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<p class="MsoNormal"><span style="color:#1F497D">Daniel,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">That seems to be correct from the RFCs I just took a quick look at. Would have to take a look in the SDLs to see if CUCM is actually putting the SIPInterface into a sessionEstablished state after it sends the
183 w/SDP. It may still be waiting for the Prack though before it marks it as sessionEstablished.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">In the incoming Invite from the Nortel side, does it have 100rel in the supported or required headers?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Ideally, this would be our call flow:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> A B<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> | |<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> |-------------(1) INVITE SDP1--------------->|<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> |<-----------(2) 100 Trying--------------------|<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> |<------(3) 183 Session Progress SDP2-----|<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> |-------------(4) PRACK---------------------->|<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> | |<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> |<--------(5) 200 OK (PRACK)----------------|<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> | |<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> |<----------(6) 183 Session Progress--------|<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> | |<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> |-----------------(7) PRACK------------------>|<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> | |<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> |<------------(8) 200 OK (PRACK)------------|<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> | |<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> |-------------(9) UPDATE SDP3-------------->|<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> | |<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> |<--------(10) 200 OK (UPDATE) SDP4------|<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> | |<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> | |<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> |<-----------(11) 200 OK (INVITE)------------|<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> | |<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> |------------------(12) ACK------------------->|<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> | |<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Thanks,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Brian Meade<o:p></o:p></span></p>
<div>
<div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> Daniel Pagan [mailto:dpagan@fidelus.com]
<br>
<b>Sent:</b> Thursday, February 13, 2014 6:16 PM<br>
<b>To:</b> Brian Meade (brmeade); cisco-voip@puck.nether.net<br>
<b>Subject:</b> RE: SIP Stack & Trace Question<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Brian:<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">Thanks for the response.<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">I’d have to review traces for a non-transfer scenario but it’s my understanding that, in this scenario, the 183 w/SDP from CUCM was the answer in the offer/answer model – the offer being Nortel’s INVITE w/SDP. Just after allocation of the
MTP, SIP Interface shows “SIPInterface-(292194)::handleOutgoingSDPAnswer”, which, correct me if I’m wrong, should complete the offer/answer:<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">INVITE (SDP offer) <span style="font-family:Wingdings">
à</span> CUCM<o:p></o:p></p>
<p class="MsoNormal">100 Trying <span style="font-family:Wingdings">
ß</span> <o:p></o:p></p>
<div>
<p class="MsoNormal"><span style="color:black">183 (SDP answer) </span>
<span style="font-family:Wingdings;color:black">ß</span><span style="color:black">
</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:black">183 (No SDP)</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:black">UPDATE (SDP) </span>
<span style="font-family:Wingdings;color:black">à</span><span style="color:black">
</span><o:p></o:p></p>
</div>
<p class="MsoNormal"><b><span style="font-size:10.0pt">==</span></b><b><span style="font-size:10.0pt;font-family:"Courier New"">
<span style="color:red">SIP/Stack/Error/0x0/Last Offer not answered yet</span></span></b><o:p></o:p></p>
<p class="MsoNormal"><b><span style="font-size:10.0pt">== Note: Context ID (ccb=<id>) matches the ID created at the start of the dialogue</span></b><o:p></o:p></p>
<p class="MsoNormal">500 Internal SvrErr <span style="font-family:Wingdings">
ß</span> <o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal">Thoughts? Thanks again Brian.<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">- Daniel<o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> </span><o:p></o:p></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> Brian Meade (brmeade) [<a href="mailto:brmeade@cisco.com">mailto:brmeade@cisco.com</a>]
<br>
<b>Sent:</b> Thursday, February 13, 2014 5:59 PM<br>
<b>To:</b> Daniel Pagan; <a href="mailto:cisco-voip@puck.nether.net">cisco-voip@puck.nether.net</a><br>
<b>Subject:</b> RE: SIP Stack & Trace Question</span><o:p></o:p></p>
</div>
</div>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">Daniel,</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">It seems to me like CUCM is waiting for an answer to the offer it sent in the 183 w/SDP. In a non-transfer scenario, does the Nortel side normally send a PRACK at that point? Possibly the Nortel side is sending
the Update before the PRACK?</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">Thanks,</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">Brian</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> </span><o:p></o:p></p>
<div>
<div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> cisco-voip [<a href="mailto:cisco-voip-bounces@puck.nether.net">mailto:cisco-voip-bounces@puck.nether.net</a>]
<b>On Behalf Of </b>Daniel Pagan<br>
<b>Sent:</b> Thursday, February 13, 2014 5:08 PM<br>
<b>To:</b> <a href="mailto:cisco-voip@puck.nether.net">cisco-voip@puck.nether.net</a><br>
<b>Subject:</b> [cisco-voip] SIP Stack & Trace Question</span><o:p></o:p></p>
</div>
</div>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal"><b>Folks</b>:<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">I’m reviewing an issue and looking for some feedback on a specific SIP stack error. In a nutshell, what appears to be happening is CUCM (8.6.2.24090-1) responding to an UPDATE request with a 500 Internal Server Error in a very specific
transfer call flow:<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal"><b>.::: Call is established :::</b><o:p></o:p></p>
<p class="MsoNormal"><b>.::: Nortel Begins a xfer to CUCM :::</b><o:p></o:p></p>
