Re: [SR-Users] [Kamailio-Users] Relaying NOTIFY UDP messages over TCP

Hi Pascal,

On 4/14/10 11:42 AM, Pascal Maugeri wrote:

Hi Daniel

Just to let you know I followed your advice and we deployed kamailio 3.0.1. We are still doing several tests, but I can say already we don't have anymroe errors with tcp connections ...

ok, thanks for feedback. Indeed, 3.0+ is far more improved than what was in openser/kamailio 1.0 to 1.5 in respect to tcp, therefore anyone facing heavy tcp needs should consider this 3.0+.

Cheers, Daniel

Cheers Pascal

On Fri, Mar 12, 2010 at 6:04 PM, Daniel-Constantin Mierla <miconda@gmail.com mailto:miconda@gmail.com> wrote:

Hello,


On 03/11/2010 05:58 PM, Iñaki Baz Castillo wrote:

    2010/3/11 Pascal Maugeri<pascal.maugeri@gmail.com
    <mailto:pascal.maugeri@gmail.com>>:

            Does such NOTIFY go to a TCP registered user? Of
            course if there is
            not an existing TCP connection between Kamailio and
            the final natted
            user then it's not possible to send such NOTIFY.


        Do you mean that the user is sending "transport=tcp" in
        his Contact header ?

    This must be present in the initial SUBSCRIBE. However if the
    client
    is behind NAT and uses TCP it's required some way to mantain the
    keepalive in the router, if not a future NOTIFY could not
    arrive. A
    common approach is the client sending some TCP data through the
    existing connection (i.e.<CRLF><CRLF>  as defined in
    defat-oubound,
    now RFC XXXX).

I have seen clients sending registration over UDP requiring to be
contacted via TCP.

To be sure it registers via TCP check the configuration of the
phone and watch the sip traffic with ngrep (or ethereal) to see
the transport layer protocol.

Connecting from server to a client behind nat is possible only if
you have port forwarding on your nat box to phone IP address.
Therefore, if the phone connects via tcp it must keep the
connection open. If for some reason it closes, it must re-open it.
Otherwise it becomes unreachable.

In the server side there are lot of tcp options to tune the
behavior and optimize. I do suggest using version 3.0 for a much
improved TCP architecture and implementation (including
asynchronous tcp -- in case you deal with lot of tcp connections,
then this saves you).
http://www.kamailio.org/dokuwiki/doku.php/core-cookbook:3.0.x#tcp_parameters

Worth to mention as well that you can change the value of tcp
parameters at runtime without need to restart (e.g., connecting
timeout, send timeout, etc) using sercmd.

Cheers,
Daniel

-- 
Daniel-Constantin Mierla
Kamailio SIP Router Masterclass, Berlin, March 22-26, 2010
* http://www.asipto.com/index.php/sip-router-masterclass/