KR20030021511A - Method and server for RTP channel - Google Patents

Abstract

PURPOSE: A method for setting an RTP(Real-time Transport Protocol) channel is provided to set the RTP channel between clients who belong in various network environment. CONSTITUTION: An RTP channel setup module transmits an NPBP(NAT(Network Address Translation) Port Binding Packet) to an NAT server(20)(31). The NAT server(20) transmits the NPBP to an object client(32). The object client transmits an RTP packet to a source IP address recorded in the received NPBP and a port(33). The NAT server(20) transmits the received RTP packet to a client(3)(34). An RTP channel is set up between the client(3) and the object client.

Description

How to set up RTP channel {Method and server for RTP channel}

The present invention relates to RTP channel establishment, and more particularly, to an RTP channel establishment method for establishing an RTP channel in a NAT / firewall environment.

As the Internet spreads rapidly, security problems are on the rise. Increasingly, companies are setting up firewalls to block outsiders from accessing private resources and to control external resources for their employees to access.

On the other hand, many schools, businesses, etc., use NAT (Network Address Translation) servers internally to use private IP addresses. By adopting NAT, a large number of clients can access the Internet even with a limited public IP address, and it is very advantageous to solve the security problem because I / O packets must pass through a NAT server for address translation. Thus, a NAT server may be installed as part of a router or firewall.

However, as the network environment of the client is variously changed, that is, it is impossible to transmit or receive a packet according to a specific protocol by a firewall or the like, it is difficult to properly perform an application service based on a specific protocol. For example, voice communication, video communication, and the like are performed through a real-time transport protocol (RTP) channel, and the RTP channel is generally performed based on a user datagram protocol (UDP) protocol. However, clients connected to NAT servers or firewalls cannot receive UDP packets directly from outside. Therefore, an application program running on the client's computer cannot establish an RTP channel directly. In other words, according to the network environment of a client, a service provider cannot provide a service to a specific client, and the client cannot receive the service.

Accordingly, an object of the present invention is to provide a method for establishing an RTP channel in a NAT / firewall environment.

1 is a network configuration diagram in which the client 3 belongs to a NAT environment and the counterpart client 6 belongs to a public IP environment.

2 is a detailed block diagram of the client 3, 6 of FIG.

3 is a reference diagram for explaining a RTP channel setting method according to a first embodiment;

4 is a network diagram when the client 3 belongs to a public IP environment and the other client 6 belongs to a NAT / firewall environment.

5 is a block diagram of the channel setting server 1 of FIG.

6 is a reference diagram for explaining a method of setting up an RTP channel when a counterpart client 6 is connected to a NAT / firewall 40 according to a second embodiment;

7 is a reference diagram for explaining a method of setting up an RTP channel when the counterpart client 6 is connected to a normal NAT or a symmetric NAT according to the third embodiment;

8 is a reference diagram for explaining a method of setting up an RTP channel when a counterpart client 6 is connected to a firewall according to a fourth embodiment;

9 is a reference diagram for explaining a method of setting up an RTP channel when the counterpart client 6 is connected to a strict firewall according to the fifth embodiment;

10 is a network diagram when the client 3 and the counterpart client 6 belong to a NAT / firewall environment.

11 to 14 are reference diagrams for explaining a method for establishing an RTP channel according to a sixth embodiment of the present invention.

11 is a reference diagram for explaining a T-to-T scheme;

12 is a reference diagram for explaining a T-to-U method;

13 is a reference diagram for explaining a U-to-T scheme;

14 is a reference diagram for explaining a U-to-U method;

15 is a reference diagram for explaining a RTP channel setting method according to a seventh embodiment of the present invention;

16 is a network diagram when the client 7 belongs to a NAT / firewall environment and the counterpart client 14 belongs to an H.323 gateway environment.

17 is a reference diagram for explaining a method of establishing an RTP channel according to an eighth embodiment of the present invention;

18 is a reference diagram for explaining a RTP channel setting method according to a ninth embodiment of the present invention;

19 is a reference diagram for explaining a method of establishing an RTP channel according to a tenth embodiment of the present invention;

20 is a reference diagram for explaining a method of establishing an RTP channel according to an eleventh embodiment of the present invention.

The object of the present invention is to provide a connection between a client and a counterpart client in accordance with the present invention, and if a UDP channel can be established between the client and the counterpart client based on a network environment to which the client and the counterpart client belong, This is accomplished by the channel setup server, which allows a TCP channel to be established if the UDP channel is not configurable and the TCP channel is configurable.

The channel setting server may include a client database storing address information of the counterpart client; And receiving a port binding packet from the client and delivering the port binding packet to the counterpart client based on the address information.

