KR100438182B1 - Method of different IP-address attaching for gatekeeper and NAT-PT - Google Patents

Abstract

The present invention is to secure the address information for translation in the gatekeeper through the simple control message processing between the gatekeeper and NAT-PT, so that the voice Internet protocol traffic between the IPv6 network and the IPv4 network can be efficiently converted. According to the present invention, a method for interworking different IP addresses for NAT-PT interworking with a gatekeeper includes: a first step of opening a channel for information exchange between the gatekeeper and a NAT-PT router for address translation; A second step in which the gatekeeper informs the IPv6 address information of the terminal in the IPv6 network in the H.225.0 RAS signaling step; A third step of allocating an IPv4 address to the gatekeeper when the NAT-PT router receives the IPv6 address information from the gatekeeper; A fourth step of regenerating the H.224.0 and H.245 messages directed to the IPv4 terminal in the IPv4 network by reflecting the allocated IPv4 address information by the gatekeeper; When the call is terminated, the gatekeeper comprises a fifth step of returning the NAT-PT resource allocated from the NAT-PT router to the NAT-PT router.

According to the present invention, the gatekeeper makes the translation address through a simple control message processing between the gatekeeper and the NAT-PT without using the ALG of NAT-PT for VoIP application-dependent Internet protocol address information conversion. It provides information and enables address translation for VoIP applications.

Description

Method of different IP-address attaching for gatekeeper and NAT-PT} for gatekeeper and NAT-PT interworking

The present invention provides a method for translating a different IP address for a gatekeeper and NAT-PT interworking, and in particular, for interworking with an existing IPv4 network during the initial introduction of an IPv6 network. This paper relates to an efficient address translation method of H.323-based Voice of Internet Protocol (VoIP) traffic when Protocol Translation is used.

In detail, the present invention secures address information for translation in the gatekeeper through a brief control message exchanged between the gatekeeper and NAT-PT in an environment where VoIP and NAT-PT based translation / routing services are provided as an integrated solution, The present invention relates to a method of translating different IP addresses for a gatekeeper and NAT-PT interworking to efficiently convert VoIP traffic between IPv6 and IPv4 networks by performing address translation for VoIP applications.

In order to solve the problem of address exhaustion, one of the biggest problems of the Internet, IPv6 protocol with extended address space has been proposed. However, the transition from the current IPv4-based Internet to the next-generation Internet based on IPv6 will not evolve in the short term and will gradually evolve. Therefore, NAT-PT technology has been proposed to solve the intercommunication needs between IPv4 / IPv6 hosts that occur while the network evolves.

Network Address Translation-Protocol Translation (NAT-PT) exists in the border router between IPv4 and IPv6 networks, and allows protocol translation and application transparent to end hosts so that communication sessions between IPv4 and IPv6 networks can be protocol-independent. It is a dependent transformation.

Address management facility provisioning is a feature that allows NAT-PT to manage IPv4 addresses into an address pool so that hosts on different networks can assign IPv4 addresses to IPv6 hosts.

The protocol translation function used by NAT-PT converts IP and ICMP packet headers between different IPv4 / IPv6 protocols without additional state management by using a stateless IP / ICMPTranslation (SIIT) mechanism.

Application-dependent translation is called ALG (Application Level Gateway) in NAT-PT, and a specific packet converts IP and ICMP packet headers without additional state management. Application-dependent translation is named as Application Level Gateway (ALG) in NAP-PT, and it performs necessary translation when certain packet includes IP information in payload of application itself in addition to IP and ICMP translation. Perform. The current NAT-PT version implements File Transfer Protocol-ALG (FTP-ALG) and Domain Name Service-ALG (DNS-ALG).

Meanwhile, H.323, a communication protocol proposed by ITU-T, is in the spotlight as a new telephone system in a packet-based network (PBN). IP telephony terminal conforming to H.323 protocol must send and receive RAS (Request, Admission and Status) signal with gatekeeper if there is a gatekeeper, RAS signaling step, Q. 931 signaling step, H.245 signaling step, logical channel signaling step must go through.

A brief description of the H.323 signaling procedure is provided with reference to FIG. 1.

