Subject: I-D ACTION:draft-ietf-tcplw-sack-00.txt
From: [email-masked]
To: IETF-Announce:;@cnri.reston.va.us
Cc: [email-masked]
Date: Fri, 26 Jan 96 09:37:13 -0500

A New Internet-Draft is available from the on-line Internet-Drafts 
directories. This draft is a work item of the TCP Large Windows Working 
Group of the IETF.                                                         

       Title     : TCP Selective Acknowledgement Options                   
       Author(s) : M. Mathis, J. Mahdavi, S. Floyd, A. Romanow
       Filename  : draft-ietf-tcplw-sack-00.txt
       Pages     : 9
       Date      : 01/25/1996

TCP may experience poor performance when multiple packets are lost from one
window of data.   With the limited information available from cumulative 
acknowledgements, a TCP sender can only learn about a single lost packet 
per round trip time.  An aggressive sender could choose to retransmit 
packets early, but such retransmitted segments may have already been 
successfully received.                  
                             
A Selective Acknowledgement (SACK) mechanism, combined with a selective 
repeat retransmission policy, can help to overcome these limitations.  The 
receiving TCP sends back SACK packets to the sender informing the sender of
data that has been received. The sender can then retransmit only the 
missing data segments.           
                                          
This draft proposes an implementation of SACK and discusses its performance
and related issues.                                                        

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