JP2005033302A - Method of automatically assigning ip address, and terminal device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for automatically assigning a unique address with which devices never coexist even if a device having a function of substitutional response to an ARP request addressed to an IP address having a different network address, and a device for conducting the same. <P>SOLUTION: An apparatus to be connected to a network issues an ARP request to a temporary IP address, and compares a received ARP response with the MAC address of an ARP response stored in itself in the case of a plurality of ARP responses and one ARP response. If they are different, the apparatus determines that an apparatus using the temporary IP address and an apparatus having a function of performing ARP substitutional response of its own address to the ARP request to the IP address having a different network address exist on the same network, and selects another temporary IP address to repeats an ARP request. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for automatically assigning IP addresses of devices connected to a network.
[0002]
[Prior art]
When connecting a device to an IP network environment, it is necessary to set a unique IP address that does not overlap with other network devices.
[0003]
For setting the IP address, a method in which the user manually inputs the IP address to the network device or a method in which the IP address is dynamically assigned is used. A typical example of the dynamic address allocation method is DHCP (Dynamic Host Configuration Protocol) (reference: Droms, R., “Dynamic Host Configuration Protocol”, March 1997, RFC2131). In DHCP, a server that centrally manages IP addresses is provided, and IP addresses are assigned to network devices in response to inquiries from network devices.
[0004]
In the case of manual IP address setting, since the user can arbitrarily set the IP address, an increase in the number of devices connected to the network tends to cause human error such as setting an IP address redundantly. If it is set while confirming the IP addresses that do not overlap, it will take time. In addition, in the case of dynamic address assignment by a DHCP server, if there is a DHCP server on the network to be connected, the IP address is uniquely determined and communication is possible, but if there is no DHCP server, an IP address is assigned. Communication is impossible.
[0005]
As an example of a method for solving the above problem, an automatic IP address assignment method has been proposed (Non-Patent Document 1).
[0006]
Hereinafter, an IP address automatic assignment method described in Non-Patent Document 1 will be described with reference to the drawings. FIG. 4 is a flowchart showing a conventional IP address assignment method of a network apparatus, and FIG. 5 is a network configuration diagram in the conventional IP address assignment method.
[0007]
Queries the address to the DHCP server. (Step 51)
It is determined whether a response from the DHCP server to the address inquiry is received. (Step 52)
When the response from the DHCP server is received, the IP address assigned by the DHCP server is determined as the IP address of the apparatus. (Step 53)
When a response from the DHCP server is not received, an IP address is automatically assigned. As a range of addresses to be allocated, a network address of “169.254 / 16” registered in an international organization IANA (Internet Assigned Numbers Association) as a link local network is used. (Reference: Manning, B., “Documenting Special Use IPv4 Address Blocks that have bean registered with IANA / RIR”, May 2002) (Step 54).
Select a random value as the host address. (Step 55)
An ARP (Address Resolution Protocol) request is sent to detect whether the selected IP address is not being used by another network device. (Reference: Plummer, D., “An Ethernet Address Resolution Protocol --- or --- Converting Network Protocol Address to 48.bit Ethernet Address for Transnet Address, HR, and RB,” Is a protocol used to obtain the physical address (MAC address) of (Step 56)
It is determined whether an ARP response to the ARP request has been received. (Step 57)
When the ARP response cannot be received, it is determined that the IP address selected by the other network device is not used, and is determined as its own address. (Step 58)
When the ARP response is received, another random host address is selected because another network device uses the selected IP address. Returning to the process of (Step 55), the subsequent processes are repeated. (Step 59)
In IPv6 (Internet Protocol version 6), an automatic IP address assignment method has been proposed. (Reference: Thomson, S., “IPv6 Stateless Address Auto-configuration”, December 1998, RFC 2462)
In the above IP address assignment method, each device inquires the router for a prefix indicating the network address of the IP address. The prefix sent from the router and the MAC address of the own device are combined and set as the IP address of the own device. Since the IPv6 address length is as long as 128 bits and the MAC address can be used as the host address of the IP address as it is, there is little possibility that the IP address will be duplicated.
