JPH0662020A - Constructing system and changing system for computer network - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a computer network construction method and a change method having an address and name management function in consideration of node relocation. [Configuration] When there is an address request message from a node, the management server allocates an already-assigned address if the node name specified in the message is registered, and if not registered, selects from a free address and allocates it. Also, the valid period of the assigned address is determined according to the designation of the valid period length of the address in the message. When there is an address request message in which a node name belonging to another network is set, the management server selects from free addresses, allocates an address, and creates and sends a change information message to the management server of the current network. The management server of the current network receives the change information message, and based on the change information, makes the address used by the node whose connection has been changed reusable as a free address.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a computer address and name management system for a computer system using a network such as a LAN, and particularly to simplify the configuration change operation at the time of system construction and configuration change. The present invention relates to a characteristic computer network construction method and modification method.

[0002]

2. Description of the Related Art In the prior art, as described in Japanese Patent Laid-Open No. 22336/1990, an address inquiry message is transmitted to an address server, the address of its own computer is acquired from the response message, and stored. It was supposed to do.

[0003]

The above-mentioned conventional computer address management system does not provide a procedure for resetting the address used before the relocation as an empty address when the address is changed due to the node relocation. . When the address used by the relocation node is reset using message transmission / reception processing, it is necessary to activate the node once during relocation and reset the address before relocation as an empty address. Also, there is a method of resetting the address information by a local operation on the address server side, but there is a disadvantage that it requires manual intervention. In view of the above points, an object of the present invention is to provide a computer network construction method and a change method having an address and name management function in consideration of node relocation.

[0004]

According to the computer network construction method of the present invention, a node requesting allocation of an address of its own node comprises means for setting a node name in an address request message, and the management server for allocating the address is the address Using the node name specified in the request message as a key, the self-management server checks whether or not there is the same node name that has already been given and is currently valid. If there is, the already given address is given to the requesting node. It is provided with means for giving an address, and when not giving, selecting from free addresses and giving an address to the requesting node. Further, the node requesting the allocation of the address of its own node is provided with means for setting the length specification of the valid period of the allocated address in the address request message, and the management server specifies the length of the valid period specified in the address request message. Means for determining the valid period of the assigned address based on the above. According to the computer network changing method of the present invention, a node requesting allocation of the address of the own node is a node indicating that it belongs to another network in the address request message when changing the connection from the current network to which the own node is connected to another network. The management server of the other network is provided with a unit for setting a name, and the management server of the other network uses the node name designated in the address request message as a key, and the same node name as the node name that has already been assigned by the management server and is currently valid. Check whether or not there is, and if there is, assign the already given address to the requesting node, and if not, select from free addresses and give the address to the requesting node, and to the management server of the current network And a means for creating and transmitting a change information message of Network management server receives the change information message, comprising means for enabling reuse the connection changed address is used to nodes that request on the basis of the change information as free addresses. Further, the management server of the current network includes means for registering the changed node name as an alias corresponding to the original node name used for the connection-requested requesting node based on the change information.

[0005]

According to the computer network construction method of the present invention, when an address request message from a node is received, the management server, if the same node name as specified in the address request message is registered, the already assigned address. Is assigned, and if the same one is not registered, it is assigned by selecting from free addresses. Also, the valid period of the assigned address is determined according to the designation of the valid period length of the address in the address request message. In the computer network change method, when there is an address request message from a node in which a node name indicating that it belongs to another network is set, the management server
An address is selected from free addresses, an address is assigned, and a change information message to the management server of the current network is created and sent. The management server of the current network is
Upon receiving the change information message, the address used by the node whose connection has been changed based on the change information can be reused as a free address, and the management server of the current network uses it for the node whose connection has been changed based on the change information. The changed node name is registered as an alias corresponding to the original node name that has been set.

[0006]

[Embodiment] Hereinafter, in (1) to (2), an environment in which the network system shown in this embodiment operates will be described, and in (3) to (4), a procedure for constructing a network will be described. To do.

