Subject: I-D Action: draft-white-httpbis-spdy-analysis-00.txt

From: [email-masked]
Date: Fri, 06 Jul 2012 15:30:23 -0700

A New Internet-Draft is available from the on-line Internet-Drafts directories.

	Title           : Analysis of SPDY and TCP Initcwnd
	Author(s)       : Greg White
                          Dan Rice
	Filename        : draft-white-httpbis-spdy-analysis-00.txt
	Pages           : 34
	Date            : 2012-07-06

Abstract:
   Making the Internet faster is the goal of many product and service
   companies.  Many strategies exist, from data caching to packet
   switching, performance improvements in Internet browser clients and
   server software, without forgetting the transport network scaling
   from the fiber core to the access edges.

   This report investigates two proposed protocol enhancements aimed at
   making the web browsing user experience better by optimizing the
   transport of web objects and thereby reducing the page load time.
   The two enhancements are SPDY, a replacement of the HyperText
   Transfer Protocol (HTTP) requiring client and server changes, and a
   TCP tune-up, an increase in the TCP initial congestion window
   accomplished by a setting change on the web servers.  Both show
   promise, but there are some caveats, particularly with SPDY.  SPDY is
   a candidate for standardization as HTTP/2.0.

   In addition to a discussion of the two enhancements, this report
   provides the results of laboratory testing on SPDY version 2 and the
   proposed increase in the TCP initial congestion window in a variety
   of simulated conditions, comparing the page load time when using the
   proposed enhancement to the page load time for the default case of
   HTTPS and current initial congestion window settings.

   The proposed enhancements generate mixed results: web page load times
   were reduced in some scenarios but increased significantly in others.
   The performance improvement (or degradation) varied depending on the
   number of servers, configuration of the initial TCP congestion
   window, and especially any network packet loss.  The following
   results were obtained across all scenarios comparing SPDY and
   congestion window enhancements to standard HTTPS.

   o  Average reduction in page load time was 29%

   o  Best improvement was over 78% reduction in page load time
   o  Worst cases showed a negative impact, resulting in a 3.3x increase
      in page load time

   These results lead us to the following conclusions:

   o  The SPDY protocol is currently a moving target, and thus it would
      be challenging to realize a return on investment for general-
      purpose usage in web servers.

   o  Protocol improvements, standardization in the IETF and wider
      adoption by the client/server software may warrant a second look
      at SPDY.

   o  Some applications in controlled environments may gain by
      leveraging SPDY.  SPDY might be a valuable tool where the a single
      entity provides the servers, the client software, and the web
      content.

   o  If SPDY were adopted very widely it may have some secondary
      benefits for network operators through improved infrastructure
      scalability due to a significant reduction in concurrent TCP
      sessions, as well as a reduction in Packets Per Second.

   o  The proposed increase in the TCP initial congestion window is
      straightforward, requires no client modifications, and on its own
      provides consistent (albeit modest) performance gains.

   This report is available in a somewhat more detailed form in
   [SPDY-ANALYSIS].

The IETF datatracker status page for this draft is:
https://datatracker.ietf.org/doc/draft-white-httpbis-spdy-analysis

There's also a htmlized version available at:
http://tools.ietf.org/html/draft-white-httpbis-spdy-analysis-00

Internet-Drafts are also available by anonymous FTP at:
ftp://ftp.ietf.org/internet-drafts/