JP2004165823A - Ip address converting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an IP address converting apparatus which decreases the number of finite virtual IP address information items in use prepared in advance for IP address conversion in an SIP message. <P>SOLUTION: The IP address converting apparatus is provided with: an extract means for extracting the IP address information in the SIP message; a discrimination means for discriminating the necessity of converting the extracted IP address into a virtual IP address when the extracted IP address information includes the IP address; a replacement means for replacing the IP address with IP address identification information when the determination means determines that the conversion of the IP address into the virtual IP address is not required; a cross reference management table for registering the cross reference between the IP address identification information replaced by the replacement means and the IP address; and a conversion means for converting the IP address into the virtual IP address when the determination means determines that the conversion of the IP address into the virtual IP address is required. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an IP address translator, and more particularly, to an IP address translator in an SIP message in transmitting and receiving a SIP message between IP networks having different IP address systems.
[0002]
[Prior art]
Since the number of IP addresses allocated in IPv4 (Internet Protocol version 4) is limited to 2 32 (about 4.3 billion), a private IP address that can be used only in a private IP network is assigned, and an external public IP address is assigned. When communicating with a network, in most cases, a NAT (Network Address Translator) that converts a private IP address set in an IP header of a network layer into a global IP address is introduced.
In recent years, IPv6 (Internet Protocol version 6) has begun to be introduced as a key to solving the problem of IPv4 address depletion.
On the other hand, SIP (Session Initiation Protocol) has attracted attention as a protocol for controlling the setting, change, and release of a session used for communication between terminals on an IP network.
The SIP transmits / receives IP address information necessary for setting a session in an application layer, and IP address information of a real-time transport protocol (RTP) used between destination terminals.
RTP is a real-time data transfer protocol used in a VoIP (Voice over IP) service for transmitting voice in IP packets, and is standardized by the IETF (Internet Engineering Task Force). See RFC 1889 for details of RTP.
SIP has also been standardized by IETF, and is specified in RFC 2543, RFC 3261, and the like.
[0003]
Prior art document information related to the present invention includes the following.
[Non-patent document 1]
IETF RFC 1889 "RTP: A Transport Protocol for Real-Time Applications"
[Non-patent document 2]
IETF RFC 2543 "SIP: Session Initiation Protocol"
[Non-Patent Document 3]
IETF RFC 3261 "SIP: Session Initiation Protocol"
[Non-patent document 4]
IETF RFC 3303 "Middlebox communication architecture and framework"
[Non-Patent Document 5]
IETF RFC 1035 "DOMAIN NAMES-IMPLEMENTATION AND SPECIFICATION"
[0004]
[Problems to be solved by the invention]
When communication is desired from a private IP network in which NAT is introduced to an external public IP network or another private IP network using SIP, there are the following problems.
The IP address information described in the header part of the network layer IP packet is translated by NAT (for example, from a private IP address to a global IP address), but the IP address for RTP described in the SIP message of the application layer Since the information and the like are not converted by the NAT, the RTP packet cannot be transmitted from the receiving side to the transmitting side.
Similarly, when communication is performed between the IPv6 network and the IPv4 network using the SIP, the IP address information of the IP packet is translated by the NAT corresponding to the IPv6 in the same manner as described above. Since the RTP IP address information and the like described in (1) are not converted, the RTP packet cannot be transmitted from the receiving side to the transmitting side.
[0005]
As one of the methods for solving this problem, an IP address conversion in a SIP message by an ALG (Application Level Gateway) is described in RFC 3303 or the like. The ALG extracts the IP address information in the SIP message, identifies the difference in the IP address format between the source IP network and the destination IP network, and associates it with the virtual IP address in the IP address format of the destination IP network. Converts the IP address in the SIP message into the IP address format of the destination IP network, and transmits the SIP message.
The SIP message is composed of header information and body information. In the header information, there are several SIP headers in which IP address information is set. Among them, there is an SIP header in which a plurality of IP address information is set, such as a Record-Route header, but the IP address information is transmitted. Some SIP headers do not need to be referred to by the previous network device.
