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Document Action: 'Improving the Robustness of TCP to Non-Congestion Events' to Experimental RFC
The IESG has approved the following document:
- 'Improving the Robustness of TCP to Non-Congestion Events '
<draft-ietf-tcpm-tcp-dcr-07.txt> as an Experimental RFC
This document is the product of the TCP Maintenance and Minor Extensions
Working Group.
The IESG contact persons are Lars Eggert and Magnus Westerlund.
A URL of this Internet-Draft is:
http://www.ietf.org/internet-drafts/draft-ietf-tcpm-tcp-dcr-07.txt
Technical Summary
This document specifies Non-Congestion Robustness (NCR) for TCP.
One of the ways TCP detects loss is using the arrival of three duplicate
acknowledgments. However, this heuristic is not always correct, notably
in the case when network paths reorder segments. TCP-NCR is designed
to mitigate this degraded performance by increasing the number of
duplicate acknowledgments required to trigger loss recovery, based on
the current state of the connection, in an effort to better disambiguate
true segment loss from segment reordering.
Working Group Summary
This draft has attracted considerable interest in the WG, with many
different people commenting on reviewing various iterations. The
consensus was that although the specific benefits of the NCR
extensions remain to be investigated, the mechanism itself is
suitably ready for publication as an Experimental RFC.
Protocol Quality
PROTO Shepherd: Ted Faber (faber at isi.edu)
The Gen-ART reviewer (Eric Gray, eric.gray at marconi.com) has found this
ready for publication as an Experimental RFC.
Chris Lonvick (clonvick at cisco.com) has reviewed this draft for the
Security Directorate.
Lars Eggert has reviewed this spec for the IESG.
Note to RFC Editor
Section 7, the only paragraph
OLD:
We do not believe there are security implications involved with TCP-
NCR over and above those for general TCP congestion control
[RFC2581]. In particular, the Extended Limited Transmit algorithms
specified in this document have been specifically designed not to be
susceptible to the sorts of ACK splitting attacks TCP's general TCP
congestion control is vulnerable to (as discussed in [RFC3465]).
NEW:
General attacks against the congestion control of TCP are described
in [RFC2581]. SACK-based loss recovery for TCP [RFC3517] mitigates
some of the duplicate ACK attacks against TCP's congestion control.
This document builds upon that work, and the Extended Limited
Transmit algorithms specified in this document have been designed to
thwart the ACK division problems that are described in [RFC3465].
(I.e., just replace the entire paragraph.)
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