draft-ietf-tcpm-rtorestart-09.txt   draft-ietf-tcpm-rtorestart-10.txt 
TCP Maintenance and Minor Extensions (tcpm) P. Hurtig TCP Maintenance and Minor Extensions (tcpm) P. Hurtig
Internet-Draft A. Brunstrom Internet-Draft A. Brunstrom
Intended status: Experimental Karlstad University Intended status: Experimental Karlstad University
Expires: April 22, 2016 A. Petlund Expires: May 8, 2016 A. Petlund
Simula Research Laboratory AS Simula Research Laboratory AS
M. Welzl M. Welzl
University of Oslo University of Oslo
October 20, 2015 November 5, 2015
TCP and SCTP RTO Restart TCP and SCTP RTO Restart
draft-ietf-tcpm-rtorestart-09 draft-ietf-tcpm-rtorestart-10
Abstract Abstract
This document describes a modified sender-side algorithm for managing This document describes a modified sender-side algorithm for managing
the TCP and SCTP retransmission timers that provides faster loss the TCP and SCTP retransmission timers that provides faster loss
recovery when there is a small amount of outstanding data for a recovery when there is a small amount of outstanding data for a
connection. The modification, RTO Restart (RTOR), allows the connection. The modification, RTO Restart (RTOR), allows the
transport to restart its retransmission timer using a smaller delay, transport to restart its retransmission timer using a smaller timeout
so that the effective RTO becomes more aggressive in situations where duration, so that the effective RTO becomes more aggressive in
fast retransmit cannot be used. This enables faster loss detection situations where fast retransmit cannot be used. This enables faster
and recovery for connections that are short-lived or application- loss detection and recovery for connections that are short-lived or
limited. application-limited.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 22, 2016. This Internet-Draft will expire on May 8, 2016.
Copyright Notice Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
skipping to change at page 11, line 23 skipping to change at page 11, line 23
All the authors are supported by RITE (http://riteproject.eu/ ), a All the authors are supported by RITE (http://riteproject.eu/ ), a
research project (ICT-317700) funded by the European Community under research project (ICT-317700) funded by the European Community under
its Seventh Framework Program. The views expressed here are those of its Seventh Framework Program. The views expressed here are those of
the author(s) only. The European Commission is not liable for any the author(s) only. The European Commission is not liable for any
use that may be made of the information in this document. use that may be made of the information in this document.
11. Changes from Previous Versions 11. Changes from Previous Versions
RFC-Editor note: please remove this section prior to publication. RFC-Editor note: please remove this section prior to publication.
11.1. Changed from draft-ietf-...-08 to -09 11.1. Changed from draft-ietf-...-09 to -10
o Changed wording in abstract, from "delay" to "timeout duration".
11.2. Changed from draft-ietf-...-08 to -09
o Clarified, in the abstract, that the modified restart causes a o Clarified, in the abstract, that the modified restart causes a
smaller retransmission delay in total. smaller retransmission delay in total.
o Clarified, in the introduction, that the fast retransmit algorithm o Clarified, in the introduction, that the fast retransmit algorithm
may cause retransmissions upon receiving duplicate may cause retransmissions upon receiving duplicate
acknowledgments, not that it unconditionally does so. acknowledgments, not that it unconditionally does so.
o Changed wording from "to proposed standard" to "to the standards o Changed wording from "to proposed standard" to "to the standards
track". track".
o Changed algorithm description so that a TCP sender MUST track the o Changed algorithm description so that a TCP sender MUST track the
time elapsed since the transmission of the earliest outstanding time elapsed since the transmission of the earliest outstanding
segment. This was not explicitly stated in previous versions of segment. This was not explicitly stated in previous versions of
the draft. the draft.
11.2. Changes from draft-ietf-...-07 to -08 11.3. Changes from draft-ietf-...-07 to -08
o Clarified, at multiple places in the document, that the o Clarified, at multiple places in the document, that the
modification only causes the effective RTO to be more aggressive, modification only causes the effective RTO to be more aggressive,
not the actual RTO. not the actual RTO.
o Removed information in the introduction that was too detailed, o Removed information in the introduction that was too detailed,
i.e., material that is hard to understand without knowing details i.e., material that is hard to understand without knowing details
of the algorithm. of the algorithm.
o Changed the name of Section 3 to more correctly capture the actual o Changed the name of Section 3 to more correctly capture the actual
skipping to change at page 12, line 17 skipping to change at page 12, line 20
o Moved text from the algorithm description (Section 4) to the o Moved text from the algorithm description (Section 4) to the
introduction of the discussion section (Section 5). The text was introduction of the discussion section (Section 5). The text was
discussing the possible effects of the algorithm more than discussing the possible effects of the algorithm more than
describing the actual algorithm. describing the actual algorithm.
o Clarified why the RECOMMENDED value of rrthresh is four. o Clarified why the RECOMMENDED value of rrthresh is four.
o Reworked the introduction to be suitable for both TCP and SCTP. o Reworked the introduction to be suitable for both TCP and SCTP.
