JPH09282259A - Network system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable communication including a network application only by simply physically connecting a terminal to a LAN by using a name, which is common for the entire network and general, for the communicating party of the terminal. SOLUTION: The host name of a server common for the entire network system and address information are correspondently set to a DNS server. Besides, a network client 2 is provided with a DNS server information setting means 24 for setting the information of the DNS server acquired from a DHCP server by a DHCP client function 23 to a DNS server information storage means 26. Further, the host name common for a correspondent server function is set to client functions 20 and 23 of the application inside a client 2 as well. Then, when performing access from the client functions 20 and 23 to the server function of the network server, based on the information set into the DNS server information storage means 26, the address information of the network server is inquired to the DNS server.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention realizes automatic distribution of various network information including address information of each terminal constructed on a LAN in a network system using a client-server type application via a network. The present invention relates to a network system in which a protocol DHCP or BOOTP is introduced.

[0002]

2. Description of the Related Art Conventionally, a LAN (Local Area) has been used.
To construct a network, a LAN system administrator or user needs to set network information including terminal-specific address information for each connection terminal. However, with the recent large-scale network, L
Construction of AN is becoming a great effort.

In order to solve such a problem, RFC
(Request For Comment) 1541
As described above, DHCP (Dynam) is a means for automatically distributing address information and the like to terminals connected to a LAN.
ic Host Configuration Pro
tocol) has been devised and is about to be realized.

By using DHCP, the terminal is
The address information and the like can be acquired only by physically connecting to the AN, and it is possible to freely move between different LANs.

Further, the network application used on the LAN can specify the partner terminal communicating via the LAN with a name that is more familiar to people, instead of the address information of numerical information. The technology that realizes this is the DNS (Domain) described in RFC1035.
(Name System). The DNS provides a function of uniquely associating the address information unique to the terminal on the LAN and the name with each other and converting them.

[0006]

[0005] DHCP is an independent technology and is not considered in cooperation with the above DNS or network application. Therefore, when actually using the network application on the terminal, it is necessary to set the settings for the user to manually use the DNS and the information of the other party with which the network application communicates.

Similarly, when the terminal is moved to another LAN, the user has to manually correct the above settings.

[0008] The first object of the present invention is to provide a network system capable of communication including network applications by simply physically connecting to a LAN without the above settings. .

A second object is to provide a network system in which the user does not need to modify the above settings even when the terminal moves to another LAN.

[0010]

In order to solve the above problems, according to the present invention, the name (host name) of the partner (network server) with which the network application of the terminal communicates is not a local one determined at each network site. Instead, use a common name that is common to all network sites and manage it.

Then, the common host name of the above-mentioned network server and the address information relating to the network server are uniquely set in advance in the DNS server which provides the DNS function.

When a terminal that receives network information including address information by DHCP has a function of using DNS, means for setting information necessary for using DNS based on the information distributed by DHCP is provided. . If the terminal cannot use DNS, DH
A means for storing the address information regarding the network server among the information distributed by the CP in association with the common host name is provided.

Further, the network application on the terminal has the common host name of the network server for each application as a default value from the beginning.

As a result, the network application of the terminal can acquire the correct address information of the communication partner regardless of whether the DNS is used or not.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

1. Case of using DHCP and DNS First, the case of introducing DHCP and DNS into a network system will be described.

FIG. 2 shows an example of a network in which DHCP and DNS are introduced and electronic mail is operated as a network application.

As shown, two network sites, site A (FIG. 2A) and site B (FIG. 2).
(B)) exists. Both sites provide DHCP servers 1 and 6 having a DHCP server function 30 that distributes network information including terminal address information, and DNS that provides means for mutually converting terminal-specific address information and host names. There are DNS servers 3 and 7 having the server function 34 and mail servers 4 and 8 having the electronic mail server function 36. The site A further has an electronic mail client function 33 and a network client 2 having a DHCP client function 32 for acquiring network information from a DHCP server. Each terminal is connected to LAN 5 at site A and LAN 9 at site B. Both sites use TCP / IP (Transmission) as a communication protocol.
on Control Protocol / Inter
It is assumed that the IP address is used as the address information for uniquely identifying each terminal.

