Johan, Does your 3G provider support mobile IP? May the mobile IP over 3G is causing the difference in behaviour. Ramesh ________________________________ From: Johan Lantz <johan.lantz@xxxxxxxxxxx> To: pjsip at lists.pjsip.org Sent: Tuesday, January 27, 2009 9:21:01 AM Subject: Sending large SIP packets over UDP? Hi all I have a two questions regarding TCP/UDP transports, the first one is probably simple: 1. How do I force pjsip to use TCP for outgoing requests. I have configured two transports, one for TCP and one for UDP. Both calls to pjsua_transport_create(..) return successfully but all messages are always sent on UDP. I found some old posts on that ;transport=tcp should be added so I did this and it can be seen in the Request-Line. However the INVITE packet is always sent over UDP anyway. What do I need to do to properly force usage of TCP for outgoing requests? 2. We have encountered a problem which we have most likely narrowed down to payload size when transmitting over UDP. From a Windows Mobile phone connected over WiFi sending arbitrary INVITES always work but when we connect over 3G the successrate is random once the packet size gets to large. RFC 3261 states that TCP should be used for packages larger then 1300 bytes so one guess here is that somewhere in the 3G network our packages are discarded when they get to large. I need assistance with if the problem is due to my TCP transport is not properly configured or if 18.1.1. below is not handled by pjsip they way I interpret it. Does pjsip cater for switching to TCP like specified below? RFC 3261 states the following: (18.1.1 Sending Requests) :? If a request is within 200 bytes of the path MTU, or if it is larger ? than 1300 bytes and the path MTU is unknown, the request MUST be sent ? using an RFC 2914 [43] congestion controlled transport protocol, such ? as TCP. If this causes a change in the transport protocol from the ? one indicated in the top Via, the value in the top Via MUST be ? changed.? This prevents fragmentation of messages over UDP and ? provides congestion control for larger messages.? However, ? implementations MUST be able to handle messages up to the maximum ? datagram packet size.? For UDP, this size is 65,535 bytes, including ? IP and UDP headers. Thanks Johan _______________________________________________ Visit our blog: http://blog.pjsip.org pjsip mailing list pjsip at lists.pjsip.org http://lists.pjsip.org/mailman/listinfo/pjsip_lists.pjsip.org -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.pjsip.org/pipermail/pjsip_lists.pjsip.org/attachments/20090127/4983a805/attachment.html>
