Its implementation dependent for the proxy .. I think there is absolutely no
harm in proxying 422 back to UA1 because anyways UA1 would interpret it as 400,
if it cannot understand.
But if the proxy takes into consideration the fact that UA1 doesn't support
timers, it has two choices.
(1) It *may* map the 422 to something like 480 or 503 and send it back to UA1.
(2) It *may* even try another INVITE to UA2 with the Session-Expires value of
greater than
or equal to Min-SE which you receive in 422. ( I believe Min-SE is MUST in
422 )
-Somesh
* Please do not take print out of this e-mail unless its absolutely necessary *
-----Original Message-----
From: Radha krishna [mailto:[email protected]]
Sent: Wed 2/18/2009 12:42 PM
To: Somesh S. Shanbhag; [email protected]
Subject: Re: [Sip-implementors] Sending 422
Thanks somesh,
it can do but in RFC section 9 explicitly says when UAS can send 422
If an incoming request contains a Supported header field with a value
'timer' and a Session Expires header field, the UAS MAY reject the
INVITE request with a 422 (Session Interval Too Small) response if
the session interval in the Session-Expires header field is smaller
than the minimum interval defined by the UAS' local policy
Regards
S.Radha krishna
________________________________
From: Somesh S. Shanbhag <[email protected]>
To: Radha krishna <[email protected]>;
[email protected]
Sent: Wednesday, February 18, 2009 12:16:31 PM
Subject: RE: [Sip-implementors] Sending 422
RE: [Sip-implementors] Sending 422
Proxy can forward 422 to UA1. If UA1 doesn't understand 422, it will treat it
as 400 and process it.
* Please do not take print out of this e-mail unless its absolutely necessary *
-----Original Message-----
From: Radha krishna [mailto:[email protected]]
Sent: Wed 2/18/2009 11:44 AM
To: Somesh S. Shanbhag; [email protected]
Subject: Re: [Sip-implementors] Sending 422
But proxy cannot forward the 422 to UA1 since it is not supporting right? Also
it cannot retry with new INVITE if it is not a B2BUA.
Regards
S.Radha krishna
________________________________
From: Somesh S. Shanbhag <[email protected]>
To: Radha krishna <[email protected]>;
[email protected]
Sent: Wednesday, February 18, 2009 10:27:16 AM
Subject: RE: [Sip-implementors] Sending 422
RE: [Sip-implementors] Sending 422
Since the proxy is call stateful, the INVITE which goes to UA2 shall have
Sesssion-Expires field and hence UA2 can reject with 422.
Somesh
* Please do not take print out of this e-mail unless its absolutely necessary *
-----Original Message-----
From: [email protected] on behalf of Radha krishna
Sent: Wed 2/18/2009 8:18 AM
To: [email protected]
Subject: [Sip-implementors] Sending 422
Hi
Consider the following topology
UA1 ----- Call-stateful-proxy ------ UA2
UA1 does not support session timer, Make a call to UA2.
Call-stateful-proxy adds Session-Expires:100 header and forwards to UA2. UA2
minimum session expires is 900. But in this case INVITE will not contain
"support: timer". According section 9, UAS can reject with 422 only if there is
a timer tag in supported header
<Snip from RFC>
If an incoming request contains a Supported header field with a value
'timer' and a Session Expires header field, the UAS MAY reject the
INVITE request with a 422 (Session Interval Too Small) response if
the session interval in the Session-Expires header field is smaller
than the minimum interval defined by the UAS' local policy. When
sending the 422 response, the UAS MUST include a Min-SE header field
with the value of its minimum interval. This minimum interval MUST
NOT be lower than 90 seconds.
</Snip from RFC>
Also UAS cannot increase the session expires duration
<Snip from RFC>
The UAS MUST
NOT increase the value of the Session-Expires header field.
</Snip from RFC>
What should be the behavior of UAS here?
1) accept the call with 100 seconds?
2) Increase the duration to 900 seconds while sending 200 Ok?
Note: Session timer should not be turned-off
Regards
S.Radha krishna
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shall be understood to be neither given nor endorsed by Mascon. Any information
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can not guarantee that any email or attachment is free from computer viruses
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