figref> equivalent to is. The network interface<figref>504</figref> receives an information packet, to which the self-managed low-level layer address is added, from the transfer controller <figref>501</figref> and outputs the packet to the Network. Unlike transferred to when a from the network addressed received information packet to the own terminal is, the network interface <figref>504</figref> the packet to the transfer controller <figref>501</figref>,

0200Of the Operation of the packet transfer unit of the seventh embodiment is next with reference to the block diagram of <figref idrefs="S88">17</figref> and the flowchart of <figref idrefs="S90">20</figref> described.

0201If a low-level multicast communication setting with respect to a plurality of specific terminals by multicast communication interface <figref>502</figref> performed or a low-level multicast communication setting by the user a specific or arbitrary terminal is in is the address management device <figref>503</figref> the Einstellabschlussinformation including the low-level multicast address communicated (step E1).

0202at Receiving information indicating the completion of the low-level multicast communication setting of the multicast communication interface <figref>502</figref> indicates adds the Address management device <figref>503</figref> the high-level layer address of a specific device, called an address management server, the associated α to a network is added to a high-level layer address acquisition request and transfers the resulting request to the Transfer Controller <figref>501</figref>, around outputting the request to the specific device to a according to high-level layer address to produce the low-level multicast address (step E2).

0203<figref idrefs="S92">22</figref> shows the relationship between a packet transfer unit <figref>410</figref> and an address management server <figref>412</figref>, The address management server<figref>412</figref> has corresponding to a function for generating a high-level-layer address the low-level multicast address upon receiving the multicast address acquisition request and a function for transmitting the result to the request source.

0204In <figref idrefs="S90">20</figref> receives the transfer controller <figref>501</figref> a packet the address acquisition request includes corresponding result, by the multicast communication interface <figref>502</figref> or the network interface <figref>504</figref> and transferred to the package the address management device <figref>503</figref> (Step E3) The Address management device <figref>503</figref> extracted by the address management server generated high-level layer address of the packet and transfers the high-level-layer address and the low-level-layer address of the corresponding terminals, in the address management apparatus <figref>503</figref> saved are, as a pair to the transfer controller <figref>501</figref> together with additional Information. Upon receipt of the above address information stores the transfer controller <figref>501</figref> In the address table (step E4).

0205The High-level multicast information and the low-level multicast information are added to the multicast communication interface <figref>502</figref> passed, them to other terminals as targets of multicasting as needed to transfer (step E5).

0206at Receive Multicast Einstellbenachrichtigungspakets with the low-level multicast information and the high-level multicast information by the processing be transferred at step E5 (step E6), extracts the Multicast communication interface <figref>502</figref> of the low-level layer address corresponding terminals the high- and low-level multicast addresses from the packet and directs it to the transfer controller <figref>501</figref>, Upon receiving the above address information it stores the Transfer Controller in the in <figref idrefs="S85">12</figref> shown Address Table (Step E7).

0207at Receiving a packet whose destination by a high-level layer address by a user, the multicast communication interface <figref>502</figref> or the network interface <figref>504</figref> is in gets the Transfer Controller <figref>501</figref> according to a low-level multicast address the high-level-layer address of the address table and transferred the packet to the multicast communication sections <figref>502</figref> With Transfer information containing the added to the header of the packet low-level multicast address to which to transfer packet to its destination. Alternatively transferred the Transfer Controller<figref>501</figref> the contained package itself and the low-level multicast address Transfer information in response to different instructions.

0208If addressed the package to a network β is, is that of the high-level layer address corresponding low-level multicast address obtained from the address table, and the packet is transmitted to the network interface <figref>504</figref> With the transfer information transferred ,, the to the header of the Package added contains low-level multicast address to to transfer the packet to its destination. Alternatively, the contained package itself and the low-level multicast address Transfer of information transferred in response to different instructions.

0209A Packet transfer unit according to the eighth embodiment, is next described. The circuit arrangement of this embodiment is the same as in the <figref idrefs="S88">17</figref> shown and is thus related on <figref idrefs="S88">17</figref> described.

0210The same reference numerals in the eighth embodiment denote the same Parts as in the seventh embodiment and only a different portion will be described. The eighth embodiment differs in operation of the address management device of the seventh embodiment <figref>503</figref>,

0211at Receiving a low-level multicast Einstellbenachrichtigung of a multicast communication interface <figref>502</figref> adds an address management device <figref>503</figref> a High-level broadcast address added to an address acquisition request and transferred the Request to transfer controller <figref>501</figref>To the request output to a high-level layer address to create. When the transfer controller<figref>501</figref> the result the address detecting a multicast communication interface <figref>502</figref> or a network interface <figref>504</figref> receives, the result is transferred. In order of arrival or under a predetermined condition are the high-level layer address written in the result is, and the low-level-layer address of the corresponding terminals, in the address management apparatus <figref>503</figref> saved are, as a pair to the transfer controller <figref>501</figref> together with additional Information transferred. The high-level multicast address information is transferred to a specific terminal as needed.

