CN101188582A

Movatterモバイル変換

Info

Publication number: CN101188582A
Application number: CNA2006101458012A
Authority: CN
Inventors: 田东旭; 王�忠; 张大勇
Original assignee: ZTE Corp
Current assignee: ZTE Corp
Priority date: 2006-11-17
Filing date: 2006-11-17
Publication date: 2008-05-28
Anticipated expiration: 2026-11-17
Also published as: CN101188582B

Abstract

The invention discloses a terminal device based on H.323 in an IPv6 network, and a system and a method among the terminal devices based on the H.323 and positioned in an IPv4 network and outside the device. The invention relates to the network communication field, and is proposed to solve the multimedia communication among the H.323 based terminal devices in a heterogeneous network. In the condition of not changing the original IPv4 device and network deployment, the problem of H.323 terminal communication in the heterogeneous network can be well solved only by adding an NAT-PT proxy device and an H.323 proxy device in the IPv6 network. In the invention, the H.323 proxy plays the function of communication transfer, and simultaneously, a static mapping of the H.323 proxy device is required to be provided on the NAT-PT, in order to map the v6 address to be a global unique v4 address. The invention is suitable for the media communication of the heterogeneous network.

Description

System and method for H.323 terminal communication through heterogeneous network

Technical Field

The invention relates to the field of network communication, in particular to a method for carrying out multimedia communication between an IPv6 network and an IPv4 network by an H.323 terminal.

Background

In recent years, VoIP has attracted more and more interest, and many organizations are dedicated to research and develop the standards for real-time calls over IP networks, wherein the h.323 standard was established by the ITU-T organization in 1996 on the basis of h.320/h.324, and the application goal is to realize reliable real-time application facing audio and video and data in an IP-based network environment. At present, through technical development and continuous improvement of standards for many years, h.323 becomes a mature standard group accepted by vast ITU members and clients, and products based on h.323 can realize reliable intercommunication, and also realize reliable intercommunication with multimedia communication networks based on h.320 and h.324. With the gradual maturity of h.323, more and more manufacturers compete to invest in the development of new h.323 products, more and more users adopt h.323 technology and products to construct their own video conference systems, and most multimedia communication services adopt the h.323 protocol especially in china.

However, with the rapid development of the Internet, the IPv4(Internet Protocol version 4) address space is becoming increasingly scarce, and a new Internet Protocol is urgently needed to replace the IPv6(Internet Protocol version 6) address space. Compared with the IPv4 protocol, IPv6 has a series of advanced features, such as sufficient address space, automatic configuration, improved mobility and security, which make it increasingly attractive, and IPv6 has entered a substantial construction stage. However, in view of the operation cost and the urgency of demand, the deployment of the IPv6 network is a gradual process, and inevitably coexists with the existing IPv4 network for a long period of time, and finally replaces the IPv 4.

The H.323 protocol is irrelevant to an IP layer and is suitable for an IPv4 network and an IPv6 network, but when connection is established, the address and the port number established by the connection need to be specified in a payload, pure NAT-PT (network address translation and protocol translation) can translate the IPv4 and the IPv6 addresses, but the H.323 data can not be subjected to the conversion, and normal communication can not be carried out between H.323 terminals traversing heterogeneous networks by only relying on NAT-PT equipment.

In order to enable the h.323 terminals passing through the heterogeneous network to normally communicate through the firewall, a general method may use a method of an h.323 application Layer gateway ALG (application Layer gateway) and change the firewall device to enable the firewall device to support the ALG, but this method aggravates the processing task of the firewall due to the analysis of the packet load, affects the operation of the network, and becomes a potential network bottleneck; meanwhile, if there are multiple layers of firewalls and NAT-PT, each firewall in the call path must be upgraded to support ALG functionality, requiring changes to existing network devices.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a system and a method for carrying out H.323 terminal communication by traversing heterogeneous networks, which can carry out multimedia communication between the H.323 terminal in an IPv6 network and the H.323 terminal in an IPv4 network.

In order to solve the technical problem, the method for carrying out H.323 terminal communication by traversing a heterogeneous network in the technical scheme comprises the following steps:

(1) adding an intermediate conversion proxy device in the IPv6 network;

(2) the H.323 terminal in the IPv6 network and the H.323 terminal in the IPv4 network are connected with each other through the intermediate conversion proxy equipment and perform multimedia communication. Wherein,

the step (1) is specifically as follows:

(11) adding network address translation and protocol translation equipment and proxy equipment in the IPv6 network;

(12) the network address translation and protocol translation device does a static mapping between the v6 address and the v4 address of the proxy device.

