Abstract:
An internet protocol address converting apparatus has an address acquiring unit for acquiring a first private IP address in a first IP address format by connecting to a HDCP server that dynamically allots the IP address, and also acquiring a second private IP address for the second terminal; a network address providing unit for allotting the second terminal with a network address to generate a global IP address; a storing unit for storing a mapping table, the mapping table saving the second private IP address of the second terminal and the global IP address; an address converting unit for converting the second private IP address into the global IP address; and a control unit for performing an announcing, requesting a registration of the second terminal to a master server.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention generally relates to an apparatus for converting an Internet protocol address for exclusive use in a home network system and a home network system using the same, and more particularly, the present invention relates to an apparatus for converting an Internet protocol address for exclusive use in a home network that is capable of providing a service for achieving a communication between an IPv4 terminal using an Internet Protocol version 4 (IPv4) as a communication protocol and an IPv6 terminal using Internet Protocol version 6 (IPv6) as a communication protocol, and a home network system using the same. This application claims priority from Korean Patent Application No. 2002-0005227, filed on Jan. 29, 2002, which Korean Application is incorporated herein in full by reference.  
           [0003]    2. Description of the Prior Art  
           [0004]    Internet Protocol (IP) is one of the most generally known protocols used for the network layer of TCP/IP communication. The IP is the addressing service provided by a network layer of third layer of Open Systems Interconnection model, which designates a plurality of nodes connected to the network as a destination to perform communication. Among the IPs that are currently available, the most popular one is the Internet Protocol version 4 (IPv4). The IPv4 uses an IP address of 32 bits.  
           [0005]    With the ever-growing number of users, computers are now becoming a necessity in people&#39;s daily lives. The number of addresses of Internet users has been exploding, while the IPv4 IP address format of 32 bits hardly satisfies such continuously growing demands. In an attempt to solve this problem, IPv6 has been developed by the Internet Engineering Task Force (IETF) as the next generation Internet Protocol.  
           [0006]    The IPv6 uses the address format of 128 bits. The IPv6 not only extends the number of IP addresses, but also reduces costs for broadband width and processing of a common header, as it is capable of simplifying the common header format. Also, by adopting a concept of ‘flow label,’ IPv6 enables efficient real-time processing of multimedia data. Moreover, the IPv6 provides much strengthened security functions like verification, faultless data, airtight data, etc.  
           [0007]    The Internet communication infrastructure used for the IPv4 is also used for the IPv6. Accordingly, in order to accomplish a communication between the IPv4 terminal and the IPv6 terminal, an IPv4-IPv6 converter that connects the IPv4 net and the IPv6 net is necessary.  
           [0008]    [0008]FIG. 1 is a block diagram showing network system using a conventional IPv4-IPv6 converter. Referring to FIG. 1, conventionally, the IPv4 network  20  and the IPv6 network  40  are connected by the IPv4-IPv6 converting device  10 . The IPv4 network  20  is connected with an IPv4 terminal  31 , a domain name service version 4 server (DNSv4) 33, and a dynamic host configuration protocol version 4 server  35  (DHCPv4). The DNSv4 server  33  manages the domain name information within the IPv4 network  20 . The DHCPv4 server  35  dynamically allots the IPv4 address to the IPv4 terminal  31  that is connected to the IPv4 network  20 .  
           [0009]    The IPv6 network  40  is connected to an IPv6 terminal  51 , a DNSv6 server  53  and a DHCPv6 server  55 . The DNSv6 server  53  manages the domain name information within the IPv6 network  40 . The DHCPv6 server  55  dynamically allots the IPv6 address to the IPv6 terminal  51  that is connected to the IPv6 network  40 .  
           [0010]    The communication operation between the IPv4 terminal  31  and the IPv6 terminal  51  will be described below.  
