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<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">There are multiple ways this outage can impact CL 911 service not just related to IP. Here are a few of them:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo1"><![if !supportLists]><span style="font-size:11.0pt;color:#1F497D"><span style="mso-list:Ignore">1.<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="font-size:11.0pt;color:#1F497D"> You have a POTS line and you dial 911 which gets to your central office but the CO switch had no trunks out, either because they were TDM but riding one of the optical carriers or
IP based. Both go down when the optical mux chokes.<o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo1"><![if !supportLists]><span style="font-size:11.0pt;color:#1F497D"><span style="mso-list:Ignore">2.<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="font-size:11.0pt;color:#1F497D">911 center is probably connected to multiple COs (usually at least two) but since this outage was nationwide it is very likely that adjacent COs could have lost transmission trunks
isolating the 911 center.<o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-.25in;mso-list:l0 level1 lfo1"><![if !supportLists]><span style="font-size:11.0pt;color:#1F497D"><span style="mso-list:Ignore">3.<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="font-size:11.0pt;color:#1F497D">If you are a cellular customer, that data is getting backhauled to a central office and then getting inserted into the same CO switches that lost their transmission capacity.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">It is important to remember that a lot of stuff is using IP for transport but the IP network is also controlling the L1 infrastructure. In this case it looks like the IP network transmitted
bad control data to the underlying fiber network.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">Steven Naslund<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">Chicago IL<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">></span><span style="font-size:11.0pt">Guys,
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">></span><span style="font-size:11.0pt">While reading CL network down impacting 911 services, was trying to get more information about how does this network looks like. From end user to center,
I guess VOIP is used. Wondering what is the communication method <span style="color:#1F497D">
></span>from Emergency service center to end units (Police, Fire or any other services). Do they also use IP ? or its Still Radio only ? if it is IP, do they use Unicast or multicast or broadcast ?
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">></span><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">></span><span style="font-size:11.0pt">Tried googling, but did not get much information. Any insight would be appreciated.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">></span><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Times New Roman",serif;color:#1F497D">></span><span style="font-family:"Times New Roman",serif">Thanks
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Times New Roman",serif;color:#1F497D">></span><span style="font-family:"Times New Roman",serif">Mankamana
<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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