In both sites, "mail_server" is used as the common host name of the network server.
(Mail server), "news_server" (electronic news server), "www_server" (WWW
(World Wide Web) server) is used. The electronic news server and the WWW server are not shown in FIG. 2 in order to simplify the drawing, but will be described below as being present.

Each of the DHCP servers 1 and 6 has an IP address that can be distributed to the network client 2 and
It holds DHCP management tables 31 and 37 for managing IP addresses of various servers.

The DHCP management tables 31 and 37 are shown in FIGS. 3 (a) and 3 (b), respectively. As shown, D
The HPC management tables 31 and 37 are composed of an item number 40, an IP address 41 to be distributed to a DHCP client, various server addresses 42, and a domain name 47. Here, as various server addresses 42, a DNS server 43,
And mail server 44, electronic news server 45, WW
It is assumed that there are four items of the W server 46. Further, the IP address is different at each site.

The DNS servers 3 and 7 are the DNS tables 35 and 38 in which the host name and IP address of each terminal are associated with each other.
Holding The DNS tables 35 and 38 are shown in FIGS. 4 (a) and 4 (b), respectively. As shown, DN
The S tables 35 and 38 are composed of an item number 50, a host name 51, and an IP address 52. The host name 51 is common to both sites ("mail_server").
r ”,“ news_server ”,“ www_ser ”
“Ver”) is set, and the IP address 52 is set to the IP address for each site.

FIG. 1 is a block diagram of the network client 2 according to the present invention. As shown in the figure, the network client 2 includes a CPU 10, a memory 11, and a LAN I / O 12 for transmitting and receiving packets, which are connected to each other via a bus
Take the configuration connected by.

The memory 11 also has a DHCP client program 23 for realizing the DHCP client function.
And network communication control, and LAN I / O12
A communication program 22 for controlling the IP address, an IP address table 25 for registering the IP address of the network client, and a DNS server table 26 for registering a DNS server used to acquire the IP address from the host name of the communication partner. , Host table 2 for registering the correspondence between the host names of terminals on the LAN and their IP addresses
7, and among the information distributed by DHCP, the information necessary for using the DNS is set in the DNS server table.
An S server table setting program 24 exists. Furthermore, as a network application in memory,
The electronic mail client program 20 is incorporated, and the electronic mail client program 20 has a server table 21 for setting the host name of the mail server. In the server table 21, the name "ma" common to all network sites is used as the host name of the mail server.
il_server ”is set.

The operation of the network client 2 having the above configuration will be described below.

(1) Operation of Network Client 2 at Site A The operation of the network client 2 at site A will be described.

(DHCP Process) First, a DHCP process for acquiring information such as an IP address from a DHCP server will be described.

FIG. 5 shows an operation flow chart of the DHCP client program 23.

As shown in the figure, the DHCP client program 23 first transmits a DHCP DISCOVER packet which is a packet for searching for a DHCP server in order to obtain information such as an IP address from the DHCP server (step 1). Then, the DHCP client program 23 sends the DH which is a response from the DHCP server.
Wait until a CP OFFER packet is received (step 2).

The packet format of the DHCP DISCOVER packet is shown in FIG. 6 (a). As shown, the DHCP DISCOVER packet 60 has a destination I
An IP consisting of a P address 71 (= broadcast), a source IP address 72 (= “0”), and other 73
The header etc. 70 and the message type 81 (= “DIS
COVER ”), distribution IP address 82 (=“ 0 ”),
And a DHCP section 80 including the others 83.

The DHCP DISCOVER packet 60 is sent from the LAN / IO 12 to the LAN 5 by the communication program 22 and sent to the DHCP server 1.