           [0011]    First, the IPv4 terminal  31  makes a query to the DNSv4 server  33  for an IPv4 address that corresponds to the domain name of the IPv6 terminal  51 . The DNSv4 server  33  provides the IPv4-IPv6 converting device  10  with the information about the requested IPv4 address that corresponds to the domain name of the IPv6 terminal  51 . The sender address is the IPv4 address of the DNSv4 server  33 , while the destination address is the IPv4 address of the IPv4-IPv6 converting device  10 . The IPv4-IPv6 converting device  10  converts the IPv4 address of the sender, i.e., of the DNSv4 server  33  into the IPv6 address. At this time, the IPv4-IPv6 converting device  10  converts the IPv4 address of the DNSv4 server  33  into the IPv6 address by adding a prefix to the IPv4 address of the DNSv4 server  33 . The IPv4-IPv6 converting device  10  also has the IPv6 address of the DNSv6 server  53  that manages the domain information of the terminal like the IPv6 terminal  51  that is connected to the IPv6 network  40 . Accordingly, the IPv4-IPv6 converting device  10  is connected to the DNSv6 server  53  and requests the IPv6 address corresponding to the domain name of the IPv6 terminal  51 . The sender address is the IPv6 address of the DNSv4 server  33 , while the destination address is the IPv6 address of the DNSv6 server  53 .  
           [0012]    The IPv6 address corresponding to the domain name of the IPv6 terminal  51  being requested, the DNSv6 server  53  extracts the IPv6 address from a stored table and provides the IPv4-IPv6 converting device  10  with the extracted information. The IPv4-IPv6 converting device  10  converts such received IPv6 address of the IPv6 terminal  51  into the IPv4 address, and provides the DNSv4 server  33  with such converted IPv4 address of the IPv6 terminal  51 . The DNSv4 server  33  provides the IPv4 terminal  31  with such received IPv4 address of the IPv6 terminal  51 . Accordingly, the IPv4 terminal  31  is enabled to find out the IPv4 address that corresponds to the domain name of the IPv6 terminal  51 .  
           [0013]    Provided with the IPv4 address corresponding to the domain name of the IPv6 terminal  51 , the IPv4 terminal  31  sends a communication request signal with the IPv6 terminal  51  to the IPv4-IPv6 converting device  10 . The sender address is the IPv4 address of the IPv4 terminal  31 , while the destination address is the IPv4 address of the IPv6 terminal  51 . When the IPv4 terminal sends the control information to the terminal in the IPv6 network  40 , a mapping table within the converting device  10  is searched. If there is an IPv6 terminal  51  registered for the IPv4 address, i.e., the destination address, there is no need to perform the converting process additionally. With the address of IPv6 system with respect to the IPv4 terminal  31  and the IPv6 terminal  51 , the IPv4-IPv6 converting device  10  sends a connection request signal from the IPv4 terminal  31  to the IPv6 terminal  51 . With the address conversion by the IPv4-IPv6 converting device  10 , the IPv4 terminal  31  and the IPv6 terminal  51  communicates with each other.  
           [0014]    [0014]FIG. 2 is a view showing one example in which the network system using the IPv4-IPv6 converting device  10  of FIG. 10 is used in the home network system. The IPv4-IPv6 converting device  10  as used in the home network is called a home-only IP address converting device. However, it will be understood by those of ordinary skill in the art that the devices, systems and methods disclosed herein are not restricted to use In a home. Rather, what is intended is any application, including an office, vehicle, school, or other such environment, for which the devices, systems and method herein disclosed are suitable.  
           [0015]    Hereinbelow, the communication operation between the IPv4 terminal  31 , namely, a personal computer  31   a  and a refrigerator  31   b  and the IPv6 terminal  51 , namely, a digital television  51   a  and a laptop computer  51   b.    
           [0016]    Based on the services provided by the DNSv4 server  33  and the DHCPv4 server  35 , the personal computer  31   a  and the refrigerator  31   b  perform a communication with the devices within the IPv4 network  20   a . Also, based on the services provided by the DNSv6 server  53  and the DHCPv6 server  55 , the digital television  51   a  and the laptop computer  51   b  perform the communication with the devices within the IPv6 network  40   a.    
           [0017]    Meanwhile, in order to achieve a home networking among the communicable devices within the home network, the home network system is provided with a master server  37 . The master server  37  manages and registers the registration information of the devices of the home network. The registration information may not necessary include additional information about IP address, as it will become known through a FPC communication.  