0212Of the Operation of the packet transfer unit according to the eighth embodiment, is next with reference to the flowchart of <figref idrefs="S92">22</figref> described. The same reference numerals in <figref idrefs="S92">22</figref> describe the same parts as in <figref idrefs="S90">20</figref> and only a different portion will be described. the called, that steps E2 and E3 in <figref idrefs="S90">20</figref> with steps E10 and E11 in <figref idrefs="S92">22</figref> be replaced.

0213at Step E10 is the address management device <figref>503</figref>. the low-level multicast communication setting information of the multicast communication interface <figref>502</figref> has received, an instruction to broadcast an address acquisition request packet the transfer controller <figref>501</figref> out to a high-level layer address acquisition request outputting, to produce a high-level-layer address. The broadcast Multicast address acquisition request packet from a server received the present on the network and the address management server <figref>412</figref> in <figref idrefs="S91">21</figref> equivalent to is. The server then generates a high-level-layer address corresponding to the low-level multicast address, and transmits the result to the request source.

0214at Step E11 transferred on reception of a packet, the result of the the address acquisition request, by the multicast communication interface <figref>502</figref> or the network interface <figref>504</figref> contains, the transfer controller the packet to the address management device <figref>503</figref>, In this case can returned results of a plurality of address management servers will. In this case, one of a plurality of calculation results as a result, information based on a predetermined rule, for example, the order of arrival, used.

0215<figref idrefs="S91">23</figref> shows the main part of the arrangement of the address management server <figref>412</figref> (please refer <figref idrefs="S91">21</figref>) the seventh and eighth in the above embodiments is used. Upon receiving an address acquisition request from another terminal generates the address management server <figref>412</figref> a according to high-level layer address the low-level multicast address, and transmits the high-level-layer address to the request source.

0216The in <figref idrefs="S91">23</figref> Arrangement shown is the address management server <figref>412</figref> and the packet transfer unit <figref>421</figref> in <figref idrefs="S84">10</figref> applied.

0217In <figref idrefs="S91">23</figref> consists the address management server <figref>412</figref> mainly of an address generating section <figref>511</figref>, An address management section <figref>512</figref> and a network interface <figref>513</figref>,

0218Of the Address generating section <figref>511</figref> generates an address (high-level layer address) on the basis of one of the network interface <figref>513</figref> received Address acquisition request and transfers the generated address to the address management section <figref>512</figref>To manage it. In addition, there the address generating section <figref>511</figref> an instruction to the Network interface <figref>513</figref> out to the address generated return to the acquisition request source.

0219Of the Address management section <figref>512</figref> managed by the Address generating section <figref>512</figref> generated address information.

0220The Network interface <figref>513</figref> transferred from the network a received information packet to the address generating section <figref>511</figref>. if the packet is addressed to its own server, and address detection request information. The network interface <figref>513</figref> transferred also from the Address generating section <figref>512</figref> information sent to the network.

0221Of the Operation of the address management server, which in the <figref idrefs="S91">23</figref> shown An assembly, is next described.

0222The Network interface <figref>513</figref> transferred from the network a received information packet to the address generator <figref>511</figref>. if the address is addressed to the own server, and Address acquisition request.

0223For example generates the address generator <figref>511</figref> an address by using a technique for generating candidate in advance on the basis of one of the address generator <figref>511</figref> received address acquisition request and selecting one of the candidates. For example, the address generator<figref>511</figref> a the addresses in a reserved address space, similar to a DHCP server on the Internet choose. In this case, the address generator <figref>511</figref> address information Look, the generated / used and in the address management device <figref>512</figref> saved were. The address generator<figref>511</figref> transfers the generated Address to the address management device <figref>512</figref> and are an instruction to the network interface <figref>513</figref> in order return the address to the acquisition request source, thereby the address generated customized in one package and send them to the network is output.

0224The by the address generator <figref>511</figref> be generated addresses as multicast addresses in a table in the address management device <figref>512</figref> together with addresses a one-to-one communication is stored, to a centralized on Way similar a conventional DHCP server to be managed. A field can on this table be added as needed, to indicate whether each address for the unicast or multicast communication. <figref idrefs="S91">24</figref> shows a concrete example of such a table. In<figref idrefs="S91">24</figref> gives a flag of "0" type in the Type field, that the appropriate address for Unicast communication , whereas a flag of "1" type indicates that the appropriate address for multicast communication is.

0225It Note that the by the address generator <figref>511</figref> generated Addresses to the same square are. That is, a Address alone does not indicate whether they for unicast or multicast communication is used. Therefore, when an address acquisition request multicast communication when Detecting an address or Return indicating a result, a flag of the corresponding type set. Otherwise, "unknown" is set. If the return generated address is when the Flagtyp "1" / "0", is added to the address to the appropriate information notified. Otherwise, "unknown" is set. The above Techniques and the like are available.

0226As is described above, according to the fifth to eighth embodiments, when multicast communication with reference to specific terminals is supported on the low-level layer, a given terminal a high-level multicast address according to the set Low-level multicast address upon receipt of a notification of completion of the low-level multicast communication setting on. In this case, the. set to high-level multicast address a terminal other than a target of multicasting as needed transferred, and the terminal that has received the address stores, the multicast address therein, and it provides routing information as on. With this operation, when transferring packets to each Terminal transfer information management much easier. In addition to conventional One-to-one communication (unicast communication) used used address for multicast communication be, and there is no improvement for the routing for the data transfer necessary on a network. Therefore, the compatibility with a can usual System to ensure and various conventional Address management tools that have been developed for unicast communication, can not any modification or used with a small improvement will.