DHCP DISCOVER packet 60
The DHCP server 1 of the site A, which receives the message, refers to the DHCP management table 31 held in itself and sets a distributable IP address, various server addresses, and a domain name in the DHCP OFFER packet which is a response packet. , To the network client 2. Here, item number 40 in the DHCP management table 31
“1” shall be assigned and distributed. That DHCP
Fig. 6 shows the packet format of the OFFER packet.
(B). As shown in the figure, the DHCP OFFER packet 61 includes a destination IP address 71 (= “1”), a source IP address 72 (= “20”), and an IP header etc. 70 including other 73, and a message type 81.
(= “OFFER”), distribution IP address 82 (=
“1”), DNS server address 84 (= “10”),
Domain name 85 (= “siteA”), mail server address 86 (= “11”), electronic news server address 87 (= “12”), WWW server address 88 (=)
“13”), and a DHCP section 80 including the others 83. The IP address of the DHCP server 1 itself is “20”.

DHCP O sent by the DHCP server 1
The FFER packet 61 is received by the LAN I / O 12 of the network client 2 and passed by the communication program 22 to the DHCP client program 23.

The DHCP client program 23 is
When the DHCP OFFER packet 61 is received, DH
A DHCP REQUEST packet, which is a packet for officially requesting information such as an IP address from the CP server, is transmitted to the DHCP server 1 (step 3). FIG. 6C shows the packet format of the DHCP REQUEST packet. DHC as shown
The P REQUEST packet 62 is the destination IP address 7
1 (= broadcast), source IP address 72
(= “0”), and the other part 73 such as an IP header 70, and a message type 81 (= “REQUES”).
T "), distribution IP address 82 (=" 0 "), request IP
Address 89 (= “1”) and D consisting of others 83
It is composed of an HCP unit 80.

After that, the DHCP client program 23 proceeds to the next step and waits until it receives a DHCP ACK packet which is a response from the DHCP server 1 (step 4).

Here, the DHCP server 1 that has received the DHCP REQUEST packet 62 officially transmits a DHCP ACK packet, which is a response packet, to the network client 2 in order to permit distribution of information such as an IP address. The packet format of the DHCP ACK packet is shown in FIG. As shown, the DHCP ACK packet 63 has the destination IP address 71.
(= “1”), source IP address 72 (= “2”
0 ″) and other 73 such as an IP header 70
And message type 81 (= "ACK"), distribution IP
Address 82 (= “1”), DNS server address 8
4 (= “10”), domain name 85 (= “site”)
A ”), mail server address 86 (=“ 11 ”), electronic news server address 87 (=“ 12 ”), WWW
It is composed of a server address 88 (= “13”) and a DHCP unit 80 including the others 83.

The DHCP client program 23 is D
When the DHCP ACK packet 63 is received, the DHCP
The distribution IP address 82 (= "1") set in the ACK packet 63 is set in the IP address table 25 (step 5). This completes the DHCP client program.

Subsequently, the DNS server table setting program 24 is executed. An operation flow chart of the DNS server table setting program 24 is shown in FIG. As shown in the figure, the DNS server table setting program 24 uses the DNS server address 8 which is information required when using the DNS, from the DHCP ACK packet 63 received by the above-mentioned DHCP client program 23.
4 (= “10”) and domain name 85 (= “site”)
A ") is set in the DNS server table 26 (step 6).

FIG. 8 shows the DNS server table 26.
(A). As shown in the figure, the DNS server table 26 is composed of a DNS server IP address 90 and a domain name 91, and "1" is set in each field.
0 "and" siteA "are set.

The DHCP process is completed as described above, and thereafter the network client 2 communicates using the distributed IP address (= "1").

(Electronic Mail Process) Next, the operation of the network client 2 when using electronic mail will be described below.

FIG. 9 shows an operation flow chart of the electronic mail client program 20. As shown, the email client program 20 first creates the body of the email (step 7). Then, the e-mail client program 20 sets the created e-mail in the e-mail packet and sets the destination IP of the e-mail packet.
Attempts to set the IP address of the mail server 4 to the address. The format of the e-mail packet is shown in FIG.

As shown, an email packet 100
Is composed of a destination IP address 71, a source IP address 72, and an IP header section 70 including others 73, an email body 111, and an email section 110 including others 112.

