JP2004172730A - Application level gateway in application layer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the processing performance of both an application level gateway (ALG) in an application layer and a network address translation (NAT) in a network layer. <P>SOLUTION: The application level gateway (ALG) 10 in the application layer includes a database 110 for storing entry information and also an information processing section 100 having functions of confirming the entry information by referencing the database 110 when requesting the entry information, accessing the network address translation (NAT) 20 in the network layer when no entry information is registered to acquire the entry information, registering it to the internal database 110, referencing the entry information registered in the internal database 110 to perform address translation without the need for accessing the NAT 20 when the result of referencing the database 110 indicates the presence of the registered entry information. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a network layer address translator (NAT) and an application layer address translator (NAT) when performing communication between networks having different address systems using a protocol for setting IP address information also in an application layer. In particular, the present invention relates to an address translation technology realized using ALG), and in particular, a request for entry information initially held in the network layer address translation device (NAT) from the address translation device (ALG) for performing the application layer address translation. When the entry is performed, the entry information is stored in the internal database, so that for the subsequent conversion, the entry information stored in the internal database is not accessed without accessing the network layer address translator (NAT). About address translator application layer for realizing the address translation application layer by irradiation (ALG).
[0002]
[Prior art]
Conventionally, the Domain Name System (DNS), which is a fundamental technology of the Internet, employs a technology of accelerating processing by holding a cache in a DNS server when performing conversion between a domain name and an IP address ( Non-Patent Document 1).
[0003]
However, when communication is performed between networks having different address systems using a protocol for setting IP address information in an application layer, firstly acquired entry information is registered in an internal database, and address conversion is performed with reference to the entry information. There is no example in which the processing after registration has been speeded up.
[0004]
[Non-patent document 1]
P. Mockapetris, "RFC1035 DOMAIN NAMES-IMPLEMENTATION AND SPECIFICATION", November 1987, IETF, P47 7.4. Chapter using the cache
[0005]
[Problems to be solved by the invention]
However, when requesting entry information to the network layer address translation device (NAT) every time the address translation is performed as described above, the application layer address translation device (ALG) and the network layer Since communication for requesting and responding to entry information between the address translators (NATs) is required, processes relating to the application layer address translator (ALG) and the network layer address translator (NAT) are respectively performed. Will occur. In such a situation, when a heavy load is applied to the application layer address translation device (ALG) and the network layer address translation device (NAT), there is a concern that a sufficient processing speed cannot be secured. .
[0006]
SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has as its object to request the entry information initially set by the network layer address translator (NAT) from the application layer address translator (ALG). In this case, the entry information is stored in an internal database, and subsequent conversion is performed by referring to the entry information stored in the internal database without accessing the network layer address translator (NAT). By realizing layer address translation, the number of accesses from the application layer address translator (ALG) to the network layer address translator (NAT) is greatly reduced, thereby enabling the application layer address translator. (ALG) and in said address translation unit of the network layer (NAT) to improve both the performance.
[0007]
[Means for Solving the Problems]
(1) In order to achieve the above object, the application layer address translation device (ALG) according to the present invention first requests entry information held in the network layer address translation device (NAT). And a database for holding entry information.
[0008]
(2) The application layer address translation device (ALG) according to the present invention refers to an internal database when making a request for entry information, confirms the entry information, and when no entry information is registered, that is, a certain IP When the address conversion is performed first, entry information is obtained by accessing the address translation device (NAT) of the network layer, registered in an internal database, and as a result of referring to the database, the entry information is obtained. If there is a registration, that is, if the above-mentioned translation of a certain IP address is performed for the second time or later, by referring to the entry information registered in the internal database without accessing the network layer address translator (NAT). To realize the function of performing address translation Characterized in that it includes an information processing unit.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, as an embodiment of the present invention, a protocol for holding an IP address in an application layer, which has been applied to Voice over IP (VoIP) in recent years, is based on Session Initiation Protocol (SIP), and has an address system different between networks. The case where VoIP communication is performed using SIP will be described in detail with reference to FIGS.
[0010]
FIG. 1 is a block diagram for explaining an example of the overall configuration of a system when performing VoIP communication between networks having different IP address systems using an application layer address translator (ALG) according to the present invention.
[0011]
FIG. 2 is a diagram for explaining an example of a case in which VoIP communication is performed between networks having different IP address systems by referring to entry information held therein using the application layer address translation device (ALG) of FIG. It is a flowchart.
[0012]
FIG. 3 shows an application layer address translator in the case of performing VoIP communication between networks having different IP address systems by referring to internally stored entry information using the application layer address translator (ALG) of FIG. It is a block diagram for explaining an example of processing inside (ALG).
[0013]
FIG. 4 shows a case where SIP is used when performing VoIP communication between networks having different IP address systems by referring to entry information held internally using the application layer address translation device (ALG) of FIG. FIG. 3 is a diagram for explaining a general signal sequence.
[0014]
An example of the overall configuration of a system using an application layer address translation device (ALG) according to the present invention will be described with reference to FIG.
[0015]
The application layer address translator (ALG) 10 in FIG. 1 is connected to a network (A) 30 and a network (B) 31 having different address systems from the network layer address translator (NAT) 20. . The application layer address translator (ALG) 10 includes an information processing unit 100 and a database 110.
[0016]
The information processing unit 100 performs a process for performing address conversion of an application layer, refers to a database 110 that stores entry information when requesting entry information, and, if no entry information is registered, the network layer. By accessing the address translation device (NAT) 20 to register the entry information in the database 110, and if the entry information is registered as a result of referring to the database, the network layer It is characterized by realizing a function of performing address translation by referring to entry information registered in the database 110 without accessing an address translation device (NAT).