(1) Explanation of Terms Terms used in this embodiment will be explained. (A) Management server The management server is a server that holds and manages address information and directory information of the network system, and includes an address management server application (hereinafter referred to as address server) that manages addresses and a directory management server application (hereinafter referred to as address management server) that manages names. , Directory server). Note that the management program and the control program are referred to as applications here. (B) Domain The domain is the management range of the management server, and the nodes, user terminals, applications, peripheral devices, etc. that make up the network system of this embodiment are under the control of the management server. (C) Logical Address A logical address is an address assigned to a node and is a hardware address (for example, MAC (Media Acces) when constructing a network over a wide area.
It is possible to facilitate the route selection to the destination node by absorbing the difference in the specification of the (s Control) address) or by giving a hierarchical addressing. TCP / IP (Transmission) is used as the logical address.
Control Program / Internet
Protocol IP address, OSI (Ope)
n Systems Interconnection
n) NSAP (Network Service A)
access point) and the like are known.
In this embodiment, a 3-digit number string delimited by "." Is used.

(D) Application address The application address is a plurality of applications (management program, control program) on one node.
Is used to identify this, if present. In this embodiment, a one-digit number string is used. (E) Node name The node name is a name assigned to a node and is used to identify a node in a human readable form. (F) Application name The application name is a name assigned to the application and is used to identify the application in a human readable form.

(G) Valid period The valid period is the life (unit: minutes) of the logical address assigned by the address server, and the requester of the logical address acquisition can use the assigned logical address during this period. . Also, the previously assigned logical address must be deleted at node startup. In this way, the assigned logical address has a life span or is deleted at the time of start-up, thereby eliminating the operation of canceling the use of the logical address due to the node relocation or the like. (E) Valid period level The valid period level is a proposed value on the request side for the valid period of the logical address assigned by the address server, and hi
gh (when you want to use the assigned address for a long time), m
It is selected from three values of "edium" (when it is desired to use the allocated address in the medium term) and "low" (when it is desired to use the allocated address in the short term). For example, when using a stationary high-performance workstation as a file server, it is rare to move a node, so "high"
As a result, the address server allocates a long-lived effective period to the requesting node, which reduces the re-allocation request processing with the life of the logical address and may change the logical address. Also, select "low" for portable workstations that frequently move around the network, so that the address server allocates a short-lived lifetime to the requesting node. It is possible to effectively reuse a logical address that is not used due to movement.

(2) Overall Configuration of the Embodiment The network system targeted in this embodiment has the following features. (A) The network system includes an external storage device,
And a node having a relatively large memory and computing capacity (hereinafter referred to as a server), for example, a stationary high-performance workstation and a node having a more limited memory and computing capacity or a node having no external storage device ( Hereinafter, a client), for example, is constructed from a portable workstation, and the server supplements the functions lacking in the client, thereby providing a higher-performance and high-performance service to the application program or the user who is the client user. . (B) The network system manages addresses and names using the concept of domain. The domain is the management range of the management server. By introducing the concept of domain like this, the management range is divided,
It realizes automatic allocation of logical addresses and automatic updating of databases when logical addresses and names are changed. (C) The present network system transfers information between nodes in the form of a message with a destination set, and each node is based on the destination set in the message and the route (destination designation) table in its own node. It has the function of relaying received messages and delivering them to the correct destination.

Next, the configuration of this network system will be described. FIG. 5 is a diagram showing an example of the present network system configuration. This network system includes one domain A (50 managed by the management server 502.
1), and the nodes in the domain A are connected to each other by a link 506. Management server 5
02 is a node that manages logical addresses and names in the domain A, and the node name “name = adm.01”,
The logical address “addr = 13.7.15” is assigned, and the application name “ap-name =
adm. 01. An address server with the name "addr" and an application name "ap-name = ad"
m. 01. A directory server having the name "dir" operates. The mail server 504 is a node that provides a mail service, and this node has a node name "name = adm. 02 "is assigned,
As the application name, "ap-name = ad
m. 02. A mail server application having "mail" runs. The file server 505 is a node that provides a file registration reference service, and this node has a node name "name = adm. 03 ”is assigned, and“ ap-name is used as the application name ”
= Adm. 03. A file server application having “file” operates. The clients 503a and 503b are users of servers existing in the domain A, and node names “name = adm. client
1 "," name = adm. "client2" is allocated. The management server 502 dynamically allocates the logical addresses of the mail server, file server, and client nodes when the network system is constructed.