If the IP address described in the SIP header is also converted to a virtual IP address, a limited virtual IP address is wasted, and an ALG that processes a large amount of SIP messages cannot be realized. .
[0006]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the related art, and an object of the present invention is to use a limited number of virtual IP address information prepared in advance for IP address conversion in a SIP message. An object of the present invention is to provide an IP address conversion device capable of reducing the number of IP addresses.
The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.
[0007]
[Means for Solving the Problems]
The following is a brief description of an outline of typical inventions disclosed in the present application.
In order to achieve the above object, according to the present invention, the IP address information of the SIP header that the transmission destination network device does not need to refer to is uniquely associated with the original IP address without being converted into the virtual IP address. The feature is that the virtual IP address is saved by replacing the character string with the IP address identification information.
As a description format of the IP address identification information, an FQDN (Fully Qualified Domain Name) format generally used in an IP network is used. For details of FQDN, see RFC 1035.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In all the drawings for describing the embodiments, components having the same function are denoted by the same reference numerals, and repeated description thereof will be omitted.
Also, in the following embodiments, SIP communication from an IPv4 network to an IPv6 network will be described as an example.
FIG. 1 is a functional block diagram showing an overall configuration of an IP address translator according to an embodiment of the present invention.
As shown in FIG. 1, the IP address translator according to the present embodiment includes a SIP message receiving unit 101, a SIP message transmitting unit 107, an IP address extracting function 102 in a SIP message, a function 103 for determining whether or not address translation is necessary, Address identification information assigning function 104, correspondence management table 105 of IP address and IP address identification information, replacement function 108 for replacing IP address with virtual IP address or virtual IP address with IP address, IP address with IP address identification information Or a replacement function 106 for replacing the IP address identification information with the IP address.
Here, the SIP message receiving unit 101 is a receiving unit of the present invention, the SIP message transmitting unit 107 is a transmitting unit of the present invention, the IP address extracting function 102 is an extracting unit of the present invention, and the determining function 103 is a determining unit of the present invention. The replacement function 108 constitutes the conversion means of the present invention.
The IP address identification information assigning function 104 and the replacing function 106 constitute a replacing unit of the present invention.
[0009]
FIG. 2 is a diagram for explaining the operation of the IP address translating apparatus according to the present embodiment, and is a diagram for explaining an example of a system configuration when a SIP message is transmitted.
In the figure, a terminal T1 (211) is an SIP terminal on the IPv4 network (21) side, and a terminal T2 (223) is an SIP terminal on the IPv6 network (22) side.
The proxy server P1 (212) and the proxy server P2 (213) are proxy servers (SIP Proxy) in the IPv4 network (21), and the proxy server P3 (221) and the proxy server P4 (222) are IPv6 networks (22). Is a proxy server.
The proxy servers (212, 213, 221, 222) are SIP message transfer devices that determine the destination of the SIP message.
The ALG (23) is an IP address translator that performs the v4-v6 translation of the IP address of the SIP message having the device configuration of FIG.
[0010]
In FIG. 2, the IP address in the SIP message transmitted from the SIP terminal T1 (211) in the IPv4 network is in the IPv4 format, and the IP address information in the received SIP message needs to be in the IPv4 format.
Further, the IP address in the SIP message transmitted from the SIP terminal T2 (223) of the IPv6 network is in the IPv6 format, and the IP address information in the received SIP message is also in the IPv6 format.
In the prior art, the SIP terminal T2 replaces all IP address information described in the IPv4 format in the SIP message transmitted from the SIP terminal T1 (211) with the virtual IP address information in the IPv6 format in the ALG (23). (223).
However, since the virtual IP address information registered in advance in the ALG (23) is finite, if the IP address conversion of a large number of SIP messages is performed, the virtual IP addresses that can be allocated are depleted, and the address conversion service becomes unavailable. It cannot be offered.
