JP2002237816A - Automatic address assigning method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automatic address assigning method by which an effec tive address can be assigned by avoiding addresses using undesirable network numbers, by discriminating whether or not the automatic assignment of an IP address is to be performed based on the network number of a network of a connecting destination. SOLUTION: When a DHCP-Offer is not able to be received in a step 12, a host discriminates whether or not the automatic assignment of the IP address is to be performed in a step 13, because no DHCP server exists. This discrimination is performed by monitoring an IP packet flowing on a network and checking whether or not the IP address of the connecting destination belongs to the network number '169.254' for automatic assignment. When the IP address does not belong to the number '169.254', the host computer discriminates that the execution of the automatic assignment is inappropriate and terminates the processing. In this case, the host computer can assign its own address by using the network number of an address contained in the IP pack flowing on the network.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an address allocating method, and more particularly to an address allocating method capable of automatically allocating an address to a device such as a personal computer or a printer connected to a network such as a LAN. .

[0002]

2. Description of the Related Art In recent years, with the spread of the Internet, many devices have been using TCP / IP as a network protocol.
Is to be installed. One problem with TCP / IP is that when a device is connected to a network, it is necessary to set an address (hereinafter, an IP address) that is unique on the network. The setting of the IP address is usually performed by either manually inputting the IP address by the user or automatically acquiring the IP address from the DHCP server by a device according to a procedure determined by RFC2131. However, it is very difficult for a general user without network expertise to enter an IP address or install a DHCP server.

As one of the techniques for solving the above-mentioned problem, for example, “draft-ietf-dhc-ipv4-autoconfig-05.tx”
There is known an automatic IP address assignment technique proposed in "t".

FIG. 5 is a flowchart for explaining an IP address automatic assignment process according to the prior art. Hereinafter, the automatic address assignment according to the prior art will be described with reference to the flow shown in FIG.

(1) When a device requesting an IP address is connected to a network, first, a device on the network
A DHCP-Discover packet is sent to search for an HCP server (step 51).

(2) As a response of DHCP-Discover, D
It is determined whether the HCP-Offer can be received. If the DHCP-Offer can be received, D
Since the DHCP server exists, the IP address from the DHCP server
An address is obtained (steps 52 and 59).

[0007] (3) If the DHCP-Offer cannot be received in step 2, since there is no DHCP server, processing for automatically assigning an IP address is started. First, a number reserved in advance for automatic assignment is selected as a network number. Network number "16
9.254 "was created by an international organization (Internet Assi
gned Numbers Authority) (cf.draft-manning-d
sua-03.txt) and assigned (step 53).

(4) Next, one random host number is selected. For example, assume that “218.43” is selected. Subsequently, an address resolution (ARP) request for “169.254.218.43” is transmitted to detect whether or not the selected address is being used by another device. The ARP packet is defined by RFC 826 and is used to obtain a physical address corresponding to an IP address (steps 54 and 55).

(5) It is checked whether or not a response to the ARP request has been received, and if no response has been received, it is determined that no device uses the IP address, and the address is determined. The address is determined as the own address, and the process ends (steps 56 and 57).

(6) On the other hand, if a response to the address resolution request is received in step 56,
Since the P address means that it is being used by another device, another host number is selected.
And the subsequent processing is repeated (step 5).
8).

The above-described technology for automatically assigning an IP address according to the prior art has an advantage that an IP address can be automatically acquired without manual intervention even in an environment where there is no DHCP server.

As another prior art relating to automatic assignment of an IP address, for example, Japanese Unexamined Patent Publication No. Hei.
No. 6, JP-A-8-223169 and the like are known.

[0013]

However, the above-mentioned technology of automatic address assignment according to the prior art is operated with a network number other than the network number for automatic assignment.
For a network without a CP server, D
When the HCP server is installed but no address is assigned by chance, or when the DHCP server is set to distribute the address only to the registered device and not to distribute the address to other devices, etc. To
There is a problem that the device operates not at the address including the own network number but at the address including the undesired network number defined for the automatic assignment.

An object of the present invention is to determine whether or not to automatically assign an IP address based on the network number of a connection destination network, thereby avoiding an address using an undesired network number and enabling an effective address. It is an object of the present invention to provide an automatic address assignment method which can assign an address.

[0015]

According to the present invention, it is an object of the present invention to provide a network system in which a host connected to a network using an address comprising a network number part and a host number part has a network number reserved in advance for automatic assignment. And an arbitrary host number that is unique on a network, wherein the host uses a network number that is connected to a connected network and that is reserved in advance for automatic allocation. In some cases, this is achieved by automatically allocating the own address.