           [0018]    The conventional home network system requires the IPv4-IPv6 converting device  10  that provides a converting service of converting the IP address formats for a communication between the IPv4 terminal  31  and the IPv6 terminal  51 . By the services provided by the IPv4-IPv6 converting device  10 , communication among the personal computer  31   a  and the refrigerator  31   b , and the digital television  51   a  and the laptop computer  51   b  is enabled. In order to apply the IPv4 terminal  31  and the IPv6 terminal  51  in the home network system, the home network requires the DNSv4 server  35  and the DHCPv4 server  35  that provide the IPv4 terminal of the home network with the IP address and the domain name, and also the DNSv6 server  53  and the DHCPv6 server  55  that provide the IPv6 terminal of the home network with the EP address and the domain name, which generates inconvenient jobs such as system establishment, etc.  
           [0019]    There is another problem that the services of the DNSv6 server  53  and the DHCPv6 server  55  become redundant with respect to the services of the DNSv4 server  33  and the DHCPv4 server  35 . Also, in order for the IPv4 terminal  31  and the IPv6 terminal  51  to communication with each other, the IPv4 terminal  31  and the IPv6 terminal  51  have to use the services of the DNSv4 server  33  and the DHCPv4 server  35  and the DNSv6 server  53  and the DHCPv6 server  55 . Accordingly, communication among the IPv4 terminal  31  and the IPv6 terminal  51  sometimes causes overload in the operation of the respective servers  33 ,  35 ,  53 ,  55 .  
           [0020]    Also, since the conventional home network requires the installation of all of the DNSv4 server  33 , the DHCPv4 server  35 , the DNSv6 server  53  and the DHCPv6 server  55  therein, a problem of taking too much space arises.  
         SUMMARY OF THE INVENTION  
         [0021]    The present invention has been made to overcome the above-mentioned problems of the prior art. Accordingly, it is a first object of the present invention to provide an IPv4-IPv6 converting device that solves the problem of the high costs for building a home network that requires a DNSv4 server  33 , a DHCPv4 server  35 , a DNSv6 server  53  and a DHCPv6 server  55  for a communication among an IPv4 terminal and an IPv6 terminal within a home network.  
           [0022]    It is a second object of the present invention to provide an IPv4-IPv6 converting device that solves the problem of transmission overload between an IPv4 terminal and an IPv6 terminal.  
           [0023]    It is a third object of the present invention to provide an IPv4-IPv6 converting device that reduces a space occupied by a DNSv4 server, a DHCPv4 server, a DNSv6 server and a DHCPv6 server during the establishment of home network for communication between an IPv4 terminal and an IPv6 terminal.  
           [0024]    In order to accomplish the above objects, an apparatus for converting an IP address format for a communication between a first terminal and a second terminal having different IP address formats according to the present invention includes an address acquiring unit for acquiring a first private IP address in a first IP address format by connecting to a DHCP server that dynamically allots the IP address, and also acquiring a second private IP address for the second terminal; a network address providing unit for allotting the second terminal with a network address according to a network address request by the second terminal to generate a global IP address of a second IP address format; an address converting unit for converting the second private IP address into the global IP address; a storing unit for storing a mapping table, the mapping table saving the second private IP address of the second terminal and the global IP address; and a control unit for performing an announcing, requesting a registration of the second terminal to a master server that manages and provides registration information about the second terminal having the global IP address.  
           [0025]    The control unit controls the address converting unit so that the second private IP address is converted into the global IP address according to the mapping table, when received with the control signal with respect to the second terminal having the second private IP address. The control unit controls the address converting unit so that the global IP address is converted into the second private IP address according to the mapping table, when being requested by the second terminal having the global IP address to register the information about the second terminal in the master server. The first IP address format is an IPv4, and the second IP address format is an IPv6.  
           [0026]    The second terminal combines the network address provided by the network address providing unit with a hardware address of the second terminal, to generate the global IP address. The hardware address is a media access control address, which is an interface ID distinguishing one interface from another connected in a network. Each of the media access control address and the network address is comprised of 64 bits.  
           [0027]    Also in order to accomplish the above objects, a home network system according to the present invention includes an IPv4 terminal for performing a communication with a device connected to an IPv4 network with a hardware address and a private IPv4 address in an IPv4 system; an IPv6 terminal for performing a communication with a device connected to the IPv6 network with the hardware address and a global IPv6 address in the IPv6 system; an address converting device for performing a communication with the IPv4 terminal in the IPv4 network with the private IPv4 address, and providing the IPv6 terminal with a network address so that the IPv6 terminal can generate the global IPv6 address; a DHCP server for allotting the IPv4 terminal, the IPv6 terminal and the address converting device with the private IPv4 address in the IPv4 system; and a master server for managing and providing registration information about the IPv4 terminal and the IPv6 terminal.  