Next, referring to FIG. 14, a name system used when constructing a network system will be described.
FIG. 14 shows a name system used when constructing the network system shown in FIG. 5 and FIG. 10 described later. ”
/ ”(1401) is domain A (501) and domain B
It is a higher-level name that summarizes (1001). The name directly under "/" is a name uniquely assigned to the domain, "adm" (1402) indicates the domain A, and "b".
dm ”(1403) indicates the domain B. The name immediately below the domain name is the name (1
404, 1405), and the node name is created by concatenating with the domain name. Therefore, the node name of the management server 502 of the domain A is “adm.01”, the node name of the mail server 504 is “adm.02”, and the node name of the file server 505 is “adm.03”. Similarly, the node name of the management server 1002 of the domain B is “bdm.ax” and the node name of the mail server 504 is “bdm.sx”. Further, the name immediately below is a name (1406, 1407) uniquely assigned to the application on each node, and the application name is created by linking with the node name. Therefore, the application name of the address server application of domain A is "adm.01.addr",
The application name of the directory server application is "adm.01.dir", and the application name of the mail server application is "adm.0".
2. mail ”, the application name of the file server application is“ adm. 03. Similarly, the application name of the address server application of the domain B is “bdm. ax. add
r ", and the application name of the directory server application is" bdm. ax. dir ", the application name of the mail server application is" bd
m. sx. mail ”.

FIG. 4 shows the hardware configuration of the node,
FIG. 2 shows a software configuration example of a mail server, a file server, and a client node made according to the hardware configuration example. Reference numeral 403 is a line connection control unit that controls input / output and the like of lines connecting nodes, 405 is a control unit that controls input / output and the like with the external storage device to store information in the external storage device 406, and 407 is A control unit that controls input from a keyboard and display on a display, and controls a device connected by a processor and a program respectively existing in these control units. 404
Is a memory for storing address information and a received message in addition to the program. A processor 402 controls the internal hardware of the node. 404 is a memory, 4
Reference numeral 08 is a display and a keyboard.

Reference numeral 202 denotes a mail server, a file server application, and a program for accessing these applications. Reference numeral 203 is a program for inquiring the management server about a logical address and receiving a response. Reference numeral 204 is a link control program for controlling the input / output of the device, and is placed in the line control unit 403, the external storage device control unit 405, and the terminal input / output control unit 407. The program scheduler 205 schedules and manages program executions 203 to 204.

FIG. 3 shows a software configuration example of a management server node created according to a hardware configuration example. The address server 302 manages logical address information in the domain A. Directory server 303 is domain A
It manages the name information inside, derives the logical address and AP address from the name, and provides these address information to the client. The link control unit 304 is a link control program that controls the input / output of the device, and the program scheduler 305 schedules and manages the program execution from 302 to 304.

FIG. 6 shows a message format used for obtaining and responding to a logical address. (A) is a request message transferred to the address server to obtain the logical address. The LI 601a is a length field of the message, and the type 602a is this message ADDRre.
It indicates that q (Address request) is the information transferred to obtain the logical address, and the address server checks this information and fetches the request message. The node name 603a is a field for setting the source node name, and the name is given by the user of the source node. The valid period level 604a is a proposal value on the transmitting side for the valid period of the logical address assigned by the address server. The history information 605a is a field used when the node name is changed. (B) is
It is a response message sent by the address server to allocate a logical address. The type 602b is this message ADDRresp (Address response).
se) indicates that the information is transferred to notify the assigned logical address, the destination node name is set in the node name 603b, and the logical address assigned by the address server is stored in the logical address 606. The valid period 607 is the life of the assigned logical address, and the address acquisition requester can use the logical address of this period (unit: minutes). (C) is a request message transferred to the address server when the node management information is reset, and the content thereof is the same as that of (a).
This will be further described in the section “(4-2) Acquisition of logical address” described later.

(3) New construction of network Client 503 in the network system shown in FIG.
The case of newly introducing a will be described.

(3-1) Setting Node Management Information FIG. 1 is a flow chart showing a procedure for setting node management information.
Step 102 is an operation for confirming the setting of the node name, and since the client 503a has not set the node name because it is newly introduced, the node name "ad" is added in step 103.
m. "client1" is set. If the node name has already been set and this is changed, step 104
To execute. In step 106, the change of the node name is confirmed, and if there is a change, the previously set node name is registered as history information (107), and if not, the currently set node name is registered as history information (10).
8). Step 109 is an operation for confirming the setting of the valid period level. Since the client 503a has not yet set the valid period level due to new installation, the valid period level is set in step 110, but the client 503a moves through the network and uses it. Since it is such a portable workstation, "low" is set as the valid period level in step 110. After that, client 5
When the node 03a is started, the address acquisition procedure is executed based on the node name and the valid period level set here. The valid period level has already been set, and if this is to be changed, step 111 is executed. In the flow, "→ (1)" branches to "← (1)",
“(2)” indicates a branch to “← (2)”.

