draft-ietf-tcpm-1323bis-18.txt   draft-ietf-tcpm-1323bis-19.txt 
TCP Maintenance (TCPM) D. Borman TCP Maintenance (TCPM) D. Borman
Internet-Draft Quantum Corporation Internet-Draft Quantum Corporation
Obsoletes: 1323 (if approved) B. Braden Obsoletes: 1323 (if approved) B. Braden
Intended status: Standards Track University of Southern Intended status: Standards Track University of Southern
Expires: June 8, 2014 California Expires: July 28, 2014 California
V. Jacobson V. Jacobson
Google, Inc. Google, Inc.
R. Scheffenegger, Ed. R. Scheffenegger, Ed.
NetApp, Inc. NetApp, Inc.
December 5, 2013 January 24, 2014
TCP Extensions for High Performance TCP Extensions for High Performance
draft-ietf-tcpm-1323bis-18 draft-ietf-tcpm-1323bis-19
Abstract Abstract
This document specifies a set of TCP extensions to improve This document specifies a set of TCP extensions to improve
performance over paths with a large bandwidth * delay product and to performance over paths with a large bandwidth * delay product and to
provide reliable operation over very high-speed paths. It defines provide reliable operation over very high-speed paths. It defines
the TCP Window Scale (WS) option and the TCP Timestamps (TS) option the TCP Window Scale (WS) option and the TCP Timestamps (TS) option
and their semantics. The Window Scale option is used to support and their semantics. The Window Scale option is used to support
larger receive windows, while the Timestamps option can be used for larger receive windows, while the Timestamps option can be used for
at least two distinct mechanisms, PAWS (Protection Against Wrapped at least two distinct mechanisms, PAWS (Protection Against Wrapped
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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 June 8, 2014. This Internet-Draft will expire on July 28, 2014.
Copyright Notice Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the Copyright (c) 2014 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 respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
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This option is an offer, not a promise; both sides MUST send Window This option is an offer, not a promise; both sides MUST send Window
Scale options in their <SYN> segments to enable window scaling in Scale options in their <SYN> segments to enable window scaling in
either direction. If window scaling is enabled, then the TCP that either direction. If window scaling is enabled, then the TCP that
sent this option will right-shift its true receive-window values by sent this option will right-shift its true receive-window values by
'shift.cnt' bits for transmission in SEG.WND. The value 'shift.cnt' 'shift.cnt' bits for transmission in SEG.WND. The value 'shift.cnt'
MAY be zero (offering to scale, while applying a scale factor of 1 to MAY be zero (offering to scale, while applying a scale factor of 1 to
the receive window). the receive window).
This option MAY be sent in an initial <SYN> segment (i.e., a segment This option MAY be sent in an initial <SYN> segment (i.e., a segment
with the SYN bit on and the ACK bit off). It MAY also be sent in a with the SYN bit on and the ACK bit off). If a Window Scale option
<SYN,ACK> segment, but only if a Window Scale option was received in was received in the initial <SYN> segment, then this option MAY be
the initial <SYN> segment. A Window Scale option in a segment sent in the <SYN,ACK> segment. A Window Scale option in a segment
without a SYN bit MUST be ignored. without a SYN bit MUST be ignored.
The window field in a segment where the SYN bit is set (i.e., a <SYN> The window field in a segment where the SYN bit is set (i.e., a <SYN>
or <SYN,ACK>) MUST NOT be scaled. or <SYN,ACK>) MUST NOT be scaled.
2.3. Using the Window Scale option 2.3. Using the Window Scale option
A model implementation of window scaling is as follows, using the A model implementation of window scaling is as follows, using the
notation of [RFC0793]: notation of [RFC0793]:
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therefore RECOMMENDED to generate a random, per-connection offset to therefore RECOMMENDED to generate a random, per-connection offset to
be used with the clock source when generating the Timestamps option be used with the clock source when generating the Timestamps option
value (see Section 5.4). value (see Section 5.4).
Furthermore, the combination, relative ordering and padding of the Furthermore, the combination, relative ordering and padding of the
TCP options described in Section 2.2 and Section 3.2 will reveal TCP options described in Section 2.2 and Section 3.2 will reveal
additional clues to allow the fingerprinting of the system. additional clues to allow the fingerprinting of the system.
8. IANA Considerations 8. IANA Considerations
This document has no actions for IANA. The described TCP options are The described TCP options are well known from the superceded
well known from the superceded [RFC1323]. [RFC1323]. IANA is requested to update the "TCP Option Kind Numbers"
table under "TCP parameters" to list <this-RFC-to-be> as the
reference for the options "WSopt - Window Scale Option" and "TSopt -
Timestamps Option".
9. References 9. References
9.1. Normative References 9.1. Normative References
[RFC0793] Postel, J., "Transmission Control Protocol", STD 7, [RFC0793] Postel, J., "Transmission Control Protocol", STD 7,
RFC 793, September 1981. RFC 793, September 1981.
[RFC1191] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191, [RFC1191] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191,
November 1990. November 1990.
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