<p class="MsoNormal"><b> </b><o:p></o:p></p>
<p class="MsoNormal"><b><span style="font-size:12.0pt">Nortel ==== CUCM</span></b><o:p></o:p></p>
<p class="MsoNormal"><b>>>> INVITE w/SDP</b><o:p></o:p></p>
<p class="MsoNormal"><b> 100 Trying <<<</b><o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal"><span style="color:#4A452A">=======DA Successful</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#4A452A">=======Outbound to ITSP</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#4A452A">=======MTP Required on Rx SIP Trunk</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#4A452A">=======MTP resource allocated</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#4A452A">=======SDI trace events show </span>
<b><span style="font-size:10.0pt;color:#4A452A">SIPInterface-(292194)::handleOutgoing<u>SDPAnswer</u></span></b><span style="font-size:10.0pt;color:#4A452A">
</span><span style="color:#4A452A">once media info is collected for MTP</span><o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal"><b> 183 w/ SDP </b><b><span style="font-size:9.0pt">(for MTP)</span> <<<</b><o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal"><span style="color:#4A452A">=====ITSP returns 183 w/ SDP</span><o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal"><b> 183 <u>no</u> SDP <<<</b><o:p></o:p></p>
<p class="MsoNormal"><b>>>> UPDATE w/SDP</b><o:p></o:p></p>
<p class="MsoNormal"><b> </b><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#4A452A">=====SIP stack detects an existing connection</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#4A452A">=====SIP stack detects an SDP offer has yet to be answered</span><o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal"><b> 500 Internal Svr Error <<<</b><o:p></o:p></p>
<p class="MsoNormal"><b> w/ retry-timer header</b><o:p></o:p></p>
<p class="MsoNormal"><b> ::: Call Xfer attempt fails :::</b><o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">The SIP stack trace excerpt that raised a flag states<b>:</b><o:p></o:p></p>
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Courier New";color:red">SIP/Stack/Error/0x0/Last Offer not answered yet</span></b><o:p></o:p></p>
<p class="MsoNormal">This occurs after the UPDATE w/ SDP offer is received and immediately before the 500 response is generated.<o:p></o:p></p>
<p class="MsoNormal">SDI traces show the event was added to the UAS response table using same context ID created for the original INVITE.<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">With this error in mind I decided to review the RFC for SIP UPDATE and found a very interesting piece of information:<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";color:black">“If an UPDATE is received that contains an offer, and the UAS has</span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";color:black"> generated an offer (in an UPDATE, PRACK or INVITE) to which it has</span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";color:black"> not yet received an answer, the UAS MUST reject the UPDATE with a 491</span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";color:black"> response.
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#C00000">Similarly, if an UPDATE is received that contains an</span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";color:#C00000"> offer, and the UAS has received an offer (in an UPDATE, PRACK, or</span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";color:#C00000"> INVITE)
<u>to which it has not yet generated an answer</u>, the UAS MUST</span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";color:#C00000"> reject the UPDATE with a 500 response, and MUST include a Retry-After</span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";color:#C00000"> header field with a randomly chosen value between 0 and 10 seconds.”</span><o:p></o:p></p>
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Courier New""> </span></b><o:p></o:p></p>
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Courier New""><a href="http://www.rfc-editor.org/rfc/rfc3311.txt">http://www.rfc-editor.org/rfc/rfc3311.txt</a></span></b><o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">The 500 response to the UPDATE does indeed contain a Retry-After header. CUCM did generate an answer (see above) but SIP stack detects the last offer wasn’t answered. Although the Nortel PBX doesn’t reattempt after x seconds, a related
RFC states the UAC *may* reattempt but it’s not a requirement. With that said, I’m wondering if anyone can help answer a few questions:<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo2"><![if !supportLists]><b><span style="mso-list:Ignore">1.<span style="font:7.0pt "Times New Roman"">
</span></span></b><![endif]>Has anyone encountered this before?<o:p></o:p></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo2"><![if !supportLists]><b><span style="mso-list:Ignore">2.<span style="font:7.0pt "Times New Roman"">
</span></span></b><![endif]>Bug toolkit doesn’t return any good matches. Perhaps there’s an internal defect?<o:p></o:p></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo2"><![if !supportLists]><b><span style="mso-list:Ignore">3.<span style="font:7.0pt "Times New Roman"">
</span></span></b><![endif]>The 2<sup>nd</sup> 183 from CUCM (with no SDP) contains a CSeq header for the original INVITE from Nortel.<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in">This is the most recent provisional from CUCM in response to the offer from Nortel.<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in">My initial thought is CUCM is referring back to this 2<sup>nd</sup> 183 when determining no answer was generated for the last offer. This would explain the 500 response w/ Retry-After header
<u>and</u> the SIP stack error stating that an answer has yet to be generated.<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in">:: Note: Call-ID headers are confirmed to be consistent throughout the SDI traces reviewed
<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in">:: Note: The Allow header contains UPDATE<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in">:: Note: CUBE is not involved in this call-flow<o:p></o:p></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo2"><![if !supportLists]><b><span style="mso-list:Ignore">4.<span style="font:7.0pt "Times New Roman"">
</span></span></b><![endif]>Can anyone tell me what CCB is in the context of UAS response tables? Seeing quite a few “Adding to Response/Request Table” also piques my interest. Is there anything useful from a troubleshooting standpoint from these tables when
the ccb=<ID> is identified and marked in Notepad++?<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in"> <o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in">Thoughts?<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">Thanks ahead of time.<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">- Daniel<o:p></o:p></p>
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