[0011]
The IP address translation device of the present embodiment solves such a situation, and will be described in detail with reference to FIGS.
FIG. 3 shows that the SIP terminal T1 (211) passes through the proxy server P1 (212) → proxy server P2 (213) → ALG (23) → proxy server P3 (221) → SIP terminal P4 (222). The SIP message is transmitted to T2 (223), and the response is sent from the SIP terminal T2 (223) to the proxy server P4 (222) → proxy server P3 (221) → ALG (23) → proxy server P2 (213) → proxy It shows a signal sequence example of a SIP message when returning to the SIP terminal T1 (211) via the server P1 (212).
Here, the SIP message will be described with INVITE and its response "200 OK", but it goes without saying that the same applies to other SIP messages.
[0012]
(1) 301: A SIP message (INVITE) is transmitted from the SIP terminal T1 (211) to the proxy server P1 (212), and the SIP message that the proxy server P1 (212) should transfer the message to the proxy server P2 (213). , And transfer it to the proxy server P2 (213).
(2) 302: Similarly to the proxy server P1 (212), the proxy server P2 (213) identifies that the information should be transferred to the ALG (23) from the information in the SIP message, and transfers it to the ALG (23).
Hereinafter, the transfer destination of the SIP message is determined by the same procedure in the ALG (23), the proxy server P3 (221), and the proxy server P4 (222), and the SIP terminal T2 (223) receives the SIP message from the proxy server P4 (222). The message is forwarded.
(3) 303: The ALG (23) converts IP address information in the SIP message transmitted from the proxy server P2 (213).
[0013]
(4) 304: The response destination of the response (200 OK) to INVITE is performed based on the information described in the Via header of the INVITE message, and is transmitted in the reverse direction on the transmission route of the INVITE message.
The SIP terminal T2 (223) identifies from the description information of the Via header that "200 OK" should be transmitted to the proxy server P4 (222), and transmits the information to the proxy server P4 (222).
(5) 305: Similarly, the proxy server P4 (222) identifies from the Via header information in the SIP message that transfer to the proxy server P3 (221) is necessary, and transfers the proxy server P3 (221).
Hereinafter, the transfer destination of "200 OK" is determined in the same procedure in the ALG (23), the proxy server P2 (213), and the proxy server P1 (212), and the proxy server P1 (212) is determined for the SIP terminal T1 (211). Is transferred from the server to "200 OK".
(6) 306: The ALG (23) performs a conversion process of the IP address information in the SIP message transmitted from the proxy server P3 (221).
[0014]
FIGS. 4 to 7 show examples of SIP messages transmitted and received by the ALG (23) in the signal sequence of FIG.
FIG. 4 is an example of the SIP message (INVITE) transmitted from the proxy server P2 (213) to the ALG (23) (message 1).
An IP address in the IPv4 format surrounded by an ellipse 411 in FIG. 4 is a target of address conversion to the IPv6 format. In this example, four IP addresses are to be converted.
FIG. 5 is an example of a SIP message (INVITE) obtained by converting the IP address information (IPv4 format) of the message 1 into the IPv6 format by the ALG (23) (message 2).
Note that this message 2 represents a conversion method according to the prior art. In this message 2, four types of virtual IP addresses in the IPv6 format corresponding to the four conversion target IP addresses of the message 1 are issued. .
When the message 2 is transmitted from the ALG (23) to the proxy server P3 (221), it reaches the SIP terminal T2 (223) as described above, and the SIP message (INVITE response “200 OK”) from the SIP terminal T2 (223). Is returned.
[0015]
FIG. 6 is an example of a SIP message (response "200 OK" to INVITE) transmitted from the proxy server P3 (221) to the ALG (23) (message 3).
The IP address in the IPv6 format surrounded by the ellipse 431 in FIG. 6 is the same as the virtual IP address set in the message 2, and it can be seen that the virtual IP address information set in the message 2 is returned as it is.
