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Computing TCP's Retransmission Timer

Approval announcement
Draft of message to be sent after approval:


From: The IESG <>
To: IETF-Announce <>
Cc: RFC Editor <>,
    tcpm mailing list <>,
    tcpm chair <>
Subject: Protocol Action: 'Computing TCP's Retransmission Timer' to Proposed Standard (draft-paxson-tcpm-rfc2988bis-02.txt)

The IESG has approved the following document:
- 'Computing TCP's Retransmission Timer'
  (draft-paxson-tcpm-rfc2988bis-02.txt) as a Proposed Standard

This document is the product of the TCP Maintenance and Minor Extensions
Working Group.

The IESG contact person is Wesley Eddy.

A URL of this Internet Draft is:

Ballot Text

Technical Summary

This document defines the standard algorithm that Transmission
Control Protocol (TCP) senders are required to use to compute and
manage their retransmission timer.  It expands on the discussion in
section of RFC 1122 and upgrades the requirement of
supporting the algorithm from a SHOULD to a MUST.  It also
modifies the initial RTO defined in RFC 2988.

Working Group Summary

Nothing exceptional occurred during the working group process for this

Document Quality

Implementations of the methods described in this document have been
running on the Internet for many years.  The change in the initial
RTO parameter from 3 s to 1 s has been implemented to lesser extent,
though no significant issues have been found that would block wider
deployment and Appendix A of the document contains substantial
motivations and analysis of the change. 


Wesley Eddy ( is the document shepherd and
the responsible AD.

RFC Editor Note

- Please add to the document header that this obsoletes RFC 2988

- Please add to the end of the abstract:
  "This document obsoletes RFC 2988."

- Please add to the end of the introduction section:
  "This document obsoletes [RFC2988]."

- Please add a Section called "Changes from RFC 2988" which
  follows the IANA considerations and contains the text:

  This document reduces the initial RTO from the previous 3 seconds
  [RFC2988] to 1 second, unless the ACK of the SYN is lost in which
  case the default RTO is reverted to 3 seconds before data transmission

- Please add to the document header that this updates RFC 1122

- Please add to the security considerations section:
  "The security considerations in [RFC5681] are also applicable
   to this document." 

RFC Editor Note