E-mail client program 20
First, in the DNS server table 26, the DNS server IP
It is investigated whether or not the address 90 and the domain name 91 are set (step 8). As mentioned above, D
The DNS server table 26 already has a DNS server IP address 90 (= “10”) and a domain name 91 (= “s”).
teA ") is set, the e-mail client program 20 recognizes that the DNS is used to obtain the IP address of the mail server. Then, the e-mail client program 20 informs the DNS server of the terminal. Host name of the mail server (= “mail_ser”) in the DNS QUERY packet, which is a packet for requesting conversion from the host name of
"ver") is set and transmitted to the DNS server 3 (step 9).

Then, the electronic mail client program 20 sends a DNS RE response from the DNS server 4.
Wait until the SPONSE packet is received (Step 1
0).

FIG. 11A shows the packet format of the DNS QUERY packet. DN as shown
The S QUERY packet 120 has the destination IP address 71
(= “10”), source IP address 72 (=
"1"), and an IP header etc. 70 composed of others 73
And a DNS unit 130 composed of a message type 131 (= “QUERY”), a host name 132 (= “mail_server”), and 133.
The destination IP address 71 (= “10”) is quoted from the DNS server IP address 90 in the DNS server table 26.

Upon receiving the DNS QUERY packet 120, the DNS server 3 of the site A holds the DN stored therein.
Referring to the S table 35, the host name 132 (= “mai” set in the DNS QUERY packet 120)
l_server ”) is searched for, where the host name“ mail_server ”is D
Since it matches the item number “1” in the NS table 35, DNS
The server 3 generates a DNS RESPONSE packet, sets a corresponding IP address (= “11”), and responds to the network client 2.

The packet format of the DNS RESPONSE packet is shown in FIG. 11 (b).

As shown, DNS RESPONSE
The packet 121 is the destination IP address 71 (= “1”),
Source IP address 72 (= “10”) and other 7
IP header etc. 70 consisting of 3 and message type 1
31 (= “RESPONSE”), host name 132 (=
"Mail_server"), IP address 134
(= “11”) and other 133 DNS section 1
It consists of 30.

After that, the DNS RESPONSE packet 121 is transmitted to the LANI in the network client 2.
/ O12, and it is passed to the electronic mail client program 20 by the communication program 22.

When the electronic mail client program 20 receives the DNS RESPONSE packet 121, the IP address 134 (= “1” of the mail server 4 set in the DNS RESPONSE packet 121).
1 ") is set to the destination IP address 71 of the e-mail packet 100, and the e-mail packet 100 is sent to the mail server 4 (step 11). After that, the e-mail packet 100 is sent to the LAN 5 and the mail server 4 is sent. Will be sent to.

The e-mail process is executed as described above.

(2) Operation of Network Client After Moving to Site B Next, a case where the network client 2 moves from the site A to the site B will be described.

(DHCP Process) When the network client 2 moves to the site B, the DHCP client program 23 first causes the DHCP server 6 at the site B to move.
In order to get information such as IP address from
The operation flow (steps 1 to 4) shown in FIG. Here, it is assumed that the DHCP server 6 allocates and distributes the item number 40 “1” of the DHCP management table 37 to the network client 2.

After that, the DHCP client program 23 uses the IP distributed from the DHCP server 6 of the site B.
The address (= “50”) is set in the IP address table 25, and the process is completed (step 5).

Subsequently, the DNS server table setting program 24 shown in FIG. 7 is executed, and the DNS server IP address 90 (= “6
0 ”) and the domain name 91 (=“ siteB ”) are set (step 6).

FIG. 8 shows the DNS server table 26.
(B). As illustrated, in the DNS server table 26, the DNS server IP address 90 (= “6
0 ”) and the domain name 91 (=“ siteB ”) are set.

With the above, the DHCP process is completed. After that, the network client 2 uses the IP address (= “50”) available at the site B to perform communication.

As described above, the IP address and the like used by the network client 2 at the site B are automatically distributed and set.

