Re: PRACK: Does non-200 response cease re-transmission ofreliable 18x?

["Christer Holmberg" <christer.holmberg@xxxxxxxxxxxx>]

Hi,

>Is the other scenario raised by Paul below? 
> 
>      -> INVITE
>     <- 180rel
>     -> PRACK
>     <- 401
> 

>And are there any other cases?IMO, only prack with new offer could cause this problem. 
 

A SIP request can be rejected e.g. because the UAS is overloaded.

 

I don't we can assume that a PRACK will never be rejected, and as long as it may be rejected we need to know how to handle it.

>Also another question: 
> 
>Is the flows below valid according to recent arguments? 
> 
>   UAC                  UAS 
>    |----invite(SDP)--->| 
>    |<--- 183(SDP)------| 
>    |-----prack(SDP)--->| 
>    |<--- 200(SDP)------| 
>

>       flow 1

 

Assuming the 200 is the PRACK response, yes.

 
>UAC                  UAS 
>    |----invite-------->| 
>    |<--- 183-----------| 
>    |-----prack(SDP)--->| 
>    |<--- 200(SDP)------| 
>   
>       flow 2 
 

Not valid. If the INVITE does not contain SDP, a reliable answer must contain SDP. We are currently discussing whether the FIRST reliable response must contain SDP, or whether that rule can be related. But, that is a separate thread.

 

Regards,

 

Christer

 

 

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