Further, the object is that the host determines its own address using a network number included in a source IP address or a destination IP address in a packet or a broadcast packet flowing on a network. Achieved.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a flowchart for explaining an IP address automatic assignment process according to an embodiment of the present invention. Hereinafter, the automatic address assignment according to the present invention will be described with reference to the flow shown in FIG. . In addition,
Here, a description will be given assuming that a host having an IP address automatic assignment function is connected to a network.

(1) The host requesting the IP address is:
When connected to the network, first, a DHCP-Discover packet is sent to search for a DHCP server on the network (step 11).

(2) As a response of DHCP-Discover, D
It is determined whether the HCP-Offer can be received. If the DHCP-Offer can be received, D
Since the DHCP server exists, the IP address from the DHCP server
An address is obtained (steps 12 and 20).

(3) In step 12, DHCP-Offer
Has not been received, the DHCP server does not exist, and the host determines whether or not automatic assignment of an IP address may be performed. The details of the determination method will be described later. If it is determined that automatic assignment should not be performed, the process ends without performing automatic address selection (step 13).

(4) If it is determined in step 13 that automatic assignment is possible, the host selects a number "169.254" reserved in advance for automatic assignment as the network number, as described in the background art. Then, one random host number is selected (steps 14, 1).
5).

(5) Subsequently, an address resolution (ARP) request for detecting whether the selected address is being used by another device is transmitted (step 1).
6).

(6) It is checked whether or not a response to the ARP request has been received, and if no response has been received, it is determined that there is no device using the IP address, and the address is determined. The address is determined as the own address, and the process is terminated (steps 17 and 18).

(6) On the other hand, if a response to the address resolution request is received in step 18, the I
Since the P address means that it is being used by another device, another host number is selected and step 16 is performed.
And the subsequent processing is repeated (step 1).
9).

FIG. 2 is a diagram showing a state in which a host C having the function of automatically assigning an IP address as described with reference to FIG. 1 is newly connected to a network, and FIG.
FIG. 2 is a diagram showing a format of an IP packet which is a basic unit of data transfer on a network. Hereinafter, FIGS. 2 and 3
The method for determining whether the automatic assignment of the IP address may be performed in step 13 of the processing described with reference to FIG. 1 when the host C is connected to the network will be specifically described with reference to FIG.

It is assumed that a host A and a host B are already connected to the illustrated network 1, and a DHCP server is not connected. It is also assumed that the network number of the network 1 is “192.168.100”, the host A has “192.168.100.3” as the IP address, and the host B has “192.168.100.5” as the IP address.

(1) When the host C is connected to the network, first, according to the flow shown in FIG. 1, the host C searches for a DHCP server on the network by DHCP-Discover.
It sends out packets and waits for DHCP-Offer,
Since there is no DHCP server on the network,
HCP-Offer cannot be received (steps 11, 1
2).

(2) For this reason, the host C determines whether it is OK to automatically assign an IP address. This determination is made by the host C monitoring the IP packets flowing on the network 1 (step 13).

Hereinafter, a method of determination by monitoring the IP packet will be described.

As is well known, the format of an IP packet, which is a basic unit of data transfer in a TCP / IP network, is configured as shown in FIG. The IP packet includes information such as a source IP address and a destination IP address, and the location where each piece of information is located is determined in advance. The host C monitors the IP packets flowing on the network and checks whether or not the source IP address belongs to the network number “169.254” for automatic assignment. In this case, the host C determines that the source IP address of the IP packet flowing through the network 1 is
"192.168.100.3" and "192.168.100.5". For this reason, since the host C knows that the network to be connected does not belong to "169.254", it determines that it is not appropriate to automatically assign an IP address. Then, the host C receives the IP
The process of address assignment ends without performing automatic address assignment.

FIG. 4 is a diagram showing a state in which the host C having the function of automatically assigning an IP address as described with reference to FIG. 1 is newly connected to a network having a configuration different from that described above. Then, a method of determining whether or not the automatic assignment of the IP address may be performed in step 13 of the process described with reference to FIG. 1 when the host C is connected to the network will be specifically described.

The network shown in FIG. 4 is configured by connecting a network 1 and a network 2 via a router, and a host A and a host B are already connected to the network 1 and another network via a router is connected to the network 1. 2 is connected to a host D and a host E,
It is assumed that the server is not connected. The network number of the network 1 is “192.168.100”, the host A is “192.168.100.3”, and the host B is “192.168.100.3”.
168.100.5 "is set as the IP address by the administrator, the network number of the network 2 is" 192.168.101 ", and the host D is" 192.168.101.2 ".
0 ", and the host E has been set by the administrator with" 192.168.101.25 "as the IP address.

(1) When the host C is connected to the network, the host C first searches for a DHCP server on the network according to the flow shown in FIG.
It sends out packets and waits for DHCP-Offer,
Since there is no DHCP server on the network,
HCP-Offer cannot be received (steps 11, 1
2).