The sender terminal (Endpoint 1) 20 transmits an ARQ message to the gatekeeper (s1), and receives an ACF message or an ARJ message in response to whether the call is allowed (s2). The sender terminal 20 enters a call setup process with the gatekeeper 10 when receiving the ACF message, and terminates the call when receiving the ACF message (s3).

Then, the gatekeeper 10 performs a call setup process with the receiver terminal 30 (s4), and after receiving the ARQ message from the receiver terminal 30 (s5), the ACF message or ARJ to the receiver terminal 30 Send a message (s6).

Here, the ARQ (Admissions Request) message is a message for requesting permission from the gatekeeper 10 to generate a call by the H.323 sender terminal 20, who is the caller, and who is making the call. Includes information such as desired bandwidth. The ACF (Admissions Confirm) message is a message for granting a call to the H.323 sender terminal 20 to which the gatekeeper 10 sends an ARQ. The ACF message determines the gatekeeper route or direction, and includes information such as the bandwidth to allow and the address (or its own address) of the party to which the connection is to be made. The ARJ (Admissions Reject) message is a message indicating that the call to the other party is not allowed to the H.323 terminal that has sent the gatekeeper ARQ. It is sent with a reason not to be granted, for example, during a call, resource empty, unknown destination (not registered), rejected (rejected).

Subsequently, when the gatekeeper 10 receives the connection permission message after receiving the ACF message, the gatekeeper 10 transmits the connection permission message to the sender terminal (s7) (s8), so that the sender and receiver terminals 20 and 30 receive the gatekeeper 10. Information is transmitted through the H.245 channel (s9, s10) and directly communicated through the media data channel (s11).

Here, the H.225.0 RAS channel is an unreliable channel used to transmit registration, admission, bandwidth change, and status messages (see H.225.0 Recommendation) between H.323 terminals 20 and 30. The H.225.0 Q.931 call signaling channel is a reliable channel used to transmit call setup and teardown messages (see H.225.0 Recommendations) between H.323 terminals. The H.245 channel is a reliable channel used to transmit H.245 control information messages (see H.245 Recommendations) between H.323 terminals 20,30. Media data channel is a channel used to transmit multimedia data such as actual audio or video set through RAS, Q.931, H.245 signaling steps.

At this time, each step is to inform the address and port to be used for the next step. This method has the advantage of dynamically setting the necessary address when moving to the next step in the call setup process, but in IPv6 network operated by NAP-PT When communicating with external terminals, NAP-PT router has a disadvantage of not knowing next IPv4 address and port.

In this system, gatekeepers correspond to the call processing process of existing private exchanges, and allow users to make calls only by phone number without knowing their IP address. According to the system configuration, there is a method in which an IP terminal (eg, a phone) directly establishes a call by knowing the other party's IP address and port without a gatekeeper, but in this case, the user of the IP terminal must know the other party's IP address. It is common to configure the system using a gatekeeper because the overall management of the system is not possible.

NAT-PT is a function that translates protocols when hosts in an IPv6 network want to communicate with hosts in an IPv4 network. This is accomplished by managing the pool of available IPv4 addresses and standardizing translations between different protocol fields and payloads. IP address information translation of applications that include address information should be supported.

The specific operation of NAP-PT is as follows.

As shown in Fig. 2, the NAP-PT section 102 maintains an address pool 104 that holds available IPv4 addresses. When the host 101 located in the IPv6 network wants to communicate with the host 105 in the IPv4 network, the host 101 in the IPv6 network uses its IPv6 address as a source address and is managed by the NAP-PT router 103. The packet is sent to the destination address by combining the destination IPv4 address with the domain prefix.

The NAP-PT router 103 assigns an IPv4 address available in the address pool 104 to the corresponding IPv6 sender address and converts the translation information (source IPv6 address, assigned IPv4 address pair) to the NAT-PT address translation table shown in FIG. Etc.).

The NAP-PT router 103 forwards the packet by converting the protocol header by using the newly assigned IPv4 address as the source address and the IPv4 address where the domain prefix of the IPv6 destination address is removed as the destination address.

Meanwhile, the Internet Protocol (H.323) does not include the IPv6-based H.323 standard, but like other proposed IPv6-based applications (FTP, DNS, etc.), the IPv6-based H.323 protocol is an address. Assuming that it is not significantly different from the existing IPv4 based H.323 protocol except for the area, the operation method is as follows.