0227At the Multicasting information from a terminal, according to a usual Protocol operates to a specific terminal group, if a corresponding multicast address is known, the information are transmitted in the same manner as the conventional unicast transfer. This means, the invention can be applied easily to conventional systems will.

0228There no conventional Device having the above functions, corresponding functions must added will. In this case, the features added are roughly classified into a function for setting the high-level multicast addresses and a function of determining, if a given address for Multicast / unicast communication, and for transferring the determination results classified to the low-level layer. The two functions can in a conventional Device are implemented. The high-level multicast can Adresseneinstellfunktion but which is used in common; sharing this function is sometimes effective. The following method is therefore effective. A unit with the high-level multicast Adresseneinstellfunktion is independent of the Packet transfer unit created. One requirement is to this unit output, and receives the unit the result. In this case, the invention is directed to a unit in a conventional system, eg a device with a Adresseneinstellserverfunktion, such as BOOTP or DHCP in an Internet system, with a small Improvement are applied. That is, the invention is simpler conventional Systems can be applied.

0229A Data communication unit to a data controller in accordance with the ninth embodiment is next regarding <figref idrefs="S93">25</figref> described.

0230<figref idrefs="S93">25</figref> shows the arrangement of a given terminal, a data communication unit. This Terminal is a user data processor <figref>601</figref> to the perform an application, a group controller <figref>602</figref> for managing a group and a communications processor <figref>603</figref> to the perform formed of communication. A communicable-terminal management apparatus<figref>611</figref> managed Data about a terminal that can communicate with the own terminal. A Group operating device <figref>612</figref> leads a group operating as for example, forming a plurality of terminals marked in a group participating in a designated group, retraction one marked by a marked group or Delete Group in response to a request from the user data processor <figref>601</figref> by.

0231On Group Information Controller <figref>613</figref> updated a group information management device <figref>614</figref> as Response to a request from the Group operating device <figref>612</figref> or a group holding data receiver <figref>616</figref>, The group information management device <figref>614</figref> stores group information, produced the own through the terminal or to another terminal and has been modified. A periodic group information transmitter<figref>618</figref> periodically transmits the group identification information of the group information management device <figref>614</figref> and Data about Group connection terminals participating in the group as a periodic Group information.

0232On Group operating data transmitter <figref>615</figref> transmits group operating data indicate that the group configuration by the group operating device <figref>612</figref> will be changed. A periodic group information receiver <figref>619</figref> receives from another terminal transmitted periodic group information. If the Periodic Group information receiver<figref>619</figref> periodic Group receives information was the not registered, the data will be in the group information management device <figref>614</figref> by the group information controller <figref>613</figref> registered. Of the Group operating data receiver <figref>616</figref> Calls the group information controller <figref>613</figref> on, the data in the group information management device <figref>614</figref> on based on the received group operating data change.

0233The by the group information controller <figref>613</figref> in the terminal the ninth embodiment conducted Processing is next with in reference to <figref idrefs="S95">27</figref> described.

0234<figref idrefs="S95">27</figref> shows seven terminals C1 to C6 and Cn. In<figref idrefs="S95">27</figref> are the areas where the terminals Cn and C4 directly with other Terminals can communicate, enclosed within lines. That is, the terminal Cn can with the terminals C1, C2, C3, C4 and C5 communicate, but not with the terminal C6 communicate. <figref idrefs="S95">28</figref> shows a List of terminals communicate with which the terminals C1 to C6 and Cn can.

0235In each terminal manages the communicable terminal management apparatus <figref>611</figref> a table similar to the in <figref idrefs="S96">29</figref> shown, indicating specific terminals, with each terminal can communicate. A search for communicable Terminals is performed by broadcasting terminal of search data. terminals, the answer to the terminal search data than communicable Terminals considered.

0236A Procedure by which the terminal Cn a group together with the Terminals C1 and C2 ceases in this state, first, with Referring to the flowchart of <figref idrefs="S98">35</figref> described.

0237first of all receives Group operating device <figref>612</figref> the terminal Cn To form request the terminal Cn, C1 and C2 in a group, of the user data processor <figref>601</figref> (Step a1). The group operating device<figref>612</figref> then checks whether the own terminal can communicate with all the terminals, to the on-forming group include (step a2). The Group operating unit<figref>613</figref> Splits the group information controller <figref>613</figref> a group operation attribute and the terminals which will be participating in the group. It should Note that the following four operating group attributes used will: <ul><li>1. "Education", which is used a new group set;</li><li>2. "participation", which is used participate in a group that has already been set;</li><li>3. "withdrawal", which is used to retire from a group, in the corresponding terminal has been a participant; and</li><li>4. "erasure", which is used To delete a group, which has already been set.</li></ul>

0238at Receiving a request from "education" or "participation" asks the group operating device <figref>612</figref> at the communicable terminal management apparatus <figref>611</figref> at, whether the own terminal with the terminals C1 and C2 communicate can. When the own terminal communicate with terminals may receive Group operating device <figref>612</figref> the request and tells the group information controller <figref>630</figref> the request With. The flow advances then proceeds to step a4 ago. If there is a terminal nichtkommunizierbares is, the request is denied. The process then proceeds to step a3 before. At step a3, the non-communicable Terminal removed from the group, and the processing proceeds to step a4 ago.