In addition, the server connected to the client, the server, comprising a storage unit for storing the program code constituting the RTP channel setting module to be executed in the client, the RTP channel setting module is executed in the client connected to the NAT server to the NAT server It is also achieved by the server, characterized in that for transmitting the port binding packet with the address information for the other client attached to the NAT server to transmit the port binding packet from the other client.

In addition, in the server connected to be connected between the client and the counterpart client, if the UDP channel can be set between the client and the counterpart client based on the network environment to which the client and the counterpart client belong, respectively, the UDP channel is established. If the UDP channel is not set and the TCP channel is settable, the TCP channel is set so that the RTP packet is received by the client and delivered to the counterpart client.

In addition, the channel setting server connected to communicate with the client via the Internet, the RTP packet received from one client through the TCP channel to the TCP channel associated with the other client, or RTP received through the TCP channel from one client Forward the packet to the other client through the UDP channel, forward the RTP packet received from the one client through the UDP channel, or forward the RTP packet received from the one client through the UDP channel to the other client. It is also achieved by a channel setting server, characterized in that the transmission through the channel.

According to another aspect of the present invention, the above object is a method for establishing an RTP channel between a client and a counterpart client, and (a) receiving a port binding packet from the client and delivering the port binding packet to the counterpart client. It is also achieved by the RTP channel establishment method comprising the step of performing.

Here, the method may further include performing port binding by receiving another port binding packet from the counterpart client and delivering the port binding packet to the client.

In addition, in a method for establishing an RTP channel between a client and a counterpart client, (a) a UDP channel is established if a UDP channel can be established with the client or the counterpart client based on a network environment to which the client and the counterpart client belong. Making it possible; (b) allowing a TCP channel to be established if a UDP channel cannot be established with the client or the counterpart client and a TCP channel can be established; And (c) receiving the RTP packet transmitted from the client through the TCP channel or the UDP channel set through the steps (a) and (b) and forwarding the received RTP packet to the counterpart client. Is also achieved.

Step (c) preferably includes adding a header having identification information indicating the length and the combination order of the RTP packet to the RTP packet transmitted through the TCP channel.

In addition, the step (b) includes receiving a TCP connection request from the client of the other party and establishing a TCP channel, and the step (c) alternately receives an RTP packet from the client through the UDP channel to transmit a TCP channel. It is effective to include the step of delivering to the other client.

In addition, in a method of establishing an RTP channel between a client and a counterpart client, (a) both the client and the counterpart client are located inside a strict firewall that does not allow transmission and reception of RTP packets over a UDP channel, When the client is located inside a strict firewall that allows only TCP connections and does not allow UDP channels, the other client is located inside a normal firewall that does not allow the reception of UDP packets. It is also achieved by the RTP channel establishment method comprising the step of transmitting to the TCP channel with the counterpart client.

Here, the RTP channel setting method is (b) is located inside a strict firewall that allows the client to make only a TCP connection to the outside without allowing a UDP channel, and the counterpart client allows normal reception of UDP packets from the outside. When located inside a NAT or symmetric NAT, it is preferable to include transmitting the RTP packet received from the client via the TCP channel to the counterpart client via the UDP channel.

Also, (c) when the client is located inside a normal firewall and the counterpart client is located inside a strict firewall or a normal firewall, an RTP packet received from the client through a UDP channel is transferred to a TCP channel associated with the counterpart client. It is more preferred to include the step of delivering.

Further, (d) when the client is located inside a normal NAT or a symmetric NAT that allows a UDP channel and the counterpart client is located inside a symmetric NAT that allows the reception of RTP packets over a specific UDP channel, the client It is particularly desirable to include the step of forwarding the RTP packet received from the UDP channel via the UDP channel to the counterpart client.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The network environment to which the client belongs can be largely divided into NAT or firewall environment and public IP environment. The NAT environment is subdivided into normal NAT and symmetric NAT in this embodiment, and the firewall is subdivided into a normal firewall and a strict firewall. This is classified with an application service based on RTP communication in mind. In other words, the network environment is classified according to whether the client can directly send and receive UDP packets. Therefore, the network environment may be classified differently from the present embodiment according to the request characteristics of the application service for the communication environment.

On the other hand, the channel setting server according to the present invention, if the client and the counterpart client is in a NAT or firewall environment and the path for transmitting and receiving the RTP packet is set, if the RTP packet can be transmitted and received over the UDP channel, the routing is set. . If the RTP packet cannot be directly transmitted and received, the RTP packet is received and relayed.

1 is a network configuration diagram in which the client 3 belongs to a NAT environment and the counterpart client 6 belongs to a public IP environment.

Referring to FIG. 1, the client 3 is connected to the Internet via a NAT server 20. The counterpart client 6 is assigned a public IP address. The client 3 is a home computer user or a work computer of a school, a public institution, a company, or the like, assigned a private IP address. NAT server 20 is a normal NAT or a symmetric NAT.