[0008]
However, IPv4 (Internet Protocol version 4) is used in the current IP network. Although the number of users connected to the network increases and IPv4 has a short address length of 32 bits and IPv4 addresses are in a depletion direction, there is a problem that it still takes time to move the entire network to the IPv6 network.
[0009]
[Non-Patent Document 1]
Troll, R.M. , “Automatically Choosingan IP Address in an Ad-Hoc IPv4 Network”, March 2000.
[0010]
[Problems to be solved by the invention]
In the conventional automatic IP address assignment method, there is no ARP response as a condition for determining that the IP address is not used by another device. However, when a device having the function of ARP replying to its own address on behalf of an ARP request addressed to an IP address having a different network address is installed on the same network, depending on the IP address to be set, the ARP A response may always be returned. A router generally corresponds to a device having the above functions. The above function will be described with reference to FIG. In FIG. 3, a network 400 is a network conforming to the IP network, and the network device 501 is connected to the network 400. The network 600 is a network that conforms to the IP network, and the network device 701 is connected to the network 600. The relay device 801 is installed at a relay point between the network 400 and the network 600, and responds to an ARP request addressed to a packet having a different network address.
[0011]
The network 400 has a network address “192.168.8.0/24”, and the IP address of the network device 501 is “192.168.0.10/24”. The network 600 has a network address of “192.168.1 / 24”, and the IP address of the network device 701 is “192.168.1.10/24”. The interface on the network 400 side of the relay device 801 is the IP address “192.168.0.1”, the MAC address “00: 00: BE: 77: 00: 5E”, and the interface on the network 600 side is the IP address “192.168.”. 1.1 ”and the MAC address“ 00: 00: BE: 77: 00: 5F ”.
[0012]
When an ARP request is issued from the network device 501 to the network device 701 on a different network, the relay device 801 acts as a proxy for the network device 701 and the MAC address “00: 00: BE: 78: "00: 5F".
[0013]
In particular, when a network device fails to obtain an address from a DHCP server and determines an IP address having a link local network, if there is a device that makes a proxy response to ARP, the selected temporary IP address is connected to the network. Even if the IP address is not used in, if the ARP request is for an IP address that is a network address different from that of the proxy responding device, an ARP response is always returned. When such a device is on the same network, an ARP response is always returned, so that there is no determination condition for determining an IP address if there is no ARP response as in the conventional automatic address assignment method described above. In addition, since the ARP request is repeatedly transmitted unnecessarily, there is a problem of placing a burden on the network.
[0014]
The present invention has been made to solve the conventional problems, and an apparatus having a function of ARP replying on its own address on behalf of an ARP request addressed to an IP address having a different network address is installed on the same network. It is an object of the present invention to provide a method capable of automatically setting a unique IP address in a network device even when the network device is used.
[0015]
[Means for Solving the Problems]
In the IP address assignment method of the present invention, a device connected to a network selects a temporary IP address consisting of a network address reserved in advance for automatic IP address assignment and a randomly selected host address, and the temporary IP address A device that makes an ARP (Address Resolution Protocol) request to an address and uses the temporary IP address as an official IP address when there is no ARP response, and uses a temporary IP address when there are multiple ARP responses In response to an ARP request addressed to an IP address having a different network address, it is determined that a device having a function of performing an ARP response on its own address as a proxy is on the same network, holds ARP information, and uses another temporary IP. Select the address and repeat the ARP request, AR If the response is one and the MAC address of the received ARP response is the same as the MAC address of the held ARP response, it is determined that the response is from a device having a function of making an ARP response on behalf of the response, If the temporary IP address is used as a formal IP address and there is only one ARP response, and the MAC address of the received ARP response is different from the MAC address of the stored ARP response, the temporary IP address is It is determined that a device having the function of ARP replying its own address on behalf of an ARP request addressed to an IP address having a different network address from the device being used is on the same network, and holding ARP information, The method is characterized by selecting another temporary IP address and repeating the ARP request.