           [0028]    The address converting device includes a mapping table saving the private IPv4 address of the IPv6 terminal and the global IPv6 address. The registration information comprises the hardware address of the IPv4 terminal and the IPv6 terminal, the private IPv4 address and the global IPv6 address.  
           [0029]    The address converting device converts the private IPv4 address into the global IPv6 address according to the mapping table, when being received with the control signal for the IPv6 terminal having the private IPv4 address. The address converting device converts the global IPv6 address into the private IPv4 address according to the mapping table, when being requested by the IPv6 terminal having the global IPv6 address to perform an announcing for registering the information about the IPv6 terminal in the master server.  
           [0030]    The IPv6 terminal generates the global IPv6 address by combining the network address provided by the address converting device with the hardware address of the IPv6 terminal. The hardware address is a media access control address, an interface ID distinguishing one interface from another which are connected in a network. Each of the media access control address and the network address is comprised of 64 bits.  
           [0031]    Also in order to accomplish the above objects, a communication method using an address converting apparatus which converts an IP address format to enable a communication between a first terminal and a second terminal having different IP address formats according to the present invention includes the steps in which: the first terminal is connected to a DHCP server that allots a private IP address in a first IP address format, and acquires a first private IP address in the first IP address format of the first terminal; the apparatus for converting the address is connected to the DHCP server, and acquires a second private IP address thereof; the second terminal is connected to the apparatus for converting the address and generates a global IP address in a second IP address format through a network address provided by the apparatus for converting the address; the apparatus for converting the address is connected to the DHCP server and acquires a first private IP address in the first IP address format corresponding to the global IP address of the second terminal; a mapping table saving the global IP address and the first private IP address of the second terminal is stored in a storing unit of the apparatus for converting the address; and the information about the first and the second terminals are managed and provided.  
           [0032]    The address generating step generates the global IP address by combining the network address provided by the apparatus for converting the address with the hardware address of the second terminal. The hardware address is a media access control address, an interface ID distinguishing one interface from another which are connected in the network. Each of the network address and the media access control address is comprised of 64 bits.  
           [0033]    In one embodiment, the first IP address format is an IPv4, and the second IP address format is an IPv6. However, it will be understood that the devices, systems and methods disclosed herein are suitable also for other IP protocol conversion applications.  
           [0034]    According to the present invention, the IPv6 address is generated through the network address provided by the network address providing unit  130 , and the DHCPv4 server  350  allots the IPv4 address corresponding to the IPv6 address of the IPv6 terminal  510 , and the IPv4 address and the IPv6 address of the IPv4 terminal  310  and the IPv6 terminal  510  are stored in the mapping table of the storing unit  140 , and the master server  330  manages and provides the registration information about the IPv4 terminal  310  and the IPv6 terminal  510 . As a result, there is no need to employ the DHCPv6 server and the DNSv6 server for communication. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0035]    The above-mentioned object and the feature of the present invention will be more apparent by describing the preferred embodiments of the present invention by referring to the appended drawings, in which:  
         [0036]    [0036]FIG. 1 is a block diagram showing a network system using a conventional IPv4-IPv6 converting device;  
         [0037]    [0037]FIG. 2 is a view showing one example in which a network system using the IPv4-IPv6 converting device of FIG. 1 being applied in a home network;  
         [0038]    [0038]FIG. 3 is a block diagram showing a home-only IP address converting device according to a preferred embodiment of the present invention;  
         [0039]    [0039]FIG. 4 is a block diagram showing in detail the address acquiring unit of FIG. 3;  
         [0040]    [0040]FIG. 5 is a block diagram showing a home network system employing the home-only IP address converting device of FIG. 3;  
         [0041]    [0041]FIG. 6 is a view showing an example in which the home network system of FIG. 5 being applied in the respective devices of home network;  
         [0042]    [0042]FIG. 7 is a flowchart for explaining an announcement of an IPv4 terminal in the home network system using the home-only IP address converting device according to the present invention;  
         [0043]    [0043]FIG. 8 is a flowchart for explaining an announcement of an IPv6 terminal in the home network system using the home-only IP address converting device according to the present invention;  
         [0044]    [0044]FIG. 9 is a flowchart showing in detail the operation of the home-only IP address converting device in response to a registration request of IPv6 terminal of FIG. 8;  
         [0045]    [0045]FIG. 10 is a flowchart showing a method of an IPv4 terminal for controlling an IPv6 terminal in the home network system according to the present invention; and  
         [0046]    [0046]FIG. 11 is a flowchart showing in detail the operation of the home-only IP address converting device in the step of transmitting the control signal of FIG. 10 to the home-only IP address converting device. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0047]    The present invention will be described in greater detail by referring to the appended drawings.  