0239at receiving step a4 the group information controller <figref>630</figref> an alert of the group operating device <figref>612</figref> and recorded a group operating attribute. In this case, since the group operation attribute "education", the group information controller <figref>630</figref> Group identification data for Identifying a group of these. This group identification data be by creating a plurality of group identification data and selecting set of unused group identification data. The set group identification data and data on terminals, who will participate in the group are in the group information management device <figref>614</figref> each Terminals registered, which is participating in the group (step a5). <figref idrefs="S96">31</figref> shows how these data are registered.

0240at Step a6 multicast terminal Cn the data on the group formed by the group operational data transmitter <figref>615</figref> to the terminals C1 and C2. <figref idrefs="S96">30</figref> shows from the terminal Cn transferred Group operating data. In this case, the group operation attribute "education", the group identification data G1 and the group member terminals are the terminals Cn, C1 and Cn.

0241Each the group operational data receiver <figref>616</figref> the Terminals C1 and C2, which can receive the group operational data passes the group operational data to the group information controller <figref>613</figref> (Step a6). The group information controller<figref>613</figref> recognized the Group operational attribute of the group operating data. In this Case registered since the group operation attribute "education", the group information controller <figref>613</figref> the Group identification information and the group member terminal data Group operating data in the group information management device <figref>614</figref> (Step a7).

0242Of the Periodic group information transmitter <figref>618</figref> each of said terminals Cn, C1 and Cn belonging to the group G1, broadcasts periodic group information similar to in <figref idrefs="S97">34</figref> shown. This periodic group information be of the Periodic Group Information receivers <figref>619</figref> the terminal C3 to C6 received and the group information management devices <figref>614</figref> by the group information controller <figref>613</figref> registered. With This process will find the terminals C3 through C6 out that the current set group G1 formed by the terminal Cn, C1 and C2 is.

0243A Procedure by which the terminal C4 in the group set G1 participates, is next with reference to the flowchart of <figref idrefs="S99">36</figref> described.

0244at receiving step b1 the group operation unit <figref>612</figref> the terminal C4 a request, in the group participate. G1, from the user data processor <figref>601</figref>, The Group operating unit <figref>612</figref> then divides the group information controller <figref>613</figref> the Group operational attribute and the group identification data with (Step b2). Upon receipt of the notification of the group operating unit<figref>612</figref> detected the group information controller <figref>613</figref> the group attribute. In this case adds, since the group operation attribute "participation", the group information controller <figref>613</figref> the Terminal C4 to the terminals participating in the group G1, in the Group information device <figref>614</figref> added (Step b3).

0245the Terminal C4 multicast over the data participating in the group terminals and the group operation attribute "participation" of the group operating data transmitter <figref>615</figref> at belonging to the group G1 Terminals (step b4). In this case, the group operation attribute "participation", the group identification data G1 and the group member terminals are the terminals Cn, C1, C2 and C4. The group operating data receiver<figref>616</figref> each of Terminals Cn, C1 and C2, which received this group operational data has, leads the group operational data to the group information controller <figref>613</figref> (Step b5).

0246Of the Group Information Controller <figref>613</figref> detects the group operation attribute of the group operating data. In this case, adds, since the group operation attribute "participation", the group information controller<figref>613</figref> the Terminal C4 to in Group participating added terminals, according to the group identification information "G1" in the group information management device <figref>614</figref> similarly Way to the transmission side added (step b6).

0247Of the Periodic group information transmitter <figref>618</figref> each of said terminals CN, C1, C2 and C4, which belong to the group G1 broadcasts the periodic similar group information the group operation attribute "participation". The Periodic group information receiver<figref>619</figref> the Terminals C3 through C6, these periodic group information to to detect that the group G1 and through the terminals Cn, C1, C2 C4 is formed (step b7).

0248It Note that the "Zrückziehung" and "deletion" operations assigned by procedures similar to Procedure be carried out for "participation" can. also a plurality of groups by performing the "forming" operation associated with a plurality set of number of times.

0249It Assume that in the <figref idrefs="S96">31</figref> shown Groups are set by the above procedure. A procedure, through a new terminal Cx in a group has already been set participates, is described by the in <figref idrefs="S97">32</figref> shown State is taken as an example. <figref idrefs="S97">33</figref> show the Terminals, communicating with which the terminals C1 to C3, Cn and Cx can.

0250the Cx terminal can communicate with the terminals C1, C2, C4, C6 and Cn. At this time transfers the Periodic group information transmitter <figref>618</figref> from each of communicable terminals periodic group information similar to the in <figref idrefs="S97">34</figref> shown. The operation, to be performed, if the group operational data receiver <figref>616</figref> the terminal Cx receives the periodic group information is below with reference to the flowchart of <figref idrefs="S100">37</figref> described.