<normal NAT>

Referring to FIG. 1, the client 3 is connected to a NAT server 20. Accordingly, in order for the client 3 to send a packet to the counterpart client 6 having a public IP address, the public IP address of the NAT server 20 and the source address and source port to be attached to the packet are passed through the NAT server 20. It should be changed to the port of NAT server 20. The NAT server 20 arbitrarily determines the port to be changed. When the client 3 sends the packet to the counterpart client 6, the NAT server 20 sets the source address of the packet as "the private IP address of the client 3: the local port of the client 3" to the "NAT server 20". IP address: local port of NAT server 20 ”. Therefore, if the IP addresses of the client 3 and the NAT server 20 are 192.168.10.2 and 210.108.147.53, respectively, and a packet is sent from the local port 10000 of the client 3 to the local port 20000 of the other client 6, it is attached. The source address is replaced by 210.108.147.53: 60000 from 192.168.10.2:10000. 60000 indicates a local port of the NAT server 20. At this time, 192.168.10.2:10000 and 210.108.147.53:60000 are said to be "NAT port binding". The packet used for this purpose is called "Port Binding Packet NAT Port Binding Packet, NPBP", and 210.108.147.53:60000 is called "Port Binding Address". Subsequently, all packets sent out from 192.168.10.2:10000 are bound to local port 60000 of NAT server 20, so packets sent from other client 6 to local port 60000 of NAT server 20 are forwarded to client (3). Is sent to local port 10000).

<symmetric NAT>

Referring to FIG. 1, when the client 3 sends a port binding packet to the counterpart client 6, in the normal NAT, only the client 3 and the NAT server 20 are bound in "NAT port binding". In NAT, the other client 6 is bound. That is, in the above example, if the IP address of the counterpart client 6 is 208.185.147.100 and the local port 20000 is used, up to 208.185.147.100:20000 is bound. At this time, there are two port binding addresses, 210.108.147.53:60000 of the NAT server 20 and 208.185.147.100:20000 of the counterpart client 6.

In summary, NAT port bindings in normal NAT are all bound to the same local port of NAT server 20, even if the destination addresses are different, and in the case of symmetric NAT, different ports of NAT server 20 are assigned to different destinations. Is bound.

FIG. 2 is a detailed block diagram of the clients 3, 6 of FIG.

Referring to FIG. 2, the clients 3 and 6 may include a processor 31 such as a Pentium, a memory 33, a storage unit 34 implemented as a hard disk, a flash memory, an input device 35 such as a keyboard, a mouse, and the like. And an internet connection 32 for internet access.

The memory 33 is equipped with an operating system 30, an application program, and an RTP channel setting module 4. In particular, the operating system 30 manages the RTP channel setting module 4 or an application program by being loaded and executed for the first time in the memory 33. In this embodiment, the application program is a program executed in the client 3 for a service performed based on the RTP channel. An example of an application is a program for a user to receive an Internet phone service. The RTP channel setting module 4 is also a kind of application program for performing the RTP channel setting method according to the present invention by being installed and executed in the client 3. However, the RTP channel setting module 4 is present in the application program or exists independently of the application program, and is executed first to set the RTP channel. In other words, when the user requests execution of an application program, the RTP channel setting module 4 is executed first to set the RTP channel. The RTP channel setting module 4 is distributed through a recording medium such as a CD or provided through the Internet. For example, it may be downloaded to the clients 3 and 6 from a service server system that provides Internet telephony service based on the RTP channel.

Referring to the RTP channel setting method according to the first embodiment of the present invention by the above configuration as follows.

3 is a reference diagram for explaining a method of setting an RTP channel according to a first embodiment.

Referring to FIG. 3, the dotted line means UDP communication. In the OSI reference model or TCP / IP model, UDP is responsible for the transport layer along with TCP. However, TCP is a connection-oriented protocol that establishes a virtual circuit between a client and a counterpart client and transmits packets through these paths. Since TCP performs end-to-end error control, it is reliable but based on real-time transmission in terms of transmission speed. It is not appropriate for application services. On the other hand, UDP is a connectionless-oriented protocol that does best end-to-end transmission of each packet but does not perform end-to-end error control. Suitable.

Regardless of whether the NAT server 20 is a normal NAT or a symmetric NAT, the client 3 can export UDP packets, so the RTP channel establishment module 4 exports the port binding packet NPBP to the NAT server 20 ( Step 31). The NAT server 20 transmits this to the counterpart client 6 again (step 32). The counterpart client 6 then sends an RTP packet to the source IP address and port recorded in the received port binding packet NPBP (step 33). NAT server 20 sends the received RTP packet to client 3 (step 34). Accordingly, an RTP channel is established between the client 3 and the counterpart client 6.