Well-known IPs and ports used by Internet Protocol (H.323) terminals include Gatekeeper UDP Discovery Multicast IP (224.0.1.41), Gatekeeper UDP Discovery Port (1718), Gatekeeper UDP Registration and Status Port (1719), End TCP call signaling port 1720.

Assuming that the Internet Protocol (H.323) terminal already knows the IP address of the gatekeeper, the terminal does not need to perform the gatekeeper discovery process. The process for establishing a call using both the RAS and the Q.931 message by both Internet protocol terminals registered to the gatekeeper is shown in FIG. 1, and the well-known port necessary for this process is the gatekeeper RAS 1719 port.

The sender terminal transmits ARQ to the gatekeeper's RAS well-known port and, upon receiving the ACF from the gatekeeper, initiates the Q.931 call signaling procedure using the Q.931 signaling address and port on the ACF.

At this time, depending on the Q.931 address in the ACF, call signaling may be through the gatekeeper and directly communicate with the receiver terminal.

The Internet Protocol receiver terminal sends a Q.931 connection message at the end of Q.931 call signaling and contains an H.245 control channel address and port, so that when the sender terminal initiates an H.245 logical channel connection procedure. Make sure to use that address and port.

When the H.245 control channel is connected, an H.245 logical channel signaling process is performed to deliver an address and a port where each terminal can receive voice data to the other party. The sender and receiver terminal transmits RTP voice data to the other party using the corresponding address and port.

However, when performing the protocol conversion based on NAT-PT, if the IP information is included in the payload of the application itself in addition to the conversion for IP and ICMP packets, application-dependent conversion is performed through ALG. In the current NAT-PT version, FTP-ALG and DNS-ALG are implemented. When VoIP traffic is forwarded through a NAT-PT based router, messages of each signaling step of the H.323 protocol include IP information. Therefore, a separate application level gateway (ALG) for H.323 is established in the NAT-PT node. It is necessary to perform protocol conversion for IP information. However, the current NAT-PT standard does not support H.323 ALG.

And, NAT-PT puts a separate ALG for each application to convert the IP address information of the application layer, and performs the IP address information conversion work in the application. Currently proposed ALGs are FTP-ALG and DNS-ALG. However, if each application-dependent ALG is put on NAT-PT which performs general purpose translation / routing service, it has a disadvantage that overall routing performance is degraded because packets are converted to the application layer.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and in order to improve the packet routing performance degradation problem of the system caused by converting a packet to an application layer by placing an H.323 ALG on a NAT-PT node, the VoIP is improved. By distributing the address translation of the application layer for traffic to the gatekeeper, it provides a different IP address interworking method for NAT-PT interworking with a gatekeeper that can efficiently convert VoIP traffic between IPv6 and IPv4 networks. There is a purpose.

1 is a flowchart illustrating an H.323 signaling procedure between a gatekeeper and a transmitting / receiving terminal.

2 is a configuration diagram illustrating a NAT-PT operation procedure.

3 is an address mapping table of NAT-PT.

4 is a flowchart illustrating a method for interworking different IP addresses for NAT-PT interworking with a gatekeeper according to an exemplary embodiment of the present invention.

In order to achieve the above object, the gatekeeper according to the present invention and the different IP address interworking method for NAT-PT interworking,

NAT-PT address translation of H.225.0 message and H.245 message exchanged between sender / receiver terminal and gatekeeper server based on different IP protocol in the environment where VoIP and NAT-PT based translation / routing service are provided as integrated solution In the method of interlocking the gatekeeper and NAT-PT so that this can be done dynamically,

Opening a channel for information exchange for address translation between the gatekeeper and the NAT-PT router;

A second step in which the gatekeeper informs the IPv6 address information of the terminal in the IPv6 network in the H.225.0 RAS signaling step;

A third step of allocating an IPv4 address to the gatekeeper when the NAT-PT router receives the IPv6 address information from the gatekeeper;

A fourth step of regenerating the H.224.0 and H.245 messages directed to the IPv4 terminal in the IPv4 network by reflecting the allocated IPv4 address information by the gatekeeper;

When the call is terminated, the gatekeeper comprises a fifth step of returning the NAT-PT resource allocated from the NAT-PT router to the NAT-PT router.

