Data transmission system with a mechanism enabling any application to run transparently over a network address translation device

• US 20040205245A1
• Filed: 08/11/2003
• Published: 10/14/2004
• Est. Priority Date: 03/28/2003
• Status: Active Grant

• Current Assignee: AT&T Corporation (AT&T, Inc.)
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Amadei, Bernard, Bruno, Aurelien, Grisi, Nicolas, Le Pennec, Jean-Francois, Sommerlatt, Jean-Marie
• Granted Patent: US 7,716,369 B2
• Time in Patent Office: Days
• US Class Current: 709/245
• CPC Class Codes: H04L 61/2567 for reachability, e.g. inquiring the address of a correspondent behind a NAT server
• CPC Class Codes: H04L 61/2578 without involvement of the NAT server
• CPC Class Codes: H04L 63/0272 Virtual private networks
• CPC Class Codes: H04L 63/164 at the network layer

Abstract

Data transmission system based upon the Internet protocol (IP) comprising a private transmission network (18) and a public transmission network or the like (16) interconnected by a network address translation device NAT (12) wherein at least a workstation WS (10) connected to said private transmission network has to establish a communication with a peer device (14) connected to the public transmission network, the local IP address of each data packet from the workstation WS being translated into a NAT address used to provide the route through the public transmission network. The system includes a registration server (19) connected to the public transmission network for registering the local IP address corresponding to the NAT address and providing the correspondence between the NAT address and the local IP address to the peer device in order for this one to replace in the IP header of each data packet received by the peer device, the NAT address by the local IP address.

Claims

1-19. -19 (Canceled)

20. A data transmission system operating with the Internet protocol (IP) comprising:

a workstation

a peer device;

a private transmission network;

a network address translation device (NAT);

a public transmission network interconnected by the NAT to the private transmission network, wherein the workstation connected to the private transmission network is operative for communicating the peer device, the peer device connected to the public transmission network, the local IP address of each data packet from the workstation is translated into a NAT address used to provide the routing through the public transmission network; and

a registration server connected to the public transmission network for registering a local IP addresses corresponding to a NAT address and for providing the correspondence between the NAT address and the local IP address to the peer device in order to replace the NAT address with the local IP address in an IP header of each data packet received by the peer device,.

21. The data transmission system of claim 20, wherein the NAT address is shared by more than one workstation, the workstations are connected to different ports sharing the same address, and wherein the network address translation device further includes a means for providing port number translation.

22. The data transmission system of claim 21, wherein the peer device comprises a proxy for replacing in the IP header of each received data packet, the NAT address with the corresponding local IP address.

23. The data transmission system of claim 22, wherein the peer device is a hub and wherein an IPsec tunnel is established between the workstation and the hub.

24. The data transmission system of claim 22, wherein the peer device is connected to a server by means of a local network, a connection being established between the workstation and the server by an application.

25. The data transmission system of claim 24, wherein a tunnel is established between the workstation and the peer device.

26. The data transmission system of claim 25, wherein the tunnel established between the workstation and the peer device is an IPsec tunnel.

27. The data transmission system according to claim 22, wherein the peer device is a voice server and a voice connection using H.323 protocol is established between the workstation and the voice server.

28. The data transmission system of claim 22, wherein the peer device is a proxy and is connected to a voice server by means of a local network and a voice connection using H.323 protocol is established between the workstation and the voice server.

29. The data transmission system of claim 21, wherein the peer device is an end server comprising a proxy connected to the public transmission network by means of a local network, the local network being connected to the private transmission network by a network address translation device.

30. The data transmission system of claim 29, wherein the registration server is adapted for registering the local IP address of the end server corresponding to the network address resulting from the translation of the server local IP address by the address of the network address translation device and for providing to the end server the correspondence between the network address translation device address and the server local IP address.

31. The data transmission system of claim 30, wherein the end server is a voice server and a voice connection using H.323 protocol is established between the workstation and the voice server.

32. A method of enabling an application to run transparently in a data transmission system operating with the Internet protocol (IP) comprising a public transmission network, a public network, a workstation, interconnected by a network address translation device (NAT) to the private transmission network, wherein the workstation connected to the private transmission network is operative for communicating the peer device, the peer device connected to the public transmission network, the local IP address of each data packet from the workstation is translated into a NAT address used to provide the routing through the public transmission network, the method comprising the steps of:

registering (REG) in a registration server the local IP address corresponding to the NAT address,

requesting from the peer device to the registration server, the local IP address corresponding to an unknown NAT address of a received data packet,

receiving at the peer device, the local IP address from the registration server; and

replacing in the peer device, the NAT address of a received data packet with a local IP address.

33. The method of claim 32, wherein when a plurality of workstations establish a communication with the peer device, a local port number is assigned to the workstation and the NAT is used to translate both the local IP address and the local port number of the workstations into a corresponding NAT address and a NAT Port number;

the method further comprising the steps of;

registering in the registration server the local IP address and the local port number corresponding to a NAT address and a NPAT Port number;

requesting from the peer device through the registration server, the local IP address and the local port number corresponding to a NAT address and a NPAT port number of a received data packet;

receiving in at the peer device, the local IP address and local port number from the registration server; and

replacing in the peer device, the NAT address and NAT port number of a received packet by with a corresponding local IP address and a local port number.

34. The method according to claim 33, wherein an IPsec tunnel is established between the workstation and the peer device, the method further comprising the steps of:

sending from the peer device to the registration server an activation request to the workstation to start a session through the IPsec tunnel, and polling regularly the registration server the workstation for detecting the activation request and start of a IPsec session.

35. The method according to claim 33, wherein the public transmission network is connected to the peer device by means of a second network address translation device, the method further comprising the step of registering in the registration server, the local IP address of the peer device corresponding to the address resulting from the translation of the local IP address of the peer device by the second network address translation device.

36. The method according to claim 35, further comprising the following steps when a data packet is transmitted from the peer device to the workstation, the steps comprising:

requesting from the workstation through the registration server, the peer device local IP address corresponding to an unknown second network address translation device address;

receiving at the workstation, the peer device local IP address;

, and

replacing in the workstation the second network address translation device address of the received packet by the peer device local IP address.

37. The method of claim 33, wherein the peer device is a voice server and a voice connection using H.323 protocol is established between the workstation and the voice server.

38. The method according to claim 37, wherein the peer device is a voice server and a voice connection using H.323 protocol is established between the workstation and the voice server.