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

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

Hi, 

>>Adam, I think you also had an issue regarding the proposal that a 
>>non-200 response would not cease the re-transmission of 18x?
>   
>
>I agree that a UAC can't *count* on a non-200 response stopping the
provisional retransmission, since the error may have 
>come from an intermediary. Of course, if the error has an obvious
recovery path (e.g. 
>407), then the UAC should attempt recovery (largely because it doesn't
know whether the error came from the UAS or from 
>an intermediary).
>
>However, if the PRACK makes it all the way to the UAS, reliability has
been achieved. Continued retransmission of the 
>provisional response by the UAS at that point provides no benefit. It
does, however, consume gratuitous bandwidth. (The 
>UAS does need to deal with the possibility that the UAC will re-attempt
the PRACK, however).
>
>Otherwise, you just have the UAS yelling, "I Want My Acknowledgment!" 
>and the UAC yelling back "You Have Your Acknowledgment!" over and over.

I guess it doesn't hurt if the UAS chooses to stop the re-transmission
in case it sends a non-200 response.

But, in thaht case the UAS needs to "remember" for which 18x it sent a
non-200 response to the PRACK, and be able to deal with a new PRACK
(sent by the UAC which received the non-200 response) as if the 18x had
NOT yet been acknowledged.

Regards,

Christer




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