0251Of the Group operating data receiver <figref>616</figref> of Terminals Cx receives periodic group information (step c1). The group information controller<figref>613</figref> then checks whether the data in the group information management device <figref>614</figref> registered were (step c2).

0252If the data were recorded, updated the group information controller <figref>613</figref> the group information in the group information management device <figref>614</figref> (Step c3). With this operation, the white Terminal Cx, that the groups G1, G2 and G3 currently set are. If the data has not been registered, registered the group information controller<figref>613</figref> the Data in the group information management device <figref>614</figref> from new (step c4).

0253the Terminal Cx can in the group G1 to participate by the same procedure for "participation", the described above. The new terminal Cx can multicast communication perform with the terminals Cn, C1 and C2 in the group G1 participate, by using the group information already was adjusted.

0254It Note that the programs for executing the content of the flowcharts from <figref idrefs="S98">35</figref>. <figref idrefs="S99">36</figref> and <figref idrefs="S100">37</figref> in the user data processor <figref>601</figref>, The Group Controller <figref>602</figref> and the communication processor <figref>603</figref> in a recording medium, such as an FD or a CD-ROM, are stored. The program data in this recording medium can be used in an existing Computers are entered, and this computer as the user data processor <figref>601</figref>. the group controller <figref>602</figref> and the communication processor <figref>603</figref> operated will.

0255The tenth embodiment is next described. The processing in the tenth embodiment is by the same procedure as that for the processing in the ninth embodiment performed. The group member terminal information of group operational data by a group operating data receiver <figref>616</figref> are received, be with the data in a communicable terminal management apparatus <figref>611</figref> compared, and one of the group member terminal that is not in the communicable terminal management apparatus <figref>611</figref> registered is removed from the group. A method for maintaining the consistency of the group operation data by the respective terminals are managed in this state, is described below.

0256The tenth embodiment differs from the ninth embodiment in that a Gruppeninformationskomparator <figref>617</figref> will be added, as in <figref idrefs="S94">26</figref> is shown.

0257It Assume that a terminal Cx appears and the in <figref idrefs="S95">27</figref> shown State to the in <figref idrefs="S97">32</figref> shown state changes. In this case registers the terminal Cx terminals C1, C2, C4, C6 and Cn in the communicable terminal management apparatus <figref>611</figref>, Each of the terminals C1, C2, C4, C6 and Cn additionally registers the Terminal Cx in communicable terminal management apparatus <figref>611</figref>,

0258A Procedure by which the terminal Cx Cx terminals, C1, C2 and c6 forms in a Group in a state, in which groups such as those described in <figref idrefs="S96">31</figref> are shown by the same Procedure to that in the ninth embodiment WUR setthe, in appearance of the terminal Cx, is described with reference to the flow chart from <figref idrefs="S100">38</figref> described.

0259first of all a user inputs data processor <figref>601</figref> the terminal Cx a Request to the terminal Cx, C1, C2 and C6 in a group to form, to a group operating device <figref>612</figref> (step d1). The group operating device <figref>612</figref> then, whether the terminals C1 checks X2 and C6 in the communicable terminal management apparatus <figref>611</figref> registered (step d2). If one of the terminals C1, C2 and C6 do not is registered, the training request is denied or the Form a group with the exception of the terminal that is not registered is granted.

0260In this case, since all the terminals are registered, the request granted and group identification data "G10" and in the group participating terminal Cx, C1, C2 and C6 are as a group operating data in a group information management device <figref>614</figref> registered, and the group operational data of a periodic group information transmitter <figref>618</figref> transmitted (step d3). The terminals C1, C2 and C6 receive the group operational data (Step d4).

0261at will step d5, because the terminal C1 to the group member terminal Cx, C2 and C6 can communicate by the group operational data are specified, the group identification data "G10" and in the group participating terminal Cx, C1 and C2 and C6 in the group information management device <figref>614</figref> registered. There the terminal c2 can not communicate with the terminal C6, are the above data, with the exception of the terminal C6 in the group information management device <figref>614</figref> registered. Similarly Way registers the terminal C6, the above data excluding the Terminal C2 in the group information management device <figref>614</figref>, The terminal Cx, C1, C2 and C6 broadcast periodically periodic Group information (step d6).

0262The Processing, carried out is when the terminal Cx periodic group of information the terminals C2 and C6 receives, is described below with reference to the flowchart of <figref idrefs="S101">39</figref> described.

0263first of all receives the terminal Cx periodic group information from the terminal C2 (step e1). The terminal Cx then checks whether it by the received data specified group belongs. If the terminal Cx to belongs to the group, puts the Flow advances to step in front of e4. Otherwise, the flow advances to step e3 (step e2).

0264at Step e3, the data in the group information management device <figref>614</figref> in accordance updated with this periodic group information. At step e4 introduces Periodic group information receiver <figref>619</figref> the periodic group information to the Gruppeninformationskomparator <figref>617</figref>, The Gruppeninformationskomparator <figref>617</figref> compares the group operational data in the group information management device <figref>614</figref> With the content of the received periodic group information. If they coincide with each other, engaged the flow advances to step before e4. Otherwise, the flow advances to step e5 in front.

