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On 3/14/2012 7:20 AM, Smith Bill wrote:
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<p class="MsoNormal">Hi<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Does anyone have any detailed information
regarding the communication that happens between two dhcp
servers configured for failover – I have two servers that
don’t seem to talk to each other and the tcpdump is showing
block icmp traffic so I guess I need to know if dhcp
communicates with its failover partner via icmp.</p>
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<br>
The DHCP Failover protocol uses TCP only. I believe this IETF
Internet Draft<o:p> discusses a proposed version of it, but as it
never became an RFC, it may not be 100% accurate.<br>
<br>
<a class="moz-txt-link-freetext" href="http://tools.ietf.org/html/draft-ietf-dhc-failover-12">http://tools.ietf.org/html/draft-ietf-dhc-failover-12</a><br>
<br>
As for using tcpdump, set a capture filter like "tcp port 9999"
and replace 9999 with the port line you used in the failover peer
block from dhcpd.conf. To analyze the protocol, I recommend using
Wireshark. You can use Wireshark to do the capture directly, or
you can tell tcpdump to save it's capture to a file which
Wireshark can open. Use the tcpdump options "-w
dhcp-failover.pcap -s 0" to save it to a file. Wireshark can
decode a decent amount of the protocol and it shouldn't be too
hard to figure out what's wrong. Here's my failover
configuration:<br>
<br>
failover peer "peer" {<br>
secondary;<br>
address 192.168.1.5;<br>
port 7111;<br>
peer address 192.168.1.7;<br>
peer port 7111;<br>
max-response-delay 60;<br>
max-unacked-updates 10;<br>
mclt 3600;<br>
load balance max seconds 3;<br>
}<br>
<br>
<br>
</o:p>
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<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Arial","sans-serif"">Regards<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Arial","sans-serif""><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Arial","sans-serif"">Bill
Smith</span><span
style="font-size:12.0pt;font-family:"Times New
Roman","serif""><o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Arial","sans-serif"">Senior
Solutions Architect<o:p></o:p></span></p>
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style="mso-margin-top-alt:0cm;margin-right:3.75pt;margin-bottom:0cm;margin-left:3.75pt;margin-bottom:.0001pt"><span
style="font-size:10.0pt;font-family:"Arial","sans-serif"">Architecture
& Design H&NS North<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Arial","sans-serif"">Fujitsu
Services</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Arial","sans-serif"">Tel:
07867 821165</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Arial","sans-serif""><a class="moz-txt-link-abbreviated" href="mailto:Email:bill.smith@uk.fujitsu.com">Email:bill.smith@uk.fujitsu.com</a></span><o:p></o:p></p>
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<pre class="moz-signature" cols="72">--
Loren M. Lang
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