TCP User Timeout Option
RFC 5482
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Document |
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RFC - Proposed Standard
(March 2009; No errata)
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Authors |
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Fernando Gont
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Lars Eggert
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Last updated |
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2015-10-14
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IETF
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plain text
html
pdf
htmlized
bibtex
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Reviews |
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WG state
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(None)
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Document shepherd |
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No shepherd assigned
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IESG |
IESG state |
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RFC 5482 (Proposed Standard)
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Consensus Boilerplate |
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Unknown
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Telechat date |
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Responsible AD |
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Magnus Westerlund
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Send notices to |
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(None)
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Network Working Group L. Eggert
Request for Comments: 5482 Nokia
Category: Standards Track F. Gont
UTN/FRH
March 2009
TCP User Timeout Option
Status of This Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
Copyright (c) 2009 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents in effect on the date of
publication of this document (http://trustee.ietf.org/license-info).
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document.
Abstract
The TCP user timeout controls how long transmitted data may remain
unacknowledged before a connection is forcefully closed. It is a
local, per-connection parameter. This document specifies a new TCP
option -- the TCP User Timeout Option -- that allows one end of a TCP
connection to advertise its current user timeout value. This
information provides advice to the other end of the TCP connection to
adapt its user timeout accordingly. Increasing the user timeouts on
both ends of a TCP connection allows it to survive extended periods
without end-to-end connectivity. Decreasing the user timeouts allows
busy servers to explicitly notify their clients that they will
maintain the connection state only for a short time without
connectivity.
Eggert & Gont Standards Track [Page 1]
RFC 5482 TCP User Timeout Option March 2009
Table of Contents
1. Introduction ....................................................2
2. Conventions .....................................................3
3. Operation .......................................................4
3.1. Changing the Local User Timeout ............................5
3.2. UTO Option Reliability .....................................8
3.3. Option Format ..............................................8
3.4. Reserved Option Values .....................................9
4. Interoperability Issues .........................................9
4.1. Middleboxes ................................................9
4.2. TCP Keep-Alives ...........................................10
5. Programming and Manageability Considerations ...................10
6. Security Considerations ........................................10
7. IANA Considerations ............................................12
8. Acknowledgments ................................................12
9. References .....................................................12
9.1. Normative References ......................................12
9.2. Informative References ....................................13
1. Introduction
The Transmission Control Protocol (TCP) specification [RFC0793]
defines a local, per-connection "user timeout" parameter that
specifies the maximum amount of time that transmitted data may remain
unacknowledged before TCP will forcefully close the corresponding
connection. Applications can set and change this parameter with OPEN
and SEND calls. If an end-to-end connectivity disruption lasts
longer than the user timeout, a sender will receive no
acknowledgments for any transmission attempt, including keep-alives,
and it will close the TCP connection when the user timeout occurs.
This document specifies a new TCP option -- the TCP User Timeout
Option (UTO) -- that allows one end of a TCP connection to advertise
its current user timeout value. This information provides advice to
the other end of the connection to adapt its user timeout
accordingly. That is, TCP remains free to disregard the advice
provided by the UTO option if local policies suggest it to be
appropriate.
Increasing the user timeouts on both ends of a TCP connection allows
it to survive extended periods without end-to-end connectivity.
Decreasing the user timeouts allows busy servers to explicitly notify
their clients that they will maintain the connection state only for a
short time without connectivity.
Eggert & Gont Standards Track [Page 2]
RFC 5482 TCP User Timeout Option March 2009
In the absence of an application-specified user timeout, the TCP
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