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<p class="MsoNormal"><span style="font-size:11.0pt">Here is the scenario:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">My servers are only listening on a private IP address. There is a public address on our SBC. I have a carrier that requires that the Contact IP address matches the public address we provided to them. So when
I do TH on my server I have to also do set_advertised_address to advertise the public address in the Contact header. Sequential requests use the Contact as the Request URI and the SBC is doing RR so all requests will come back through it. When the SBC receives
a sequential request it strips its Route headers and forwards to the Request URI (previous Contact URI). But that URI now points back to the SBC, so it cannot deliver the request. If my server could Record-Route the initial request with its private address,
the SBC would be able to route the request back to it.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Here is a trace of my scenario:
<a href="http://pastebin.com/x927mFtq">http://pastebin.com/x927mFtq</a>. I created it with SIPp so some endpoints are on the same IPs but with different ports. The public IP is 192.168.99.100, with port 7060 representing the PSTN carrier and port 5060 the SBC.
The private IP is 10.0.2.15, with port 5060 being the SBC again and port 6060 being my server. You can see that the ACK cannot be delivered correctly to my server with this configuration.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">The problem here stems from the fact that Topology Hiding should really be done at the edge of the network in order to be most effective. But my OpenSIPS server doesn’t sit on the Edge of the network, it is
behind an SBC. So TH is complicated by the fact that my OpenSIPS has no public IP of its own and must advertise the public IP of the SBC instead, but future requests must still be routable into the private network. I am really using TH to hide the two ends
of the call from each other, not to hide my internal network topology.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;color:black">Ben Newlin</span><span style="font-size:11.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b><span style="color:black">From: </span></b><span style="color:black">Bogdan-Andrei Iancu <bogdan@opensips.org><br>
<b>Date: </b>Friday, July 29, 2016 at 8:40 AM<br>
<b>To: </b>"Newlin, Ben" <Ben.Newlin@inin.com>, OpenSIPS users mailling list <users@lists.opensips.org><br>
<b>Subject: </b>Re: [OpenSIPS-Users] Record-Route and Dialog topology_hiding()<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-family:"Times New Roman","serif""><o:p> </o:p></span></p>
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<p class="MsoNormal"><tt><span style="font-size:10.0pt">Hi Ben,</span></tt><span style="font-size:10.0pt;font-family:"Courier New","serif""><br>
<br>
<tt>Sorry to disagree, but IMHO they do exclude one each other. </tt><br>
<br>
<tt>Adding RR to TH should not be seen as a way of fixing some broken TH scenarios (with advertise).</tt><br>
<tt>So, let me try to understand what is not working for you. You do TH and advertise. In this case, normally, in the Contact headers generated by OpenSIPS (as a result of TH), it should be the TH interface, right ? What exactly seems to be the problem ? do
you have a trace to show the issues ?</tt><br>
<br>
<tt>Regards,</tt><br>
<br>
</span><o:p></o:p></p>
<pre>Bogdan-Andrei Iancu<o:p></o:p></pre>
<pre>OpenSIPS Founder and Developer<o:p></o:p></pre>
<pre><a href="http://www.opensips-solutions.com">http://www.opensips-solutions.com</a><o:p></o:p></pre>
<div>
<p class="MsoNormal">On 27.07.2016 16:05, Newlin, Ben wrote:<o:p></o:p></p>
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<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<p class="MsoNormal"><span style="font-size:11.0pt">I understand that normally you would not need RR with TH, but the two concepts are not mutually exclusive in SIP. As I said, I have a need to Record-Route the call on my server as I am advertising a different
address than I am listening on. This means that TH will populate the Contact header with the advertised address and if I cannot Record-Route with the actual address then I will not receive sequential requests.</span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> </span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;color:black"> </span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;color:black">Ben Newlin</span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> </span><o:p></o:p></p>
<div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b><span style="color:black">From: </span></b><span style="color:black">Bogdan-Andrei Iancu
<a href="mailto:bogdan@opensips.org"><bogdan@opensips.org></a><br>
<b>Date: </b>Wednesday, July 27, 2016 at 3:59 AM<br>
<b>To: </b>OpenSIPS users mailling list <a href="mailto:users@lists.opensips.org">
<users@lists.opensips.org></a>, "Newlin, Ben" <a href="mailto:Ben.Newlin@inin.com">
<Ben.Newlin@inin.com></a><br>
<b>Subject: </b>Re: [OpenSIPS-Users] Record-Route and Dialog topology_hiding()</span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><span style="font-family:"Times New Roman","serif""> </span><o:p></o:p></p>