0265at are e4 step, the data in the group information management device <figref>614</figref> in accordance updated with this periodic group information. In this Comparison know Terminal Cx that the terminal C6 not participating in the group Terminal is. In this case, the stores Gruppeninformationskomparator<figref>617</figref> the Data about the terminal C2, and the flow waits for the reception of the periodic Group information from the terminals C1 and C6.

0266at receiving step e6 the terminal Cx all periodic group information from the terminals Cl, C2 and C6 and comparing the periodic-group information to find out, that a communication can not be performed with the terminals C2 and C2 can. In this case, the terminal with the smaller number is terminal away from the group and the group operational data in the group information management device <figref>614</figref> will updated to indicate that participating in the group Terminals group G6 are the terminal Cx, C1 and C6. The same Processing is performed with respect to the terminals C1, C2 and C6 to the participating terminals in the group G10 in the terminal Cx, C1 and C6 to change in each terminal, whereby the consistency of the group operational data of the respective terminals is maintained.

0267It Note that the terminal having the larger number of the terminal Group will be deleted can. also may, if it is determined in comparison to the group operational data in the group information management device of the content of the received group operational data differs, the deleted groups will.

0268It Assume that the communication link between the terminals C2 and C4 is disconnected, because the terminal has moved C4 after the in <figref idrefs="S96">31</figref> Group shown was formed. In this case is the terminal C4 of the data in the communicable terminal management apparatus <figref>611</figref> deleted, and the terminal C4 is also of the group G2 in the group information management device <figref>614</figref> deleted. Of the movingche operation is performed in the terminal C4. In such a case also differ when each of the terminals Cn, C1, C2 and C4 periodic group receives information, the data in the group information management device <figref>614</figref> from the received group operating data, and the consistency of the group operating data in the terminal, by the same procedure as which are maintained for "education" described above.

0269On this way can participating in the group terminals always multicast communication carry out, while the respective terminals are communicable with each other, and Consistency of the respective terminals through the group operational data can be maintained.

0270It Note that the programs for executing the content of the flowcharts from <figref idrefs="S100">38</figref> and <figref idrefs="S101">39</figref> in the user data processor <figref>614</figref>, The Group Controller <figref>602</figref>. a communications processor <figref>603</figref> and the Gruppeninformationskomparator <figref>617</figref> in a recording medium such as an FD or a CD-ROM, are stored. The program data in this recording medium k LEVERAGING are input to an existing computer, and this computer may as the user data processor <figref>601</figref>, The group controller <figref>602</figref> and the communication processor <figref>603</figref> operate.

0271According to the ninth and tenth embodiments even a terminal that does not currently participate in a group, the contents of the currently selected group of the periodic know group information and thus readily in the group take part. also can Terminals of the group, that can not communicate with each detected be, and the communication links between the terminals belonging to the group guaranteed whereby the consistency of the group operational data in the Terminal is maintained.

0272A Multicast communication control apparatus according to the eleventh embodiment is next regarding <figref idrefs="S102">40</figref> described.

0273In <figref idrefs="S102">40</figref> an output buffer <figref>701</figref> for temporary Storing transmission data a buffer management section <figref>702</figref> to manage the connected data storage state of the buffer. A timer<figref>703</figref> is a transmission timer for determining the transmission timing an acknowledgment packet. The timer <figref>703</figref> is a confirmation packet generating section <figref>708</figref> to the Generating an acknowledgment packet connected. A timer for the retransmission <figref>704</figref> is a Timer for determining the timing for retransmission of data. The timer for the retransmission <figref>704</figref> is with a data packet generation section <figref>707</figref> to produce a data packet associated. The data packet generation section<figref>707</figref> transferred the transmission data generated a reception buffer <figref>705</figref>, The data storage state of this Buffer is a buffer management section <figref>706</figref> managed.

0274Of the Output terminal portion of the data packet generation section <figref>707</figref> is with the acknowledgment packet generating section <figref>708</figref> and a multicast communication section <figref>707</figref> to the Carry out multicast communication connected. The input / output terminal portions of the data packet generation section<figref>707</figref> are with a confirmation number storage section on receiver wise Base <figref>711</figref> connected. The output of the acknowledgment packet generating section<figref>708</figref> is with a reception sequence number storage section to sender wise Base <figref>710</figref> connected. The input terminal portions of the confirmation number storage section on receiver wise Base <figref>711</figref> are connected to the output terminal portions of a transmission cable <figref>712</figref> and the multicast communication section <figref>713</figref> connected. The output terminal portion of the multicast communication section <figref>713</figref> is with the reception sequence number storage section on transmitter wise basis <figref>710</figref> for storing the sequence numbers associated data that are sent at a transmitter basis. The reception sequence number storage section on transmitter wise basis <figref>710</figref> transferred the received Sequence numbers to the buffer management section <figref>702</figref> and a Receiving group table <figref>709</figref>,

0275A Plurality of multicast communication control devices A to G each having the above arrangement, are connected to a Multicast communication So that a multicast communication to be connected performed , as in <figref idrefs="S103">41</figref> is shown. The header section one of these multicast communication control devices Package used includes target group identification data Identification data of a transmitter, a sequence number, a packet type and a packet length, as in <figref idrefs="S103">42</figref> is shown. In this case, the packet type an area for storing one on the transmission side set value to allow the receiving side that received packet as a data packet, an acknowledgment packet or of another type of packet to be identified. "0" is in the running of a number field acknowledgment packet set to have no meaning.