11.3. Changes from draft-ietf-...-06 to -07 11.4. Changes from draft-ietf-...-06 to -07
o Clarified, at multiple places in the document, that the o Clarified, at multiple places in the document, that the
modification is sender-only. modification is sender-only.
o Added an explanation (in the introduction) to why the mechanism is o Added an explanation (in the introduction) to why the mechanism is
experimental and what experiments are missing. experimental and what experiments are missing.
o Added a sentence in Section 4 to clarify that the section is the o Added a sentence in Section 4 to clarify that the section is the
one describing the actual modification. one describing the actual modification.
11.4. Changes from draft-ietf-...-05 to -06 11.5. Changes from draft-ietf-...-05 to -06
o Added socket API considerations, after discussing the draft in o Added socket API considerations, after discussing the draft in
tsvwg. tsvwg.
11.5. Changes from draft-ietf-...-04 to -05 11.6. Changes from draft-ietf-...-04 to -05
o Introduced variable to track the number of previously unsent o Introduced variable to track the number of previously unsent
segments. segments.
o Clarified many concepts, e.g. extended the description on how to o Clarified many concepts, e.g. extended the description on how to
track outstanding and previously unsent segments. track outstanding and previously unsent segments.
o Added a reference to initial measurements on the effects of using o Added a reference to initial measurements on the effects of using
RTOR. RTOR.
o Improved wording throughout the document. o Improved wording throughout the document.
11.6. Changes from draft-ietf-...-03 to -04 11.7. Changes from draft-ietf-...-03 to -04
o Changed the algorithm to allow RTOR when there is unsent data o Changed the algorithm to allow RTOR when there is unsent data
available, but the cwnd does not allow transmission. available, but the cwnd does not allow transmission.
o Changed the algorithm to not trigger if RTOR <= 0. o Changed the algorithm to not trigger if RTOR <= 0.
o Made minor adjustments throughout the document to adjust for the o Made minor adjustments throughout the document to adjust for the
algorithmic change. algorithmic change.
o Improved the wording throughout the document. o Improved the wording throughout the document.
11.7. Changes from draft-ietf-...-02 to -03 11.8. Changes from draft-ietf-...-02 to -03
o Updated the document to use "RTOR" instead of "RTO Restart" when o Updated the document to use "RTOR" instead of "RTO Restart" when
refering to the modified algorithm. refering to the modified algorithm.
o Moved document terminology to a section of its own. o Moved document terminology to a section of its own.
o Introduced the rrthresh variable in the terminology section. o Introduced the rrthresh variable in the terminology section.
o Added a section to generalize the tracking of outstanding o Added a section to generalize the tracking of outstanding
segments. segments.
o Updated the algorithm to work when the number of outstanding o Updated the algorithm to work when the number of outstanding
segments is less than four and one segment is ready for segments is less than four and one segment is ready for
transmission, by restarting the timer when new data has been sent. transmission, by restarting the timer when new data has been sent.
o Clarified the relationship between fast retransmit and RTOR. o Clarified the relationship between fast retransmit and RTOR.
o Improved the wording throughout the document. o Improved the wording throughout the document.
11.8. Changes from draft-ietf-...-01 to -02 11.9. Changes from draft-ietf-...-01 to -02
o Changed the algorithm description in Section 3 to use formal RFC o Changed the algorithm description in Section 3 to use formal RFC
2119 language. 2119 language.
o Changed last paragraph of Section 3 to clarify why the RTO restart o Changed last paragraph of Section 3 to clarify why the RTO restart
algorithm is active when less than four segments are outstanding. algorithm is active when less than four segments are outstanding.
o Added two paragraphs in Section 4.1 to clarify why the algorithm o Added two paragraphs in Section 4.1 to clarify why the algorithm
can be turned on for all TCP traffic without having any negative can be turned on for all TCP traffic without having any negative
effects on traffic patterns that do not benefit from a modified effects on traffic patterns that do not benefit from a modified
timer restart. timer restart.
o Improved the wording throughout the document. o Improved the wording throughout the document.
o Replaced and updated some references. o Replaced and updated some references.
11.9. Changes from draft-ietf-...-00 to -01 11.10. Changes from draft-ietf-...-00 to -01
o Improved the wording throughout the document. o Improved the wording throughout the document.
o Removed the possibility for a connection limited by the receiver's o Removed the possibility for a connection limited by the receiver's
advertised window to use RTO restart, decreasing the risk of advertised window to use RTO restart, decreasing the risk of
spurious retransmission timeouts. spurious retransmission timeouts.
o Added a section that discusses the applicability of and problems o Added a section that discusses the applicability of and problems
related to the RTO restart mechanism. related to the RTO restart mechanism.
 End of changes. 14 change blocks. 
18 lines changed or deleted 22 lines changed or added

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