Re: [Sip] Reg. refresher param in 2xx response

[Harbhanu <[e-mail]>]

Precisely, IMO too RFC doesn't specify UAC behavior for this situation.

So, we think that in order to have a better error tolerance or say
flexibility, this behavior SHOULD be fine.

 

So can anybody suggest/highlight any scenario/use-case wherein this
'tolerance' might prove otherwise? :-)

Also, please specify if you are aware of its handling in any of the
commercial implementations.

 

Thanks again!!

 

Regards,

Harbhanu

 

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From: Brett Tate [mailto:[e-mail]] 
Sent: Tuesday, May 18, 2010 5:46 PM
To: Harbhanu; [e-mail]
Subject: RE: [Sip] Reg. refresher param in 2xx response

 

If 2xx's session-expires doesn't contain the mandatory refresher parameter,
it is likely because interworking with an old implementation of the draft:

http://tools.ietf.org/wg/sip/draft-ietf-sip-session-timer/

 

The refresher parameter was added within version 5 of the draft.

 

Per RFC4028, it is an abnormal situation; I don't recall the RFC indicating
how to act within the abnormal situation.  Thus you can however you want.

 

From: [e-mail] [mailto:[e-mail]] On Behalf Of
Harbhanu
Sent: Tuesday, May 18, 2010 4:49 AM
To: [e-mail]
Subject: [Sip] Reg. refresher param in 2xx response

 

As per 4028, for the following case UAS MUST specify the refresher parameter
in 2xx response.

 

UAC ----INV ----> supported=timer, SE=90-----> UAS

 

UAC <----2XX INV -- SE=90- ---------------- UAS

 

[Section-9, page-16]

The UAS MUST set the value of the refresher parameter in the Session-Expires
header field in the 2xx response.
 

But IMO when UE sends response for INVITE and it adds Session-Expires but
doesn't specify the refresher parameter.

Then in this case UAC can safely assume that, either the UAS doesn't support
session-timer or it doesn't want to act as a 'refresher'.

 

So instead of sending a BYE UAC MAY treat this as a buggy/naive UE & hence
"UAC" SHOULD act as 'refresher'.

 

Please share your opinion. Thanks!

 

Regards,

Harbhanu

 

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