Preferably, when the internal receiver terminal located in the IPv6 network attempts to make an internal call from the inside, the IPv6 sender address information of the signaling message is secured as the IPv6 address of the internal terminal and transmitted to the NAT-PT router. do.

Preferably, when the external sender terminal located in the IPv4 network attempts to make a call from the outside to the inside, the receiver telephone number is found in the payload of the signaling message, so the gatekeeper finds an IPv6 address corresponding to the receiver telephone number and then selects the corresponding IPv6 address. It is characterized by forwarding to a NAT-PT router.

Referring to the accompanying drawings, a method for interworking different IP addresses for NAT-PT interworking with a gatekeeper according to the present invention as described above is as follows.

4 is a flowchart illustrating a method of interworking different IP addresses for NAT-PT interworking with a gatekeeper according to an exemplary embodiment of the present invention.

First, in order to operate on a NAT-PT basis, only the IP address is converted without using a multiplexing identifier (port concept of TCP and UDP) of the transport layer together with IP address translation.

In addition, since the gatekeeper plays the role of ALG of NAT-PT, the gatekeeper participates in the entire H.323 signaling process until the RTP media channel is opened, and performs the message conversion. Therefore, when the traditional NAT-PT router works with the gatekeeper, the addresses that need to be translated are the gatekeeper's address and the call terminal's address.

Gatekeepers and NAT-PT routers open special channels and send and receive each address. To do this, the gatekeeper checks to see if it uses a NAT-PT router at boot, registers its IPv6 address with the NAT-PT router, and if this particular channel is boiled, it should try to reconnect from time to time.

Since NAT-PT only needs the address information of the H.323 terminal when the call session is opened, when the H.225.0 RAS message is exchanged via the gatekeeper, the gatekeeper NAT-enhances the IPv6 address of the H.323 terminal. The PT router can be informed and assigned an available IPv4 address.

When the sender is in the IPv6 network inside NAT-PT, the gatekeeper knows the IPv6 address of the terminal, so it informs NAT-PT of the internal sender's IPv6 information and is assigned an available IPv4 address.

If for some reason the IPv4 address is not assigned from NAT-PT, the ARJ is sent to the H.323 terminal to terminate the call.

If the terminal sending the ARQ is on the outside network, look at the fake address field in the ARQ, find the recipient in the database, inform the NAT-PT of the recipient's IPv6 address, and send an ARJ if no available IPv4 address is assigned. To end the call.

The gatekeeper transfers only the IPv6 address of the gatekeeper and the IPv4 H.323 terminal to the IPv4 address in the contents of the message transmitted to the H.323 terminal of the IPv4 network in the entire H.323 signaling process.

The above procedure will be described with reference to FIG. 4 step by step as follows.

In the gatekeeper booting step (S200), the gatekeeper 210 queries to check whether the router uses NAT-PT (S201), and receives a response (S203) if the router is using NAT-PT (S203). The IPv6 address is transmitted to the NAT-PT router (S205).

The NAT-PT router adds an IPv6 address of the gatekeeper 210 to the table (S207), and then allocates a well known IPv4 address for the gatekeeper server from the IPv4 address pool for the gatekeeper 210 (S209). The IPv4 address is transmitted to 210 (S211). Then, the gatekeeper 210 stores the allocated IPv4 address (S213).

Then, in the RAS signaling step (S215), when the call is initiated from the IPv6 network or IPv4 network, ARQ message is transmitted from the gatekeeper 210 (S217), the sender IPv6 address in the case of the IPv6 network to NAT-PT 220, In the case of an IPv4 network, a recipient IPv6 address is transmitted (S219).

The NAT-PT 220 adds an IPv6 address to the sender (IPv6 network) or the receiver (IPv4 network) in the table (S221), and allocates an IPv4 address for the sender or the receiver (S223).

The NAT-PT 220 transmits a response message including the IPv4 address for the sender (IPv6 network) or the receiver (IPv4 network) to the gatekeeper 210 (S227), and the gatekeeper 210 transmits the IPv4 address. Store and replace all messages received with IPv4 addresses (S229).