The step (2) is specifically as follows:

(21) h.323 terminals in the IPv6 network are registered on the proxy equipment;

(22) the proxy equipment replaces an H.323 terminal in an IPv6 network to register on a gatekeeper of the IPv4 network;

(23) h.323 terminals in IPv6 network and H.323 terminals in IPv4 network, through the said proxy device, establish connection and carry on multimedia communication each other. Wherein,

the step (21) is specifically as follows:

(211) and H.323 terminals in the IPv6 network change the setting of the proxy equipment and register the proxy equipment.

The step (22) is specifically as follows:

(221) after the agent equipment converts the source address in the received gatekeeper request message sent by the H.323 terminal in the IPv6 network, the agent equipment forwards the message to the gatekeeper in the IPv4 network through network address conversion and protocol conversion equipment;

(222) after receiving a gatekeeper confirmation message sent by a gatekeeper through network address translation and protocol translation equipment, the proxy equipment translates a source address in the message and forwards the translated source address to an H.323 terminal in an IPv6 network;

(223) the agent equipment receives a registration request message sent by an H.323 terminal in an IPv6 network, converts a source address in the message, and forwards the message to a gatekeeper in the IPv4 network through network address conversion and protocol conversion equipment;

(224) after receiving the registration confirmation message responded by the gatekeeper in the IPv4 network, the proxy equipment converts the source address in the message and forwards the converted source address to the H.323 terminal in the IPv6 network; if the gatekeeper responds to the registration rejection message, the agent directly forwards the message.

The step (23) is specifically as follows:

(2301A) The proxy equipment receives admission request information of an H.323 terminal in an IPv6 network calling an H.323 terminal in an IPv4 network, modifies a source address in the information and forwards the information to a gatekeeper in an IPv4 network;

(2302A) H.323 terminal in IPv6 network, after receiving the admission acknowledgement message that the gatekeeper in IPv4 network forwarded through the proxy equipment, send and establish the connection message to the proxy equipment, after the proxy equipment receives the establishment connection message, initiate the call to H.323 terminal in IPv4 network after modifying the address in the message;

(2303A) H.323 terminal in IPv4 network responds to the call, the proxy equipment receives the call and forwards the call to H.323 terminal in IPv6 network;

(2304A) After receiving the call sent by the proxy equipment, the H.323 terminal in the IPv4 network sends an admission request message to a gatekeeper in the network, and the gatekeeper sends an admission confirmation message back to the H.323 terminal in the IPv4 network;

(2305A) H.323 terminal station in IPv4 network, send the linkage message to the proxy equipment, after the proxy equipment receives, modify the address in the message and transmit to H.323 terminal station in IPv6 network;

(2306A) H.323 terminals in IPv6 network establish connection to agent equipment, the agent equipment establishes H.245 connection to H.323 terminals in IPv4 network, and master-slave decision and capability negotiation of H.245 are carried out;

(2307A) H.323 terminal station in IPv6 network sends the open logic channel message to the agent equipment, after the agent equipment receives, revise the address in the message, transmit to H.323 terminal station in IPv4 network through network address translation and protocol translation equipment;

(2308A) H.323 terminal in IPv4 network responds to the answer of open logical channel, the channel address is T2IPv4 address, after the agent equipment receives, revise the address in the message, and transmit to H.323 terminal in IPv6 network;

(2309A) The H.323 terminal in the IPv4 network also repeats the steps (2307A) and (2308A) to the H.323 terminal in the IPv6 network;

(2310A) Media channels are established between the H.323 terminal in the IPv6 network and the proxy equipment, and between the proxy equipment and the H.323 terminal in the IPv4 network, and media stream transmission is carried out.