         [0048]    [0048]FIG. 3 is a block diagram showing a home-only IP address converting device according to the present invention. Referring to FIG. 3, the home-only IP address converting device includes an address acquiring unit  120 , a network address providing unit  130 , a storing unit  140 , an address converting unit  150  and a control unit  110 .  
         [0049]    The address acquiring unit  120  is connected to a DHCPv4 server (not shown) that dynamically allots IP addresses to the devices in the network and acquires a first private IPv4 address and a second private IPv4 address of IPv4 system. The first private IPv4 address is for the home-only IP address converting device to communicate with the devices connected to an IPv4 home network  200 . The second private IPv4 address corresponds to the IPv4 address of IPv4 system of an IPv6 terminal (not shown) that is connected in an IPv6 home network  400 .  
         [0050]    The network address providing unit  130  provides an IPv6 terminal requesting a network address by automatically generating an IPv6 address of IPv6 system. Generally, a network address is comprised of 64 bits. Accordingly, the IPv6 terminal has a media access control address (MAC address), which is an interface ID that distinguishes interfaces connected in the network one from another. Such MAC address is comprised of 64 bits. The network address provided to the IPv6 terminal is comprised of 64 bits. Accordingly, the IPv6 terminal adds the network address to its MAC address, and thereby, automatically generates the IPv6 address of the IPv6 system. The IPv6 address of the IPv6 system that is automatically generated by the IPv6 terminal is comprised of 128 bits. The IPv6 address automatically generated for the IPv6 terminal is transmitted by the IPv6 terminal to the control unit  110  via the IPv6 home network  400  and the interface unit  160 .  
         [0051]    The storing unit  140  stores the first private IPv4 address of the IPv4 terminal and the second private IPv4 address of IPv6 terminal, both acquired by the address acquiring unit  120 , and also stores the IPv6 address of the IPv6 terminal provided by the IPv6 terminal in a mapping table that is constructed under the control of the control unit  110 . The address converting unit  150  converts the second private IPv4 address to the IPv6 address or vice versa based on the mapping table stored in the storing unit  160 . Preferably, the address converting unit  150  generates the IPv6 address of the IPv6 system that corresponds to the IPv4 address of the IPv4 terminal. As a result, the IPv6 terminal can identify the address of the IPv4 terminal that transmits the control signal.  
         [0052]    When the request signal for connection with the IPv6 terminal is received from the IPv4 terminal having the first private IPv4 address via the interface unit  160 , the control unit  110  extracts the mapping table stored in the storing unit  160  and provides the address converting unit  150  with such extracted mapping table, to thereby control the address converting unit  150  to convert the second private IPv4 address into the IPv6 address based on the mapping table.  
         [0053]    As the network address providing unit  130  provides the IPv6 terminal with the network address and the IPv6 terminal generates the IPv6 address through the provided network address, there is no need for the DHCPv6 server for providing the IPv6 terminal with the IPv6 address of the IPv6 system.  
         [0054]    [0054]FIG. 4 is a block diagram showing the address acquiring unit  120  of FIG. 3 in greater detail. The address acquiring unit  120  has a first address acquiring unit  122  and a second address acquiring unit  124 . The first address acquiring unit  122  is connected to the DHCPv4 server so as for the home-only IP address converting device to communicate within the IPv4 home network  200 , and acquires the first private IPv4 address of the IPv4 system. The second address acquiring unit  124  is connected to the DHCPv4 server and acquires the private IPv4 address of the IPv4 system of the IPv6 terminal, which is required for the IPv4 terminal to transmit the control signal to the IPv6 terminal.  