FIG. 7 shows an example in which IP address information that does not need to be converted into the IPv6 format using the IP address (IPv4) of message 1 is converted into IP address identification information (message 4).
The part surrounded by the ellipse 441 in FIG. 7 is an example of the IP address identification information, which is not referred to from the proxy server P3 (221) to the SIP terminal T2 (223).
Note that this message 4 represents the conversion method according to the present embodiment, and in this message 4, the IP address information described in the Recoed-Route header or Via header is replaced with IP address identification information. It can be seen that the number of issued virtual IP addresses is one, and the number of issued virtual IP addresses is 1/4 of that of the message 2.
[0016]
FIG. 8 is a flowchart showing a processing procedure of a conversion process of IP address information in a SIP message in the IP address conversion device according to the embodiment of the present invention.
With reference to FIG. 8, a description will be given of a process of converting IP address information in a SIP message in the IP address conversion device.
The IP address extraction function 102 sets a line number counter N to 1 in order to confirm, line by line, whether or not the IP message received by the receiving unit 101 includes the IP address information in the received SIP message ( In step ST1), IP address information (IP address, virtual IP address, or IP address identification information) is extracted in the Nth line (N = 1 at this stage) of the received SIP message.
The determination function 103 determines whether or not the extracted IP address information includes an IP address (step ST2). If the IP address information includes an IP address, conversion to a virtual IP address is required It is determined whether or not this is the case (step ST3).
In this case, as shown in FIG. 6, since the IP address information described in the SIP Via header and the Record-Route header is directly returned from the receiving side of the SIP message, the SIP Via header and the Record-Route header are returned. Is determined that the conversion to the virtual IP address is unnecessary, and the other IP address information is determined to require the conversion to the virtual IP address.
[0017]
If it is determined in step ST3 that the conversion into the virtual IP address is unnecessary, the IP address identification information assigning function 104 issues the IP address identification information (step ST4), and furthermore, the IP address and the IP address identification information are added. The correspondence is registered in the management table (step ST5).
For example, in the process 303 of FIG. 3, among the IP addresses shown in FIG. 4, the portion of the IP address surrounded by the ellipse in FIG. 7 is converted into the IP address identification information 411.
Next, the replacement function 106 replaces the IP address in the SIP message with the IP address identification information (step ST6).
If it is determined in step ST3 that the conversion to the virtual IP address is necessary, the replacement function 108 converts the IP address in the SIP message into a virtual IP address (step ST7).
For example, in the process 303 in FIG. 3, among the IP addresses shown in FIG. 4, the IP addresses other than the portion surrounded by the ellipse in FIG. 7 are converted into virtual IP addresses.
[0018]
In step ST2, the determination function 103 also determines whether or not the extracted IP address information includes a virtual IP address. If the virtual IP address is included in the IP address information, in step ST3, It is determined that conversion to an address is necessary.
Then, in step ST7, the replacement function 108 converts the virtual IP address in the SIP message into an IP address.
For example, in the process 306 of FIG. 3, the converted virtual IP address is converted to an IP address.
Although not shown in FIG. 1, the IP address and the converted virtual IP address are registered in a management table for registering the correspondence between the IP address and the virtual IP address.
If the extracted IP address information does not include the IP address or the virtual IP address in step ST2, the determination function 103 determines whether or not the IP address identification information is included (step ST8).
[0019]
In step ST8, when the IP address identification information is included, the IP address identification information assigning function 104 searches the correspondence management table of the IP address and the IP address identification information, acquires the IP address (step ST9), and executes the SIP. The IP address identification information in the message is replaced with the IP address (step ST10).
For example, in the process 306 of FIG. 3, the IP address identification information 441 shown in FIG. 7 is converted into an IP address.
After performing step ST6, step ST7, or step ST10, the row number counter is increased by one. (Step ST11)
Next, it is determined whether it is the end of the SIP message (step ST12). If it is the end of the SIP message, the process is terminated. If it is not the end of the SIP message, the process returns to step ST2 to continue the process.
