Re: [Sip-implementors] Handling of message cross over between 200OK(INVITE) and 200OK(PRACK)

2017-05-26 Thread Dale R. Worley 
Dinoop  writes:
>UAC  B2BUA UaB
>   | 1:INVITE(SDP)  ||
>   +--->||
>   |   2:100[INV]   ||
>   |<---+|
>   || 3:INVITE(SDP)  |
>   |+--->|
>   ||   4:D1.183[INV](SDP)   |
>   ||<---+
>   |   5:D1.183[INV](SDP)   ||
>   |<---+|
>   |   6:D1.PRACK   ||
>   +--->||
>   ||   7:D1.PRACK   |
>   |+--->|
>   ||   8:D1.200[INV](SDP)   |
>   ||<---+
>   || 9:D1.200[PRA]  |
>   ||<---+
> 
> 
> Where the 200[INVITE] has reached B2BUA before 200[PRACK]. What should be
> the behavior of B2BUA as Ua-Client on right side. Or in general what
> handling should be done at Ua-client side when this occurs?. Is there any
> standard defined to handle this message crossing?

It seems that the key to this is in section 3 of RFC 3262:

   The UAS MAY [...] unless the final response is 2xx and any of the
   unacknowledged reliable provisional responses contained a session
   description.  In that case, it MUST NOT send a final response until
   those provisional responses are acknowledged.

UaB follows this rule, because message 4 is acknowledged (UaB receives
message 7) before UaB sends the 200 (message 9).  Similarly, at the
end of this sequence, B2BUA can send a 200 for message 1, having
received message 6.

Reading this section, it doesn't seem that there is any constraint
regarding when a UAS has to send 200 for PRACK compared to any other
messages.

Dale
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Re: [Sip-implementors] Handling of message cross over between 200OK(INVITE) and 200OK(PRACK)

2017-05-26 Thread Dinoop 
Thanks Worley and Paul,

My scenario is,

 UAC  B2BUA UaB

  | 1:INVITE(SDP)  ||

  +--->||

  |   2:100[INV]   ||

  |<---+|

  || 3:INVITE(SDP)  |

  |+--->|

  ||   4:D1.183[INV](SDP)   |

  ||<---+

  |   5:D1.183[INV](SDP)   ||

  |<---+|

  |   6:D1.PRACK   ||

  +--->||

  ||   7:D1.PRACK   |

  |+--->|

  ||   8:D1.200[INV](SDP)   |

  ||<---+

  || 9:D1.200[PRA]  |

  ||<---+


Where the 200[INVITE] has reached B2BUA before 200[PRACK]. What should be
the behavior of B2BUA as Ua-Client on right side. Or in general what
handling should be done at Ua-client side when this occurs?. Is there any
standard defined to handle this message crossing?

On 25 May 2017 at 23:43, Dale R. Worley  wrote:

> Dinoop  writes:
> > How can a B2BUA handle message crossing of 200OK(invite) over
> 200OK(PRACK)?
> > Is it a correct approach  for the implementation to reject the
> > 200OK(INVITE) until it receives PRACK response?
> >
> > I have gone through the RFC 6337, unfortunately nothing is mentioned
> about
> > this scenario.
>
> As Paul says, the B2BUA has to behave correctly "on each side".  In your
> situation, we would need to see a detailed diagram of the message flow
> you are contemplating before we would know exactly what the situation is
> and what possible strategies the B2BUA could use.
>



-- 
Thanks & Regards
Dinoop p
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Re: [Sip-implementors] Handling of message cross over between 200OK(INVITE) and 200OK(PRACK)

2017-05-26 Thread Paul Kyzivat 

Dinoop,

On 5/26/17 4:50 AM, Dinoop wrote:

Thanks Worley and Paul,

My scenario is,

  UAC  B2BUA UaB

   | 1:INVITE(SDP)  ||

   +--->||

   | 2:100[INV]   ||

   |<---+|

   || 3:INVITE(SDP)  |

   |+--->|

   ||   4:D1.183[INV](SDP)   |

   | |<---+

   | 5:D1.183[INV](SDP)   ||

   |<---+|

   |   6:D1.PRACK   ||

   +--->||

   ||   7:D1.PRACK   |

   | +--->|

   ||   8:D1.200[INV](SDP)   |

   | |<---+

   || 9:D1.200[PRA]  |

   | |<---+


Where the 200[INVITE] has reached B2BUA before 200[PRACK]. What should 
be the behavior of B2BUA as Ua-Client on right side. Or in general what 
handling should be done at Ua-client side when this occurs?. Is there 
any standard defined to handle this message crossing?


I don't see any particular issue here. The response to the PRACK is 
required to complete its transaction, but the 200 to the INVITE is 
evidence that the PRACK had been received and that its 200 will be 
forthcoming. You can simply forward the 200 (INV) and the 200 (PRA) as 
they are received, or you could synthesize and send a 200 for the PRACK 
before forwarding the 200 (INV). Or you *could* hold the 200 (INV) until 
you get the 200 (PRA) and reorder them if you wish, though in some 
extreme cases that might lead to timing issues.


Thanks,
Paul

On 25 May 2017 at 23:43, Dale R. Worley > wrote:


Dinoop mailto:dinoop...@gmail.com>> writes:
> How can a B2BUA handle message crossing of 200OK(invite) over 
200OK(PRACK)?
> Is it a correct approach  for the implementation to reject the
> 200OK(INVITE) until it receives PRACK response?
>
> I have gone through the RFC 6337, unfortunately nothing is mentioned about
> this scenario.

As Paul says, the B2BUA has to behave correctly "on each side".  In your
situation, we would need to see a detailed diagram of the message flow
you are contemplating before we would know exactly what the situation is
and what possible strategies the B2BUA could use.




--
Thanks & Regards
Dinoop p



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Re: [Sip-implementors] Handling of message cross over between 200OK(INVITE) and 200OK(PRACK)

2017-05-25 Thread Dale R. Worley 
Dinoop  writes:
> How can a B2BUA handle message crossing of 200OK(invite) over 200OK(PRACK)?
> Is it a correct approach  for the implementation to reject the
> 200OK(INVITE) until it receives PRACK response?
>
> I have gone through the RFC 6337, unfortunately nothing is mentioned about
> this scenario.

As Paul says, the B2BUA has to behave correctly "on each side".  In your
situation, we would need to see a detailed diagram of the message flow
you are contemplating before we would know exactly what the situation is
and what possible strategies the B2BUA could use.
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Re: [Sip-implementors] Handling of message cross over between 200OK(INVITE) and 200OK(PRACK)

2017-05-24 Thread Paul Kyzivat 

On 5/24/17 2:53 AM, Dinoop wrote:

Hi,

How can a B2BUA handle message crossing of 200OK(invite) over 200OK(PRACK)?
Is it a correct approach  for the implementation to reject the
200OK(INVITE) until it receives PRACK response?

I have gone through the RFC 6337, unfortunately nothing is mentioned about
this scenario.


The fundamental rule to keep in mind for B2BUAs is that each "leg" must 
obey the UA rules. The logic you use to bridge the two legs is up to you.


Thanks,
Paul
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