[0016]
According to this method, a unique IP address can be assigned to a device connected to the network regardless of whether or not there is a device that makes a proxy response to ARP on the network.
[0017]
The IP address assignment method of the present invention is characterized in that, in the above IP address assignment method, (the lower 2 bytes of the MAC address + the number of times the temporary IP address is selected) is selected as the host address of the temporary IP address. Have taken.
[0018]
According to this method, it is possible to select a temporary IP address that is unlikely to overlap by using a MAC address unique to hardware as a host address.
[0019]
Each terminal device includes means for assigning a unique IP address to a device connected to the network by comparing the number of received ARP responses with the MAC address.
[0020]
Each terminal device further includes means for selecting (the lower 2 bytes of the MAC address + the number of times the temporary IP address is selected) as the host address of the temporary IP address.
[0021]
The function of each terminal device is a program for operating as a means for assigning a unique IP address to a device connected to the network by comparing the number of ARP responses received by the computer and the MAC address, or the host address of the temporary IP address. This is realized by installing in each terminal device a medium that records a program for operating as a means for selecting (lower 2 bytes of MAC address + number of times a temporary IP address has been selected).
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0023]
FIG. 1 is a flowchart of a network apparatus for explaining an IP address automatic assignment process according to an embodiment of the present invention. FIG. 2 is a network configuration diagram in the IP address assignment method according to the embodiment of the present invention.
[0024]
Queries the address to the DHCP server. (Step 11)
It is determined whether a response from the DHCP server to the address inquiry is received. (Step 12)
When the response from the DHCP server is received, the address assigned from the DHCP server is determined as the own address. (Step 13)
When a response from the DHCP server is not received, an IP address is automatically assigned. The link local network “169.254 / 16” is used as the network address. (Step 14)
The lower 2 bytes of the hardware-specific MAC address are selected as the host address. (Step 15)
In order to detect whether or not the temporary IP address selected in step 14 and step 15 is being used by another device, an ARP request is transmitted. (Step 16)
ARP response reception is determined. (Step 17)
If the ARP response is not received, it is determined that neither the device using the temporary IP address nor the device having the function of performing the ARP response on behalf of the device exists on the network to be connected, and sets the temporary IP address. It is determined as its own address. (Steps 17 and 20)
When one ARP response is received, the MAC address of the received ARP information is compared with the MAC address of the held ARP information. (Steps 17, 18, and 19)
If the compared MAC addresses are the same, a device having a function of making an ARP response on behalf of the device is present on the network to be connected, and it is determined that the response is from the device, and a temporary IP address is determined as its own address. To do. (Steps 19 and 20)
If the compared MAC addresses are different, or if there is no ARP information to be compared, it is impossible to determine whether the response is from a device having a function of making an ARP response on behalf of the proxy, so the ARP information is retained and used as another temporary host address. (The lower 2 bytes of the hardware-specific MAC address + the number of times the temporary host address has been selected) is selected and the processing returns to step 16 to repeat the subsequent processing. (Steps 19 and 21) When a plurality of ARP responses are received, it is determined that a device using a temporary IP address and a device having a function of making an ARP response on behalf exist on the same network. Holds the ARP information, selects (the lower two bytes of the hardware-specific MAC address + the number of times the temporary host address has been selected) as another temporary host address, returns to the processing of step 16 and performs the subsequent processing repeat. (Steps 17, 18, and 21)
By the above procedure, IP addresses that do not overlap each other are finally determined, and automatic IP address assignment is achieved.
[0025]
Next, the embodiment of the present invention described above will be described in more detail with reference to the drawings.
