Re: p1: Via and gateways

Mark Nottingham <mnot@mnot.net> Sat, 20 April 2013 06:45 UTC

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From: Mark Nottingham <mnot@mnot.net>
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Date: Sat, 20 Apr 2013 16:44:30 +1000
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To: Willy Tarreau <w@1wt.eu>
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Subject: Re: p1: Via and gateways
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On 20/04/2013, at 4:23 PM, Willy Tarreau <w@1wt.eu> wrote:

> On Sat, Apr 20, 2013 at 02:07:11PM +1000, Mark Nottingham wrote:
>> 
>> p1 Section 2.3 says:
>> 
>>> However, an HTTP-to-HTTP gateway that wishes to interoperate with third-party HTTP servers must conform to HTTP user agent requirements on the gateway's inbound connection and must implement the Connection (Section 6.1) and Via (Section 5.7.1) header fields for both connections.
>> 
>> This means that accelerators and CDNs MUST generate a Via header on the outbound connection. This isn't widely practiced, and I'm not sure it's necessary. Comments?
> 
> I know no load-balancer which does it anyway. Especially in hosted
> environments where it is desired that the infrastructure is as much
> transparent to the hosted servers as possible.
> 
> I must say I never understood the rationale behind Via because for
> incoming traffic we don't care and for outgoing traffic we don't
> want to disclose to the world our inside details.

Yes. It makes sense for proxies, so that the endpoints can discover the capabilities of the whole path. I'm not convinced that applies to gateways, because they're taking the responsibility of the origin server.

> Another example of a MUST which makes people think that MUSTs are at user
> option I think.


Indeed.

--
Mark Nottingham   http://www.mnot.net/