The step (23) further specifically includes:

(2301B) An H.323 terminal in the IPv4 network initiates an admission request to a gatekeeper in the network, calls the H.323 terminal in the IPv6 network, and the gatekeeper responds;

(2302B) H.323 terminal station in IPv4 network sends and sets up the message of connecting to the proxy equipment, the proxy equipment modifies the address in the message, initiate the call to H.323 terminal station in IPv6 network;

(2303B) After receiving the call response of the H.323 terminal in the IPv6 network, the proxy equipment forwards the call response to the H.323 terminal in the IPv4 network;

(2304B) The H.323 terminal in IPv6 network sends the admission request to the agent equipment, the agent equipment receives and forwards to the gatekeeper in IPv4 network, the gatekeeper responds to the admission acknowledgement message and forwards to the H.323 terminal in IPv6 network through the agent equipment;

(2305B) H.323 terminal station in IPv6 network sends the connection message to the proxy equipment, the proxy equipment modifies the address in the message, transmit to H.323 terminal station in IPv4 network;

(2306B) H.245 channels are respectively established between the agent equipment and the H.323 terminal in the IPv6 network, and master-slave decision and capability negotiation are carried out between the H.323 terminal in the IPv6 network and the H.323 terminal in the IPv4 network through the agent equipment;

(2307B) H.323 terminal station in IPv6 network sends the open logic channel message to the agent equipment, the agent equipment revises the address in the message, transmit to H.323 terminal station in IPv4 network through network address translation and protocol translation equipment;

(2308B) H.323 terminal in IPv4 network responds to open logical channel and responds, after the agent equipment receives, modify the address in the message, transmit to H.323 terminal in IPv6 network;

(2309B) The H.323 terminal in the IPv4 network also repeats the steps (2307B) and (2308B) to the H.323 terminal in the IPv6 network;

(2310B) Media channels are established between the H.323 terminal in the IPv6 network and the proxy equipment, and between the proxy equipment and the H.323 terminal in the IPv4 network, and media stream transmission is carried out.

Replacing the h.323 terminal in the IPv4 network in the step (23) with the multimedia conference unit that receives the conference opening notification of the operating system and obtains the conference terminal list, so that the h.323 terminal in the IPv6 network can be called point-to-multipoint by using the multimedia conference unit.

A system for H.323 terminal communication through heterogeneous network includes IPv6 network and IPv4 network based on H.323 terminal, in which,

an intermediate conversion proxy device is arranged in the IPv6 network;

the H.323 terminal in the IPv6 network is connected with the H.323 terminal in the IPv4 network through the intermediate conversion proxy equipment;

the H.323 terminal in IPv6 network and the H.323 terminal in IPv4 network initiate calling information mutually through the intermediate conversion proxy equipment, establish connection and carry out multimedia communication.

The intermediate conversion proxy equipment comprises network address conversion and protocol conversion equipment and proxy equipment;

the proxy equipment is arranged between the network address translation and protocol translation equipment and the H.323 terminal equipment; the IPv6 network and the IPv4 network are interconnected through the network address translation and protocol translation device;

through the proxy device, the H.323 terminal in the IPv6 network passes through the network address translation and protocol translation device, establishes connection with the H.323 terminal in the IPv4 network and carries out media stream transmission.

Compared with the prior art, the invention can well solve the problem that the H.323 terminal in the heterogeneous network directly carries out multimedia communication by only adding the network address translation and protocol translation equipment and the proxy equipment in the IPv6 network under the condition of not changing the original IPv4 equipment and network deployment by adopting the mode of proxy + network address translation and protocol translation equipment.

Drawings

Fig. 1 is a schematic diagram of communication between an h.323 terminal and an external IPv4h.323 terminal in an IPv6 network.

Fig. 2 is a schematic diagram of communication between an IPv6H.323 terminal device and an H.323 terminal in a peer-end IPv6 network.

Fig. 3 is a RAS registration flowchart of the ipv6h.323 terminal device.

Fig. 4 is a flow chart of h.323 terminal in IPv6 network calling h.323 terminal in v4 network.

Fig. 5 is a flow chart of h.323 terminal in IPv4 network calling h.323 terminal in v6 network.

FIG. 6 is a flow chart of an H.323 terminal in an IPv6 network for point-to-multipoint calling by MCU in the IPv4 network.

Detailed Description

The following describes the embodiments in further detail with reference to the accompanying drawings.

The core idea of the invention is as follows: an H.323 proxy is added in an IPv6 network, the H.323 proxy is a functional entity technology for realizing the traversing of multimedia services such as voice, video and the like through a v4/v6 network by adopting a signaling proxy and a media proxy mode, an H.323 proxy server has a globally unique IPv4 address mapped by NAT-PT equipment, the H.323 proxy forwards all H.323 flows to the NAT-PT for processing, and from the perspective of a user, the H.323 proxy server is transparent to the user, equipment and the network, and the specific working steps mainly comprise:

in the first step, the NAT-PT device performs static mapping between the v6 address and the v4 address of the H.323 proxy.

