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<p class="MsoNormal">We recently had an incident where a power dialer inadvertently was programmed to dial thousands of our numbers. The rate of dialing was such that two of our subscribers went into a code yellow condition so in effect created a Denial of
Service condition. Both of these servers (7845H2) have a lot of MGCP and H323 PRIs associated with them. I am looking for ways to prevent this in the future. I see there is a call spike command available on gateways but I am not sure what thresholds would
be used. Any ideas…..What would be a good threshold to set to prevent a denial of service condition but still support normal heavy inbound calling?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><b><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#336666">call spike
<o:p></o:p></span></b></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><a name="wp1212235"></a><span style="font-size:9.5pt;font-family:"Arial","sans-serif";color:black">To configure the limit on the number of incoming calls received in a short period
of time (a call spike), use the <b>call spike</b> command in global or dial peer voice configuration mode. To disable this command, use the<b> no</b> form of this command.
<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><a name="wp1212236"></a><b><span style="font-size:9.5pt;font-family:"Arial","sans-serif";color:black">call spike</span></b><span style="font-size:9.5pt;font-family:"Arial","sans-serif";color:black">
<i>call</i>-<i>number</i> [<b>steps</b> <i>number</i>-<b><i>of</i></b>-<i>steps</i>
<b>size</b> <i>milliseconds</i>] <o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><a name="wp1212237"></a><b><span style="font-size:9.5pt;font-family:"Arial","sans-serif";color:black">no</span></b><span style="font-size:9.5pt;font-family:"Arial","sans-serif";color:black">
<b>call spike </b><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><a name="wp1212238"></a><span style="font-size:9.5pt;font-family:"Arial","sans-serif";color:black">Dial Peer Voice Configuration Mode
<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><a name="wp1212239"></a><b><span style="font-size:9.5pt;font-family:"Arial","sans-serif";color:black">call spike</span></b><span style="font-size:9.5pt;font-family:"Arial","sans-serif";color:black">
<i>threshold </i>[<b>steps</b> <i>number-of-steps</i> <b>size</b> <i>milliseconds</i>]
<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><a name="wp1212257"></a><b><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#336666">Syntax Description<o:p></o:p></span></b></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><a name="wp1212242"></a><i><span style="font-size:9.5pt;font-family:"Arial","sans-serif";color:black">call</span></i><span style="font-size:9.5pt;font-family:"Arial","sans-serif";color:black">-<i>number</i>
<o:p></o:p></span></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><a name="wp1212244"></a><span style="font-size:9.5pt;font-family:"Arial","sans-serif";color:black">Incoming call count for the spiking threshold. Range is 1 to 2147483647.
<o:p></o:p></span></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><a name="wp1212246"></a><b><span style="font-size:9.5pt;font-family:"Arial","sans-serif";color:black">steps
</span></b><i><span style="font-size:9.5pt;font-family:"Arial","sans-serif";color:black">number</span></i><span style="font-size:9.5pt;font-family:"Arial","sans-serif";color:black">-<i>of</i>-<i>steps</i>
<o:p></o:p></span></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><a name="wp1212248"></a><span style="font-size:9.5pt;font-family:"Arial","sans-serif";color:black">(Optional) Specifies the number of steps for the spiking sliding window. Range
is from 3 to 10. The default is 5.steps for the spiking sliding window. <o:p></o:p></span></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><a name="wp1212250"></a><b><span style="font-size:9.5pt;font-family:"Arial","sans-serif";color:black">size
</span></b><i><span style="font-size:9.5pt;font-family:"Arial","sans-serif";color:black">milliseconds</span></i><span style="font-size:9.5pt;font-family:"Arial","sans-serif";color:black">
<o:p></o:p></span></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><a name="wp1212252"></a><span style="font-size:9.5pt;font-family:"Arial","sans-serif";color:black">(Optional) Specifies step size in milliseconds. Range is from 100 to 250. The
default is 200. <o:p></o:p></span></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><a name="wp1212254"></a><i><span style="font-size:9.5pt;font-family:"Arial","sans-serif";color:black">threshold</span></i><span style="font-size:9.5pt;font-family:"Arial","sans-serif";color:black">
<o:p></o:p></span></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><a name="wp1212256"></a><span style="font-size:9.5pt;font-family:"Arial","sans-serif";color:black">Threshold for the incoming call count for spiking. Range is 1 to 2147483647.
<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><b><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#336666">Usage Guidelines
<o:p></o:p></span></b></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><a name="wp1212297"></a><span style="font-size:9.5pt;font-family:"Arial","sans-serif";color:black">A call spike occurs when a large number of incoming calls arrive from the Public
Switched Telephone Network (PSTN) in a short period of time (for example, 100 incoming calls in 10 milliseconds). Setting this command allows you to control the number of call requests that can be received in a configured time period. The sliding window buffers
the number of calls that get through. The counter resets according to the specified step size.
<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><a name="wp1212298"></a><span style="font-size:9.5pt;font-family:"Arial","sans-serif";color:black">The period of the sliding window is calculated by multiplying the number of steps
by the size. If an incoming call exceeds the configured call number during the period of the sliding window the call is rejected.
<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><a name="wp1212299"></a><span style="font-size:9.5pt;font-family:"Arial","sans-serif";color:black">If the
<b>call spike</b> is configured at both the global and dial-peer levels, the dial-peer level takes precedence and the call spike is calculated. If the call spike threshold is exceeded the call gets rejected, and the call spike calculation is done at the global
level. <o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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