Repeated Lost Packet Retransmission in a TCP/IP Network

• US 20120155458A1
• Filed: 12/20/2010
• Published: 06/21/2012
• Est. Priority Date: 12/20/2010
• Status: Abandoned Application

• Current Assignee: Brocade Communications Systems, Inc. (Broadcom, Inc.)
• Original Assignee: Brocade Communications Systems, Inc. (Broadcom, Inc.)
• Inventors: LARSON, ISAAC, ADIRAJU, SIVA SANKAR, NARAYANASAMY, SENTHILKUMAR
• Application Number:
  US12/972,713
• Publication Number:
  US 20120155458A1
• Time in Patent Office: Days
• US Class Current: 370/389
• CPC Class Codes: H04L 1/1809 Selective-repeat protocols
• CPC Class Codes: H04L 1/188 Time-out mechanisms
• CPC Class Codes: H04L 1/1887 Scheduling and prioritising arrangements
• CPC Class Codes: H04L 47/522 Dynamic queue service slot or variable bandwidth allocation
• CPC Class Codes: H04L 67/1097 for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS]
• CPC Class Codes: H04L 69/161 Implementation details of TCP/IP or UDP/IP stack architecture; Specification of modified or new header fields
• CPC Class Codes: H04L 69/163 In-band adaptation of TCP data exchange; In-band control procedures

Abstract

Periodically retransmitting of multiply lost TCP/IP packets until either an ACK is received or the timeout finally occurs. By retransmitting the packet more than the once as done with prior art SACK approaches, there is a possibility of not having to wait until the timeout period elapses if one of the other retransmissions successfully transits the network. If the packet is successfully received and acknowledged before the timeout period ends, then the more extensive timeout procedures need not be invoked and traffic is much less affected.

Claims

1. An apparatus comprising:

a buffer holding a plurality of transmitted TCP packets;

timeout logic coupled to said buffer for indicating that a TCP packet held in said buffer has timed out; and

acknowledgement logic coupled to said buffer and said timeout logic for receiving acknowledgements and selective acknowledgements for TCP packets held in said buffer, said acknowledgement logic directing repeated retransmission of at least one of the TCP packets held in said buffer in response to receiving at least two selective acknowledgements indicating the need to retransmit said at least one TCP packet until either an acknowledgement for said at least one TCP packet has been received or an indication is provided that said at least one TCP packet has timed out.

2. The apparatus of claim 1, wherein said acknowledgement logic further directs removal of a TCP packet from said buffer if an acknowledgement is received indicating that said TCP packet has been successfully received.

3. The apparatus of claim 1, wherein said directing repeated retransmission of said at least one TCP packet includes determining that TCP packets transmitted after a first retransmission of said at least one TCP packet were properly received.

4. A method comprising:

transmitting a plurality of TCP packets;

receiving at least two selective acknowledgements indicating that at least one of said plurality of TCP packets needs to be retransmitted; and

repeatedly retransmitting said at least one TCP packet based on said receipt of at least two selective acknowledgments until either an acknowledgement for said at least one TCP packet is received or said at least one TCP packet times out.

5. The method of claim 4, further comprising:

receiving acknowledgement or selective acknowledgement that a TCP packet has been successfully received; and

indicating that said TCP packet can be removed from a buffer as retransmission is not required.

6. The method of claim 4, wherein said repeatedly retransmitting said at least one TCP packet includes determining that TCP packets transmitted after a first retransmission of said at least one TCP packet were properly received.