In the second step, for the terminal in the IPv6 network, the h.323 proxy can be regarded as a gatekeeper, and the terminal only needs to change the setting of the gatekeeper and register the change on the h.323 proxy server.

And thirdly, the H.323 proxy server is registered on the gatekeeper in the IPv4 network instead of the terminal, and the registration information displayed on the gatekeeper is the IPv4 address and the port mapped by the H.323 proxy server because the conversion from the IPv6 address to the v4 address is intelligently solved.

Fourthly, the terminal in the IPv6 network completely passes through the firewall equipment between NAT-PT or v4/v6 through the H.323 proxy server, and establishes connection with other equipment (such as a gatekeeper, a proxy, a terminal or a multipoint control unit and the like) in the IPv4 network, so that the voice and video communication is ensured to be smooth.

It needs to be proposed here that for h.323 terminals in IPv4 public network, no h.323 proxy device needs to be added in IPv4 network, and their registration process is still directly registered with gatekeeper device in IPv4 network. H.323 terminal RAS registration flow in IPv6 network

An h.323 terminal RAS (registration, admission, status) registration process in an IPv6 network is shown in fig. 3, which includes an address translation process for all signaling messages that may be used in the h.323 terminal RAS registration process, instead of a specific complete registration process. All addresses depicted in this figure are addresses in the message payload of the RAS registration process, not IP layer addresses. The flow of each step is briefly described as follows:

firstly, a proxy receives a gatekeeper request GRQ (gatekeeper request) message sent by H.323 terminal equipment T1 in an IPv6 network, modifies a T1IPv6 address in the message into an IPv4 address statically mapped in NAT-PT by the proxy equipment, and then forwards the message to a gatekeeper in an IPv4 network through the NAT-PT equipment.

And secondly, the gatekeeper sends a gatekeeper confirmation message GCF (gatekeeper confirmation) to the H.323 proxy mapping v4 address, the address is converted by NAT-PT and then reaches the H.323 proxy, the proxy equipment converts the source address in the message load, namely the gatekeeper IPv4 address, into the IPv6 address of the proxy after receiving the message, and forwards the address to the T1, and if the gatekeeper responds to a gatekeeper rejection message GRJ (gatekeeper reject), the address format is not required to be modified, and the address is directly forwarded to the T1 terminal equipment.

And thirdly, the agent receives a registration request message RRQ (registration request) sent by the T1, converts a source address in the message from a T1IPv6 address into an IPv4 address statically mapped by the agent, and then forwards the message to a gatekeeper in the IPv4 network through NAT-PT equipment.

Fourthly, the gatekeeper responds to a registration confirmation RCF (registration configuration) message to the H.323 proxy equipment, and after the proxy receives the message, the proxy converts the source address from the gatekeeper IPv4 address into the IPv6 address of the proxy and forwards the address to the H.323 terminal T1; if the gatekeeper responds to the RRJ (registration reject) message, the agent forwards the message directly without any modification.

Fifthly, the agent receives the ARQ (automatic repeat request) message of T1, modifies the T1IPv6 address in the message into the IPv4 address mapped by the agent, and forwards the modified message to the gatekeeper.

Sixthly, the gatekeeper responds to an ACF (admission control) message, the proxy modifies the called terminal address in the message into a proxy IPv6 address and forwards the proxy IPv6 address to the T1; if the gatekeeper responds with an ARJ (advertisement) message, the proxy forwards directly.

Seventhly, the agent receives the IRQ (information request) message of the gatekeeper, modifies the IPv4 address of the gatekeeper in the message into the IPv6 address of the agent, and forwards the IPv6 address to the T1.

And step eight, the agent receives an IRR (information request response) message of the terminal T1, modifies the T1IPv6 address in the message into an IPv4 mapping address corresponding to the agent, and forwards the address to the gatekeeper.

Ninth, the agent receives the brq (bandwidth change request) message from T1 and forwards the brq (bandwidth change request) message to the gatekeeper.

Tenth, the agent receives BCF/BRJ (bandwidth change confirmation/bandwidth change) message returned by the gatekeeper and forwards the message directly to T1.

Step ten, the agent receives the DRQ (discovery request) message of T1, and directly forwards the message to the gatekeeper through NAT-PT.

In the twelfth step, the agent receives the DCF/DRJ (disconnect configuration/disconnect request) message of the gatekeeper and directly forwards the message to T1.

Step thirteen, the agent receives DRQ message of gatekeeper and forwards it to T1

And step fourteen, the agent receives DCF message of T1 and forwards the message to the gatekeeper.