That is, when a call is attempted from the inside (an H.323 terminal located in an IPv6 network) to the outside (an H.323 terminal located in an IPv4 network), NAT- is used to set the IPv6 address information of the H.323 terminal attempting the call in a signaling message. Send to PT and get available IPv4 address from NAT-PT. The gatekeeper then replaces the IPv6 address with the newly assigned IPv4 address for all internal and external messages.

When attempting a call from the outside (H.323 terminal located in the IPv4 network) to the inside (H.323 terminal located in the IPv6 network), find the IPv6 corresponding to the recipient's telephone number, and transmit the IPv6 address to the NAT-PT. Get an available IPv4 address from -PT The gatekeeper then replaces the IPv6 address with the newly assigned IPv4 address for all messages sent internally and externally.

Referring to the return step at the end of the call (S231), when the call is terminated (S233) by returning the IPv4 address for the sender (IPv6 network) or the receiver (IPv4 network) (S235), the gatekeeper returns the corresponding IPv4 address. When the gatekeeper ends (S239), by returning the IPv4 address for the gatekeeper (S241), NAT-PT returns the corresponding IPv4 address (S243).

In this way, through the simple control message processing between the gatekeeper and the NAT-PT without placing an ALG for processing H.323 in the NAT-PT, the gatekeeper ensures the address information for translation and is applied to the VoIP application. By performing address translation for IP traffic, application translation work for VoIP traffic is distributed to gatekeepers to efficiently convert VoIP traffic between IPv6 and IPv4 networks. Since the gatekeeper and NAT-PT are interworked, the VoIP and NAT-PT based conversion / routing services are more suitable for the environment provided as an integrated solution.

In addition, since an environment in which a signaling message is used and NAT-PT is located at a boundary between an IPv6 network and an IPv4 network to perform an address translation service is the same as the SIP technology, this basic concept may be applied to the SIP technology.

As described above, the gatekeeper according to the present invention and the different IP address interworking method for NAT-PT interworking, the gatekeeper without using the ALG of NAT-PT for IP address-dependent Internet protocol address translation The gatekeeper allows the gatekeeper to obtain address information for translation through simple control message exchange between the network and NAT-PT, and performs address translation of the application layer for VoIP traffic. It is possible to efficiently convert VoIP traffic between IPv6 network and IPv4 network. When each application-dependent ALG is uploaded to NAT-PT which performs general purpose translation / routing service, it is caused by raising the packet to the application layer. This can improve the packet routing performance degradation problem of the system.

Since the present invention is a structure in which the gatekeeper and NAT-PT are interworked, the VoIP and NAT-PT based conversion / routing services can be more suitably serviced in an environment in which an integrated solution is provided.

Claims (4)

NAT-PT address translation of H.225.0 message and H.245 message exchanged between sender / receiver terminal and gatekeeper server based on different IP protocol in the environment where VoIP and NAT-PT based translation / routing service are provided as integrated solution In the method of interlocking the gatekeeper and NAT-PT so that this can be done dynamically, Opening a channel for information exchange for address translation between the gatekeeper and a NAT-PT router; A second step of the gatekeeper informing the NAT-PT router of the first address information of the terminal in the first network in the RAS signaling step; A third step of informing the gatekeeper by allocating a second address when the NAT-PT router receives the first address information from the gatekeeper; A fourth step of regenerating a message directed to a terminal in a second network by reflecting the second address information allocated by the gatekeeper; When the call is terminated, the gatekeeper comprises a fifth step of returning the NAT-PT resource allocated from the NAT-PT router to the NAT-PT router. Interlock method. The method of claim 1, When an internal receiver terminal located in the first network attempts to make a call from the inside to the outside, a gate, characterized in that the source address information itself of the signaling message is secured as the first address of the internal terminal and transmitted to the NAT-PT router. Different IP address association for Keeper and NAT-PT. The method of claim 1, When the external sender terminal located in the second network attempts to make a call from the outside to the inside, because the receiver telephone number is present in the payload of the signaling message, the gatekeeper finds a first address corresponding to the receiver telephone number and sends it to the NAT-PT router. Gatekeeper and a different IP address interworking method for NAT-PT interworking, characterized in that for transmitting. The method of claim 1, The first network and the first address information is an IPv6 network and an IPv6 address, and the second network and the second address information are IPv4 network and IPv4 address, characterized in that different IP addresses for NAT-PT interworking with the gatekeeper Interlock method.