draft-ietf-tcpm-tcp-edo-08.txt   draft-ietf-tcpm-tcp-edo-09.txt 
TCPM WG J. Touch TCPM WG J. Touch
Internet Draft USC/ISI Internet Draft
Updates: 793 Wes Eddy Updates: 793 Wes Eddy
Intended status: Standards Track MTI Systems Intended status: Standards Track MTI Systems
Expires: December 2017 June 26, 2017 Expires: July 2018 January 19, 2018
TCP Extended Data Offset Option TCP Extended Data Offset Option
draft-ietf-tcpm-tcp-edo-08.txt draft-ietf-tcpm-tcp-edo-09.txt
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), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet- other groups may also distribute working documents as Internet-
Drafts. Drafts.
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months and may be updated, replaced, or obsoleted by other documents months and may be updated, replaced, or obsoleted by other documents
at any time. It is inappropriate to use Internet-Drafts as at any time. It is inappropriate to use Internet-Drafts as
reference material or to cite them other than as "work in progress." reference 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
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The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
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This Internet-Draft will expire on December 26, 2017. This Internet-Draft will expire on July 19, 2018.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2018 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
carefully, as they describe your rights and restrictions with carefully, as they describe your rights and restrictions with
respect to this document. Code Components extracted from this respect to this document. Code Components extracted from this
document must include Simplified BSD License text as described in document must include Simplified BSD License text as described in
Section 4.e of the Trust Legal Provisions and are provided without Section 4.e of the Trust Legal Provisions and are provided without
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This document specifies the TCP Extended Data Offset (EDO) option, This document specifies the TCP Extended Data Offset (EDO) option,
and is independent of (and thus compatible with) IPv4 and IPv6. EDO and is independent of (and thus compatible with) IPv4 and IPv6. EDO
extends the space available for TCP options, except for the initial extends the space available for TCP options, except for the initial
SYN and SYN/ACK. This document also explains why the option space of SYN and SYN/ACK. This document also explains why the option space of
the initial SYN segments cannot be extended as individual segments the initial SYN segments cannot be extended as individual segments
without severe impact on TCP's initial handshake and the SYN/ACK without severe impact on TCP's initial handshake and the SYN/ACK
limitation that results from potential middlebox misbehavior. limitation that results from potential middlebox misbehavior.
Multiple other TCP extensions are being considered in the TCPM Multiple other TCP extensions are being considered in the TCPM
working group in order to address the case of SYN and SYN/ACK working group in order to address the case of SYN and SYN/ACK
segments [Bo14][Br14][To17]. Some of these other extensions can work segments [Bo14][Br14][To18]. Some of these other extensions can work
in conjunction with EDO (e.g., [To17]). in conjunction with EDO (e.g., [To18]).
2. Conventions used in this document 2. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC-2119 [RFC2119]. document are to be interpreted as described in RFC-2119 [RFC2119].
In this document, these words will appear with that interpretation In this document, these words will appear with that interpretation
only when in ALL CAPS. Lower case uses of these words are not to be only when in ALL CAPS. Lower case uses of these words are not to be
interpreted as carrying RFC-2119 significance. interpreted as carrying RFC-2119 significance.
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segments. segments.
The full combination of the above options (47 bytes for TS, WS, MSS, The full combination of the above options (47 bytes for TS, WS, MSS,
SACK, TCP-AO, and MPTCP) does not fit in the existing SYN option SACK, TCP-AO, and MPTCP) does not fit in the existing SYN option
space and (as noted) that space cannot be extended within a single space and (as noted) that space cannot be extended within a single
SYN segment. There has been a proposal to change TS to a 2 byte "TS SYN segment. There has been a proposal to change TS to a 2 byte "TS
permitted" signal in the initial SYN, provided it can be safely permitted" signal in the initial SYN, provided it can be safely
enabled during the connection later or might be avoided completely enabled during the connection later or might be avoided completely
[Ni15]. Even using "TS-permitted", the total space is still too [Ni15]. Even using "TS-permitted", the total space is still too
large to support in the initial SYN without SYN option space large to support in the initial SYN without SYN option space
extension [Bo14][Br14][To17]. extension [Bo14][Br14][To18].
The EDO Extension option has negligible impact on other headers, The EDO Extension option has negligible impact on other headers,
because it can either come first or just after security information, because it can either come first or just after security information,
and in either case the additional 4 or 6 bytes are easily and in either case the additional 4 or 6 bytes are easily
accommodated within the TCP Data Offset length. Once the EDO option accommodated within the TCP Data Offset length. Once the EDO option
is processed, the entirety of the remainder of the TCP segment is is processed, the entirety of the remainder of the TCP segment is
available for any remaining options. available for any remaining options.
6.5. Connectionless Resets 6.5. Connectionless Resets
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larger than the required Kind and Length components, so the larger than the required Kind and Length components, so the
resulting efficiency is typically insufficient for additional resulting efficiency is typically insufficient for additional
options. options.
The option space of an initial SYN segment might be extended by The option space of an initial SYN segment might be extended by
using multiple initial segments (e.g., multiple SYNs or a SYN and using multiple initial segments (e.g., multiple SYNs or a SYN and
non-SYN) or based on the context of previous or parallel non-SYN) or based on the context of previous or parallel
connections. This method may also be needed to extend space in the connections. This method may also be needed to extend space in the
SYN/ACK in the presence of misbehaving middleboxes. Because of their SYN/ACK in the presence of misbehaving middleboxes. Because of their
potential complexity, these approaches are addressed in separate potential complexity, these approaches are addressed in separate
documents [Bo14][Br14][To17]. documents [Bo14][Br14][To18].