After the processing is completed, the SIP message transmitting unit 107 transmits the SIP message whose IP address information has been changed.
Note that the above description is merely an example, and it goes without saying that the above applies to all conversion patterns that are combinations of the IPv4 private address, the IPv4 global address, and the IPv6 address.
As described above, the invention made by the inventor has been specifically described based on the embodiment. However, the present invention is not limited to the embodiment, and can be variously modified without departing from the gist of the invention. Needless to say,
[0020]
【The invention's effect】
The following is a brief description of an effect obtained by a representative one of the inventions disclosed in the present application.
ADVANTAGE OF THE INVENTION According to the IP address translation device of this invention, it becomes possible to avoid wasteful consumption of the limited virtual IP address for translation, and to process a large amount of SIP messages.
[Brief description of the drawings]
FIG. 1 is a functional block diagram illustrating an overall configuration of an IP address translator according to an embodiment of the present invention.
FIG. 2 is a diagram for explaining an operation of the IP address translator according to the embodiment of the present invention, and is a diagram for explaining an example of system connection at the time of sending a SIP message.
FIG. 3 shows a signal sequence example of a SIP message when a SIP message is transmitted from a SIP terminal T1 to a SIP terminal T2 and a response is returned from the SIP terminal T2 to the SIP terminal T1 in the system configuration shown in FIG. It is a thing.
FIG. 4 is a diagram showing an example of a SIP message transmitted and received by ALG in the signal sequence example of FIG. 3;
FIG. 5 is a diagram illustrating an example of a SIP message transmitted and received by ALG in the signal sequence example of FIG. 3;
FIG. 6 is a diagram showing an example of a SIP message transmitted and received by ALG in the signal sequence example of FIG. 3;
FIG. 7 is a diagram showing an example of a SIP message transmitted and received by ALG in the signal sequence example of FIG. 3;
FIG. 8 is a flowchart showing a processing procedure of a conversion process of IP address information in a SIP message in the IP address conversion device according to the embodiment of the present invention.
[Explanation of symbols]
21: IPv4, 22: IPv6 network, 23: ALG, 101: SIP message receiving unit, 102: IP address extraction function, 103: discrimination function, 104: IP address identification information adding function, 105: correspondence management table, 106: IP Replacement function for replacing the address with the IP address identification information or the IP address identification information with the IP address, 107 ... SIP message transmission unit, 108 ... Replace the IP address with the virtual IP address, or replace the virtual IP address with the IP address. Proxy server P1, 213 proxy server P2, 221 proxy server P3, 222 proxy server P4, 223 SIP terminal T2.

Claims (3)

Receiving means for receiving the SIP message;
Extracting means for extracting IP address information in the SIP message received by the receiving means;
It is determined whether the IP address information extracted by the extracting means includes an IP address. If the extracted IP address information includes an IP address, the IP address is changed to a virtual IP address of the extracted IP address. Determining means for determining whether or not the conversion of
Replacement means for replacing the IP address determined to be unnecessary to be converted into a virtual IP address by the IP address identification information,
A correspondence management table for registering a correspondence relationship between the IP address identification information replaced by the replacement means and the IP address;
Converting means for converting the IP address determined to need to be converted to a virtual IP address by the determining means into a virtual IP address;
A transmission unit for transmitting a SIP message whose IP address information has been changed. The determining means determines whether the IP address information extracted by the extracting means includes IP address information,
When the extracted IP address information includes IP address identification information, the replacement unit searches the correspondence management table and converts the extracted IP address identification information into an IP address. The IP address translator according to claim 1, wherein The determining means determines whether or not a virtual IP address is included in the IP address information extracted by the extracting means, and when the extracted IP address information includes a virtual IP address, the Determines that the virtual IP address needs to be converted to an IP address,
3. The IP address conversion device according to claim 1, wherein the conversion unit converts the extracted virtual IP address into an IP address.

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