Subject: Re: [Sip] INVITE 200 OK - TCP retransmission

From: "Rockson Li (zhengyli)" <[email-masked]>
Date: Tue, 16 Sep 2008 11:39:25 +0800

Yes, only UAS retransmits 200(INVITE).
 
check the same section.
 
   Once the response has been constructed, it is passed to the INVITE
   server transaction.  Note, however, that the INVITE server
   transaction will be destroyed as soon as it receives this final
   response and passes it to the transport.  Therefore, it is necessary
   to periodically pass the response directly to the transport until the
   ACK arrives.  The 2xx response is passed to the transport with an
   interval that starts at T1 seconds and doubles for each
   retransmission until it reaches T2 seconds (T1 and T2 are defined in
   Section 17).  Response retransmissions cease when an ACK request for
   the response is received.  This is independent of whatever transport
   protocols are used to send the response.
 
FYI
 
-Rockson

________________________________

From: Thomas george [mailto:[email-masked]] 
Sent: Tuesday, September 16, 2008 11:30 AM
To: Rockson Li (zhengyli); [email-masked]
Subject: Re: [Sip] INVITE 200 OK - TCP retransmission

So you are telling that the 200 OK to INVITE is only retransmitted by
UA, not by a Proxy?
And also in INVITE server transaction flow diagram (Section 7.2.1),
there is no Timer to retransmit 200 OK. Then on what basis a TU will
retransmit 200 OK?
 
rgds,
Thomas

----- Original Message ----
From: Rockson Li (zhengyli) <[email-masked]>
To: Thomas george <[email-masked]>; [email-masked]
Sent: Tuesday, 16 September, 2008 8:30:37 AM
Subject: RE: [Sip] INVITE 200 OK - TCP retransmission

check RFC3261 sec 13.3.1.4
 
      Since 2xx is retransmitted end-to-end, there may be hops between
      UAS and UAC that are UDP.  To ensure reliable delivery across
      these hops, the response is retransmitted periodically even if the
      transport at the UAS is reliable.
 
-Rockson

________________________________

From: [email-masked] [mailto:[email-masked]] On Behalf Of
Thomas george
Sent: Tuesday, September 16, 2008 10:17 AM
To: [email-masked]
Subject: [Sip] INVITE 200 OK - TCP retransmission

Hi,

Why the 200 OK to INVITE is retransmitted even if we are using TCP?

rgds,

Thomas

________________________________

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