Fifteenth step, the agent receives URQ (unregister request) message of T1, modifies the source address in the message from IPv6 address of T1 to proxy mapping IPv4 address, and forwards the message to the gatekeeper through NAT-PT.

Sixthly, the agent receives the UCF/URJ (unregister configuration/unregister object) message of the gatekeeper and forwards the message to T1.

Seventhly, the agent receives URQ message of the gate keeper, modifies the source address in the message from IPv4 address of the gate keeper to IPv6 address of the agent itself, and forwards the message to T1.

Eighteenth step, the proxy receives the UCF message of T1, and forwards the UCF message to the gatekeeper through the NAT-PT device. Initiating a call from an H.323 terminal in an IPv6 network to a terminal in an IPv4 network

Referring to fig. 1, an h.323 terminal in an IPv6 network initiates a call to a terminal in an IPv4 network. The process of h.323 terminal T1 in IPv6 network calling h.323 terminal T2 in IPv4 network is shown in fig. 4, where terminal T1 performs RAS registration to gatekeeper in IPv4 network through h.323 agent, and then initiates a call, the solid line in the figure is an initiating call message, the dotted line indicates a response message, and the specific call implementation process is as follows:

firstly, a calling terminal T1 initiates a call to a terminal T2 in an IPv4 network, sends an admission request ARQ to an H.323 proxy, the source address in the message is the IPv6 address of T1, and after the proxy receives the ARQ, the source address in the message load is modified into a mapping IPv4 address of the proxy and is forwarded to a gatekeeper.

And secondly, the gatekeeper responds to the proxy to accept and confirm the ACF message, the message load carries the called terminal T2 address, and the proxy modifies the destination address field in the received ACF message load from the IPv4 address of T2 into a proxy IPv6 address and forwards the proxy IPv6 address to T1.

Thirdly, the T1 establishes connection with the agent, sends a setup message for establishing connection to the agent, the source address is a T1IPv6 address, the agent modifies the source address in the message load into an agent mapping IPv4 address after receiving the setup message, and initiates a call to the T2 according to the recorded call information.

Fourthly, T2 responds to calling process call proceeding, and the agent forwards the call to T1 after receiving the call proceeding.

In the fifth step, T2 sends ARQ message to gatekeeper after receiving the call from agent.

Sixthly, the gatekeeper sends an ACF message back to the T2, wherein the destination address field of the T1 in the message is the proxy IPv4 address.

Seventhly, after receiving the gatekeeper ACF message, the T2 sends a connection connect message to the H.323 proxy, wherein the H.245 address in the message is a proxy IPv4 address, and after receiving the connect message of the T2, the proxy modifies the H.245 address in the message into a proxy IPv6 address and then transfers the address to the T1.

And step eight, the T1 establishes connection to the agent, the agent establishes H.245 connection to the T2, and the master-slave decision and capability negotiation of the H.245 are carried out.

Ninthly, the T1 sends an OLC (h.24yopenlogical channel message) message to the proxy, the reverse control channel address is a T1IPv6 address, and after receiving the message, the proxy modifies the reverse control channel address into a proxy mapping IPv4 address and forwards the address to the T2 through NAT-PT.

Step ten, T2 responds to the OLCACK, the channel address is T2IPv4 address, after the agent receives it, the channel address is modified to agent IPv6 address, and it is transferred to T1.

Eleventh, T2 repeats the steps nine and ten to T1.

The twelfth step, media channels are established between the T1 and the agent, and between the agent and the T2, for media streaming. 3, H.323 terminal in IPv4 network initiates call to terminal in IPv6 network

Referring to fig. 1, an h.323 terminal in an IPv4 network initiates a call to a terminal in an IPv6 network. Fig. 5 shows a flow of an h.323 terminal T2 in an IPv4 network calling an h.323 terminal T1 in an IPv6 network, where the terminal T1 performs RAS registration with a gatekeeper in an IPv4 network through an h.323 agent, a solid line in the drawing is an originating call message, a dotted line indicates a response message, and a specific call implementation flow is as follows:

in the first step, T2 initiates ARQ, calling T1.

And secondly, the gatekeeper replies H.323 to map the IPv4 address by proxy.

And thirdly, the T2 establishes connection with the agent, a setup message is sent, the agent modifies the source address in the message load, takes the T2IPv4 address as the agent IPv6 address and forwards the address to the T1.

Fourth, T1 responds to callprocessing to the agent, and the agent forwards to T2.