         [0055]    [0055]FIG. 5 is a block diagram showing a home network system employing the home-only EP address converting device of FIG. 3. The home-only IP address converting device  100  connects the IPv4 home network  200  that is connected with the IPv4 terminal  310  with the IPv6 home network  400  that is connected with the IPv6 terminal  510 . Referring to FIG. 5, the IPv4 home network  200  is connected with the master server  330  and the DHCPv4 server  350 . Here, the master server  330  can be connected with the IPv6 home network  400 .  
         [0056]    Generally, the master server  330  manages and provides the registration information of the devices in the home network. The master server  330  according to the present invention stores a domain name of the IPv4 terminal  310  and the information about the IPv4 terminal  310  that contains the address corresponding to the domain name. Also, the master server  330  stores the information about the IPv6 terminal  510 .  
         [0057]    Generally, in order to provide communication service between the IPv4 terminal  310  and the IPv6 terminal  510 , all the devices for performing communication among the devices having different address formats are implemented with a middleware. The middleware is the software that provides service for communication among different type of terminals, which enables the communication among a plurality of terminals within the home network. In other words, the middleware functions to independently connect to the hardware along the network so as to support with various communication protocol, system structure, management system, database and application program. Among the currently available middlewares, there are Universal Plug and Play (UPnP), Home AV Interoperability (HAVi), JINI, Home Wide Web.  
         [0058]    The DHCPv4 server  350  dynamically allots addresses according to the address allotment request of the IPv4 terminal  310 . Also, the DHCPv4 server  350  provides the first address acquiring unit  122  with the first private IPv4 address according to the request for an address in IPv4 system with respect to the home-only IP address converting device  100  of the first address acquiring unit  122 . The DHCPv4 server  350  provides the second address acquiring unit  124  with the second private IPv4 address according to a request for an address in IPv4 system with respect to the IPv6 terminal  510  of the second address acquiring unit  124 .  
         [0059]    [0059]FIG. 6 is a view showing the devices within the house used with the home network system of FIG. 5. Referring to FIG. 6, a personal computer  310   a  as the IPv4 terminal  310  is arranged within the IPv4 home network  200   a , while a digital television  510   a  as the IPv6 terminal  510  is arranged in the IPv6 home network  400   a . The DHCPv4 server  350  is additionally arranged in the house to allot the media access control address for the personal computer  310   a  to communicate with other devices in the IPv4 home network  200   a.    
         [0060]    Meanwhile, the personal computer  310   a  requests the master server  330  for the announcement in order to register the information of the personal computer  310   a  containing the media access control address of the personal computer  310   a . The information of the requesting personal computer  310   a  includes the media access address, a user name and available services of the personal computer  310   a . Accordingly, the master server  330  stores the information of the announcement-requested personal computer  310   a  in the table format. The digital television  510   a  requests the home-only IP address converting device  100  for a network address in order to generate the IPv65 address in IPv6 system. Here, in the case that the master server  330  is provided within the IPv6 home network  400   a , the personal computer  310   a  transmits the announcement to the home-only IP address converting device  100  in order to register the information of the personal computer  310   a  in the master server  330 . In such a situation, the control unit  110  in the home-only IP address converting device  100  requests the master server  330  for the announcement. Accordingly, the master server  330  stores the information of the personal computer  310   a  in the table format. The master server  330  can be provided either in the IPv4 home network  200   a  or in the IPv6 home network  400   a . In this embodiment, the master server  330  is depicted as being provided in the IPv4 home network  200   a.    
         [0061]    Also, the digital television  510   a  generates the IPv6 address in the IPv6 system by combining the network address provided by the home-only IP address converting device  100  and its own media access control address. Accordingly, the digital television  510   a  transmits the announcement to the home-only IP address converting device  100  to register in the master server  330  the information about the digital television  510   a  inclusive of the generated IPv6 address. At this time, the second address acquiring unit  124  is connected to the DHCP server  350  and acquires the second private IPv4 address corresponding to the IPv6 address of the digital television  510   a . Accordingly, the control unit  110  requests the master server  330  for the announcement to register the information about the digital television  510   a  having the second private IPv4 address in the master server  330 .  
