Subject: Protocol Action: Computing TCP's Retransmission Timer to Proposed Standard

From: The IESG <[email-masked]>
Date: Mon, 18 Sep 2000 06:43:36 -0400

The IESG has approved the Internet-Draft 'Computing TCP's
Retransmission Timer' <draft-paxson-tcp-rto-01.txt> as a Proposed
Standard.  This document is the product of the Transport Area Working
Group Working Group.  The IESG contact persons are Allison Mankin and
Scott Bradner.

Technical Summary
 
 The Transmission Control Protocol (TCP) [RFC 793] uses a
 retransmission timer to ensure data delivery in the absence of any
 feedback from the remote data receiver.  The duration of this timer
 is referred to as RTO (retransmission timeout).  RFC 1122
 specifies that the RTO should be calculated as described in
 Van Jacobson's 1988 Computer Communication Review paper on "Congestion
 Avoidance and Control"

 This document codifies the algorithm for setting the RTO.  In
 addition, this document expands on the discussion in section 4.2.3.1
 of RFC 1122 and upgrades the requirement of supporting the algorithm
 from a SHOULD to a MUST.  RFC 2581 outlines the algorithm
 TCP uses to begin sending after the RTO expires and a retransmission
 is sent.  This document does not alter the behavior outlined in RFC
 2581

 Thus this document defines the standard algorithm TCP senders are
 required to use to compute and manage their retransmission timer.

Working Group Summary

 The proposed MIB was supported by the working group and no issues
 came up during IETF last-call.

Protocol Quality

 This document was reviewed by Scott Bradner for the IESG.

Note to RFC Editor:

Please replace the first line of section 5 with the following

        An implementation MUST manage the retransmission timer(s) in
        such a way that a segment is never retransmitted too early, i.e.
        less than one RTO after the previous transmission of that segment.

        The following is the RECOMMENDED algorithm for managing the
        retransmission timer: