CN1457187A

CN1457187A - IP calling method through network address switching facilities

Info

Publication number: CN1457187A
Application number: CN 02118997
Authority: CN
Inventors: 冒晓鸣
Original assignee: BEIJING AINITONG SCI-TECH Co Ltd
Current assignee: BEIJING AINITONG SCI-TECH Co Ltd
Priority date: 2002-05-10
Filing date: 2002-05-10
Publication date: 2003-11-19

Abstract

A network address transform map of an internal network sharing an IP address is built in a user server. Users in the internal network sharing same IP address through the network address transfrom (NAT) device registers on the user sever and build the signaling channel and voice channel connection. When a call handling server receives a corresponding call signaling, the shared IP address of the user in the internal network is obtained from the user server. Moreover, in the call signaling, the IP address replaces the address of the user in the internal network. In the invention the device inside NAT and the device outside NAT through the technique of 'preempting channel' solves the issue that IP phone is available only in one way or unavailable in both way.

Description

IP phone sees through the implementation method of network address translation apparatus

Technical field

The invention belongs to a kind of implementation method of IP phone, particularly IP phone implementation method through network address translation (nat) equipment.

Background technology

IP phone is to utilize IP network to finish the system of voice call, and as shown in Figure 1, wherein: GW is gateway (Gateway), and it finishes communication network to the voice of IP network and the conversion of signaling.Along with the development of IP phone, at present the agreement of the main IP phone of using have H.323, MGCP and SIP, the voice signaling that these three kinds of agreements can be finished on the IP network is handled.H.323 protocol application is comparatively extensive, and the Session Initiation Protocol development is very fast.The voice of IP network transmit and adopt the RTP/RTCP agreement, and this agreement is based on the agreement of UDP.

In present networking, ubiquity network address translation (Network AddressTranslation; NAT) equipment, NAT mainly contain two purposes: a purpose is to solve the not enough problem in IP address; A purpose is the shielding internal network structure.NAT generally is used between enterprises and the Internet.

The realization principle of NAT: when message passes NAT and enters public network by private network, the private net address of message is converted to the public network address that NAT has, but because the public network address that NAT has is also very limited, so present NAT device mostly adopts the mode of substitute I P address and port, as shown in Figure 2, the message that internal network sends from 10.0.0.2 is converted into the message of public network address 192.69.1.1, port numbers is 5001, the message that internal network sends from 10.0.0.3 is converted into the message of public network address 192.69.1.1, port numbers is 5002, so just can finish the mapping of a lot of internal networks to external network simultaneously.When NAT device receives that the message that mails to 192.69.1.1 and port numbers are 5002, then this message is sent to the 10.0.0.3 of internal network.So just reached the purpose of internal network and the free communication of external network.

But when using IP telephony system, the internal network user can run into following point: when the internal network user when the user to public network makes a call, single-pass can appear; When the user of public network made a call to the user who is arranged in internal network, conversation can't be set up.The reason here is because the signaling in the IP phone is separated with speech processes, at first set up signalling path before the conversation, when the internal network user sets up the signalling path request to public network user, can normally set up, but the voice port that carries in the signaling is the IP address of internal network, directly voice are sent to the IP address of internal network when public network user, message can't correctly send arrival, so just produced the sound that the internal network user can't hear public network user, but public network user can hear internal network user's sound.Initiate to set up the signalling path request when public network user to the inner network user, because destination address is the IP address of internal network, sets up channel request and just can't finish, calling can't be set up.

At this problem two kinds of solutions are arranged at present:

1:ALG (Application Layer Gateway): be called ALG by the method that on NAT device, increases extra IP phone signaling processing module, its principle is that NAT device detects the message of receiving, when being found to be the signaling message of IP phone, directly revise the content in the message, the address of internal network is replaced to the appropriate address of public network.

2:NCB (NAT Control Bridge): be called NCB by increasing the mode that an extra equipment controls NAT device, its principle is for increasing an equipment, on when needing to initiate IP phone and calling out, notify entire equipment earlier, entire equipment reinforms the mapping relations that NAT sets up corresponding inner voice and public network voice then, and mapping relations are set up the back just can finish normal talking.

Two kinds of above-mentioned methods all need increase extra equipment or function at NAT, and most at present equipment does not possess two above-mentioned functions, need change network configuration like this when reality is used, therefore, its workload is big, cost is high, and can't realize under many circumstances.

Summary of the invention

The objective of the invention is to provides means easily to the user, makes only by terminal equipment is carried out corresponding modification, just can make internal network user and public network user can use I P phone freely, and not need to increase any network equipment.

Implementation method of the present invention comprises the steps:

In client server, set up the internal network user's of share I P address network address translation mapping table; The internal network of share I P address is registered in client server by address-translating device, and sets up signalling path and voice and lead to and connect; When call processing server is received the corresponding call signaling, from client server, obtain IP address and port numbers that the internal network user shares, and replace former internal network station address in call signaling with this IP address.