In a fifth step, T1 sends a response ARQ to the proxy, which forwards it to the gatekeeper.

And sixthly, the agent receives the ACF responded by the gatekeeper and forwards the ACF to T1.

Seventhly, the T1 sends a connect message to the proxy, wherein the H.245 address in the message is the IPv6 address of the T1, and the proxy modifies the address into the IPv4 address mapped by the proxy NAT and forwards the address to the T2.

And eighthly, H.245 channels are respectively established between the T2 and the agent, between the agent and the T1, and master-slave decision and capability negotiation are carried out between the T1 and the T2 through the agent.

And step nine, the T1 sends OLC information to the agent, the reverse control channel address is T1IPv6 address, after the agent receives the information, the reverse control channel address is modified into the agent mapping IPv4 address, and the information is transferred to the T2 through NAT-PT.

Step ten, T2 responds to OLCACK, the channel address is T2IPv4 address, after the proxy receives the address, the channel address is modified to proxy IPv6 address, and the address is transferred to T1.

Eleventh, T2 repeats the steps nine and ten to T1.

The twelfth step, media channels are established between the T1 and the agent, and between the agent and the T2, for media streaming. H.323 terminal in MCU mode point-to-multipoint calling IPv6 network

The flow of calling h.323 terminal T1 in IPv6 network by MCU (multimedia conference unit) in IPv4 network is as shown in fig. 6, where terminal T1 performs RAS registration to gatekeeper in IPv4 network through h.323 proxy, and first MCU receives notification of conference opening from operating system, obtains list of terminals in conference, and calls terminals in conference respectively, and this process is the same for h.323 proxy and T1 terminals in IPv6 network as for terminals in v4 network calling terminals in v6 network.

The invention uses NAT-PT + H.323 agency equipment mode, to make the H.323 equipment in IPv6 island network communicate with H.323 entity in IPv4 backbone network and H.323 equipment in opposite end IPv6 island.

It should be noted that, several specific embodiments of the present invention are only a few examples of the present invention, and multimedia communications (see fig. 2) between h.323 terminals in the same IPv6 network, between h.323 terminals between an IPv6 network and another IPv6 network (intermediate spanning an IPv4 backbone network), etc. may be implemented by using NAT-PT + h.323 proxy devices, and the specific procedures are largely the same and different, and are not described herein again. In short, the present invention shall be covered by the scope of protection of the present invention, wherein the present invention is applied to the multimedia communication between h.323 terminals.

Claims

1. A method for H.323 terminal communication through heterogeneous network is characterized by comprising the following steps:

(1) adding an intermediate conversion proxy device in the IPv6 network;

(2) the H.323 terminal in the IPv6 network and the H.323 terminal in the IPv4 network are connected with each other through the intermediate conversion proxy equipment and perform multimedia communication.

2. The method for h.323 terminal communication across a heterogeneous network according to claim 1, wherein the step (1) specifically comprises:

3. The method for h.323 terminal communication across a heterogeneous network according to claim 1 or 2, wherein the step (2) specifically comprises:

(21) h.323 terminals in the IPv6 network are registered on the proxy equipment;

(23) h.323 terminals in IPv6 network and H.323 terminals in IPv4 network, through the said proxy device, establish connection and carry on multimedia communication each other.

4. The method for h.323 terminal communication across a heterogeneous network according to claim 3, wherein the step (21) specifically comprises:

5. The method for h.323 terminal communication across a heterogeneous network according to claim 3, wherein the step (22) specifically comprises:

6. The method for h.323 terminal communication across a heterogeneous network according to claim 3, wherein the step (23) specifically comprises:

(2308A) H.323 terminal station in IPv4 network responds to the answer of open logical channel, the channel address is T2IPv4 address, after the agent equipment receives, revise the address in the message, and transmit to H.323 terminal station in IPv6 network;

7. The method for h.323 terminal communication across a heterogeneous network according to claim 3, wherein the step (23) specifically comprises:

8. The method of claim 7, wherein the method comprises the following steps: the H.323 terminal in the IPv4 network is replaced by the multimedia conference unit which receives the conference notice of the operating system and obtains the conference terminal list.

9. A system for carrying out H.323 terminal communication through heterogeneous network includes IPv6 network and IPv4 network based on H.323 terminal, characterized by that:

an intermediate conversion proxy device is arranged in the IPv6 network;

10. The system according to claim 9, wherein the system is configured to communicate with h.323 terminals via a heterogeneous network, and further configured to: