Title: Is it Still Possible to Extend TCP?
Authors: Michio Honda(micchie@sfc.wide.ad.jp)
         Yoshifumi Nishida(nishida@sfc.wide.ad.jp)
	 Costin Raiciu
	 Adam Greenhalgh
	 Mark Handley
	 Hideyuki Tokuda 
Date: 2011-11-02

%  - Refereed Conferences and Workshops
@inproceedings{micchie:imc11,
	author= {Michio Honda and Yoshifumi Nishida and Costin Raiciu and Adam Greenhalgh and Mark Handley and Hideyuki Tokuda},
	title= "{Is it Still Possible to Extend TCP?}",
	booktitle= {Proc. ACM Internet Measurement Conference (IMC)},
	pages= {181--192},
	month= {Nov},
	year= {2011},
}


# Additional data for readers

%  type =		"conference"
%  site =		[]
%  wideareaname =	[transport]
%  widewgname =		[]
%  keyword =		[]
%  references =		[]
%  summary_ja =		[] 
%  misc =		[]
%  summary =		[
% We've known for a while that the Internet has ossified as a result of the 
% race to optimize existing applications or enhance security. NATs, 
% performance-enhancing-proxies,firewalls and traffic normalizers are only a 
% few of the middleboxes that are deployed in the network and look beyond the 
% IP header to do their job. IP itself can't be extended because "IP options 
% are not an option". Is the same true for TCP?

% In this paper we develop a measurement methodology for evaluating middlebox 
% behavior relating to TCP extensions and present the results of measurements 
% conducted from multiple vantage points. The short answer is that we can still 
% extend TCP, but extensions' design is very constrained as it needs to take 
% into account prevalent middlebox behaviors. For instance, absolute sequence 
% numbers cannot be embedded in options, as middleboxes can rewrite ISN and 
% preserve undefined options. Sequence numbering also must be consistent for a 
% TCP connection, because many middleboxes only allow through contiguous flows.

% We used these findings to analyze three proposed extensions to TCP. We find 
% that MPTCP is likely to work correctly in the Internet or fallback to 
% regular TCP. TcpCrypt seems ready to be deployed, however it is fragile if 
% resegmentation does happen---for instance with hardware offload. Finally, 
% TCP extended options in its current form is not safe to deploy.
% ]