[0026]
In FIG. 2, a network 100 is a network that conforms to an IP network, and network devices 201 to 204 are connected to the network 100. The relay device 301 is connected to the network 100 and makes a proxy response to its own address in response to an ARP request addressed to an IP packet having a different network address. In addition, the DHCP server is not connected.
[0027]
The network 100 is a network address “192.168.0 / 24”, the network device 201 is a device whose lower 2 bytes of the MAC address to be connected to the network 100 are “100.10”, and the network 202 is a link local The devices in which the address “169.254.100.10” and the MAC address “00: 00: BE: 78: 00: 6A” are set, the network device 203 and the network device 204 are IP addresses having the same network address as the network 100 The devices to which “192.168.0.3” and “192.168.0.4” are set respectively, and the interface on the network 100 side of the relay device 301 is the IP address “192.168.0.1”, MAC Address “00:00: BE 78: 00: 6B "is a device that has been set. The host address of the temporary IP address is selected as (the lower 2 bits of the MAC address + the number of temporary IP address selections).
[0028]
When the network apparatus 201 is connected to the network 100, it inquires of the DHCP server about the address. (Step 11)
Since there is no DHCP server, there is no response from the DHCP server to the address inquiry. (Step 12)
Since the response from the DHCP server has not been received, the network device 201 automatically assigns an IP address. The link local network “169.254 / 16” is used as the network address. (Step 14)
The network device 201 selects “100.10” which is the lower two bytes of the MAC address as the host address. (Step 15)
The network device 201 uses the selected address “169.254.100.10” as a temporary IP address, and sends it to “169.254.100.10” in order to detect whether this address is used by another device. Send out an ARP request. (Step 16)
Since the relay device 301 is an ARP request addressed to a network address different from that of the network 100, the proxy device ARP responds with its own address. Further, since the network device 202 has the same IP address, it makes an ARP response. The network device 201 receives ARP responses from the relay device 301 and the network device 202. (Step 17)
There are two ARP responses received. (Step 18)
The network device 201 determines that a device using a temporary IP address and a device having a function of making an ARP response on behalf exist on the same network. The received ARP information is held in an address table as shown in FIG. 6, and “100.11” is obtained by adding the number of temporary IP address selections to “100.10” which is the lower two bytes of the MAC address as another host address. Select. (Step 21)
An ARP request is sent to “169.254.100.11”. (Step 16)
Since the relay device 301 is an ARP request addressed to a network address different from that of the network 100, the ARP response of its own address is made by proxy. The network device 201 receives the ARP response from the relay device 301. (Step 17)
One ARP response is received. (Step 18)
The network device 201 compares the MAC address of the received ARP information with the MAC address of the ARP information held in the address table of FIG. The source MAC addresses of the ARP response received first are “00: 00: BE: 78: 00: 6A” and “00: 00: BE: 78: 00: 6B”. The MAC address of the received ARP response is “00: 00: BE: 78: 00: 6B”, and one of the transmission sources of the first ARP response is the same as the transmission source device of the received ARP response. I understand that. (Step 19)
Since the MAC addresses are the same, it is determined that the received ARP response is a response from a device having a function of making an ARP response on behalf of the proxy. It can be seen that another device is not using the temporary address, and “169.254.100.11” is determined as its own address. (Step 20)
[0029]
【The invention's effect】
As described above, according to the present invention, a device connected to a network selects a temporary IP address composed of a network address reserved in advance for automatic IP address assignment and a randomly selected host address, and is addressed to the temporary IP address. When there is no ARP response, the temporary IP address is used as the formal IP address, and when there are a plurality of ARP responses, the device using the temporary IP address is used. It is determined that a device having a function of ARP replying its own address on behalf of an ARP request addressed to an IP address having a different network address is on the same network, holds ARP information, and has another temporary IP address Select ARP and repeat the ARP request, one ARP response In some cases, if the MAC address of the received ARP response is the same as the MAC address of the held ARP response, it is determined that the response is from a device having a function of ARP response on behalf of the proxy, and the temporary IP address Is used as a formal IP address, and if the MAC address of the received ARP response is different from the MAC address of the stored ARP response, the temporary IP address is used. It is determined that the device and the device having the function of ARP replying its own address on behalf of the ARP request destined for the IP address having a different network address are on the same network, holding the ARP information, and another temporary There is a device that has the function of ARP response of its own address on behalf of the proxy by providing means to select the IP address and repeat the ARP request It is possible to provide an IP address automatic assignment method that has the effect of being able to determine IP addresses that do not overlap even if they are not.