         [0062]    Accordingly, in order to control the operation of the digital television  510   a , the personal computer  310   a  requests the master server  330  for the information of the digital television  510   a  that is registered through the announcement. The master server  330  provides the personal computer  310   a  with the information of the registered digital television  510   a . Accordingly, the personal computer  310   a  selects a control signal from the provided information about the requested digital television  510   a , and transmits the selected signal to the home-only IP address converting device  100 . The address of the digital television  510   a , which is transmitted to the home-only IP address converting device  100 , is the second private IPv4 address. The control unit  110  of the home-only IP address converting device  100  provides the address converting unit  150  with the mapping table stored in the storing unit  140 . Accordingly, the address converting unit  150  detects the registered IPv6 address that corresponds to the second private IPv4 address of the digital television  510   a . the recipient of the control signal, and transmits the control signal to the digital television  510   a  corresponding to the detected IPv6 address.  
         [0063]    [0063]FIG. 7 is a flowchart for explaining the announcing of the IPv4 terminal  310  in the home network system using the home-only IP address converting device  100  according to the present invention. First, the IPv4 terminal  310  requests the DHCPv4 server  350  for a private IPv4 address in IPv4 system (step S 110 ). The DHCPv4 server  350  allots the IPv4 terminal  310  with the private IPv4 address (step S 120 ). Accordingly, the IPv4 terminal  310  requests the master server  330  to announce in order to register the information about the IPv4 terminal  310  (step S 150 ). At this time, the master server  330  registers the received information about the IPv4 terminal  310 , and transmits to the IPv4 terminal  310  the information as to whether the information about the IPv4 terminal  310  is registered or not (step S 160 ).  
         [0064]    In addition, the home-only IP address converting device  100  is connected to the DHCPv4 server  350  and requests the DHCPv4 server  350  for an IPv4 address in the IPv4 system to perform communication with the devices existing in the IPv4 home network  200   a  (step S 130 ). Accordingly, the DHCPv4 server  350  allots to the home-only IP address converting device  100  the private IPv4 address (step S 140 ).  
         [0065]    [0065]FIG. 8 is a flowchart for explaining the announcing of the IPv6 terminal  510  in the home network system using the home-only IP address converting device  100  according to the present invention. First, as the power is supplied, the IPv6 terminal  510  requests the home-only IP address converting device  100  for the network address (step S 210 ). The network address providing unit  130  provides the IPv6 terminal  510  with a network address (step S 220 ). Accordingly, the IPv6 terminal  510  generates the IPv6 address in IPv6 system by combining its media access control address and the received network address. At this time, the IPv6 terminal  510  performs the announcing to the home-only IP address converting device  100  to register the information about the IPv6 terminal  510  in the master server  330  (step S 230 ).  
         [0066]    The registration information being requested by the IPv6 terminal  510 , the second address acquiring unit  124  of the home-only IP address converting device  100  is connected to the DHCPv4 server  350  and requests the DHCPv4 server  350  for the IPv4 address of the IPv6 terminal  510  in IPv4 system (step S 250 ). The DHCPv4 server  350  provides the home-only IP address converting device  100  with the second private IPv4 address for the IPv6 terminal  510  (step S 260 ). Accordingly, the home-only IP address converting device  100  requests the master server  330  to register the IPv6 terminal  510  with the allotted second private IPv4 address of the IPv6 terminal  510  (step S 270 ). The master server  330  registers the IPv6 terminal  510 , and provides the home-only IP address converting device  100  with the registration result (step S 280 ). Receiving the registration result, the home-only IP address converting device  100  transmits the received registration information to the IPv6 terminal  510  (step S 290 ).  
         [0067]    [0067]FIG. 9 is a flowchart showing in detail the operation of the home-only IP address converting device  100  according to the registration requesting step (S 230 ) by the IPv6 terminal  510  of FIG. 8 to the master server  330 . First, when the announcing is received from the IPv6 terminal  510  for registering the information of the IPv6 terminal  510  in the master server  330 , the control unit  110  searches the mapping table of the storing unit  140  (step S 241 ). Accordingly, the control unit  110  determines whether or not to register the IPv4 address corresponding to the IPv6 address of the IPv6 terminal  510  through the mapping table (step S 243 ). The IPv4 address that corresponds to the IPv6 address of the IPv6 terminal  510  is the second IPv4 address. In other words, the control unit  110  determines whether or not to register the second private IPv4 address corresponding to the IPv6 address.  
