Methods and apparatus for providing improved quality of packet transmission in applications such as internet telephony

• US 6,233,249 B1
• Filed: 05/02/2000
• Issued: 05/15/2001
• Est. Priority Date: 03/17/1997
• Status: Expired due to Term

• Current Assignee: AT&T Corporation (AT&T, Inc.)
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Robinson, Bethany Scott, Katseff, Howard Paul
• Primary Examiner(s): MARCELO, MELVIN C
• Application Number:
  US09/565,281
• Time in Patent Office: 378 Days
• Field of Search: 370/466, 370/467, 370/471, 370/473, 370/474
• US Class Current: 370/466
• CPC Class Codes: H04L 12/6418 Hybrid transport
• CPC Class Codes: H04L 2012/6427 Subscriber Access Module; Concentrator; Group equipment
• CPC Class Codes: H04L 2012/6472 Internet
• CPC Class Codes: H04L 2012/6475 N-ISDN, Public Switched Telephone Network [PSTN]
• CPC Class Codes: H04L 69/08 Protocols for interworking; Protocol conversion
• 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 69/164 Adaptation or special uses of UDP protocol
• CPC Class Codes: H04L 69/165 Combined use of TCP and UDP protocols; selection criteria therefor
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

A digital data packet transmission process and system provides more efficient and higher quality of service in applications such as Internet telephony. In one aspect of this approach, transmission control protocol (“TCP”) is used to send data from a first user or client over standard telephone lines to a local Internet service provider (“ISP”). At the ISP, the data packets are converted from TCP to user datagram protocol (“UDP”). The UDP packets are then transmitted, typically over a higher bandwidth link to another local ISP serving the recipient. The UDP packets are translated back to TCP packets and routed to the receiver. Because many existing systems currently employ UDP packets, the present approach is largely backwards compatible should a recipient be hooked up to an ISP that does not employ a TCP/UDP converter. A bidirectional TCP/UDP converter is preferable for two way communication such as Internet telephony.

Claims

1. A method of digital data transmission in a packet-switched digital network, comprising the steps of:

establishing a data link between a server and a client, said client transmitting to said server digital transmission control protocol (TCP) packets addressed to an addressee;

converting each TCP packet received from said client to user datagram protocol (UDP) format; and

routing each UDP-converted packet to the addressee.

2. The method of claim 1, wherein said method is used in a packet-switched Internet telephony system.

3. The method of claim 1 wherein the step of establishing a data link between a server and a client further comprises the step of utilizing a modem at the client to connect to the server which is part of a local Internet service provider (ISP) utilizing standard telephone lines.

4. The method of claim 1 further comprising the step of:

looking up the addressee'"'"'s address information in a calling destination database.

5. The method of claim 1 wherein the step of routing each UDP-converted packet to the addressee further comprises the step of routing each UDP-converted packet to a local service provider (ISP) serving the addressee.

6. The method of claim 5 wherein the step of routing each UDP-converted packet to a local ISP serving the addressee further comprises making a connection over a high bandwidth connection.

7. The method of claim 5 further comprising the step of routing each UDP-converted packet from the local ISP, to which said addressee is connected, to the addressee utilizing a modem and standard telephone lines.

8. The method of claim 1 wherein the step of routing each UDP-converted packet to the addressee further comprises the step routing each UDP-converted packet through an Internet network to a local Internet service provider (ISP) serving the addressee.

9. The method of claim 8 further comprising the step of receiving each UDP-converted packet at the addressee.

10. The method of claim 1 further comprising the step of establishing a calling destination database.

11. A method for determining routing information between a first client and a second client to provide an Internet telephony connection, said method comprising the steps of:

sending a register message which includes routing information to a network communications manager by the first client, wherein the routing information includes an internet protocol (IP) address of a converter for converting a transmission control protocol (TCP) packet to a user datagram protocol (UDP) packet;

storing the routing information in an active user database;

sending a message from said second client to the network communications manager;

if said message is a client lookup request, sending the message from the network communications manager to a client lookup system;

looking up, by said client lookup system, the routing information associated with said first client in said active user database;

sending said routing information to said second client; and

providing a voice connection between said first client and said second client utilizing said routing information and said converter.

12. The method of claim 11 wherein the step of providing a voice connection comprises the substeps of:

transmitting TCP packets from said second client to said converter;

converting said TCP packets to UDP packets by said converter; and

transmitting said UDP packets to said first client.

13. The method of claim 11 wherein the converter further performs the function of converting a UDP packet to a TCP packet.

14. The method of claim 13 wherein the step of providing a voice connection comprises the substeps of:

transmitting UDP packets from said second client to said converter;

converting said UDP packets to TCP packets by said converter; and

transmitting said TCP packets to said first client.

15. A system for providing a voice connection utilizing digital data transmission in a packet-switched digital network, the system comprising:

means for establishing a data link between a server and a client;

means for establishing an Internet telephony connection utilizing said data link between said server and said client;

a transmitter for transmitting from said client to said server digital transmission control protocol (TCP) packets addressed to an addressee, said TCP packets being comprised of digitized Internet telephony voice data;

a converter for converting each TCP packet received from said client to user datagram protocol (UDP) format; and

a router for routing each UDP-converted packet to the addressee.

16. The system of claim 15 further comprising:

means for looking up the addressee'"'"'s address information in a calling destination database.

17. The system of claim 15 wherein the router is further operable to route each UDP-converted packet to a local Internet service provider (ISP) connected to said addressee.

18. The system of claim 17 wherein the router is further operable to establish a connection over a high bandwidth data link connection.

19. The system of claim 17 wherein the router further operable to establish a connection to the addressee utilizing a modem and standard telephone lines.

20. The system of claim 15 further comprising a second converter for converting each UDP-converted packet to a TCP packet.

21. A method of providing Internet telephony in which signal communication protocols are tailored to take advantage of characteristics of different connections, the method comprising the steps of:

transmitting a digitized Internet telephony transmission control protocol (TCP) packet utilizing a reliable first connection such that latencies caused by TCP'"'"'s retransmission are unlikely to occur;

converting the TCP packet to a user datagram protocol (UDP) packet for transmission on a fast second connection;

transmitting the UDP packet utilizing the fast second connection with bandwidth great enough to tolerate UDP overhead;

converting the UDP packet to a second TCP packet for transmission on a reliable third connection; and

transmitting the second TCP packet utilizing the reliable third connection such that latencies caused by TCP'"'"'s retransmission are unlikely to occur, said third connection communicatively connected to said second connection.

22. The method of claim 21 wherein:

the first connection utilizes a first modem and standard telephone lines;

the second connection utilizes a high bandwidth data link connection; and

the third connection utilizes a second model and standard telephone lines.