(Electronic Mail Process) Next, an operation when the network client 2 uses electronic mail at the site B will be described below.

Similar to the operation at the site A described above, the electronic mail client program 20 starts the operation flow shown in FIG. Here, as shown in FIG.
Although the DNS server table 26 has been changed to the IP address for the site B, the DNS table 38 in the DNS server 7 of the site B shows the name “mail_ser” common to all network sites as the host name of the mail server.
“Ver” has already been set. Therefore, the electronic mail client program 20 executes steps 7 to 10 in the same manner as the operation at the site A. Finally, the electronic mail client program 20 acquires the acquired mail server 8. Of the IP address (= “61”) of the e-mail packet 100 to the destination IP address 71,
The electronic mail packet 100 is transmitted to the mail server 8 (step 11). Then email packet 10
0 is sent to the LAN 9 and sent to the mail server 8.

As described above, the process of electronic mail is executed.

As described above, even when the network client moves from the site A to the site B, the user of the network client 2 manually inputs the server table 2 in the electronic mail client program 20.
1 or the DNS server table 26 does not need to be changed for the site B.

Although the operation of the electronic mail has been described in the above example, it is necessary to change the server table in each network application by using the same method for other network applications such as electronic news and WWW. Disappear.

Further, in the above-described embodiment, in the DHCP servers 1 and 6, the mail server 44 in the DHCP management tables 31 and 37, the electronic news server 45, and the WW.
Although the IP address information of the W server 46 is manually set in advance, it can be set by using DNS.
It is also possible to obtain it from the NS server and set it automatically.

As shown in FIG. 12, DHCP
The server 1 may be provided with the DHCP information acquisition program 39. FIG. 13 shows an operational flow chart of the DHCP information acquisition program 39. As illustrated, the DHCP information acquisition program 39 in the DHCP server 1 (or 6)
Sets the host name (“mail_server” or the like) of each network server in the DNS QUERY packet and sends it to the DNS server 3 (or 7) (step 13). The DN that received the DNS QUERY packet
The S server 3 (or 7) has its own DNS table 35.
(Or 38), the IP address corresponding to the host name set in the DNS QUERY packet is set in the DNS RESPONSE packet, and then DH
It is sent to the CP server 1 (or 6).

Upon receiving the DNS RESPONSE packet, the DHCP information acquisition program 39 in the DHCP server 1 (or 6) stores the IP address information of each network server set in the DNS RESPONSE packet in its own DHCP management table 31. (Or 3
7) to complete the process (steps 14 and 1)
5). After that, the DHCP server 1 (or 6) distributes the address information of the network server acquired from the DNS server to the network client.

As a result, the system administrator does not need to make some settings in the DHCP server. Further, since the network server is replaced with another terminal, even when the IP address or the like is changed, the LAN system administrator only needs to change the DNS table in the DNS server.

2. Case of Using Only DHCP Next, a case of introducing only DHCP into the network will be described.

FIG. 14 shows an example of a network in which only DHCP is introduced and electronic mail is operated as a network application.

The configuration is basically the same as that of FIG.
The only difference is that there is no S server.

Also, as in the case of using the above-mentioned DNS, as the host name of the network server common to both sites, "mail_server" (mail server), "news_server" (electronic news server), "www_server" (WWW server) is used. It should be noted that the electronic news server and the WWW server are not shown in FIG. 14 in order to simplify the drawing, but will be described below as existing.

FIGS. 15A and 15B show the structures of the DHCP management tables 150 and 151 in the DHCP servers 140 and 143 of the sites C and D, respectively. As shown in the figure, the DHCP management tables 150 and 151 have the same configuration as in FIG. 3, but values for the sites C and D are set as the IP address and domain name.

FIG. 16 shows a configuration diagram of the network client 2 in this case. The configuration is basically the same as that of FIG. 1, except that a host table setting program 28 is present instead of the DNS server setting program 24.

The operation of the network client 2 having the above configuration will be described below.

(1) Operation of Network Client 2 at Site C The operation of the network client 2 at site C will be described.