0276As in <figref idrefs="S104">43</figref> is shown, holds each communication device in a receiving group table, the identification data of groups, with whom Multicast communication accomplished is the identification data of the elements of the group, the maximum Sequence numbers of the sequence numbers of data packets which continuously received from the respective devices, and the sequence numbers of packets for the acknowledgment packets returned were. <figref idrefs="S104">43</figref> shows an example of the receiving group table the apparatus A.

0277As in <figref idrefs="S105">44</figref> shown, includes an acknowledgment packet additionally to the header portion of an area for storing the identification data of a Group, the number of belonging to the group devices with exceptions of the self apparatus and pairs of identification data of the respective Apparatus and maximum serial numbers of the sequence numbers of the continuously which received data packets. <figref idrefs="S105">44</figref> shows an example of the device A to the remaining devices transferred from Group B Acknowledgment packet.

0278As in <figref idrefs="S106">45</figref> is shown, holds each communication device in a transmission group table the identification data of groups with which multicast communication is performed, the maximum run numbers that each of the devices were transferred to the respective group, the identification data of devices other than the elements of Groups and received maximum confirmation numbers. <figref idrefs="S106">45</figref> shows an example of transmitting group table Apparatus A.

0279<Transmitting a data packet> Upon receipt of a Data transfer request of the high-level layer, the data packet generation section <figref>707</figref> the Data together into packets, stores them in the reception buffer <figref>707</figref> and adds them run numbers added. In this case is that of to the first data packet to transmitted corresponding group is added Sequence number "1", and the sequence number is incremented by one each time, when a data packet transmitted is. The timer for the retransmission <figref>707</figref> becomes for each Data packet set. The multicast communication section<figref>713</figref> multicast each data packet.

<reception a data packet>

0280If a packet by a multicast communication <figref>714</figref> arrives, receives the multicast communication section <figref>713</figref> the package. If that Packet is a data packet, it sends the multicast communication section <figref>730</figref> to reception sequence number storage section to sender wise basis <figref>710</figref>, If the packet is a confirmation packet is, it sends the multicast communication section <figref>713</figref> at the confirmation number storage section on receiver wise Base <figref>717</figref>, The receipt of an acknowledgment packet will be described later.

0281Of the Reception sequence number storage section to sender wise basis <figref>710</figref> extracted Target group identification data, the identification data of the communication device, which transmit the packet has, and a sequence number, and compares the sequence number with the maximum sequence number of the sequence numbers of packets that each of the device was received in the receiving group table <figref>709</figref> saved are. When extracted from the packet sequence number is greater than the maximum sequence number and is continuous with respect to this, the maximum sequence number in the receiving group table <figref>709</figref> With the extracted sequence number replaced. In addition, the data portion of the Packet to the buffer management section <figref>702</figref> Posted, and the acknowledgment packet transmission timer <figref>703</figref> becomes set if he is not set. In some cases, the in the acknowledgment packet transmission timer <figref>703</figref> Added value always kept constant. In other cases, random numbers are with a given probability distribution set. By Use of random numbers, the number of acknowledgment packets, at the same time to the multicast communication path <figref>714</figref> transfer will be reduced, and jam can be prevented. The Probability distribution may indicate a uniform distribution from a minimum value t1 t2 to a maximum value, a uniform distribution, in which the minimum and maximum values in relation to change to the number of elements of a group, or an exponential Distribution in which the mean value in proportion to the number of elements a group changes, be adjusted.

0282On Value is in the acknowledgment packet transmission timer <figref>703</figref> at set to one of the following two timings: the timing at which a data packet is received, as described above; and the Timing at which a time-out occurs, regardless of whether a data packet Will be received. In either case, when the timer a new value is set, set. If the acknowledgment packet transmission timer<figref>703</figref> on Timeout reached, the timer notifies the acknowledgment packet generating section <figref>708</figref> timeout With.

0283In addition, shares, if more data packets arrive than a certain number, which at the corresponding group are addressed, the reception sequence number storage section on transmitter wise basis <figref>710</figref> the acknowledgment packet generating section <figref>708</figref> the Arrival of data packets.

<transmission an acknowledgment packet>

0284at Receiving a message from the Empfang-running number-storage section on transmitter wise basis <figref>710</figref> or the acknowledgment packet transmission timer <figref>703</figref> Calls the acknowledgment packet generating section <figref>708</figref> the Reception sequence number storage section to sender wise basis <figref>710</figref> on, the identification data of the respective devices to the corresponding group belong, and the maximum sequence numbers (confirmation numbers) which are continuously received by the respective devices, to send. In addition, the acknowledgment packet transmission timer <figref>703</figref> reset.

