System and method for real-time bidirectional communication through firewalls

• US 8,230,091 B2
• Filed: 08/24/2009
• Issued: 07/24/2012
• Est. Priority Date: 09/05/2003
• Status: Active Grant

• Current Assignee: Lifesize, Inc. (Enghouse Systems Limited)
• Original Assignee: Lifesize, Inc. (Enghouse Systems Limited)
• Inventors: Kliland, Kevin, Farner, Knut
• Primary Examiner(s): Nawaz, Asad M
• Assistant Examiner(s): HENRY, MARIEGEORGES A
• Application Number:
  US12/546,366
• Publication Number:
  US 20100011115A1
• Time in Patent Office: 1,065 Days
• Field of Search: 709/230, 709/227
• US Class Current: 709/230
• CPC Class Codes: H04L 63/029 Firewall traversal, e.g. tunnelling or, creating pinholes
• CPC Class Codes: H04L 69/14 Multichannel or multilink protocols
• CPC Class Codes: H04L 69/16 Implementation or adaptation of Internet protocol [IP], of transmission control protocol [TCP] or of user datagram protocol [UDP]
• CPC Class Codes: H04L 69/163 In-band adaptation of TCP data exchange; In-band control procedures

Abstract

A system and method for real-time data transmission through data communication networks are disclosed. The system and the method allow for real time communication between applications located in different internal networks protected by firewalls by means of representing the applications by proxies and establishing TCP channels towards an intermediate proxy server localized outside the firewalls. A set of parameters residing in the server determines i.a. the number of required TCP channels based on the ratio of measured bandwidth between the data flow directions.

Claims

1. A non-transitory, computer-accessible memory medium storing program instructions for communication between a real-time client and a real-time server, wherein the program instructions are executable by a processor to:

establish at least one bidirectional connection to the real-time server through at least one of one or more firewalls or one or more NAT devices, wherein the at least one bidirectional connection comprises at least one bidirectional HTTPS connection or at least two unidirectional HTTP connections;

receive a first one or more RTP packets of a real-time application;

provide a first one or more TCP packets to the real-time server via the at least one bidirectional connection, wherein the first one or more TCP packets comprise the first one or more RTP packets;

receive a second one or more TCP packets from the real-time server via the at least one bidirectional connection;

extract a second one or more RTP packets from the second one or more TCP packets; and

provide at least one of the second one or more RTP packets to the real-time application;

wherein the program instructions are further executable to provide an acknowledgement to the real-time server for each TCP packet regardless of whether or not the TCP packet is received, and if a TCP packet is lost, modify a TCP 32-bit acknowledge number of the TCP packet to be equal to a TCP bit sequence number of a last received TCP packet.

2. The non-transitory, computer-accessible memory medium of claim 1, wherein the at least one bidirectional connection comprises a plurality of bidirectional connections, wherein each bidirectional connections comprises a bidirectional HTTPS connection or two unidirectional HTTP connections.

3. The non-transitory, computer-accessible memory medium of claim 1, wherein the program instructions are further executable to:

cache the second one or more RTP packets in a buffer; and

drop at least an RTP packet of the second one or more RTP packets from the buffer, leaving a third one or more RTP packets in the buffer;

wherein said providing comprises providing the third one or more RTP packets to the real-time application.

4. The non-transitory, computer-accessible memory medium of claim 1, wherein the program instructions are further executable to establish at least one additional bidirectional connection to perform communication between the real-time server and the real-time client.

5. The non-transitory, computer-accessible memory medium of claim 4, wherein said establishing the at least one additional bidirectional connection is performed based on one or more of the following conditions:

a first cache level is full;

a second cache level is full;

the first cache level has reached a predetermined threshold level;

the second cache level has reached a predetermined threshold level;

a rate of dropping packets has reached a predetermined drop rate level;

a function of a current drop rate and one or more previous drop rates is satisfied;

or

a ratio between a total transmitted bandwidth and a total receiving bandwidth exceeds a predetermined threshold with reference to the real-time client.

6. The non-transitory, computer-accessible memory medium of claim 4, wherein the program instructions are further executable to reduce the number of bidirectional connections based on one or more of the following conditions:

a first cache level is empty;

a second cache level is empty;

the first cache level has reached a predetermined threshold level;

the second cache level has reached a predetermined threshold level;

a rate of dropping packets has reached a predetermined drop rate level;

a function of a current drop rate and a previous drop rate or drop rates are satisfied;

or

a ratio between the total transmitted bandwidth and the total receiving bandwidth exceeds a predetermined threshold with reference to the real-time client.

7. The non-transitory, computer-accessible memory medium of claim 4, wherein the program instructions are further executable to rank a best available bidirectional connection according to one or more of the following conditions:

a first cache level is full;

a second cache level is full;

the first cache level has reached a predetermined threshold level;

the second cache level has reached a predetermined threshold level;

a rate of dropping packets has reach a predetermined drop rate level;

a function of a current drop rate and a previous drop rate or drop rates are satisfied;

or

ratio between a total transmitted bandwidth and the total receiving bandwidth exceeds a predetermined threshold with reference to the real-time client.

8. A non-transitory, computer-accessible memory medium storing program instructions for communication between a real-time client and a real-time server, wherein the program instructions are executable by a processor to:

establish at least one bidirectional connection to the real-time client through at least one of one or more firewalls or one or more NAT devices, wherein the at least one bidirectional connection comprises at least one bidirectional HTTPS connection or at least two unidirectional HTTP connections;

receive a first one or more RTP packets of a real-time application;

provide a first one or more TCP packets to the real-time client via the at least one bidirectional connection, wherein the first one or more TCP packets comprise the first one or more RTP packets;

acknowledge receipt of each of the first one or more TCP packets, regardless of whether or not the TCP is received by the real-time client, wherein said acknowledging comprises using a TCP 32-bit acknowledge number of a last provided TCP packet;

receive a second one or more TCP packets from the real-time client via the at least one bidirectional connection;

extract a second one or more RTP packets from the second one or more TCP packets; and

provide at least one of the second one or more RTP packets to the real-time application.

9. The non-transitory, computer-accessible memory medium of claim 8, wherein the at least one bidirectional connection comprises a plurality of bidirectional connections, wherein each bidirectional connections comprises a bidirectional HTTPS connection or two unidirectional HTTP connections.

10. The non-transitory, computer-accessible memory medium of claim 8, wherein the program instructions are further executable to:

cache the second one or more RTP packets in a buffer; and

drop at least an RTP packet of the second one or more RTP packets from the buffer, leaving a third one or more RTP packets in the buffer;

wherein said providing comprises providing the third one or more RTP packets to the real-time application.

11. The non-transitory, computer-accessible memory medium of claim 8, wherein the program instructions are further executable to establish at least one additional bidirectional connection to perform communication between the real-time server and the real-time client.

12. The non-transitory, computer-accessible memory medium of claim 11, wherein said establishing the at least one additional bidirectional connection is performed based on one or more of the following conditions:

a first cache level is full;

a second cache level is full;

the first cache level has reached a predetermined threshold level;

the second cache level has reached a predetermined threshold level;

a rate of dropping packets has reach a predetermined drop rate level;

a function of a current drop rate and a previous drop rate or drop rates are satisfied;

or

a ratio between the total transmitted bandwidth and the total receiving bandwidth exceeds a predetermined threshold with reference to the real-time client.

13. The non-transitory, computer-accessible memory medium of claim 8, wherein the program instructions are further executable to add a fixed bit pattern to every RTP packet.