         [0068]    When it is determined that the second private IPv4 address is registered in S 243 , the control unit  110  requests the master server  330  through the interface unit  160  for a registration of the IPv6 terminal  510  that has the second private IPv4 address (step S 245 ). Accordingly, the master server  330  registers the information of the IPv6 terminal  510 , and provides the home-only IP address converting device  100  with the information about the registration. Accordingly, the home-only IP address converting device  100  receives the registration information, and provides the IPv6 terminal  510  with the received registration information (step S 246 ).  
         [0069]    Meanwhile, if it is determined that the second private IPv4 address is not registered in S 243 , the control unit  110  controls the second private acquiring unit  124  to be connected to the DHCPv4 server  350  and to request the DHCPv4 server  350  for the IPv4 address of the IPv6 terminal  510  in IPv4 system (step S 247 ). Accordingly, the IPv4 address of the IPv6 terminal  510  provided by the DHCPv4 server  350 , i.e., the second private IPv4 address is stored in the mapping table of the storing unit  140  (step S 249 ).  
         [0070]    [0070]FIG. 10 is a flowchart showing the method of the IPv4 terminal  310  for controlling the IPv6 terminal  510  in the home network system according to the present invention. First, the IPv4 terminal  310  requests the master server  330  for the private IPv4 address of the IPv6 terminal  510  (step S 310 ). The master server  330  provides the IPv4 terminal  310  with the information about the registered IPv6 terminal  510  (step S 330 ). Accordingly, based on the information provided, the IPv4 terminal  310  selects the control signal for controlling the IPv6 terminal  510  and then transmits the selected control signal to the home-only IP address converting device  100  so that the selected control signal can be transmitted to the IPv4 address (step S 350 ). The home-only IP address converting device  100  transmits the control signal to the IPv6 terminal  510  having the IPv6 address that corresponds to the IPv4 address (step S 370 ).  
         [0071]    [0071]FIG. 11 is a flowchart showing in detail the operation of the home-only IP address converting device  100  according to S 350  of FIG. 10. First, having received with the control signal with respect to the IPv6 terminal  510 , the control unit  110  searches the mapping table of the storing unit  140  (step S 361 ). The control unit  110  determines whether or not to register the IPv4 address corresponding to the IPv6 address of the IPv6 terminal  510 , the receiver of the control signal (step S 363 ). If it is determined that the IPv4 address of the IPv6 terminal  510 , the receiver of the control signal, is registered, the control unit  110  transmits the received control signal to the IPv6 terminal  510  having the IPv6 address corresponding to the IPv4 address (step S 365 ). Meanwhile, if it is determined that the IPv4 address of the IPv6 terminal  510 , the receiver of the control signal, is not registered, the control unit  110  discards the received control signal (step S 367 ).  
         [0072]    According to the present invention, the IPv6 address is generated through the network address provided by the network address providing unit  130 . The DHCPv4 server  350  allots the IPv4 address corresponding to the IPv6 address of the IPv6 terminal  510 . The IPv4 address and the IPv6 address of the IPv4 terminal  310  and the IPv6 terminal  510  are stored in the mapping table of the storing unit  140 , and the master server  330  manages and provides the registration information about the IPv4 terminal  310  and the IPv6 terminal  510 . As a result, there is no need to employ the DHCPv6 server and the DNSv6 server for communication.  
         [0073]    Also, according to the present invention, since there is no need for the DHCPv6 server and the DNSv6 server in the home network system, cost for building network system can be reduced.  
         [0074]    Also, omission of the DNSv6 server and the DHCPv6 server during the establishment of the home network for a communication between the IPv4 terminal  310  and the IPv6 terminal  510  can reduce the space that the system occupies.  
         [0075]    Meanwhile, if added to the device for mounting the IPv6 addresses plus all the other devices that are required by the middleware to perform networking in the home network, the home network can provide users with a wide range of services while never disturbed by the characteristics of the devices and the IP address formats. Also, the service quality increases.  
         [0076]    Although the preferred embodiment of the present invention has been described, it will be understood by those skilled in the art that the present invention should not be limited to the described preferred embodiment, but various changes and modifications can be made within the spirit and scope of the present invention as defined by the appended claims.