draft-ietf-tcpm-initcwnd-01.txt   draft-ietf-tcpm-initcwnd-02.txt 
Internet Draft J. Chu Internet Draft J. Chu
draft-ietf-tcpm-initcwnd-01.txt N. Dukkipati draft-ietf-tcpm-initcwnd-02.txt N. Dukkipati
Intended status: Standard Y. Cheng Intended status: Standard Y. Cheng
Updates: 3390, 5681 M. Mathis Updates: 3390, 5681 M. Mathis
Creation date: April 15, 2011 Google, Inc. Creation date: October 16, 2011 Google, Inc.
Expiration date: October 2011 Expiration date: April 2012
Increasing TCP's Initial Window Increasing TCP's Initial Window
Status of this Memo Status of this Memo
Distribution of this memo is unlimited. Distribution of this memo is unlimited.
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.
skipping to change at page 4, line 18 skipping to change at page 4, line 18
first round trip time (RTT) of data transmission following the TCP first round trip time (RTT) of data transmission following the TCP
three-way handshake. Neither the SYN/ACK nor its acknowledgment (ACK) three-way handshake. Neither the SYN/ACK nor its acknowledgment (ACK)
in the three-way handshake should increase the initial window size. in the three-way handshake should increase the initial window size.
Furthermore, RFC 3390 and RFC 5681 [RFC5681] state that Furthermore, RFC 3390 and RFC 5681 [RFC5681] state that
"If the SYN or SYN/ACK is lost, the initial window used by a "If the SYN or SYN/ACK is lost, the initial window used by a
sender after a correctly transmitted SYN MUST be one segment sender after a correctly transmitted SYN MUST be one segment
consisting of MSS bytes." consisting of MSS bytes."
The proposed change to reduce the default RTO to 1 second [PACS11] The proposed change to reduce the default RTO to 1 second [RFC6298]
increases the chance for spurious SYN or SYN/ACK retransmission, thus increases the chance for spurious SYN or SYN/ACK retransmission, thus
unnecessarily penalizing connections with RTT > 1 second if their unnecessarily penalizing connections with RTT > 1 second if their
initial window is reduced to 1 segment. For this reason, it is initial window is reduced to 1 segment. For this reason, it is
RECOMMENDED that implementations refrain from resetting the initial RECOMMENDED that implementations refrain from resetting the initial
window to 1 segment, unless either there have been multiple SYN or window to 1 segment, unless either there have been multiple SYN or
SYN/ACK retransmissions, or true loss detection has been made. SYN/ACK retransmissions, or true loss detection has been made.
TCP implementations use slow start in as many as three different TCP implementations use slow start in as many as three different
ways: (1) to start a new connection (the initial window); (2) to ways: (1) to start a new connection (the initial window); (2) to
restart transmission after a long idle period (the restart window); restart transmission after a long idle period (the restart window);
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16. Acknowledgments 16. Acknowledgments
Many people at Google have helped to make the set of large scale Many people at Google have helped to make the set of large scale
tests possible. We would especially like to acknowledge Amit Agarwal, tests possible. We would especially like to acknowledge Amit Agarwal,
Tom Herbert, Arvind Jain and Tiziana Refice for their major Tom Herbert, Arvind Jain and Tiziana Refice for their major
contributions. contributions.
Normative References Normative References
[PACS11] Paxson, V., Allman, M., Chu, J. and M. Sargent, "Computing [RFC6298] Paxson, V., Allman, M., Chu, J. and M. Sargent, "Computing
TCP's Retransmission Timer", Internet-draft draft-paxson- TCP's Retransmission Timer", RFC6298, June 2011.
tcpm-rfc2988bis-02, work in progress.
[RFC2018] Mathis, M., Mahdavi, J., Floyd, S. and A. Romanow, "TCP [RFC2018] Mathis, M., Mahdavi, J., Floyd, S. and A. Romanow, "TCP
Selective Acknowledgement Options", RFC 2018, October 1996. Selective Acknowledgement Options", RFC 2018, October 1996.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, [RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter,
L., Leach, P. and T. Berners-Lee, "Hypertext Transfer L., Leach, P. and T. Berners-Lee, "Hypertext Transfer
Protocol -- HTTP/1.1", RFC 2616, June 1999. Protocol -- HTTP/1.1", RFC 2616, June 1999.
skipping to change at page 19, line 41 skipping to change at page 19, line 40
[SPDY] "SPDY: An experimental protocol for a faster web", URL [SPDY] "SPDY: An experimental protocol for a faster web", URL
http://dev.chromium.org/spdy http://dev.chromium.org/spdy
[Ste08] Sounders S., "Roundup on Parallel Connections", High [Ste08] Sounders S., "Roundup on Parallel Connections", High
Performance Web Sites blog. URL Performance Web Sites blog. URL
http://www.stevesouders.com/blog/2008/03/20/roundup-on- http://www.stevesouders.com/blog/2008/03/20/roundup-on-
parallel-connections parallel-connections
[Tou10] Touch, J., "Automating the Initial Window in TCP", [Tou10] Touch, J., "Automating the Initial Window in TCP",
Internet-draft draft-touch-tcpm-automatic-iw-00.txt, work Internet-draft draft-touch-tcpm-automatic-iw-01.txt, work
in progress. in progress.
[VH97] Visweswaraiah, V. and J. Heidemann, "Improving Restart of [VH97] Visweswaraiah, V. and J. Heidemann, "Improving Restart of
Idle TCP Connections", Technical Report 97-661, University Idle TCP Connections", Technical Report 97-661, University
of Southern California, November 1997. of Southern California, November 1997.
Author's Addresses Author's Addresses
H.K. Jerry Chu Jerry Chu
Google, Inc. Google, Inc.
1600 Amphitheatre Parkway 1600 Amphitheatre Parkway
Mountain View, CA 94043 Mountain View, CA 94043
USA USA
EMail: hkchu@google.com EMail: hkchu@google.com
Nandita Dukkipati Nandita Dukkipati
Google, Inc. Google, Inc.
1600 Amphitheatre Parkway 1600 Amphitheatre Parkway
Mountain View, CA 94043 Mountain View, CA 94043
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