According to according to such scheme: can dynamically revise the network address translation mapping table in the client server by the interface that hypervisor provides; The network address translation mapping table is the one-to-one relationship table between user's IP address and the port numbers in shared IP address and port numbers and the network; When maybe needing to call out in startup, registers in client server by address-translating device constantly internal network; Described signalling path is two transmission control protocol (TCP) passages and two User Datagram Protoco (UDP) (UDP) passage.

The present invention carries out a spot of modification by client server, call processing server and the PC software in IP phone, makes under situation about NAT device not being made any change, and internal network user and public network user can normally use all business of IP phone.Therefore, the present invention has easy realization and change, and cost of investment is extremely low.

Description of drawingsFig. 1 is the basic networking diagram of IP phone; Fig. 2 is connected to the schematic diagram of Internet by NAT device for the network user; Fig. 3 is the NAT fundamental diagram; Fig. 4 realizes the schematic diagram of technical solution of the present invention for the NAT networking mode; Fig. 5 is the technical scheme schematic diagram that IP phone sees through NAT in environment H.323;

Embodiment

PC to Phone, Phone to PC, PC to PC, Phone to Phone are arranged in IP phone, PC to Phone and Phone to PC typical case comparatively wherein, it is that example describes that present embodiment carries out the IP phone session with the Phone user of the pc user of internal network and public network.

H.323, all corresponding corresponding apparatus of each agreement of SIP, MGCP PC to Phone in the IP phone and the applied environment of Phone to PC are also different according to the different equipment that adopt of agreement that adopt.But their structure that possesses is an all fours, and these equipment can be simplified to two equipment: client server and call processing server, client server are finished user's registration and relevant management, and call processing server is finished the user's voice signaling process.

As shown in Figure 3: set up a TCP passage between elder generation and the client server after the PC of internal network starts, authenticate, authentication connects by TCP of rear line server initiation and is connected with two UDP, and the TCP connection is used to transmit signaling, represents with SIG among the figure; UDP connects and is used to produce voice, represents with RTP and RTCP among the figure.After call processing server is received the corresponding call signaling, just obtain the IP address that SIG, RTP, RTCP share from client server, with the address that replaces filling in originally, will make that like this address of using in all session signaling all is the address of public network, no matter make a call or receipt of call, can converse freely.

Because NAT possesses the map addresses function, after it received SIG, RTP, RTCP message, it can be forwarded on the PC of correct internal network.So just do not need NAT device to make any change, only need on client server, call processing server and the PC software of IP phone, carry out above-mentioned modification and get final product.

Fig. 4 is an example with the H.323 agreement of IP phone, introduces the specific implementation of the present invention under protocol environment H.323.

In agreement H.323, client server and call processing server are an equipment: gatekeeper, after PC starts, register to the gatekeeper, after succeeding in registration, set up a TCP passage and two UDP passages, the TCP passage is used to produce H.225 signaling, the UDP passage is used to transmit RTP and RTCP message, when the telephone subscriber made a call, gateway was initiated signaling to the gatekeeper and is called out, and the gatekeeper sends the setup requests signaling according to the H.225 signalling path of setting up in advance to PC, destination address is the public network address that NAT goes up registration, and NAT device is finished public network and transmitted to address transition and the message of the PC of internal network; After the PC call accepted, the public network address that the RTP of gatekeeper's notification gateway PC and RTCP register on NAT, gateway just sends to RTP and RTCP message on the NAT device then, and NAT device is finished public network and is transmitted to address transition and the message of the PC of internal network.PC and telephone subscriber just can converse freely like this.

The solution of PC to PC and Phone to Phone is identical with Phone to PC principle with PC to Phone.

The present invention is by taking earlier signaling and voice channel in advance between terminal and client server before calling out initiation, when call processing server is received the IP phone signaling, original channel information is rewritten as takies passage in advance, make internal network user and public network user can normally use all business of IP phone.

Claims

1, a kind of IP phone sees through the implementation method of network address translation apparatus, it is characterized in that comprising the steps:

In client server, set up the internal network user's of share I P address network address translation mapping table;

The internal network user of share I P address registers in client server by address-translating device, and sets up signalling path and be connected with voice channel;

When call processing server is received the corresponding call signaling, from client server, obtain the IP address that the internal network user shares, and replace internal network station address in call signaling with this IP address.

2, implementation method according to claim 1 is characterized in that: can dynamically revise the network address translation mapping table in the client server by the interface that hypervisor provides.

3, implementation method according to claim 1 and 2 is characterized in that: the network address translation mapping table is the one-to-one relationship table between user's IP address and the port numbers in shared IP address and port numbers and the network.

4, implementation method according to claim 1 is characterized in that: when the internal network user registers in client server by address-translating device when startup maybe needs to call out.

5, implementation method according to claim 1 is characterized in that: call processing server is by finishing the IP phone intercommunication of network address translation apparatus internal user and external user with the information interaction of client server.

6, implementation method according to claim 1, further comprise when it is characterized in that registering: set up (TCP) passage between internal network user elder generation and the client server, and authenticate through this passage, authentication by after send a transmission control protocol (TCP) passage connection request and two User Datagram Protoco (UDP) (UDP) passage connection request to client server again.

7, implementation method according to claim 1 is characterized in that: described signalling path is two transmission control protocol (TCP) passages and two (UDP) passages.