(DHCP Process) First, a DHCP process for acquiring information such as an IP address from a DHCP server will be described.

As shown in FIG. 5, the DHCP client program 23 executes steps 1 to 4 as described above.
The same is done as in the case of using P and DNS.
In this case, it is assumed that the DHCP server 140 has distributed the information of item number 40 “1” in the DHCP management table 150.

After that, the DHCP client program 23 uses the DHCP server 140 of the site C to execute the DHCP.
Receive an ACK packet. Then, the DHCP client program 23 sets the distribution IP address 122 (= “70”) set in the DHCP ACK packet to I
The P address table 25 is set and the process is completed (step 5).

Next, the host table setting program 2
8 is executed. The host table setting program 2
FIG. 17 shows an operation flow chart of No. 8. The host table setting program 28 uses the information acquired by DHCP,
The mail server address (= “81”), the electronic news server address (= “82”), and the WWW server address (= “83”) are set in the host table 27 (step 16).

The host table 27 is shown in FIG. As shown in the figure, the host table 27 has item number 16
0, a host name 161, and an IP address 162. The host name 161 has names common to both sites, “mail_server” and “news_serv”.
er ”and“ www_server ”, and the IP address 162 is set to the value for the site C distributed from the DHCP server 140.

Nothing is set in the DNS server table 26.

This completes the DHCP process.

(Electronic Mail Process) Next, the operation when using electronic mail in the network client 2 will be described below.

As already shown in FIG. 9, the electronic mail client program 20 first creates the text of the electronic mail (step 7). Then, the e-mail client program 20 sets the created e-mail in the e-mail packet 100, and attempts to set the IP address of the mail server in the destination IP address 71 of the e-mail packet 100.

E-mail client program 20
First, in the DNS server table 26, the I
It is checked whether the P address and the domain name are set (step 8). As mentioned above, DNS
Since nothing is set in the server table 26, the electronic mail client program 20 recognizes that the host table 27 is used to acquire the IP address. As described above, the host name of the mail server is 161 (= “mail_server”) in the host table 27.
Since the corresponding IP address 162 (= “81”) has already been set, the e-mail client program 20 uses the host name “mail” from the host table 27.
The IP address “81” corresponding to “_server” is acquired (step 12) and set as the destination IP address 71 of the email packet 100, and the email packet 1
00 is transmitted (step 11). After that, the electronic mail packet 100 is sent to the LAN 142 and sent to the mail server 141.

As described above, the process of the electronic mail is executed.

(2) Operation of Network Client After Moving to Site D Next, a case where the network client 2 moves from the site C to the site D will be described.

(DHCP Process) When the network client 2 moves to the site D, first, the DHCP client program 23 causes the DHCP server 1 of the site D to operate.
In order to distribute information such as IP address from 43,
The operation flow (steps 1 to 4) shown in FIG. 5 is executed in the same manner as the operation at the site C described above. Where DHC
The P server 143 is the item number 4 of the DHCP management table 151.
It is assumed that 0 “1” is assigned to the network client 2 and distributed.

After that, the DHCP client program 23 uses the DHCP server 143 of the site D to execute the DHCP.
Receive an ACK packet. Then, the DHCP client program 23 uses the DHCP server 143 of the site D.
The IP address (= “90”) distributed from is set in the IP address table 25, and the process is completed (step 5).

Next, the host table setting program 2
8 is executed, and the mail server address (= “10
1 ”), electronic news server address (=“ 10
2 ") and WWW server address (=" 103 ") are set (step 16). The host table 27 is shown in Fig. 18B. As shown in the figure, the host name 161 of the host table 27 is set. The names common to both sites are "mail_server" and "news_s".
The “server” and “www_server” are set, and the IP address 162 is set to the value for the site D distributed from the DHCP server 143.

This completes the DHCP process. After that, the network client 2 uses the IP address (= “90”) available at the site D to perform communication.

As described above, the IP address or the like used by the network client at the site D is automatically distributed and set.