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<p class="MsoNormal"><tt><span style="font-size:10.0pt">Hi Ben,</span></tt><span style="font-size:10.0pt;font-family:"Courier New","serif""><br>
<br>
<tt>As I mentioned in different thread, TH is not compatible with the RR mechanism. If you do TH, your OpenSIPS will act as and end point (from SIP perspective), so there will be no Route/RR headers at all. So no need to do loose_route or so. You just do TH
matching for the sequential requests and nothing more.</tt><br>
<br>
<tt>Regards,</tt><br>
<br>
<br>
</span><o:p></o:p></p>
<pre>Bogdan-Andrei Iancu<o:p></o:p></pre>
<pre>OpenSIPS Founder and Developer<o:p></o:p></pre>
<pre><a href="http://www.opensips-solutions.com">http://www.opensips-solutions.com</a><o:p></o:p></pre>
<div>
<p class="MsoNormal">On 22.07.2016 16:48, Newlin, Ben wrote:<o:p></o:p></p>
</div>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<p class="MsoNormal"><span style="font-size:11.0pt">Hi,</span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt">I am using the Dialog module with topology_hiding() in my server and I have a need to Record-Route the call on my server as I am advertising a different address than I am listening on. I have found what I
believe is an inconsistency in the handling of Record-Route within the Dialog topology_hiding functionality. The topology_hiding isn’t a true B2BUA, but it does set up different parameters for the incoming UAC and outgoing UAS sides of the call for the Via
headers, Record-Route and Route headers, and the Contact header(s).</span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt">The problem is that the record_route() and loose_route() functions operate on different sides of the call. The record_route() function will only add a Record-Route header to the outgoing UAS side of the call.
And since the record_route() function cannot be called from onreply_route, but is no way to add a Record-Route header to the UAC side of the call.</span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt">On the other hand, the loose_route() function only operates on the incoming UAC side of the call and there is no way to perform loose_route() on the UAS side of the call.</span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt">So there is a situation where Record-Route headers can only be added on the outgoing UAS side, but the associated Route headers can only be removed on the incoming UAC side (where they won’t exist since they
can’t be added) and any added headers on the UAS side cannot be processed properly due to the lack of loose_route.</span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt">I can provide further information if this is unclear. It should be easily reproducible by attempting to use record_route in a topology_hiding scenario. The route is added to the outbound leg, but is not removed
by loose_route so the message is looped back every time.</span><o:p></o:p></p>
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<p class="MsoNormal" style="line-height:16.8pt;background:white"><span style="font-size:9.0pt;font-family:Arial;color:#666666"> </span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="line-height:16.8pt;background:white"><b><span style="font-size:10.0pt;font-family:Arial;color:#155570">Ben Newlin</span></b><b><span style="font-size:10.0pt;font-family:Arial;color:#666666"> </span></b><span style="font-size:10.0pt;font-family:Arial;color:#666666">|
Sr Voice Network Engineer, PureCloud</span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="line-height:16.8pt;background:white"><span style="font-size:10.0pt;font-family:Arial;color:#666666">phone & fax +1.317.957.1009 | </span><span style="font-size:10.0pt;font-family:Arial;color:#0585A7"><a href="mailto:ben.newlin@inin.com">ben.newlin@inin.com</a> </span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="line-height:16.8pt;background:white"><span style="font-size:9.0pt;font-family:Arial;color:#666666;border:solid windowtext 1.0pt;padding:0in"><img border="0" width="196" height="21" id="_x0000_i1025" src="cid:Word%20Work%20File%20D_.jpg" alt="age
removed by sender."></span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="line-height:12.0pt;background:white"><span style="font-size:10.0pt;font-family:Arial;color:#0585A7"><a href="http://www.inin.com">www.inin.com</a></span><o:p></o:p></p>
</div>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal"><span style="font-family:"Times New Roman","serif""><br>
<br>
<br>
<br>
</span><o:p></o:p></p>
<pre>_______________________________________________<o:p></o:p></pre>
<pre>Users mailing list<o:p></o:p></pre>
<pre><a href="mailto:Users@lists.opensips.org">Users@lists.opensips.org</a><o:p></o:p></pre>
<pre><a href="http://lists.opensips.org/cgi-bin/mailman/listinfo/users">http://lists.opensips.org/cgi-bin/mailman/listinfo/users</a><o:p></o:p></pre>
</blockquote>
<p class="MsoNormal"><span style="font-family:"Times New Roman","serif""> </span><o:p></o:p></p>
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</blockquote>
<p class="MsoNormal"><span style="font-family:"Times New Roman","serif""><o:p> </o:p></span></p>
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