4 is a diagram illustrating a network when the client 3 belongs to a public IP environment and the counterpart client 6 belongs to a NAT / firewall environment.

Referring to FIG. 4, the client 3 is directly connected to the Internet with a public IP address, but the other client 6 is connected to the Internet through a NAT / firewall 40. Clients 3 and 6 have the same configuration as described with reference to FIG. The clients 3, 6 are provided with an RTP channel setting module 4. The channel setting server 1 is for establishing an RTP channel according to the present embodiment and is directly connected to the Internet. The channel setting server 1 is provided with a plurality of ports, and a socket is installed in a specific port for receiving requests from the clients 3 and 6. The socket is an interface for communication between the RTP channel setting module 4 and the channel setting server 2 on the network. Sockets are made and used by function calls called socket application program interfaces (APIs).

On the other hand, since NAT has been described above in the first embodiment, detailed description of NAT is omitted in this embodiment, and only the firewall will be described in detail.

<normal firewall>

Referring to FIG. 4, the counterpart client 6 located inside the normal firewall 40 may send a UDP packet and directly establish a TCP connection with the client 3. However, UDP packets coming from the client 3 cannot be received, and TCP connections from the client 3 cannot be made.

<strict firewall>

Referring to FIG. 4, the other client 6 located inside the strict firewall 40 may not exchange UDP packets with the client 3, and may not establish a TCP connection from the client 3. However, the TCP connection requested from the client 3 to the counterpart client 7 can be set.

FIG. 5 is a block diagram of the channel setting server 1 of FIG. 4.

Referring to FIG. 5, the channel setting server 1 includes a client database 50 and an RTP channel setting module 51. Furthermore, the application service module 52 may be further included.

The client database 50 stores information about the client. The client information includes the IP address (private, public) assigned to the clients 3 and 6 for TCP / UDP, and the assigned port information. Here, the IP address may be provided from the clients 3 and 6 when joining as a member for receiving the application service provided by the application service server 52. The RTP channel setting module 51 receives the port binding packet NPBP and the RTP packet on behalf of the client so that the RTP channel is established between the client 3 and the counterpart client 6 according to the present embodiment. The application service module 52 is for providing an application service to the clients 3 and 6 based on the RTP channel established by the RTP channel setting module 51. Here, the application service module 52 may be implemented as a separate system from the channel setting server 1 and connected through a LAN / WAN.

RTP packets are defined and operated on the assumption of a UDP channel. Therefore, each of the RTP packets transmitted through the UDP channel independently arrives at the destination. However, when the RTP packet is transmitted through the TCP channel, since the separation and coalescing of the packet is performed at the source and destination, the "RTP over TCP" header is added to the RTP packet transmitted through the TCP channel in the present invention.

RTP over TCP header RTP packet

In the RTP over TCP header, identification information indicating the combining order of each packet is recorded. The "RTP over TCP header" may be implemented as follows, for example.

MSB LSB

31 24 6 8 0

Length of the body (bytes) 0x53 0x54

Here, Length of the body (bytes) refers to the length of the RTP packet, and 0x53 and 0x54 are identification information indicating the information &quot; RTP packet transmitted through the TCP channel &quot; and combination order information.

Referring to the RTP channel setting method according to the present invention by the above configuration as follows.

FIG. 6 is a reference diagram for explaining a method of establishing an RTP channel when the counterpart client 6 is connected to a NAT / firewall 40 according to the second embodiment. However, the RTP channel setting method according to the present embodiment is a call signal to the counterpart client 6 through the process described with reference to FIG. 6 when the client 3 makes a call to the counterpart client 6 in the Internet telephony service. A method for arriving and receiving a response call signal of the other client 6 also arrives at the client 3.

Referring to FIG. 6, a solid line means TCP communication. The RTP channel setting module 4 of the other client 6 requests a TCP connection to the channel setting server 1 (step 61). The RTP channel setting module 4 of the client 3 also requests a TCP connection to the channel setting server 1 (step 62). Steps 51 and 52 can be performed independently in any order. The client 3 transmits a call signal to the channel setting server 1 through the TCP connection made in step 62 (step 63). The channel setting server 1 transmits the received call signal to the counterpart client 6 through the TCP connection made in step 61 (step 64). In addition, the client 6 transmits the call signal to the channel setting server 1 through the TCP connection made in step 61 (step 65), and the channel setting server 1 transmits the received call signal to the TCP made in step 62. Transfer to client 3 via connection (step 66). Accordingly, an RTP channel is established between the client 3 and the counterpart client 6.

FIG. 7 is a reference diagram for explaining a method of establishing an RTP channel when the counterpart client 6 is connected to a normal NAT or a symmetric NAT according to the third embodiment.