[0017]
The network (A) 30 and the network (B) 31 are configured by being connected to a plurality of IP telephone terminals 302-a to 302-c and 312-a to 312-c via routers 301 and 311 respectively. .
[0018]
Next, the operation of the application layer address translator (ALG) 10 will be described with reference to the flowchart of FIG. 2 and the block diagram of FIG.
[0019]
First, in order to perform communication by VoIP with an IP telephone terminal having a different address system, a message requiring address conversion is received (step 201 in FIG. 2, (1) in FIG. 3A). Next, the information processing section 100 accesses the database 110 and checks the entry information (step 202 in FIG. 2, (2) in FIG. 3A). Here, it is determined whether or not entry information necessary for conversion is registered in the database 110 (step 203 in FIG. 2). If no entry information is registered, that is, if a certain IP address is to be translated first, a request for entry information is made to the network layer address translation device (NAT) 20 (step 210 in FIG. 2, and FIG. 3A). (3)), the entry information corresponding to the request is obtained (step 211 in FIG. 2, and (4) in FIG. 3). Next, after the acquired entry information is registered in the database 110 (step 212 in FIG. 2, step (5) in FIG. 3), the address conversion of the application layer is executed (step 213 in FIG. 2), and the IP telephone having a different address system is used. The message is transmitted to the terminal (step 205 in FIG. 2, (6) in FIG. 3 (a)).
[0020]
After receiving the message requiring the address translation, the information processing unit 100 accesses the database 110 and confirms the registered entry information (step 202 in FIG. 2, (2) in FIG. 3B). When the information is registered, that is, when the corresponding IP address conversion is performed for the second time or later, and the information has already been registered in the database 110, the network layer address translation device (NAT) 20 is accessed to request entry information. Without using the registered entry information, the application layer performs address conversion of the application layer (step 204 in FIG. 2, and (3) in FIG. 3B), and transmits a message to an IP telephone terminal having a different address system. (Step 205 in FIG. 2 and (4) in FIG. 3B).
[0021]
Normally, the application layer address translator (ALG) 10 transmits an entry deletion request to the network layer address translator (NAT) 20 after receiving the final signal from the IP telephone terminal, and transmits the network layer address. The translation device (NAT) 20 releases the entry in response to this. In consideration of these, the information processing unit 100 deletes the entry information registered in the database 110 after receiving the entry deletion response from the network layer address translator (NAT).
[0022]
Finally, the above-described series of processing will be described using an example of a general signal sequence in FIG.
[0023]
First, upon establishing communication, an INVITE message is first received. At this time, since there is no entry information in the database, a request for entry information is made to the address translation device (NAT) of the network layer and registered in the database 110. Thereafter, for 100Trying, 180Ringing, 200OK, ACK, BYE, and 200OK, address conversion of the application layer is realized by referring to the entry information registered in INVITE. After receiving 200 OK for BYE, which is the final signal, the application layer address translation device (ALG) 10 transmits an entry deletion request to the network layer address translation device (NAT) 20 so that the network layer address translation is performed. The entry set in the device (NAT) 20 is released. After receiving the deletion response, the entry information registered in the database 110 is deleted. By realizing such processing, it becomes possible to perform the address translation six times after 100Trying without accessing the network layer address translator (NAT) 20.
[0024]
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,
[0025]
【The invention's effect】
By using the address translation device in the application layer according to the present invention, for the IP address registered in the internal database, the subsequent translation is performed by the entry registered in the database without accessing the address translation device (NAT) in the network layer. It can be realized only by referring to information. As a result, the number of accesses from the application layer address translator (ALG) to the network layer address translator (NAT) can be greatly reduced, and the application layer address translator (ALG) and the It is expected that the processing performance of both network layer address translators (NAT) can be greatly improved.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating an example of an overall configuration of a system when performing VoIP communication using an application layer address translation device (ALG) according to the present invention.
FIG. 2 is a flowchart for explaining an example of a case where VoIP communication is performed by using an entry information registered in an internal database in an application layer address translator (ALG) of FIG. 1;
FIG. 3 is a diagram showing the internal configuration of the application layer address translator (ALG) when performing VoIP communication using the entry information registered in the internal database in the application layer address translator (ALG) of FIG. 1; It is a block diagram for explaining an example of processing. Since (a) does not hold the corresponding entry information in the database, the entry information is acquired by accessing the network layer address translation device (NAT). The entry information is registered in the internal database, and (b) is the entry information stored in the internal database without accessing the network layer address translator (NAT) because the entry information is registered as a result of referencing the database. Shows the case where address translation is realized using There.
FIG. 4 is a diagram showing a case where SIP is used when performing VoIP communication between networks having different IP address systems by referring to entry information held therein using an address translation device (ALG) of an application layer of FIG. 1; FIG. 3 is a diagram for explaining a general signal sequence.
[Explanation of symbols]
Reference Signs List 10: Application layer address translation device (ALG), 100: Information processing unit, 110: Database, 20: Network layer address translation device (NAT), 30, 31: Network (A), (B), 301, 311 ... Routers, 302-a to 302-c, 312-a to 312-c ... IP telephone terminals

Claims (1)

When communication is performed between networks having different address systems using a protocol for setting Internet Protocol (IP) address information in an application layer, an address translation set by a network address translation device (NAT: Network Address Translation) is performed. An address translation device (ALG: Application Level Gateway) for performing address translation of an application layer using a combination of IP addresses (entry information) used,
A database for holding entry information, and
An information processing unit for realizing a function of registering entry information acquired from a network layer address translation device (NAT) in a database and referring to the entry from the database;
When a request for entry information is first made to the network layer address translation device (NAT), the entry information is held in an internal database, and for subsequent translation, the network layer address translation device (NAT) is used. ), The application layer address translator is realized by referring to an internal database without accessing the application layer.

Images