(2) For this reason, the host C determines whether it is OK to automatically assign an IP address. This determination is made by the host C monitoring the IP broadcast packet flowing on the network 1 (step 13).

Hereinafter, a method of making a determination by monitoring the IP broadcast packet will be described.

The host C receives the IP address flowing on the network.
The broadcast packet is monitored, and the IP address of the transmission source is set to the network number "169.254" for automatic assignment.
To see if it belongs to A broadcast packet is a packet in which a broadcast address is specified as a destination IP address, and is specified by setting all bits of the host unit constituting the IP address to 1. Broadcast packets are sent to all hosts on the same network, but are not routed to different networks.

Now, since the network 1 is connected to the network 2 via the router, the network 1
Are not only those transmitted from the hosts A and B, but also those transmitted from the hosts D and E.
However, since the host C monitors only the broadcast packet, the host C monitors only the packet transmitted by the host A or the host B, and the determination can be efficiently performed without processing useless packets. As described above, the host C monitors the broadcast packet, and if the network to be connected is "169.25
4 ", and judges that it is not appropriate to automatically assign an IP address. As a result, the host C ends the address assignment processing without automatically assigning the IP address.

In the above description of the embodiment of the present invention, the host C connected to the network shown in FIGS. 2 and 3 monitors a packet or a broadcast packet flowing on the connected network and When the network number included in the source IP address or the destination IP address does not match the network number "169.254" for automatic assignment, it has been described that the address is not automatically assigned.
The host C may determine its own address using the network number included in the source IP address or the destination IP address in the packet.

In this case, after the address is determined, it is necessary to send an ARP request to confirm that the addresses are not duplicated. Also, even if an ARP request is sent out, if devices that have not started up on the network are connected, it is not possible to confirm duplication of addresses with those devices. In this case, when those devices start up, they first send an ARP request to their own addresses to confirm that the addresses are not duplicated,
The address may be changed when duplication is detected.

[0040]

According to the first aspect of the present invention, the own address is automatically assigned only when the connected network uses a network number reserved in advance for automatic assignment. Automatic address assignment can be performed only when the assignment is appropriate.

According to the second and third aspects of the present invention, the host monitors a packet flowing on the network to determine which network number the connected network uses, and Can be determined automatically or not, so that the address can be automatically allocated only when it is appropriate to perform the automatic allocation, and the source IP address in the packet flowing on the network can be determined. Alternatively, since the own address can be determined using the network number included in the destination IP address, a valid IP address can be assigned as the own address.

According to the present invention, the host monitors broadcast packets flowing on the network to determine which network number is used by the connected network. Since it is possible to determine whether or not to automatically assign its own address, it is possible to make an efficient determination, and to determine the network number included in the source IP address in the broadcast packet flowing on the network. And use it to determine your own address.
A valid IP address can be assigned as the own address.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating an IP address automatic assignment process according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a state in which a host having an automatic IP address assignment function is newly connected to a network.

FIG. 3 is a diagram showing a format of an IP packet which is a basic unit of data transfer in a TCP / IP network.

FIG. 4 is a diagram showing a state in which a host C having an automatic IP address assignment function is newly connected to a network having a configuration different from that described above.

FIG. 5 is a flowchart illustrating an IP address automatic assignment process according to the related art.

[Explanation of symbols]

 1, 2 Network A to E Host

Continued on the front page F term (reference) 5B089 GA01 GB02 JB14 KA04 KB04 KB06 KC59 MB01 5K030 GA08 GA11 HA08 HC01 HC14 HD03 HD09 KA04 KA05 KA13 MA04 MD04 MD09 5K033 AA03 CB01 CB13 CC01 DA05 EA03 EA06 EA07 EC03

Claims (5)

[Claims] 1. A host connected to a network using an address consisting of a network number part and a host number part determines a network number reserved in advance for automatic allocation and an arbitrary host number unique on the network. In the address auto-assignment method for automatically assigning a self-address, the host automatically assigns a self-address when a connected network uses a network number reserved in advance for automatic assignment. Address automatic assignment method. 2. The host monitors packets flowing on the network to determine which network number the connected network uses, and determines whether to automatically assign its own address. 2. The method according to claim 1, further comprising the step of: 3. The host according to claim 2, wherein the host determines its own address using a network number included in a source IP address or a destination IP address in a packet flowing on the network. Address automatic assignment method. 4. The host monitors a broadcast packet flowing on the network to determine which network number the connected network uses, and determines whether or not to automatically allocate its own address. The method according to claim 1, wherein the address is determined. 5. The automatic address allocation according to claim 4, wherein the host determines its own address using a network number included in a source IP address in a broadcast packet flowing on a network. Method.