Option space cannot be extended in outer layer headers, e.g., IPv4 Option space cannot be extended in outer layer headers, e.g., IPv4
or IPv6. These layers typically try to avoid extensions altogether, or IPv6. These layers typically try to avoid extensions altogether,
to simplify forwarding processing at routers. Introducing new shim to simplify forwarding processing at routers. Introducing new shim
layers to accommodate additional option space would interfere with layers to accommodate additional option space would interfere with
deep-packet inspection mechanisms that are in widespread use. deep-packet inspection mechanisms that are in widespread use.
As a result, EDO does not attempt to extend the space available for As a result, EDO does not attempt to extend the space available for
options in TCP initial SYNs. It does extend that space in all other options in TCP initial SYNs. It does extend that space in all other
segments (including SYN/ACK), which has always been trivially segments (including SYN/ACK), which has always been trivially
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in this document with codepoint value. in this document with codepoint value.
The TCP Experimental ID (ExID) with a 16-bit value of 0x0ED0 (in The TCP Experimental ID (ExID) with a 16-bit value of 0x0ED0 (in
network standard byte order) has been assigned for use during network standard byte order) has been assigned for use during
testing and preliminary experiments. testing and preliminary experiments.
12. References 12. References
12.1. Normative References 12.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC793] Postel, J., "Transmission Control Protocol", STD 7, RFC [RFC793] Postel, J., "Transmission Control Protocol", STD 7, RFC
793, September 1981. 793, September 1981.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
12.2. Informative References 12.2. Informative References
[Al06] Allman, M., "TCPx2: Don't Fence Me In", draft-allman- [Al06] Allman, M., "TCPx2: Don't Fence Me In", draft-allman-
tcpx2-hack-00 (work in progress), May 2006. tcpx2-hack-00 (work in progress), May 2006.
[Bo14] Borman, D., "TCP Four-Way Handshake", draft-borman- [Bo14] Borman, D., "TCP Four-Way Handshake", draft-borman-
tcp4way-00 (work in progress), October 2014. tcp4way-00 (work in progress), October 2014.
[Br14] Briscoe, B., "Inner Space for TCP Options", draft-briscoe- [Br14] Briscoe, B., "Inner Space for TCP Options", draft-briscoe-
tcpm-inner-space-01 (work in progress), October 2014. tcpm-inner-space-01 (work in progress), October 2014.
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"TCP Extensions for Multipath Operation with Multiple "TCP Extensions for Multipath Operation with Multiple
Addresses", RFC 6824, January 2013. Addresses", RFC 6824, January 2013.
[RFC7323] Borman, D., Braden, B., Jacobson, V., and R. Scheffenegger [RFC7323] Borman, D., Braden, B., Jacobson, V., and R. Scheffenegger
(Ed.), "TCP Extensions for High Performance", RFC 7323, (Ed.), "TCP Extensions for High Performance", RFC 7323,
September 2014. September 2014.
[RFC7413] Cheng, Y., Chu, J., Radhakrishnan, S., and A. Jain, "TCP [RFC7413] Cheng, Y., Chu, J., Radhakrishnan, S., and A. Jain, "TCP
Fast Open", RFC 7413, December 2014. Fast Open", RFC 7413, December 2014.
[To17] Touch, J., T. Faber, "TCP SYN Extended Option Space Using [To18] Touch, J., T. Faber, "TCP SYN Extended Option Space Using
an Out-of-Band Segment", draft-touch-tcpm-tcp-syn-ext-opt- an Out-of-Band Segment", draft-touch-tcpm-tcp-syn-ext-opt
07 (work in progress), June 2017. (work in progress), Jan. 2018.
[Yo11] Yourtchenko, A., "Introducing TCP Long Options by Invalid [Yo11] Yourtchenko, A., "Introducing TCP Long Options by Invalid
Checksum", draft-yourtchenko-tcp-loic-00 (work in Checksum", draft-yourtchenko-tcp-loic-00 (work in
progress), April 2011. progress), April 2011.
13. Acknowledgments 13. Acknowledgments
The authors would like to thank the IETF TCPM WG for their feedback, The authors would like to thank the IETF TCPM WG for their feedback,
in particular: Oliver Bonaventure, Bob Briscoe, Ted Faber, John in particular: Oliver Bonaventure, Bob Briscoe, Ted Faber, John
Leslie, Pasi Sarolahti, Richard Scheffenegger, and Alexander Leslie, Pasi Sarolahti, Richard Scheffenegger, and Alexander
Zimmerman. Zimmerman.
This work is partly supported by USC/ISI's Postel Center. This work is partly supported by USC/ISI's Postel Center.
This document was prepared using 2-Word-v2.0.template.dot. This document was prepared using 2-Word-v2.0.template.dot.
Authors' Addresses Authors' Addresses
Joe Touch Joe Touch
USC/ISI
4676 Admiralty Way
Marina del Rey, CA 90292-6695 USA
Phone: +1 (310) 448-9151 Manhattan Beach, CA 90266 USA
Email: touch@isi.edu
Phone: +1 (310) 560-0334
Email: touch@strayalpha.com
Wesley M. Eddy Wesley M. Eddy
MTI Systems MTI Systems
US US
Email: wes@mti-systems.com Email: wes@mti-systems.com
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