Hi, Does kamailio support PRACK method ? Any configuration change is needed?It appears Kamailio does not like the PRAK when increasing Cseq. Here is the call flow: A send INVITE --> Kamailio --> proxy the packet to BB send 180 Ringing --> Kamailio -> proxy the packet to AA send PRAK (increase Cseq) --> Kamailio --> proxy the packet to BB send 200 OK --> Kamailio -> proxy the packet to AKamailio re-send 180 Ringing to A
Thanks,AS
PRACK is an in-dialog/sequential request, which will be relayed like other. So, Kamailio relays it in the same way that it supports any sequential request. Is it not necessary for a SIP proxy to do anything specific to support PRACK.
The UAC should not be increasing the CSeq when sending a PRACK. My guess is that it is the UAS which doesn't like it, rather than Kamailiio. From RFC 3262 Section 3 ("UAS Behavior"):
A matching PRACK is defined as one within the same dialog as the response, and whose method, CSeq-num, and response-num in the RAck header field match, respectively, the method from the CSeq, the sequence number from the CSeq, and the sequence number from the RSeq of the reliable provisional response.
-- Alex
On 05/13/2013 11:37 AM, Alex Solt wrote:
Hi,
Does kamailio support PRACK method ? Any configuration change is needed? It appears Kamailio does not like the PRAK when increasing Cseq. Here is the call flow:
A send INVITE --> Kamailio --> proxy the packet to B B send 180 Ringing --> Kamailio -> proxy the packet to A A send PRAK (increase Cseq) --> Kamailio --> proxy the packet to B B send 200 OK --> Kamailio -> proxy the packet to A Kamailio re-send 180 Ringing to A
Thanks, AS
SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list sr-users@lists.sip-router.org http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users
Just to confirm:Kamaili is forwarding the PRAK packet. However, it seems the kamailio ignore the Cseq increase within the PRAK and therefore it ignore the 200 Ok after that. Then, Kamailio re-send 180 again. Thank,AS
Date: Mon, 13 May 2013 11:41:09 -0400 From: abalashov@evaristesys.com To: sr-users@lists.sip-router.org Subject: Re: [SR-Users] Does Kamailio support PRACK ?
PRACK is an in-dialog/sequential request, which will be relayed like other. So, Kamailio relays it in the same way that it supports any sequential request. Is it not necessary for a SIP proxy to do anything specific to support PRACK.
The UAC should not be increasing the CSeq when sending a PRACK. My guess is that it is the UAS which doesn't like it, rather than Kamailiio. From RFC 3262 Section 3 ("UAS Behavior"):
A matching PRACK is defined as one within the same dialog as the response, and whose method, CSeq-num, and response-num in the RAck header field match, respectively, the method from the CSeq, the sequence number from the CSeq, and the sequence number from the RSeq of the reliable provisional response.-- Alex
On 05/13/2013 11:37 AM, Alex Solt wrote:
Hi,
Does kamailio support PRACK method ? Any configuration change is needed? It appears Kamailio does not like the PRAK when increasing Cseq. Here is the call flow:
A send INVITE --> Kamailio --> proxy the packet to B B send 180 Ringing --> Kamailio -> proxy the packet to A A send PRAK (increase Cseq) --> Kamailio --> proxy the packet to B B send 200 OK --> Kamailio -> proxy the packet to A Kamailio re-send 180 Ringing to A
Thanks, AS
SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list sr-users@lists.sip-router.org http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users
-- Alex Balashov - Principal Evariste Systems LLC 235 E Ponce de Leon Ave Suite 106 Decatur, GA 30030 United States Tel: +1-678-954-0670 Web: http://www.evaristesys.com/, http://www.alexbalashov.com/
SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list sr-users@lists.sip-router.org http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users
On 05/13/2013 11:49 AM, Alex Solt wrote:
Just to confirm: Kamaili is forwarding the PRAK packet. However, it seems the kamailio ignore the Cseq increase within the PRAK and therefore it ignore the 200 Ok after that. Then, Kamailio re-send 180 again.
Incorrect on all counts.
1) Kamailio does not "ignore" anything in the PRACK;
2) Kamailio cannot "ignore" 200 OKs; it simply passes all replies that it receives. It is not a recipient of 200 OKs. Its job is to pass them back to the user agent that is.
3) Kamailio likewise cannot originate replies, so it does not re-send the 180. The UAS does.
In other words, the problem you are seeing is between the endpoints that are calling each other through the proxy. Kamailio is just a dumb, disinterested messenger here.
-- Alex
Alex Solt writes:
Does kamailio support PRACK method ? Any configuration change is needed?
my understanding is that prack is like any on-dialog request and does not need any special handling on kamailio. i have not had any problems with pracks and there is nothing prack specific in my config. this is without dialog module which i don't know anything about.
-- juha
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Alex Balashov -
Alex Solt -
Juha Heinanen