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Re: WG Review: Recharter of Hypertext Transfer Protocol Bis (httpbis)

From: Mark Andrews <marka@isc.org>
Date: Mon, 27 Feb 2012 22:48:58 +0000
To: Willy Tarreau <w@1wt.eu>
Cc: Patrik Fältström <patrik@frobbit.se>, IETF Discussion <ietf@ietf.org>, Patrik Fältström <paf@frobbit.se>, "mnot@mnot.net" <mnot@mnot.net>, "iesg@ietf.org" <iesg@ietf.org>, John C Klensin <john-ietf@jck.com>, "ietf-http-wg@w3.org" <ietf-http-wg@w3.org>
Message-Id: <20120227224803.4964A1DDBB0C@drugs.dv.isc.org>

In message <20120226064025.GH8633@1wt.eu>, Willy Tarreau writes:
> On Fri, Feb 24, 2012 at 05:57:31PM +0100, Patrik F=E4ltstr=F6m wrote:
> > I am asking more generally why specifically this DNS issue is so stuck,
> > because I think that is unfair. We upgrade other protocols...

> 
> Because in HTTP, anybody can be anywhere. You can have client-side proxies,
> server-side gateways, load balancers, etc... everyone in this chain may or
> may not resolve, it's only a matter of configuration and architecture choic=
> e.
> There are plenty of places where clients won't access public resolvers at a=
> ll
> and rely on their proxies for this. So you can't make use of DNS to improve
> these users' experience.

Proxies can lookup SRV records.  They already lookup A and AAAA records.
 
> Also, DNS is SLLLLOOOOWWWWW. It's fast enough to send a mail. But for HTTP
> it adds too much latency. Some people in the mobile world would like to be
> able to configure an explicit proxy on their smartphones in order to avoid
> a very expensive round trip before fetching an object : at 20 host names
> on a web page, 300 ms round trip means 6 seconds are lost to resolve these
> objects if they can't be totally parallelized.

If they can't be parallelized then you can blame the page developer.

As for SRV you can always do SRV + AAAA + A in parallel.

> DNS suggestion is something going back and forth regularly. I think that
> people who try to push it hard only see the very simple case where users
> have a direct low-latency internet connection. The reality is much much
> different. This well reflected by the fact that in the end, after many
> proposals, it has still not been adopted !
> 
> Regards,
> Willy
> 
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Mark Andrews, ISC
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PHONE: +61 2 9871 4742                 INTERNET: marka@isc.org
Received on Tuesday, 28 February 2012 09:27:27 GMT

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