Learning HTTP/2

• Performance optimizations (DNS prefetching, Asynchronous OCSP checking, IP
coalescence, etc)
• Automatic Web Page translation
• Multi-Platform support (Windows, Mac OS, Linux, Android, iOS, Chrome OS)
Chrome implemented support for h2 in version 40 (March 2015), and since then it
added a few things that make this browser very useful for debugging h2. Some of
those features are explained below.
HTTP/2 support (and how to disable it)
Any Chrome versions newer than 41 or so have HTTP/2 enabled by default. HTTP/2
will be automatically negotiated for Websites that announce HTTP/2 during the certificate
negotiation, and where the required ciphers, and TLS negotiation protocols
are available.
HTTPS is required as Chrome does not negotiate h2c (HTTP/2
over Cleartext, also known as non-TLS HTTP/2)
You can start Chrome with the command line parameter “--use-http2=off ” to disable
for support for the HTTP/2 protocol, which is very useful for comparing the performance
of a Website with h2 on and off.
Webpagetest.org
The same command line parameter can be used with Webpagetest.org
to run a performance test on a Chrome agent with HTTP/2
on or off, and in this way compare the performance h2 brings. See
https://community.akamai.com/community/web-performance/blog/
2016/06/22/disabling-http2-on-webpagetestorg for more details.
Handling of HTTP/2 (and how it differs from HTTP/1.1)
End users may not notice any major differences when loading a Web page over
HTTP/1.1 vs. HTTP/2 (other than most likely the page will load a little faster using
the newer version of the protocol). However on the browser’s internals, there are
many differences in the version 2 of the HTTP protocol (binary frame, stream multiplexing,
header compression, server-push, etc.), which change the way the browser
processes a page when it is delivered over HTTP/2.
Google Chrome | 49