Referring to Fig. 7, the RTP channel setting module 4 of the counterpart client 6 first forwards the port binding packet NPBP to the client 3 (step 71). The RTP channel setting module 4 of the client 3 transmits the RTP packet to the other client 6 according to the port-bound path in step 71 (step 72), and the other client 6 also sends the RTP packet to the client 3. (Step 73). Accordingly, an RTP channel is established between the client 3 and the counterpart client 6.

8 is a reference diagram for explaining a method of establishing an RTP channel when the counterpart client 6 is connected to a normal firewall according to a fourth embodiment.

8, the RTP channel setting module 4 of the other client 6 establishes a TCP connection with the client 3 (step 81). The client 3 transmits an RTP packet to the counterpart client 6 via the TCP channel set up in step 71 (step 82). The other client 6 sends an RTP packet to the client 3 (step 83). In this way, an RTP channel is established.

9 is a reference diagram for explaining a method of setting up an RTP channel when the counterpart client 6 is connected to a strict firewall according to the fifth embodiment.

9, the RTP channel setting module 4 of the other client 6 establishes a TCP connection 1 (for reception) with the client 3 (step 91). The RTP channel setting module 4 of the other client 6 also establishes a TCP connection 2 (for transmission) with the client 3 (step 92). The client 3 transmits an RTP packet to the counterpart client 6 via the TCP channel set up in step 91 (step 93). The other client 6 transmits an RTP packet to the client 3 via the TCP channel set up in step 92 (step 94). Accordingly, an RTP channel is established between the client 3 and the counterpart client 6.

10 is a diagram illustrating a network when the client 3 and the counterpart client 6 belong to a NAT / firewall environment.

Referring to FIG. 10, the client 3 and the counterpart client 6 are connected to the Internet through NAT / firewall 20 and 40, respectively. Clients 3 and 6 have the same configuration as described with reference to FIG. The clients 3, 6 are each provided with an RTP channel setting module 4 according to the present embodiment.

Channel setting server (2) is connected directly to the Internet, the client (3,6) is located in the NAT / firewall (20, 40) to relay the RTP packet if it can not directly send and receive over UDP or TCP channel In charge of. To this end, the channel setting server 2 is provided with a plurality of ports, and a socket is installed at a specific port for receiving requests from the clients 3 and 6. The socket is an interface for communication between the RTP channel setting module 4 and the channel setting server 2 on the network. Sockets are made and used by function calls called socket application program interfaces (APIs). The RTP channel setting module 4 installed in the clients 3 and 6 determines whether transmission and reception through the TCP or UDP channel is possible and requests the channel setting server 2 for a predetermined relay method according to the determination result. The relaying method of the channel setting server 2 can be divided into four methods as follows.

1. T-to-T method: relays RTP packets received through TCP channel to TCP channel

2. T-to-U method: relays RTP packets received through TCP channel to UDP channel

3. U-to-T method: relays RTP packets received through UDP channel to TCP channel

4. U-to-U method: relays RTP packets received through UDP channel to UDP channel

However, when all of the clients 3 and 6 are located inside the normal NAT 20 and 40, the client 3 and 6 may follow the method described below with reference to FIG. 15.

11 to 14 are reference diagrams for explaining a method for establishing an RTP channel according to a sixth embodiment of the present invention.

11 is a reference diagram for explaining a T-to-T method.

Referring to FIG. 11, both the client 3 and the counterpart client 6 are located inside strict firewalls 20 and 40 which do not allow transmission and reception of RTP packets through the UDP channel, or the client 3 establishes a UDP channel. The other client 6 is located inside the normal firewall 40 which does not allow the reception of UDP packets. As such, the T-to-T method is used when neither the client 3 nor the counterpart client 6 can transmit or receive an RTP packet through the UDP channel.

The client 3 and the counterpart client 6 make a TCP connection to the channel setting server 2 at their specific port (steps 111 and 112). When a TCP connection for transmitting and receiving an RTP packet is established, the client 3 transmits the RTP packet to the channel setting server 2 through the TCP connection (step 113), and the channel setting server 2 transmits the received RTP packet to the TCP connection. The connection is relayed to the counterpart client 6 through the connection (step 114). As a result, an RTP channel is established between the client 3 and the counterpart client 6.

12 is a reference diagram for explaining a T-to-U method.

Referring to FIG. 12, the client 3 is located inside the strict firewall 20 that allows only a TCP connection to the outside without allowing a UDP channel (transmission and reception of UDP packets) and the counterpart client 6 is externally located. It is located inside a normal NAT or symmetric NAT 40 that allows the reception of UDP packets. Accordingly, the client 3 may allow only the transmission of the RTP packet through the TCP connection to the outside without allowing the transmission of the RTP packet through the UDP channel and the counterpart client 6 may receive the RTP packet through the UDP channel. . In this case, the T-to-U method is used.