Next, an address acquisition procedure in the client 503a will be described with reference to FIG. (3-2) Acquisition of Logical Address FIG. 7 is a flow showing a logical address acquisition procedure. In step 702, the node name "ad" is added to the node name field 603a of the request message shown in FIG.
m. client1 "is set, the valid period level" low "is set in the field 604a in step 703, and the history information" adm. cli
After setting "ent1" in the field 605a, a request message is transmitted (705). Next, in step 706, a response to the acquisition request is waited, and if the response can be received, the logical address of the response message is checked (70).
7) If the response cannot be received, the logical address acquisition procedure is executed again (711d). Step 707
Confirm the received logical address value with, and if "null", execute the logical address acquisition procedure (711c) again,
Otherwise, after registering the reception logical address (708),
The valid period subtraction procedure is entered (710). Further, in order to continue the logical address currently used in steps 709 and 711b with the subtraction of the valid period, the address acquisition procedure is executed again before the valid period expires. In the present embodiment, all valid period values are subject to subtraction, but a specific valid period value (for example, valid period value = “99
For logical addresses with "99"), it is also possible to use the logical addresses that have been assigned once without the time constraint of the valid period by subtracting the valid period and removing it from the target of logical address deletion at startup. Is.

(3-3) Logical Address Allocation FIG. 8 is a flow chart showing a logical address allocation procedure in the address server in the management server 502. When the request message is received in step 802, the node name set in the node name field 603a of the request message is referred to in step 803. Step 803 is a process for preventing the logical address from being changed as much as possible when only the node name is changed. The logical address of the specified node name is assigned by the self-address server, and the logical address is assigned. When the valid period has not expired, the same logical address as the previously assigned logical address is assigned to suppress the change of the logical address value as much as possible. Since the client 503a is a new installation, the address server does not perform the processing of step 804, searches for an empty address in step 805, allocates a logical address “13.7.4” that is not used as a logical address (806), and returns a response message. "1" in the logical address field 606 of
3.7.4 "is set, and the valid period is set in the field 607 according to the valid period level proposed in step 809, and then a response message is transmitted to the logical address acquisition request node (810). Notify other address servers and directory servers of the change information.

FIG. 9 shows address information and directory information managed by the management server 502. Address information 901
Is a database of the address server, and is composed of three items of {node name 902a, assigned logical address 903a, remaining valid period 904a}, and 902a, 903.
a, 904a are entries relating to the client 503a, and 902b, 903b, 904b are mail servers 50.
4, entries 902c, 903c, and 904c are entries related to the file server 505.
The node name 902a is the name of the logical address acquisition request node, the logical address 903a is the logical address value assigned by the address server, and the remaining valid period 904a is the remaining time of the valid period of the logical address assigned by the address server. Step 7 at the address server
The valid period subtraction procedure as shown in 09 is executed, and when the remaining valid period is exhausted, this logical address is reused as an empty address. The directory information 905 is a database of the directory server and includes {entry name 906a, logical address 907a, AP address 90.
8a, alias 909a}, and 906
a, 907a, 908a, 909a are mail servers 50
4, entries 906b, 907b, 908b,
Reference numeral 909b is an entry relating to the file server 505. The entry name 906a is an application name registered as directory information, and the logical address 907a, AP address 908a, and alias 909a are its attribute values.

(4) Reconfiguration of Network A case where the network system shown in FIG. 5 is changed to the network system shown in FIG. 10 will be described. FIG. 10 is a diagram showing an example of a configuration obtained by expanding the network system shown in FIG. Domain A (501)
Is an area managed by the management server 502 and corresponds to an existing network system. Domain B
(1001) is an area managed by the management server 1002, which is a newly added area. Domain B
Each node inside is connected to each other by a link 1008,
Further, the relay devices 1006a and 1006b and the link 100
7 is used to enable interconnection with domain A.
The management server 1002 is a node that manages logical addresses and names in the domain B, and the node name “name = bdm.ax” and logical address “add” are set by the user.
r = 13.8.3 ”is assigned, and“ ap-name = bdm. ax. a
address server having "ddr" and "ap-name = bdm. ax. A directory server having "dir" operates. Mail server 10
In No. 04, the mail server 504 placed in the domain A in FIG. 5 is moved to the domain B by the reconfiguration of this time, and the node name is “n” due to the move to the domain B.
ame = bdm. The application name is "sx"
ap-name = bdm. sx. The name was changed to "mail". In addition, various servers 10 in the domain B
05, clients 1003a and 1003b exist.

