Subject: [SIP] Max-Forwards + Proxies

From: Neil Deason <[email-masked]>
Date: Tue, 20 Jun 2000 16:42:37 +0100

According to 6.26 of the bis draft if a proxy receives a request
that has a zero value in the Max-Forwards header field it MUST
NOT forward the request. Instead, for the OPTIONS or REGISTER
methods, it MUST respond as the final recipient. For all other
methods, the server returns 483 (Too many hops).

How exactly should a Proxy respond as the final recipient to an
OPTIONS?

How should a proxy respond to a REGISTER if it is not responsible
for registrations within the domain named in the Request-URI?

In the case of other methods is sensible to always return 483?
For example what if it was an INVITE and the Proxy knows from a
location service a final response would have been 3XX/404.

Cheers,
Neil.
-- 
Ubiquity Software Corporation, UK          
http://www.ubiquity.net

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From: Jonathan Rosenberg <[email-masked]>
Date: Thu, 22 Jun 2000 17:19:06 -0400

Actually, this is in RFC2543 also.

I don't like this, in fact. I believe method-based special handling of
headers is confusing, and I would prefer that the response always be
483, for any method. I guess the objective (for OPTIONS at least), is to
query a proxy for capabilities. But, its not really clear that this
means the same thing as a user agent. For REGISTER, its not likely to do
anything useful, except result in the request being rejected, as it
probably can't be accepted locally at some intermediate proxy.

Anyone object to having this sentence stricken?

-Jonathan R.

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Jonathan D. Rosenberg                       72 Eagle Rock Ave.
Chief Scientist                             First Floor
dynamicsoft                                 East Hanover, NJ 07936
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From: "Vijay K. Gurbani" <[email-masked]>
Date: Thu, 22 Jun 2000 16:53:41 -0500

Jonathan Rosenberg wrote:
> 483, for any method. I guess the objective (for OPTIONS at least), is
> to query a proxy for capabilities. 
             ^^^^^
Is it?  How does a proxy know that this OPTIONS request is destined for
it, and not for proxying downstream?  The RFC (and the bis updates)
state that "Proxy and redirect servers simply forward the request with-
out indicating their capabilities."  I simply assumed that a proxy will
forward the request downstream and not respond upstream with _it's_ 
capability set.

> Anyone object to having this sentence stricken?

Not me, for one.  Anything stricken is good :-)

- vijay
-- 
Vijay K. Gurbani  [email-masked] [email-masked] [email-masked]
IN Architecture and Internet Software Group
Lucent Technologies/Bell Labs Innovations, 263 Shuman Blvd, Rm 1A-418
Naperville, Illinois 60566  Voice: +1 630 224 0216 Fax: +1 630 713 0184

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From: Neil Deason <[email-masked]>
Date: Fri, 23 Jun 2000 09:28:14 +0100

"Vijay K. Gurbani" wrote:
> it, and not for proxying downstream?  

Because the case we were discussing is where the Max-Forwards
header field of the OPTIONS request contains a zero.

> The RFC (and the bis updates)

Yes, this is the normal behaviour when Max-Forwards doesn't come
in to play.
Cheers,
Neil.
-- 
Ubiquity Software Corporation, UK          
http://www.ubiquity.net