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Hello,<br>
<br>
<div class="moz-cite-prefix">On 11/12/13 16:21, Grant Bagdasarian
wrote:<br>
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<div class="WordSection1">
<p class="MsoNormal">Hello,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I’m trying to understand how the dispatcher
module works and how the timers in the TM module influence the
behavior.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">My architecture looks like this:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">UA1 ---- SBC1 ---- Kamailio ----- SBC2 ----
FreeSWITCH App Server(x2)<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">What I got so far:<o:p></o:p></p>
<p class="MsoListParagraph"
style="text-indent:-.25in;mso-list:l1 level1 lfo2"><!--[if !supportLists]--><span
style="mso-list:Ignore">1)<span style="font:7.0pt
"Times New Roman""> </span></span><!--[endif]-->UA1
sends an INVITE to SBC1, which bridges the call between the
UA1 and Kamailio<o:p></o:p></p>
<p class="MsoListParagraph"
style="text-indent:-.25in;mso-list:l1 level1 lfo2"><!--[if !supportLists]--><span
style="mso-list:Ignore">2)<span style="font:7.0pt
"Times New Roman""> </span></span><!--[endif]-->INVITE
is received by Kamailio.<o:p></o:p></p>
<p class="MsoListParagraph"
style="text-indent:-.25in;mso-list:l1 level1 lfo2"><!--[if !supportLists]--><span
style="mso-list:Ignore">3)<span style="font:7.0pt
"Times New Roman""> </span></span><!--[endif]-->Kamailio
looks in its dispatcher table to dispatch the INVITE to its
destination<o:p></o:p></p>
<p class="MsoListParagraph"
style="text-indent:-.25in;mso-list:l1 level1 lfo2"><!--[if !supportLists]--><span
style="mso-list:Ignore">4)<span style="font:7.0pt
"Times New Roman""> </span></span><!--[endif]-->Kamailio
rewrites the $du value to that of the SBC2<o:p></o:p></p>
<p class="MsoListParagraph"
style="text-indent:-.25in;mso-list:l1 level1 lfo2"><!--[if !supportLists]--><span
style="mso-list:Ignore">5)<span style="font:7.0pt
"Times New Roman""> </span></span><!--[endif]-->Kamailio
rewrites the request-uri and sends the INVITE to the
destination in $du.<o:p></o:p></p>
<p class="MsoListParagraph"
style="text-indent:-.25in;mso-list:l1 level1 lfo2"><!--[if !supportLists]--><span
style="mso-list:Ignore">6)<span style="font:7.0pt
"Times New Roman""> </span></span><!--[endif]-->SBC2
is a FreeSWITCH instance which bridges the call (does not
answer). It only responds back with a 100 TRYING<o:p></o:p></p>
<p class="MsoListParagraph"
style="text-indent:-.25in;mso-list:l1 level1 lfo2"><!--[if !supportLists]--><span
style="mso-list:Ignore">7)<span style="font:7.0pt
"Times New Roman""> </span></span><!--[endif]-->SBC2
tries to contact the endpoint (FS App Server 1) in the
request-uri, but the destination does not respond because it
is unavailable. <o:p></o:p></p>
<p class="MsoListParagraph"
style="text-indent:-.25in;mso-list:l1 level1 lfo2"><!--[if !supportLists]--><span
style="mso-list:Ignore">8)<span style="font:7.0pt
"Times New Roman""> </span></span><!--[endif]-->Kamailio
keeps waiting for a final reply.<o:p></o:p></p>
<p class="MsoListParagraph"
style="text-indent:-.25in;mso-list:l1 level1 lfo2"><!--[if !supportLists]--><span
style="mso-list:Ignore">9)<span style="font:7.0pt
"Times New Roman""> </span></span><!--[endif]-->The
fr_inv_timer is set to 5000 on startup<o:p></o:p></p>
<p class="MsoListParagraph"
style="text-indent:-.25in;mso-list:l1 level1 lfo2"><!--[if !supportLists]--><span
style="mso-list:Ignore">10)<span style="font:7.0pt
"Times New Roman""> </span></span><!--[endif]-->Once
the timer hits, Kamailio executes the route set in
t_failure_route<o:p></o:p></p>
<p class="MsoListParagraph"
style="text-indent:-.25in;mso-list:l1 level1 lfo2"><!--[if !supportLists]--><span
style="mso-list:Ignore">11)<span style="font:7.0pt
"Times New Roman""> </span></span><!--[endif]-->The
failure route looks like this:<o:p></o:p></p>
<p class="MsoNormal" style="text-indent:.5in">if(t_is_expired())
{ ... }<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"> if (t_is_canceled()) { ...
}<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"> if(t_check_status("500") ||
t_branch_timeout() || !t_branch_replied()) {<o:p></o:p></p>
<p class="MsoNormal"> ....<o:p></o:p></p>
<p class="MsoNormal"> }<o:p></o:p></p>
<p class="MsoListParagraph"
style="text-indent:-.25in;mso-list:l1 level1 lfo2"><!--[if !supportLists]--><span
style="mso-list:Ignore">12)<span style="font:7.0pt
"Times New Roman""> </span></span><!--[endif]-->Kamailio
enters the third if block in which the next domain is selected
and the $du is rewritten again to that of SBC2<o:p></o:p></p>
<p class="MsoListParagraph"
style="text-indent:-.25in;mso-list:l1 level1 lfo2"><!--[if !supportLists]--><span
style="mso-list:Ignore">13)<span style="font:7.0pt
"Times New Roman""> </span></span><!--[endif]-->A
new INVITE is generated and sent to its destination (FS App
Server 2) through SBC2. Nothing is sent back to SBC1 yet,
because Kamailio handles the failover here.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Is this correct?<o:p></o:p></p>
<p class="MsoNormal">Are there any other timers which are fired
which I missed, or does the fr_inv_timer have nothing to do
with this?<o:p></o:p></p>
<p class="MsoNormal">If Kamailio is supposed to load balance
between FS App Server 1 and 2 using the Round-Robin algorithm,
does it in case of an unreachable first destination take the
next destination in the route set?</p>
</div>
</blockquote>
fr_inv_timer is more like ringing time. fr_timer is how long to try
until there is a reaction from next hop.<br>
<br>
In case on round robin, next destination is selected if you do it in
the failure route with ds_next_domain() or ds_next_dst().<br>
<br>
Cheers,<br>
Daniel<br>
<br>
<pre class="moz-signature" cols="72">--
Daniel-Constantin Mierla - <a class="moz-txt-link-freetext" href="http://www.asipto.com">http://www.asipto.com</a>
<a class="moz-txt-link-freetext" href="http://twitter.com/#!/miconda">http://twitter.com/#!/miconda</a> - <a class="moz-txt-link-freetext" href="http://www.linkedin.com/in/miconda">http://www.linkedin.com/in/miconda</a></pre>
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