The client 3 establishes a TCP connection to the channel setting server 2 (step 121), and the channel setting server 2 allocates a specific port for transmitting the RTP packet to the counterpart client 6. On the other hand, the client 6 sets the UDP channel with the channel setting server 2 by transmitting the port binding packet NPBP to the channel setting server 2 (step 122). The client 3 transmits the RTP packet to the channel setting server 2 through the TCP channel set in step 121 (step 123), and the channel setting server 2 sends the received RTP packet to the source IP obtained in step 122. Send to the port (step 124).

13 is a reference diagram for explaining a U-to-T method.

Referring to FIG. 13, the client 3 is located inside the normal firewall 20 and the other client 6 is located inside the strict firewall or the normal firewall 40. Therefore, the client 3 can send out the RTP packet through the UDP channel, but the other client 6 can not directly receive the RTP packet input through the UDP channel from the client 3, so that the external TCP connection can be used. Receive RTP packets. In this case, U-to-T method is used.

The client 3 makes a TCP connection to a socket waiting for the connection of the clients 3 and 6 on a particular port of the channel establishment server 2 (step 131). The channel setting server 2 allocates a specific port for receiving the RTP packet from the client 3, and the client 3 transmits the RTP packet through the UDP channel to the assigned port of the channel setting server 2 (step 132). The channel setting server 2 transmits the RTP packet received from the client 3 to the counterpart client 6 through the TCP channel established with the counterpart client 6 (step 133).

14 is a reference diagram for explaining a U-to-U method.

Referring to FIG. 14, the client 3 is located inside a normal NAT or symmetric NAT 20 that allows a UDP channel, and the other client 6 has a symmetric NAT that allows reception of RTP packets through a specific UDP channel. 40) is located inside. Therefore, both the client 3 and the counterpart client 6 can transmit and receive RTP packets through the UDP channel, but have limitations that cannot be directly transmitted.

The channel setting server 2 allocates a specific port for receiving the RTP packet from the client 3 and the counterpart client 6. The other client 6 sends a port binding packet NPBP for port binding to the assigned specific port (step 141). In step 141, if a UDP channel capable of transmitting and receiving an RTP packet between the client 3 and the counterpart client 6 is established, the client 3 transmits the RTP packet to a specific port assigned by the channel setting server 2 through the established UDP channel. (Step 142). The channel setting server 2 transmits the received RTP packet to the IP address and port obtained from the port binding packet NPBP received in step 141 (step 143).

15 is a reference diagram for explaining a method of setting an RTP channel according to a seventh embodiment of the present invention.

Referring to Figure 15, the channel setting server 2 is assigned a public IP address. Clients 3 and 6 are connected to normal NAT or symmetric NAT 20 and 40. Therefore, the client 3 and the counterpart client 6 cannot directly exchange port binding packet NPBP with each other.

When client 3 sends out port binding packet NPBP to channel establishment server 2 (steps 151 and 152), client 3 and NAT 20 (for normal NAT) or client 3 and NAT 20 ) And the channel setting server 2 (in the case of symmetric NAT) are "NAT port binding". The other client 6 establishes a TCP connection with the channel setting server 2 and receives address information of the client 3 (step 153). The address information of the client 3 refers to the IP address and binding port assigned to the NAT 20. The binding port points to the local port of NAT 20 assigned in step 151.

Similarly, if the other client 6 sends out the port binding packet NPBP to the channel establishment server 2 (steps 154 and 155), the client 6 and the NAT 40 (in the case of normal NAT) or the client 6 The NAT 40 and the channel setting server 2 (in the case of symmetric NAT) are "NAT port bound". The client 3 also establishes a TCP connection with the channel setting server 2 and receives address information of the other client 6 (step 156). The address information of the counterpart client 6 also refers to the IP address and binding port assigned to the NAT 40. The binding port points to the local port of NAT 40 assigned in step 144.

The client 3 sends a port binding packet NPBP to the counterpart client 6 based on the address information obtained in step 146 (step 157). This is because when the counterpart client 6 connected to the counterpart client 6 is a symmetric NAT, the counterpart client 6 accepts the RTP packet only by sending a port binding packet NPBP to the counterpart client 6. Similarly, the other client 6 also sends the port binding packet NPBP to the client 3 based on the address information obtained in step 142 (step 158). Accordingly, a UDP channel is established between the client 3 and the counterpart client 6. Accordingly, the client 3 may transmit the RTP packet to the counterpart client 6 (step 159), and the counterpart client 6 may also transmit the RTP packet to the client 3 (step 160).

FIG. 16 is a network diagram when the client 7 belongs to a NAT / firewall environment and the counterpart client 14 belongs to an H.323 gateway environment.