(Electronic Mail Process) Next, the operation when the network client 2 uses electronic mail at the site D will be described below.

Similar to the operation at the site C described above, the electronic mail client program 20 starts the operation flow shown in FIG. Here, as shown in FIG.
Although the IP address for the site D is set in the host table 27, the mail server host name is set to "mail_server" which is a common name for all the sites. Therefore, the electronic mail client program 20 executes steps 7 to 8 and step 12 as in the operation at the site C described above. Finally, the email client program 20 sets the acquired IP address (= “101”) of the mail server in the destination IP address 71 of the email packet 100,
The electronic mail packet 100 is transmitted to the mail server 144 (step 11). Then, the email packet 100 is transmitted to the LAN 145, and the email server 144
Will be sent to.

Thus, the e-mail process is executed.

As described above, even when the network client 2 moves from the site C to the site D, the user of the network client 2 manually inputs the server table 21 and the host table 27 in the electronic mail client program 20. No need to change for Site D.

In the above-described embodiment, the distribution of IP address information and the like to network clients is performed by DHCP.
RFC95, which is another protocol that automatically distributes network information, similar to DHCP.
1. BOOTP (BOOTtrap Proto described in 1)
col) may be used instead.

[0099]

As described above, according to the present invention, even when a user moves a terminal between LANs, the user does not have to change the information settings necessary for using the DNS or the host table settings. Further, the application can be used without changing the setting of the network server registration of the network application such as e-mail. Therefore, the user has information about DNS for each site,
It is not necessary to be aware of the address information, host name, etc. of network servers such as mail servers, electronic news servers, WWW servers.

As a result, by temporarily terminating the communication on the terminal, it is possible to provide a mobile system which can be freely moved between LANs and used without changing the settings.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a network client according to an embodiment of the present invention.

FIG. 2 is a diagram showing a network configuration example in which DHCP and DNS are introduced in the embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of a DHCP management table in the embodiment of the present invention.

FIG. 4 is a diagram showing a configuration of a DNS table in the embodiment of the present invention.

FIG. 5 is an operation flow diagram of a DHCP client program in the embodiment of the present invention.

FIG. 6 is a DHCP DISCO according to an embodiment of the present invention.
VER, DHCP OFFER, DHCP REQUE
It is a figure which shows the structure of ST and a DHCP ACK packet.

FIG. 7 is an operation flow diagram of the DNS server table setting program in the embodiment of the present invention.

FIG. 8 is a diagram showing a configuration of a DNS server table according to the embodiment of this invention.

FIG. 9 is an operation flow diagram of the electronic mail client program in the embodiment of the present invention.

FIG. 10 is a diagram showing a structure of an electronic mail packet according to the embodiment of the present invention.

FIG. 11 is a DNS QUER according to an embodiment of the present invention.
It is a figure which shows the structure of Y and a DNS RESPONSE packet.

FIG. 12 is a DHCP and DN in another embodiment of the present invention.
It is a figure which shows the network structural example which introduced S.

FIG. 13 is an operation flow diagram of a DHCP information acquisition program according to another embodiment of the present invention.

FIG. 14: DHC in yet another embodiment of the present invention
It is a figure which shows the network structural example which introduced only P.

FIG. 15: DHC in yet another embodiment of the present invention
It is a figure which shows the structure of the P management table.

FIG. 16 is a configuration diagram of a network client according to still another embodiment of the present invention.

FIG. 17 is an operational flowchart of a host table setting program in yet another embodiment of the present invention.

FIG. 18 is a diagram showing the configuration of a host table in yet another embodiment of the present invention.

[Explanation of symbols]

2 ... network client, 10 ... CPU, 1
1 ... memory, 12 ... LAN I / O, 13 ...
Bus, 20 ... E-mail client program,
21 ... server table, 22 ... communication program,
23 ... DHCP client program, 2
4 ... DNS server table setting program, 25 ... IP
Address table, 26 ... DNS server table,
27 ... Host table, 28 ... Host table setting program.

