Subject: [SIP] To and From headers - URL comparison

From: Itamar Gilad <[email-masked]>
Date: Thu, 1 Mar 2001 20:11:44 +0200

Everybody,

Section 2.1 was discussed a few times in the mailing list and eventually the
conflict between the "...Components not found in both URLs being compared
are ignored." and "..If a component is omitted, it matches based on its
default value." was resolved by saying that only in the case of non default
value the latter statement is used.

However what happens with the headers From and To? Some types of URL params
are not allowed in To and From, but 6.26 and 6.44 indicate that servers need
to cope with a situation in which To or From have them. What are the
comparison rules to be used when only one of the URLs have these illegal
parameters? Disregard the illegal params? Take them into account, but don't
use defaults?
It seems a picky question, but the answer can make or break interoperability
in some cases. 

A closely related question:

6.44:
"The SIP-URL MUST NOT contain the “transport-param”, “maddr-param”,
“ttl-param”, or “headers” elements. A server that receives a SIP-URL with
these elements _removes_ them before further processing."

but 6.26 says:
"...The SIP-URL MUST NOT contain the “transport-param”, “maddr-param”,
“ttl-param”, or “headers” elements. A server that receives a SIP-URL with
these elements _ignores_ them.".  

1) Why the difference? 
2) What does 'ignore' mean?  Should the server echo the illegal parameters
in the response? Note that otherwise the client may run into a comparison
problem as indicated above.

TIA

Itamar Gilad
RADVISION
[email-masked]           24 Raul Wallenberg St.
tel: +972 3 7659938                 Building D
cel: +972 56 429938                 Tel-Aviv 69719
fax: +972 3 6442903                 Israel

Itamar Gilad
RADVISION
[email-masked]           24 Raul Wallenberg St.
tel: +972 3 7659938                 Building D
cel: +972 56 429938                 Tel-Aviv 69719
fax: +972 3 6442903                 Israel

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---

From: Gethin Liddell <[email-masked]>
Date: Thu, 1 Mar 2001 18:18:53 +0000

On Thursday 01 March 2001 18:11, Itamar Gilad wrote:
> Everybody,
>
> Section 2.1 was discussed a few times in the mailing list and eventually
> the conflict between the "...Components not found in both URLs being
> compared are ignored." and "..If a component is omitted, it matches based
> on its default value." was resolved by saying that only in the case of non
> default value the latter statement is used.
>
> are not allowed in To and From, but 6.26 and 6.44 indicate that servers
> need to cope with a situation in which To or From have them. What are the
> It seems a picky question, but the answer can make or break
> interoperability in some cases.

If the parameter is not supposed to be there ignore it. No matter what 
defaults it has or does not have.

> problem as indicated above.

I would ignore them!!! By that i mean in any comparison etc... act as if they 
were not present, but when sending responses, leave them there.

-- 
Gethin Liddell
Ubiquity Software Corp.
Ubiquity House
Langstone Park
NP6 2LH
UK

Tel: 44 (0) 1633 765600
Fax: 44 (0) 1633 765601

URL: www.ubiquity.net