[0030]
Further, in the above IP address assignment method, by providing means for selecting (the lower 2 bytes of the MAC address + the number of times the temporary IP address is selected) as the host address of the temporary IP address, the MAC address unique to the hardware is hosted. It is possible to provide an IP address automatic assignment method that has the effect of being able to select a temporary IP address that is unlikely to be duplicated when used as an address.
[Brief description of the drawings]
FIG. 1 is a flow diagram of a network device for explaining the operation of an automatic IP address assignment method according to an embodiment of the present invention. FIG. 2 is a network configuration diagram of an automatic IP address assignment method according to the present invention. FIG. 4 is a flow diagram of a network device for explaining the operation of the conventional automatic IP address assignment method. FIG. 5 is a network configuration diagram of the conventional automatic IP address assignment method. FIG. 6 is a diagram showing an example of a table holding MAC addresses of devices that have made an ARP response.
100 IP network 201-204 network device 301 relay device 400 IP network 501 network device 600 IP network 701 network device 801 relay device 901-904 network device

Claims (5)

A device connected to the network selects a temporary IP address composed of a network address reserved in advance for automatic IP address assignment and a randomly selected host address, and an ARP (Address Resolution Protocol) request is sent to the temporary IP address. And
If there is no ARP response, use the temporary IP address as the official IP address,
When there are a plurality of ARP responses, a device using the temporary IP address, a device having a function of ARP replying its own address on behalf of an ARP request addressed to an IP address having a different network address, Are in the same network, hold the ARP information, select another temporary IP address and repeat the ARP request,
If there is only one ARP response and the MAC address of the received ARP response and the stored ARP response are the same, it is determined that the response is from a device having a function of ARP response on behalf of the proxy, Use the temporary IP address as the official IP address,
If there is only one ARP response, the received ARP response and the MAC address of the held ARP response are different from each other, or if the ARP response is not held and cannot be compared, the received ARP response Keep the information, select another temporary IP address and repeat the ARP request,
A method of automatically assigning an IP address. 2. The IP address automatic assignment according to claim 1, wherein the device connected to the network selects (the lower 2 bytes of the MAC address + the number of times the temporary IP address is selected) as the host address of the temporary IP address. Method. ARP request means for selecting a temporary IP address composed of a network address reserved in advance for automatic IP address allocation and a randomly selected host address, and making an ARP (Address Resolution Protocol) request to the temporary IP address;
ARP storage means for storing the ARP, and a terminal device comprising:
The ARP request means includes
If there is no ARP response, select the temporary IP address as the formal IP address,
When there are a plurality of ARP responses, the device using the temporary IP address and the device having the function of ARP replying its own address on behalf of the ARP request addressed to the IP address having a different network address are in the same network. ARP information is stored in the ARP storage means, another tentative IP address is selected, and the ARP request is repeated.
If there is only one ARP response and the MAC address of the received ARP response and the stored ARP response are the same, it is determined that the response is from a device having a function of ARP response on behalf of the proxy, Select the temporary IP address as the official IP address,
If there is only one ARP response and the MAC address of the received ARP response is different from the MAC address of the held ARP response or if there is no comparison ARP in the ARP storage means, the received ARP information In the ARP storage means, select another temporary IP address and repeat the ARP request,
A terminal device characterized by that. The program for operating the apparatus carrying a computer as a terminal device of Claim 3 A computer-readable recording medium on which the program according to claim 4 is recorded.

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