0285As Response to the request sent by the reception sequence number storage section on transmitter wise basis <figref>710</figref> the data of the respective group the acknowledgment packet generating section <figref>708</figref>, The acknowledgment packet generating section <figref>708</figref> generated an acknowledgment packet similar to in <figref idrefs="S105">44</figref> shown on the basis of the reception of sequence number storage section on transmitter wise basis <figref>710</figref> received data and multicast the packet to the group through the multicast communication section <figref>713</figref>,

<reception an acknowledgment packet>

0286If a packet arrives at the apparatus receives the communication section Multidast <figref>713</figref> the incoming packet and sends it to the reception sequence number storage section on transmitter wise basis <figref>710</figref>If the packet is a data packet is, and the confirmation number storage section on receiver wise Base <figref>711</figref>If the packet is an acknowledgment packet. The confirmation number storage section on receiver wise Base <figref>711</figref> extracted target group identification data Identification data of the communication apparatuses, to which the transfer data were, and the continuously received maximum sequence number (confirmation number) transmitted from the self apparatus Data packets and stores the confirmation number in the transmission group table. The confirmation number storage section on receiver wise Base <figref>711</figref> then instructs the packet generation section <figref>707</figref> at, delete the data packet, the transferred not again must become.

<Repeated transmission a data packet>

0287Of the Receiving a communication from the retransmission of a data packet by the timer for the retransmission sends the data generating section Pact <figref>707</figref> the sequence number of Data packet and data relating to the target group, the confirmation number storage section on receiver wise Base <figref>711</figref> and requests data that indicate whether the data packet was confirmed. The confirmation number storage section receiver wise Base <figref>711</figref> compares the sequence number of the data packet with those obtained from the elements of Group confirmation numbers. If at least a confirmation numbers less as the sequence number is, are data indicating that the confirmation is not accomplished was, at the data packet generation section <figref>707</figref> Posted. When the confirmation was not carried out, sends the data packet generation section <figref>707</figref> the corresponding Data packet to the multicast communication section <figref>713</figref>, The multicast communication section <figref>713</figref> multicast the package.

0288<figref idrefs="S107">46</figref> shows the arrangement of a multicast communication control apparatus, by adding an acknowledgment packet reception detection information adding section <figref>715</figref> to the in <figref idrefs="S102">40</figref> illustrated embodiment, was obtained. This embodiment differs from that in <figref idrefs="S102">40</figref> shown embodiment in the format of a data packet, upon reception of a data packet to be performed Processing and the processing to be carried out and a data packet transferred to.

0289<figref idrefs="S108">47</figref> shows the data format in this embodiment of a Data packet used. The header portion stores a flag, that indicates whether each device has to transmit an acknowledgment packet. In which, in <figref idrefs="S82">7</figref> case shown indicates a packet, that the sequence number "700" has and transfer apparatus A was that an acknowledgment packet received from a device F.

<transmission a data packet>

0290at Receiving a data transfer request of the high-level layer provides a data packet generation section <figref>707</figref> the Data together into packets, stores them in a buffer and adds sequence numbers added to them. The sequence numbers are then in the same way and manner as in the embodiment in <figref idrefs="S102">40</figref> added.

0291Of the Packet generating section <figref>707</figref> receives from the confirmation packet reception detection information adding section <figref>715</figref> the Identification data of a device from which an acknowledgment packet has been received with respect to the data packet, and sets the flag according to the device to "require" a. A timer for retransmission<figref>704</figref> becomes set and a multicast communication section <figref>713</figref> multicast the data packet.

<reception a data packet>

0292If arrives a package receives the Multicast communication section <figref>713</figref> the Packet and sends it to a reception sequence number storage section <figref>710</figref> on transmitter wise basis when the packet is a data packet, and to a Confirmation number storage section <figref>711</figref> on receiver wise basis, if the packet is a confirmation packet is. The receipt of an acknowledgment packet will later described.

0293Of the Reception sequence number storage section <figref>710</figref> on transmitter wise Base extracted target group identification data, the identification data of a Communication device from which the packet was transmitted, a sequence number and a flag that indicates whether an acknowledgment packet from the own Device is required or not, and compares the sequence number with the maximum sequence number of a received from the device Data packet, in a receiving group table <figref>709</figref> saved is. When extracted from the packet sequence number is greater than the maximum sequence number in the receiving group table and relative this is continuous, the maximum sequence number in the Receiving group table <figref>709</figref> by the extracted sequence number replaced. also is the data portion of the packet to a buffer management section <figref>702</figref> Posted. If the extracted from the packet flag is "necessary" and the acknowledgment packet transmission timer is not set, the timer is set. If the Timer generates a time-out, a confirmation packet generation section <figref>708</figref> the Timeout notified.

0294According to the in <figref idrefs="S102">40</figref> and <figref idrefs="S107">46</figref> embodiments shown have to no acknowledgment packets for all transmitted data packets be, and the number of acknowledgment packets can be reduced, whereby the utilization efficiency of the network is improved. also , since the concentration of acknowledgment packets at a communications device, transmit the data packets has can be prevented, reducing the load on the apparatus will. These embodiments are particularly effective when the individual communication devices transfer data equally.