Abstract:
An embodiment of the present invention relates to a method of setting an IP address of an electronic apparatus including receiving a router advertisement transmitted from the router, receiving prefix information of the router advertisement, additionally storing an IP address based upon the received prefix information as an IP address of the electronic apparatus when the electronic apparatus has setting for maintaining the prefix information, and rewriting a presently registered IP address with an IP address based upon the received prefix information when the electronic apparatus does not have the setting for maintaining the prefix information.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is based upon and claims the benefit of priority from U.S. Provisional Application No. 61/026,030 filed on Feb. 4, 2008, the entire contents of each of which are incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to an electronic apparatus that operates on a network. 
       BACKGROUND 
       [0003]    An electronic apparatus, for example, an image forming apparatus called MFP (Multi-Functional Peripheral) located on a network is connected to a router. The router is connected to a personal computer (a host apparatus) as a client or a server. Therefore, the MFP functions as a network printer or a scanner. 
         [0004]    A client and an MFP that adopt a specific OS (operating system), for example, the Windows (trademark) series OS of Microsoft Corporation operate on a network that adopts IPv6 (Internet Protocol ver. 6) as a network interface. 
         [0005]    A router corresponding to IPv6 allocates IP (Internet Protocol) addresses (stateless addresses) to the client and the MFP (stateless address autoconfiguration). The MFP acquires an IP address based upon a router advertisement (hereinafter referred to as RA) transmitted from the router in the network that adopts IPv6 as the network interface. 
         [0006]    Therefore, when setting on the router side is changed, the MFP connected to the network environment that adopts IPv6 as the network interface may become unrecognizable by the client or the server. When prefix information of the RA transmitted from the router is changed or when a term of validity of a prefix expires, the IP address is deleted regardless of convenience on the host side. 
         [0007]    The router used in the network environment that adopts IPv6 as the network interface can automatically grant an IP address. The IP address automatically granted by the router is a stateless address. A system for granting the IP address is stateless address autoconfiguration. The automatically-granted IP address includes 128 bits in total, higher order 64 bits of which are defined by the router and lower order 64 bits of which are a MAC (Media Access Control) address. 
         [0008]    For example, JP-A-2003-134116 (Patent Document 1) discloses that, in a network that adopts a DNS (Domain Name System), inconsistency and mismatch of address information is prevented from occurring between a server and an image processing apparatus that is turned on and off independently from the server. 
         [0009]    However, Patent Document 1 does not indicate expansion to the network environment that adopts IPv6 as the network interface. 
       SUMMARY 
       [0010]    It is an object of the present invention to provide an electronic apparatus connected to a network that adopts IPv6 as a network interface, the electronic apparatus having persistence in services in that a change in prefix information of an RA (Router Advertisement) transmitted from a router does not affect the services. 
         [0011]    According to an aspect of the present invention, there is provided a method of automatically setting an IP address of an electronic apparatus connected to a router via a network, the method including: receiving a router advertisement transmitted from the router; receiving prefix information of the router advertisement; additionally storing an IP address based upon the received prefix information as an IP address of the electronic apparatus when the electronic apparatus has setting for maintaining the prefix information; and rewriting a presently registered IP address with an IP address based upon the received prefix information when the electronic apparatus does not have the setting for maintaining the prefix information. 
         [0012]    Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0013]    The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the invention. 
           [0014]      FIG. 1  is a diagram of an example of a network located in an image forming apparatus (a multi-functional peripheral (MFP)) according to an embodiment of the present invention; 
           [0015]      FIG. 2  is a diagram of a configuration of the MFP used in the network shown in  FIG. 1 ; 
           [0016]      FIG. 3  is a diagram of an example of a setting screen displayed on a display unit shown in  FIG. 2 ; 
           [0017]      FIG. 4  is a table (a memory map) of an example of setting of “Keep Configuration”; and 
           [0018]      FIG. 5  is a flowchart for explaining setting of “Keep Configuration”. 
       
    
    
     DETAILED DESCRIPTION  
       [0019]    An embodiment of the present invention is explained in detail below with reference to the accompanying drawings. 
         [0020]      FIG. 1  is a diagram of an example of an electronic apparatus (an MFP (Multi-Functional Peripheral), i.e., an image forming apparatus) according to the embodiment connected to a network that adopts IPv6 (Internet Protocol ver. 6) as a network interface. 
         [0021]    A network  101  shown in  FIG. 1  includes, for example, four routers  111 ,  113 ,  115 , and  117  and at least one server  119 . At least two (first and second) MFPs (electronic apparatuses)  121  and  123  are connected to the network  101 . At least four (first to fourth) clients (electronic apparatuses, e.g., personal computers)  131 ,  133 ,  135 , and  137  are also connected to the network  101 . 
         [0022]    As indicated by an example shown in  FIG. 2 , each of the first and second MFPs  121  and  123  includes a printer section (an image forming unit)  11 , a scanner section (an image input unit)  13 , a control section (a control unit)  15 , an interface section (a communication unit)  17 , and a user interface section (a user interactive unit)  19 . The user interactive unit  19  includes a display unit  19   a  that displays input information. The control unit  15  includes a storage section (a storage unit)  15   a  that stores control (setting) information, image information, and the like. 
         [0023]    The communication unit  17  exchanges control signals and image information with unspecified clients through arbitrary ones of the routers  111 ,  113 ,  115 , and  117 . The communication unit  17  exchanges control signals and image information with the server  119  through arbitrary one of the routers  111 ,  113 ,  115 , and  117 . 
         [0024]    The image forming unit  11  includes, for example, an electrophotographic system, a thermal transfer system, or an inkjet system. 
         [0025]    The image input unit  13  is an arbitrary system that can obtain image information by photoelectrically converting, for example, reflected light or transmitted light obtained by illuminating a target image or text. 