The processing procedure for moving the mail server 504 from domain A to domain B will be described below. (4-1) Reset of Node Management Information The procedure for resetting the mail server node management information will be described with reference to FIG. Since the node name has been changed due to the relocation, the node name "bdm.sx" is set in step 104, and after confirming the node name change in step 106, step 1
The node name "adm.02" that was previously set in 07
Is registered as history information. Also, since the previous setting value "high" is used for the valid period, step 1
The setting processing from 09 to 112 is not performed. (4-2) Acquisition of Logical Address The procedure for reacquiring the logical address of the mail server node will be described with reference to FIG. In step 702, the node name "is entered in the node name field 603c of the request message.
bdm. sx "is set, the valid period level" high "is set in the field 604c in step 703, and the history information" adm. After setting 02 "in the field 605c, the request message is transmitted (705). Since the subsequent procedure for acquiring the logical address is the same as that of the client 503a of item number (3-2), (4-3) Logical address allocation and update The logical address allocation procedure of the mail server node by the address server in the management server 1002 will be described with reference to Fig. 8. When a request message is received in step 802, step 803 is executed. The node name of the request message is referred to in the mail server 1004. Since the mail server 1004 is newly introduced in the domain B, a free address is searched for in step 805, and a logical address “13.8.6” which is not used as a logical address is allocated. The logical address of the response message similar to (b) of 6 Less field 606
Is set to "13.8.6" and the validity period "9999" is set in the field 607 according to the validity period level proposed in step 809, and then a response message is transmitted to the logical address acquisition request node (810). At the same time, in step 808, the change information message is notified to the address server and directory server of the other domain.

FIG. 11 shows a change information message for notifying the address information of another domain, the own domain and the directory server of another domain of the change information notified in step 808. The LI 1101 is a message length field, and the type 1102 indicates that this message UPDATE (Address Update) is information for notifying the address server and the directory server of change information. When the change information is notified to the address server of domain A, the destination server name 1
Set the address server name of domain A to 103,
The source server name 1104 is set to the own address server name. In the change information 1108, “bdm.sx” is set as the node name 1105 of the address acquisition request node, “adm.02” is set as the history information 1106, and “13.8.6” is set as the logical address 1107. Further, when notifying the directory server of the domain A of the change information, the directory server name of the domain A is set in the destination server name 1103.

With the relocation of the mail server 504 this time,
This change information message is sent from the address server of the management server 1002 to the address server of the management server 502,
Notified to the directory server. Upon receiving the change information message, the address server of domain A receives the history information 1
Mail server 50 in domain A using 106 as a key
The address entry used in 4 is searched out and refreshed, and the used logical address is made reusable as a free logical address.

FIG. 12 shows the logical address associated with the transfer of the mail server 504 and the address server (502-1) of the management server 502 (domain A) at the time when the update process is completed.
And address information (1201, managed by the address server (1002-1) of the management server 1002 (domain B).
1211) is shown. 1202b, 1203b, 1204
b is the mail server 50 in the domain B stored as address information of the management server 1002 (domain B)
4, which is registered when the mail server 504 is moved to the domain B and the logical address acquisition process is performed. 1202a, 1203a,
An entry 1204a is used as address information of the management server 502 (domain A) when the mail server 504 existed in the domain A, is refreshed when the change information is received, and is an empty entry at the present time.

Next, the directory information of the management server after the change information is updated will be described. The directory server application in this network system is IS
In addition to the inquiry according to the OSI directory defined by O9594 and the update of the registration information, it has a procedure for updating the registration information with the address server. FIG. 13 shows a logical address associated with the relocation of the mail server 504, the directory server (502-2) of the management server 502 (domain A) and the directory server (1002- of the management server 1002 (domain B) at the time when the update process is completed. 2 shows directory information (1301, 1311) managed by 2). The directory server of domain A that has received the change information message uses the history information 1106 shown in FIG. 11 as a key.
After searching the directory entry "adm.02.mail" used for the mail server 504 in the domain A, the mail server application name "bdm.sx.mail" transferred from the node name 1105 shown in FIG. Is generated. Next, the directory server of domain A receives the logical address “13.8.6” (110) notified as the change information shown in FIG.
7) and the entry "bdm.sx.mail" (1306b, 1307) having the application address "5" (908b) stored as directory information.
b, 1308b, 1309b) is requested to the directory server of the domain B, the directory information 1307a, 1308a in the domain A is refreshed, and the application name "bdm.sx. Register "mail". Through the above processing, the logical address allocation and name changing processing at the time of network reconfiguration is completed.