Claims (6)

[Claims] 1. A LAN (Local Area Network)
The DHCP (Dynamic Ho) that distributes address information and the like for uniquely identifying the terminal on the
stConfiguration Protocol)
A DHCP server having a function and a DNS (DomainName) that extracts address information of the terminal from the name of the terminal
e System) function, a DNS server that has a server function of a client-server type application used in a network, and a D server that exchanges distribution information with the DHCP server.
A network system comprising a network client having an HCP client function, a network application client function, and a DNS server information storage means for registering the DNS server, wherein the DNS server has a network common to all network systems. The host name of the server and the address information are set in association with each other, and the network client is provided with a DNS server information setting means for setting the DNS server information acquired by the DHCP client function from the DHCP server in the DNS server information storage means. For the client function of the network application in the network client, set the common host name for all the above network systems of the network server that has the corresponding server function, and When the client function of the network client accesses the server function of the network server, an inquiry about the address information of the network server is made to the DNS server based on the information set in the DNS server information storage means. A characteristic network system that uses DHCP. 2. A DHCP server having a DHCP function for distributing address information for uniquely identifying a terminal on a LAN to each terminal, and a server function for a client-server type application used in a network. A network including a network server, a DHCP client function for exchanging distribution information with the DHCP server, a client function for a network application, and host information storage means for storing the host name and address information of a terminal in association with each other. In a network system consisting of clients, if the DHCP client function obtains the address information of the network server from the DHCP server in the network client, the host of the network server common to all network systems. A host information setting means for setting in the host information storage means in association with the name is provided, and a common host name is set for all the network systems of the network server having the corresponding server function for the client function of the network application in the network client. A network system using DHCP characterized in that, when the client function of the network client accesses the server function of the network server, the address of the network server is obtained by referring to the host information storage means. 3. The network system according to claim 1, wherein the DHCP server is provided with DHCP information acquisition means, and the DHCP information acquisition means acquires and stores the address information of the network server by inquiring the DNS server about the address information. D, which distributes information to a network client having a DHCP client function
Network system using HCP. 4. A BOOTP (BOOT) for distributing address information or the like for uniquely identifying a terminal on a LAN to each terminal.
BOOT with a "strap protocol" function
DNS (Domain Name System) that derives the address information of the terminal from the P server and the name of the terminal
A DNS server having a function, a network server having a server function of a client-server type application used in a network, a BOOTP client function for exchanging distribution information with the BOOTP server, a client function for a network application, and A network system comprising a network client having a DNS server information storage means for registering the DNS server, wherein the DNS server associates a host name and address information of a network server common to all network systems. DNS server information setting means for setting the DNS server information acquired by the BOOTTP client function from the BOOTP server in the DNS server information storage means in the network client. When a common host name is set to the client function of the network application in the network client for all the above network systems of the network server having the corresponding server function and the client function of the network client accesses the server function of the network server , BOOTP, wherein the DNS server is inquired about the address information of the network server based on the information set in the DNS server information storage means.
Network system using. 5. A BOOTP server having a BOOTP function for distributing address information for uniquely identifying a terminal on a LAN to each terminal, and a server function for a client-server type application used in a network. A BOOTP client function for exchanging distribution information with the network server and the BOOTP server,
What is claimed is: 1. A network system comprising a network client having a client function of a network application and host information storage means for storing a host name and address information of a terminal in association with each other, wherein the network client has a BOOTP client function. When the address information of the network server is acquired from the BOOTP server, a host information setting means for setting the host information storage means in association with the host name of the network server common to all network systems is provided, and the client function of the network application in the network client is provided. , A common host name is set for all network systems of the network server having the corresponding server function, and the client machine of the network client There when accessing the server functions of the network server, a network system using BOOTP, characterized in that for obtaining the address of the network server by referring to the host information storage unit. 6. The network system according to claim 4, wherein the BOOTP server is provided with BOOTP information acquisition means, and the BOOTP information acquisition means inquires and stores the address information of the network server to the DNS server, and stores the address. A network system using BOOTP, which distributes information to a network client having a BOOTP client function.