Once the first INVITE has failed, and early dialog it might have had is 
gone. The retried INVITE is working toward establishing a new dialog. So 
the CSeq values are for that dialog. I think that means the CSeq 
numbering should be permitted to restart.

OTOH, if there are any messages still in transit from the prior attempt, 
they could be a problem if the numbering resets.

        Thanks,
        Paul

ViVeK tAlWaR wrote:
> According to RFC 3261
> 
>  
> 
> "CSeq or Command Sequence contains an integer and a method name.  The
> 
>    CSeq number is incremented for each new request within a dialog and
> 
>    is a traditional sequence number.
> 
> "
> 
>  
> 
> CSeq increment is not done for specific request it is done for all  the
> request in the dialog.
> 
>  
> 
> Regards,
> 
> Vivek
> 
>   _____  
> 
> From: sip-implementors-boun...@lists.cs.columbia.edu
> [mailto:sip-implementors-boun...@lists.cs.columbia.edu] On Behalf Of
> Dushyant Dhalia
> Sent: Friday, January 29, 2010 4:52 PM
> To: OKUMURA Shinji
> Cc: sip-implementors@lists.cs.columbia.edu
> Subject: Re: [Sip-implementors] CSeq of retried INVITE
> 
>  
> 
> It must be greater that or equal to 3.
> 
> Dushyant P S Dhalia
> 
> OKUMURA Shinji wrote: 
> 
> Hi,
>  
> I have a question regarding CSeq of retried INVITE.
>  
> Consider the following scenario.
>  
>         |      INVITE(CSeq:1)        |
>         |--------------------------->|
>         |                            |
>         |      18x                   |
>         |<---------------------------|
>         |                            |
>         |      PRACK(CSeq:2)         |
>         |--------------------------->|
>         |                            |
>         |      200 OK(PRACK)         |
>         |<---------------------------|
>         |                            |
>         |      415                   |
>         |<---------------------------|
>         |                            |
>         |      ACK                   |
>         |--------------------------->|
>         |                            |
>         |      INVITE(CSeq:2)        |
>         |--------------------------->|
>         |      with the same Call-ID |
>         |                            |
>  
>  
> according to the section 8.1.3.5 in RFC3261, 2nd INVITE
>   "SHOULD have the same value of the
>    Call-ID, To, and From of the previous request, but the CSeq should
>    contain a new sequence number that is one higher than the previous."
>  
> therefore, I think the CSeq of 2nd INVITE SHOULD be "2".
>  
> Is my understanding correct?
>  
> Regards,
> Shinji
> _______________________________________________
> Sip-implementors mailing list
> Sip-implementors@lists.cs.columbia.edu
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>   
> 
> 
> 
> 
> 
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