[0028]

EFFECTS OF THE INVENTION It is possible to prevent a plurality of addresses from being assigned to one node, and to assign an address with a valid period. Also, due to the change of the logical address due to the node relocation, the logical address used before the relocation becomes an empty logical address when the new logical address is allocated, so the logical address should be used efficiently. You can Further, even when the node name is changed due to the node relocation, the new name is registered in correspondence with the old node name, so that access with the old node name is possible.

[Brief description of drawings]

FIG. 1 is a diagram showing a flow of a procedure for setting node management information.

FIG. 2 is a diagram showing a software configuration example of a mail server, a file server, and a client node created according to a hardware configuration example.

FIG. 3 is a diagram illustrating a software configuration example of a management server node created according to a hardware configuration example.

FIG. 4 is a diagram showing a hardware configuration of a node.

FIG. 5 is a diagram showing an example of the present network system configuration.

FIG. 6 is a diagram showing a message format used for acquiring and responding to a logical address.

FIG. 7 is a diagram showing a flow of a logical address acquisition procedure.

FIG. 8 is a diagram showing a flow of a logical address allocation procedure in an address server in the management server.

FIG. 9 is a diagram showing address information and directory information managed by the management server.

10 is a diagram showing an example of a configuration obtained by expanding the network system shown in FIG.

FIG. 11 is a diagram showing a format of a change information message.

FIG. 12 is a diagram showing address information managed by the address server of the management server of domain A and the address server of the management server of domain B at the end of the process associated with the relocation of the mail server.

FIG. 13 is a diagram showing the directory information managed by the directory server of the management server of domain A and the directory server of the management server of domain B at the end of processing due to the mail server relocation.

FIG. 14 is a diagram showing a name system used when constructing a network system.

[Explanation of symbols]

402 Processor 403 Line control unit 405 External storage device control unit 406 External storage device 407 Terminal input / output control unit 408 Display, keyboard 502, 1002 Management server 503a, 503b, 1003a, 1003b Client 504, 1004 Mail server 505 File server 1006a, 1006b Relay device 1005 server

Claims (4)

[Claims] 1. A computer network in a computer network system comprising a node that transmits an address request message and requests a management server to allocate an address of its own node, and a node that has a management server that allocates an address to a node that requests an address. In the construction method, the requesting node comprises means for setting a node name in an address request message, and the management server is already assigned by the own management server using the node name specified in the address request message as a key. It is checked whether or not there is the same node name that has a valid address, and if there is, the already given address is given to the requesting node, and if not, it is selected from free addresses to the requesting node. Equipped with means for assigning addresses Computer networking system, characterized in that. 2. The computer network construction method according to claim 1, wherein said requesting node comprises means for setting a designation of a valid period length of an assigned address in an address request message, and said management server is provided with said address request message. A method for constructing a computer network, comprising means for deciding the valid period of an assigned address based on the designation of the valid period specified in 1. 3. A computer comprising a plurality of networks comprising a node which transmits an address request message and requests a management server to allocate an address of its own node, and a node having a management server which allocates an address to a node requesting an address. A computer network changing method in a network system, wherein the requesting node sets a node name indicating that it belongs to another network in an address request message when changing the connection from the current network to which the own node is connected to another network. The management server of the other network determines whether or not the management server of the other network has the same node name having an address which is currently valid and already given by the management server using the node name specified in the address request message as a key. Examine whether there is Grant sometimes address already assigned to the node the request,
When there is no, it comprises means for selecting from free addresses and assigning an address to the requesting node, and means for creating and transmitting a change information message to the management server of the current network, wherein the management server of the current network is A method for changing a computer network, comprising means for receiving a change information message and reusing the address used by the requesting node whose connection has been changed as a free address based on the change information. 4. The computer network changing method according to claim 3, wherein the management server of the current network corresponds to the original node name used for the connection requesting requesting node based on the change information. A computer network changing method comprising means for registering a changed node name as an alias.