Referring to FIG. 16, the client 7 is located inside the NAT / firewall 30 and the counterpart client 14 is located inside the H.323 gateway 60. The H.323 gateway 60 may transmit and receive RTP packets only through the UDP channel. H.323 is an ITU-T (International Telecommunications Union-Telecommunication Standardization Sector) standard for transmitting multimedia video conferencing data over a packet-switched network such as TCP / IP. This includes the LAN standard for high quality video and the Internet standard for transmitting video in the low frequency band over slow lines as high as 28.8 Kbps.

The channel setting server 9 is provided with a plurality of ports, and a socket is provided at a specific port for receiving requests from the clients 3 and 6. The channel setting server 9 is directly connected to the Internet to relay the RTP packets between the gateway 60 and the client 7. The client 7 is provided with the RTP channel setting module as described above with reference to FIG. Furthermore, the other client 14 may also be installed with the RTP channel setting module.

17 is a reference diagram for explaining a method of establishing an RTP channel according to an eighth embodiment of the present invention.

Referring to FIG. 17, since the client 7 is located inside the normal firewall 30, the client 7 requests a TCP connection to the channel setting server 9 (step 171). Meanwhile, the gateway 60 transmits the RTP packet to the channel setting server 9 through the UDP channel (step 172). The channel setting server 9 transmits the received RTP packet to the client 7 through the TCP connection set up in step 171 (step 173). Client 7 sends an RTP packet to gateway 60 via a UDP channel (step 174).

18 is a reference diagram for explaining a method of setting an RTP channel according to a ninth embodiment of the present invention.

Referring to FIG. 18, the client 7 is located inside the strict firewall 30. Therefore, a TCP connection for transmission is established with the channel setting server 9 (step 181). The client 7 also establishes a receiving TCP connection with the channel setting server 9 (step 182). Meanwhile, the gateway 60 transmits an RTP packet to the channel setting server 9 through the UDP channel (step 183). The channel setting server 9 converts the received RTP packet into an RTP packet through the TCP channel set up in step 182 and transmits it to the client 7 (step 184). The client 7 transmits the RTP packet to the channel setting server 9 through the TCP channel set in step 181 (step 185), and the channel setting server 9 sends the received RTP packet to the gateway 60 through the UDP channel. (Step 186).

19 is a reference diagram for explaining a method of setting an RTP channel according to a tenth embodiment of the present invention.

Referring to FIG. 19, the client 7 is located inside the normal NAT 30. Accordingly, the client 7 sends the port binding packet NPBP to the channel setting server 9 (step 191). The channel setting server 9 establishes a TCP connection and provides the gateway 60 with the address information obtained in step 191 (step 192). The client 7 also sends the port binding packet NPBP to the gateway 60 (step 193). In response, the gateway 60 transmits the RTP packet to the client 7 through the UDP channel (step 194), and the client 7 transmits the RTP packet to the gateway 60 through the UDP channel (step 195).

20 is a reference diagram for explaining a method of establishing an RTP channel according to an eleventh embodiment of the present invention.

Referring to FIG. 20, the client 7 is located inside the symmetric NAT 30. Accordingly, the client 7 sends the port binding packet NPBP to the channel setting server 9 (step 201). Meanwhile, the gateway 60 transmits the RTP packet received from the counterpart client 14 to the channel setting server 9 through the UDP channel (step 202), and the channel setting server 9 transmits the received RTP packet to the UDP channel. Is sent to the client 7 via step 203.

As described above, according to the present invention, an RTP channel can be established between clients belonging to various network environments. Accordingly, the application service provider can provide various application services based on the RTP channel to clients belonging to various network environments, and the clients in the various network environments can also receive application services based on the RTP channel. do.

Claims (22)

