draft-ietf-tcpm-ecnsyn-04.txt   draft-ietf-tcpm-ecnsyn-05.txt 
Internet Engineering Task Force A. Kuzmanovic Internet Engineering Task Force A. Kuzmanovic
INTERNET-DRAFT A. Mondal INTERNET-DRAFT A. Mondal
Intended status: Proposed Standard Northwestern University Intended status: Proposed Standard Northwestern University
Expires: 8 July 2008 S. Floyd Expires: 19 August 2008 S. Floyd
ICIR ICIR
K.K. Ramakrishnan K.K. Ramakrishnan
AT&T AT&T
8 January 2008 19 February 2008
Adding Explicit Congestion Notification (ECN) Capability Adding Explicit Congestion Notification (ECN) Capability
to TCP's SYN/ACK Packets to TCP's SYN/ACK Packets
draft-ietf-tcpm-ecnsyn-04.txt draft-ietf-tcpm-ecnsyn-05.txt
Status of this Memo Status of this Memo
By submitting this Internet-Draft, each author represents that any By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79. aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
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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."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
This Internet-Draft will expire on December 2007. This Internet-Draft will expire on August 2008.
Copyright Notice Copyright Notice
Copyright (C) The IETF Trust (2007). Copyright (C) The IETF Trust (2008).
Abstract Abstract
This draft specifies a modification to RFC 3168 to allow TCP SYN/ACK This draft specifies a modification to RFC 3168 to allow TCP SYN/ACK
packets to be ECN-Capable. For TCP, RFC 3168 only specifies setting packets to be ECN-Capable. For TCP, RFC 3168 only specifies setting
an ECN-Capable codepoint on data packets, and not on SYN and SYN/ACK an ECN-Capable codepoint on data packets, and not on SYN and SYN/ACK
packets. However, because of the high cost to the TCP transfer of packets. However, because of the high cost to the TCP transfer of
having a SYN/ACK packet dropped, with the resulting retransmit having a SYN/ACK packet dropped, with the resulting retransmit
timeout, this document specifies the use of ECN for the SYN/ACK timeout, this document specifies the use of ECN for the SYN/ACK
packet itself, when sent in response to a SYN packet with the two ECN packet itself, when sent in response to a SYN packet with the two ECN
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timeout for a connection that has not yet started placing a load on timeout for a connection that has not yet started placing a load on
the network. The sender of the SYN/ACK packet must respond to a the network. The sender of the SYN/ACK packet must respond to a
report of an ECN-marked SYN/ACK packet by reducing its initial report of an ECN-marked SYN/ACK packet by reducing its initial
congestion window from two, three, or four segments to one segment, congestion window from two, three, or four segments to one segment,
thereby reducing the subsequent load from that connection on the thereby reducing the subsequent load from that connection on the
network. This document is intended to update RFC 3168. network. This document is intended to update RFC 3168.
Table of Contents Table of Contents
1. Introduction ....................................................4 1. Introduction ....................................................4
2. Conventions and Terminology .....................................6 2. Conventions and Terminology .....................................5
3. Proposal ........................................................6 3. Proposal ........................................................6
4. Discussion ......................................................9 4. Discussion ......................................................9
5. Related Work ...................................................12 5. Related Work ...................................................12
6. Performance Evaluation .........................................13 6. Performance Evaluation .........................................12
6.1. The Costs and Benefit of Adding ECN-Capability ............13 6.1. The Costs and Benefit of Adding ECN-Capability ............12
6.2. An Evaluation of Different Responses to ECN-Marked SYN/ACK 6.2. An Evaluation of Different Responses to ECN-Marked SYN/ACK
Packets ........................................................14 Packets ........................................................14
7. Security Considerations ........................................15 7. Security Considerations ........................................14
8. Conclusions ....................................................16 8. Conclusions ....................................................16
9. Acknowledgements ...............................................17 9. Acknowledgements ...............................................16
A. Report on Simulations ..........................................17 A. Report on Simulations ..........................................17
A.1. Simulations with RED in Packet Mode .......................17 A.1. Simulations with RED in Packet Mode .......................17
A.2. Simulations with RED in Byte Mode .........................19 A.2. Simulations with RED in Byte Mode .........................19
B. Issues of Incremental Deployment ...............................20 B. Issues of Incremental Deployment ...............................20
Normative References ..............................................23 Normative References ..............................................23
Informative References ............................................23 Informative References ............................................23
IANA Considerations ...............................................24 IANA Considerations ...............................................24
Full Copyright Statement ..........................................25 Full Copyright Statement ..........................................25
Intellectual Property .............................................25 Intellectual Property .............................................25
NOTE TO RFC EDITOR: PLEASE DELETE THIS NOTE UPON PUBLICATION. NOTE TO RFC EDITOR: PLEASE DELETE THIS NOTE UPON PUBLICATION.
Changes from draft-ietf-tcpm-ecnsyn-04:
* Updating the copyright date.
Changes from draft-ietf-tcpm-ecnsyn-03: Changes from draft-ietf-tcpm-ecnsyn-03:
* General editing. This includes using the terms "initiator" * General editing. This includes using the terms "initiator"
and "responder" for the two ends of the TCP connection. and "responder" for the two ends of the TCP connection.
Feedback from Alfred Hoenes. Feedback from Alfred Hoenes.
* Added some text to the backwards compatibility discussion, * Added some text to the backwards compatibility discussion,
now in Appendix B, about the pros and cons of using a TCP now in Appendix B, about the pros and cons of using a TCP
flag for the TCP initiator to signal that it understands flag for the TCP initiator to signal that it understands
ECN-Capable SYN/ACK packets. The consensus at this time is ECN-Capable SYN/ACK packets. The consensus at this time is
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URL: http://www.icir.org/floyd/ URL: http://www.icir.org/floyd/
K. K. Ramakrishnan K. K. Ramakrishnan
Phone: +1 (973) 360-8764 Phone: +1 (973) 360-8764
AT&T Labs Research AT&T Labs Research
Email: kkrama at research.att.com Email: kkrama at research.att.com
URL: http://www.research.att.com/info/kkrama URL: http://www.research.att.com/info/kkrama
Full Copyright Statement Full Copyright Statement
Copyright (C) The IETF Trust (2007). Copyright (C) The IETF Trust (2008).
This document is subject to the rights, licenses and restrictions This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors contained in BCP 78, and except as set forth therein, the authors
retain all their rights. retain all their rights.
This document and the information contained herein are provided on an This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
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