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Re: comments on draft-mbelshe-httpbis-spdy-00

From: Patrick McManus <pmcmanus@mozilla.com>
Date: Thu, 16 Aug 2012 09:17:47 -0400
Message-ID: <1345123067.1116.72.camel@ds9>
To: William Chan (陈智昌) <willchan@chromium.org>
Cc: "ietf-http-wg@w3.org Group" <ietf-http-wg@w3.org>
On Wed, 2012-08-15 at 21:50 -0700, William Chan (陈智昌) wrote:
> Can you clarify the reason to prefer srv over something like an
> Alternate-Protocol response header?

bootstrapping with a-p on http/1 means that while you're making the
http/2 connection you're using http/1 (or waiting idly). Obviously, we
want to be using http/2 (or we wouldn't be having the FUN FUN FUN of
this whole project) so this is suboptimal. That seems kind of self
evident. Doing the direction with DNS addresses that.

This is no doubt unavoidable in a bunch of scenarios - and people won't
setup non-{a,aaaa} records in droves out of the gate. But if we give
better performance with a srv record than without one, then that will
become a driver for seeing them deployed.

>  another DNS lookup. Chromium has already lowered our concurrent
> getaddrinfo() calls to 6 due to problems with home routers not being
> able to handle too many concurrent DNS queries. Adding more DNS
> lookups per hostname will further exacerbate the problem.
> 

I know you guys see more problems with that than we do - and I certainly
acknowledge that the difference might just be that you have better
visibility into it. Hard to know if its insurmountable at this point.
But given the racy nature of what we're talking about - what to do
might be more of an implementation choice than anything else.
Received on Thursday, 16 August 2012 13:18:21 GMT

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