         [0026]    The control unit  15  controls, according to a control input from a client or a server through the user interactive unit  19  or the communication unit  17 , acquisition of an image output by the image forming unit  11  and acquisition of image information by the image input unit  13  and supplies the image information to the communication unit  17  when necessary. The control unit  15  processes control information (setting) and the like for the image forming unit  11 , the image input unit  13 , and the communication unit  17 . 
         [0027]    The control unit  15  controls, according to a control input from a router or a server through the communication unit  17 , acquisition of an image output by the image forming unit  11  and acquisition of image information by the image input unit  13  and supplies the image information to the communication unit  17  when necessary. The control unit  15  processes control information (setting) and the like for the image forming unit  11 , the image input unit  13 , and the communication unit  17 . 
         [0028]    The first and second MFPs  121  and  123  connected to the network  101  shown in  FIG. 1  have IP addresses provided by, for example, the first router  111  according to the stateless address autoconfiguration. Each of the IP addresses provided according to the stateless address configuration includes 128 bits in total, higher order 64 bits of which are defined by the router  111  and lower order 64 bits are a MAC (Media Access Control) address. 
         [0029]    The IP addresses granted to the first and second MFPs  121  and  123  by the first router  111  have a “term of validity” according to IPv6. The IP addresses are based upon a router advertisement (RA) transmitted by the router  111 . Therefore, when prefix information of the IP addresses is changed or the term of validity of the prefix expires, the router  111  deletes the old IP addresses regardless of convenience on a host side (a client or a server). 
         [0030]    Therefore, when an environment of the network  101  is changed and the IP addresses based upon the prefix information are changed according to a setting change or the like on the router  111  ( 113 ) side, the first and second MFPs  121  and  123  may suddenly become unrecognizable by a communication partner (the client or the server) that already makes connection to the first and second MFPs  121  and  123  using the IP addresses. In this case, inconvenience such as service suspension may occur. 
         [0031]    On the basis of such a background, in each of the first and second MFPs  121  and  123  connected to the network that adopts IPv6 as the network interface, ‘valid” or ‘invalid’ of “Keep Configuration” peculiar to IPv6 is set. As the setting of “Keep Configuration”, for example, a setting program stored in the storage unit  15   a  is started from an administrator PC connected via the user interactive unit  19  or a network (not shown) and a check box of “Keep Configuration” is checked in a setting screen (displayed on the display unit  19   a ), a display example of which is shown in  FIG. 3 . Consequently, “Keep Configuration” is set ‘valid’. In other words, as indicated by an example shown in  FIG. 4 , when “1” indicates ‘valid’, a “Keep Configuration Flag” prepared in a predetermined area is set to ‘1’. 
         [0032]    “Keep Configuration” being ‘valid’ means that, as indicated by an example shown in  FIG. 4 , when prefix information of an RA provided by a router is changed or when a term of validity of a prefix expires, prefix information of an RA provided by the router anew (i.e., an IP address transmitted to a target MFP by the router and indicated as ‘fd00:3::/64’ in  FIG. 4 ) is added (old prefix information (i.e., an IP address transmitted to the target MFP before by the router and indicated as ‘fd00:1::/64’ in  FIG. 4 ) is not deleted. 
         [0033]    As the setting of ‘valid’ of “Keep Configuration” in  FIG. 3 , in terms of software, as indicated by a flowchart of  FIG. 5 , when there is a setting change in an arbitrary router, the router transmits “RA” to an MFP (ACT 1). An example of “RA” is “change prefix A to prefix B (A=(fe00:1::/64) to B=(fe00:3::/64))” indicating that a (already transmitted) prefix A (fe00:1::/64) is changed to a prefix B (fe00:3::/64). 
         [0034]    If “RA” is transmitted in ACT 1, it is determined whether “Keep Configuration” is ‘valid’, i.e., whether “Keep Configuration Flag” is “l”(Flag=1?) (ACT 2). 
         [0035]    If “Keep Configuration Flag” is “0” in ACT 2 (NO in ACT 2), the router changes the (already transmitted) prefix A to the prefix B (ACT 4). 
         [0036]    If “Keep Configuration Flag” is “1” in ACT 2 (YES in ACT 2), the router maintains the (already transmitted) prefix A and adds the prefix B (ACT 3). 
         [0037]    As a method of storing an IP address similar to the setting of ‘valid’ of “Keep Configuration”, “infinity (understood as “fixed”)” peculiar to IPv6 may be transmitted by “RA”. 
         [0038]    As explained above, in the network environment that adopts IPv6 as the network interface, when a prefix is changed on the router side, a notification of a change of the prefix is transmitted from the router to a host (an electronic apparatus), i.e., a client, for example, a personal computer, or a server or an MFP (the router transmits the prefix to the client or, the server or the MFP). Similarly, when a term of validity of the prefix expires, update (deletion) of the prefix is performed. 
         [0039]    A maximum number of IP addresses that can be stored is seven. When an IP address is added anew exceeding the maximum number of IP addresses, an oldest IP address is deleted. 
         [0040]    However, by setting “Keep Configuration” ‘valid’ such that the IP address can be permanently used unless a user explicitly permits change or deletion of the IP address, it is possible to prevent a prefix (transmitted to that point) from being updated. An IP address based upon new prefix information is added. 
         [0041]    By adopting such a configuration, even if a network environment is changed because of a setting change of a router or the like, it is possible to prevent a change of a prefix from affecting services and impart persistence to the services. 
         [0042]    Therefore, the electronic apparatus (an MFP) connected to the network that adopts IPv6 as the network interface can persistently output an image output according to a request from a client (services are not stopped). 
         [0043]    Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.