Hi Ranjit, thanks for taking a look.
However, I'm more interested in case where UAS is responding to UAC's
request with refresher as itself (uac). Consider this case -
UAC ---- INVITE (Session-Expires: 1800;refresher=uac, Supported: timer)
----> UAS
UAC <---- 200 OK (Session-Expires: 1800;refresher=uac)
--------------------- UAS
In this case, the statement in question seems to convey that UAS should
also add "Require: timer" in its 200 response. Why would this be, when
it's clear that UAC declared itself as the refresher and that timer is
supported?
For reference, RFC 4028 Section 9 UAS Behavior (or page 16)
If the refresher parameter in the Session-Expires header field in the
2xx
response has a value of 'uac', the UAS MUST place a Require header field
into the response with the value 'timer'.
Thanks,
Hoil
------------------------------
*From:* Ranjit Avasarala <ranjitka...@gmail.com>
*Sent:* Friday, May 28, 2021 12:38 PM
*To:* Hoil Choi <hoil.c...@hotmail.com>;
Sip-implementors@lists.cs.columbia.edu <
Sip-implementors@lists.cs.columbia.edu>
*Cc:* sipc...@ietf.org <sipc...@ietf.org>
*Subject:* Re: [sipcore] RFC 4028 UAS behavior requirement of Require
header
Hi Holi
the presence of the "Require" header with value "timer" from UAS
indicates
to UAC that it (UAC) is performing the refreshing operation. but if
the UAS
is the refresher, then if Require header with value "timer" is
present in
response from UAS, then UAC should send BYE if it does not receive a
session refresh request from UAS.
Regards
Ranjit
On Fri, May 28, 2021 at 10:02 AM Hoil Choi <hoil.c...@hotmail.com>
wrote:
Hello,
I hope this mail finds appropriate person or team for an answer to my
question on RFC 4028.
I am a SIP enthusiast and always learning a lot about it, but by no
means
am I an expert; so please excuse my ignorance.
I came across an interesting statement In Section 9 UAS Behavior (or
page
16).
If the refresher parameter in the Session-Expires header field in the
2xx response has a value of 'uac', the UAS MUST place a Require
header field into the response with the value 'timer'.
Statement seems to convey that UAS must place a Require header with
value
'timer' when UAC requests itself to be the refresher.
However, this statement should only be true, if UAC did not put
Session-Expire with value of 'uac'.
If UAC, in INVITE request, put Session-Expire with value of 'uac'
(itself), UAS should not bother putting Require header field in the
response. Or to be more accurate, UAC should include 'timer' in
Supported
header, so that UAS doesn't have to bother putting Require header field.
What is the reason behind the requirement of Require header, from UAS in
this case?
Thanks!
Hoil Choi
253-273-5442
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