In a server connected to connect between a client and a counterpart client, Based on the network environment to which the client and the counterpart client belong, a UDP channel may be set between the client and the counterpart client, and a TCP channel may be set if the UDP channel is not available and the TCP channel is settable. Channel setup server. The method of claim 1, A client database storing address information of the counterpart client; And And a RTP channel setting module configured to receive a port binding packet from the client and deliver the port binding packet to the counterpart client based on the address information. A server connected to connect to a client, A storage unit for storing a program code constituting an RTP channel setting module executed in the client; The RTP channel setting module is executed in a client connected to a NAT server to transmit a port binding packet including address information of a counterpart client to the NAT server so that the NAT server transmits the port binding packet from the counterpart client. Server features. In a server connected to connect between a client and a counterpart client, Based on the network environment to which the client and the counterpart client belong, a UDP channel may be set between the client and the counterpart client, and a TCP channel is set if the UDP channel is not available and the TCP channel is settable. And proxyly receiving the RTP packet from the client and transmitting the received RTP packet to the counterpart client. The method of claim 4, wherein And a header in which identification information indicating a length and a combination order of the RTP packets are recorded, is added to the RTP packet transmitted through the TCP channel. The method of claim 4, wherein Receiving a TCP connection from the counterpart client, establishing a TCP channel, and receiving an RTP packet from the client via a UDP channel, and transmitting the received TCP connection to the counterpart client through the TCP channel. A channel setting server connected to communicate with clients via the Internet, Forward RTP packet received from one client through TCP channel to TCP channel with other client, or RTP packet received from one client through TCP channel to UDP client, or UDP channel from one client. And transmitting the RTP packet received through the TCP channel established with the counterpart client or the RTP packet received from the one client through the UDP channel to the counterpart client through the UDP channel. The method of claim 7, wherein Both the client and the counterpart client are located inside a strict firewall that does not allow transmission and reception of RTP packets through a UDP channel, or the client is located inside a strict firewall that allows only TCP connections without allowing a UDP channel. Is located inside a normal firewall that does not allow the reception of UDP packets, and transmits the RTP packets received from the client to the TCP channel associated with the counterpart client through a TCP channel. The method of claim 8, The channel setting server is located inside a strict firewall that allows the client to make only a TCP connection to the outside without allowing a UDP channel. When located in the channel setting server, characterized in that for transmitting the RTP packet received from the client via the TCP channel to the counterpart client via a UDP channel. The method of claim 9, When the client is located inside the normal firewall and the counterpart client is located inside the strict firewall or the normal firewall, the channel establishment server sends an RTP packet received from the client through a UDP channel to a TCP channel connected to the counterpart client. Channel setting server, characterized in that for transmitting. The method of claim 7, wherein The channel setting server is located inside a normal NAT or a symmetric NAT that allows the client to allow a UDP channel, and the counterpart client is located inside a symmetric NAT that allows the reception of RTP packets over a specific UDP channel. And transmitting the RTP packet received from the UDP channel through the UDP channel to the counterpart client. A channel setting server connected to communicate with a client and a gateway through the Internet, Deliver RTP packets received from the client through a TCP channel to a TCP channel associated with the gateway, transfer RTP packets received from the client through a TCP channel to the gateway through a UDP channel, or transmit a UDP channel from the client. And transmitting the RTP packet received through the TCP channel associated with the gateway or the RTP packet received from the client through the UDP channel to the gateway through the UDP channel. The method of claim 12, The gateway is a channel setting server, characterized in that the gateway according to the H.323 protocol. In the method for establishing an RTP channel between the client and the other client, (a) receiving a port binding packet from the client and delivering the port binding packet to the counterpart client to perform port binding. The method of claim 14, and (b) performing port binding by receiving another port binding packet from the counterpart client and delivering the port binding packet to the client. In the method for establishing an RTP channel between the client and the other client, (a) allowing a UDP channel to be established if a UDP channel can be established with the client or the counterpart client based on a network environment to which the client and the counterpart client belong; (b) allowing a TCP channel to be established if a UDP channel cannot be established with the client or the counterpart client and a TCP channel can be established; And (c) RTP channel setting method characterized in that for receiving the RTP packet transmitted from the client via the TCP channel or UDP channel set through the steps (a) and (b) and forwarded to the counterpart client. The method of claim 16, The step (c) comprises the step of adding a header with identification information indicating the length and combination order of the RTP packet to the RTP packet transmitted through the TCP channel. The method of claim 17, Step (b) includes receiving a TCP connection request from a counterpart client and establishing a TCP channel, The step (c) comprises the step of receiving the RTP packet on behalf of the client via the UDP channel and transmitting to the counterpart client through the TCP channel. In the method for establishing an RTP channel between the client and the other client, (a) Both the client and the counterpart client are located inside a strict firewall that does not allow the transmission and reception of RTP packets over a UDP channel, or the client is located inside a strict firewall that allows only TCP connections without allowing a UDP channel. When the counterpart client is located inside a normal firewall that does not allow the reception of a UDP packet, transmitting the RTP packet received from the client through a TCP channel to a TCP channel established with the counterpart client. RTP channel setup method. The method of claim 19, (b) It is located inside a strict firewall that allows the client to make only TCP connections to the outside without allowing UDP channels and the other client is inside a normal NAT or symmetric NAT that allows the reception of UDP packets from outside. And transmitting the RTP packet received from the client through the TCP channel to the counterpart client through the UDP channel. The method of claim 20, (c) When the client is located inside the normal firewall and the counterpart client is located inside the strict firewall or the normal firewall, the RTP packet received from the client through the UDP channel is transmitted to the TCP channel established with the counterpart client. RTP channel setting method comprising the step of. The method of claim 21, (d) UDP from the client when the client is located inside a normal NAT or symmetric NAT that allows a UDP channel and the other client is inside a symmetric NAT that allows the reception of RTP packets over a particular UDP channel. And transmitting the RTP packet received through the channel to the counterpart client through a UDP channel.