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<title>OT - fault tolerant default router for Nagios host. [SEC=UNCLASSIFIED]</title>
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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>At my last company we used the Linux bonding driver for several
of our HA servers. It’s a little complicated to set up, but once
configured it ran like a gear. We used the failover mode and connected
our servers to multiple switches. I plan on implementing the same thing
at my current company once the network is ready for it.<o:p></o:p></span></p>
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<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><b><span
style='font-size:11.0pt;font-family:"Garamond","serif";color:#1F497D'>J</span></b><b><span
style='font-size:10.0pt;font-family:"Garamond","serif";color:#1F497D'>onah
Horowitz · Monitoring Manager · jhorowitz@looksmart.net<br>
W: 415-348-7694 · F: 415-348-7033 · M: 415-513-7202<br>
</span></b><b><span style='font-size:10.0pt;font-family:"Garamond","serif";
color:#0070C0'>LookSmart</span></b><b><span style='font-size:10.0pt;font-family:
"Garamond","serif";color:#1F497D'> - Premium and Performance Advertising
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625 Second Street, San Francisco, CA 94107<o:p></o:p></span></b></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"'>
nagios-users-bounces@lists.sourceforge.net
[mailto:nagios-users-bounces@lists.sourceforge.net] <b>On Behalf Of </b>Stanley.HOPCROFT@deewr.gov.au<br>
<b>Sent:</b> Friday, February 22, 2008 6:19 PM<br>
<b>To:</b> nagios-users@lists.sourceforge.net<br>
<b>Subject:</b> [Nagios-users] OT - fault tolerant default router for Nagios
host.[SEC=UNCLASSIFIED]<o:p></o:p></span></p>
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<p><span lang=EN-AU style='font-size:10.0pt;font-family:"Courier New"'>Dear
Folks,</span><span lang=EN-AU style='font-family:"Arial","sans-serif"'> </span><o:p></o:p></p>
<p><span lang=EN-AU style='font-size:10.0pt;font-family:"Courier New"'>I am
writing to request comments on a proposal to reduce the risk of loss of Network
visibility/spurious alerts etc caused by the failure of the Nagios host's
default gateway.</span><o:p></o:p></p>
<p><span lang=EN-AU style='font-size:10.0pt;font-family:"Courier New"'>When the
Nagios host is connected via multiple links, it is still necessary to ensure
that data flow either both links or that somehow traffic is diverted to the
other links.</span><span lang=EN-AU> </span><o:p></o:p></p>
<p><span lang=EN-AU style='font-size:10.0pt;font-family:"Courier New"'>Solutions
I have rejected include</span><span lang=EN-AU style='font-family:"Arial","sans-serif"'>
</span><o:p></o:p></p>
<p><span lang=EN-AU style='font-size:10.0pt;font-family:"Courier New"'>1 Link
teaming/bonding - immature in Linux</span><span lang=EN-AU style='font-family:
"Arial","sans-serif"'> </span><o:p></o:p></p>
<p><span lang=EN-AU style='font-size:10.0pt;font-family:"Courier New"'>2
HSRP/VRRP - don’t want to change network structure to suit Nagios and I
can't afford fibre links from Nag to a core switch in the 'other' data centre.</span><o:p></o:p></p>
<p><span lang=EN-AU style='font-size:10.0pt;font-family:"Courier New"'>Otherwise
this is a fine solution</span><span lang=EN-AU style='font-family:"Arial","sans-serif"'>
</span><o:p></o:p></p>
<p><span lang=EN-AU style='font-size:10.0pt;font-family:"Courier New"'>3 Load
sharing - half the traffic will be dropped if a link fails</span><span
lang=EN-AU style='font-family:"Arial","sans-serif"'> </span><o:p></o:p></p>
<p><span lang=EN-AU style='font-size:10.0pt;font-family:"Courier New"'>Here is
what I think is the best fit: an application layer (non kernel) fault tolerant
router.</span><span lang=EN-AU style='font-family:"Arial","sans-serif"'> </span><o:p></o:p></p>
<p><span lang=EN-AU style='font-size:10.0pt;font-family:"Courier New"'>This
could be implemented by</span><span lang=EN-AU style='font-family:"Arial","sans-serif"'>
</span><o:p></o:p></p>
<p><span lang=EN-AU style='font-size:10.0pt;font-family:"Courier New"'>1 a Nag
service check of the reachability of the default router</span><span lang=EN-AU
style='font-family:"Arial","sans-serif"'> </span><o:p></o:p></p>
<p><span lang=EN-AU style='font-size:10.0pt;font-family:"Courier New"'>2 an
event handler (run by sudo) that replaces the default router if the check
returns CRITICAL HARD.</span><span lang=EN-AU style='font-family:"Arial","sans-serif"'>
</span><o:p></o:p></p>
<p><span lang=EN-AU style='font-size:10.0pt;font-family:"Courier New"'>Your
comments are very welcome.</span><span lang=EN-AU style='font-family:"Arial","sans-serif"'>
</span><o:p></o:p></p>
<p><span lang=EN-AU style='font-size:10.0pt;font-family:"Courier New"'>Thank
you,</span><span lang=EN-AU style='font-family:"Arial","sans-serif"'> </span><o:p></o:p></p>
<p><span lang=EN-AU style='font-size:10.0pt;font-family:"Courier New"'>Yours
sincerely.</span><span lang=EN-AU style='font-family:"Arial","sans-serif"'> </span><o:p></o:p></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><br>
<br>
<o:p></o:p></p>
<p><b><span lang=EN-AU style='font-size:10.0pt;font-family:"Microsoft Sans Serif","sans-serif";
color:black'>Classification:</span></b><span lang=EN-AU> </span><span
lang=EN-AU style='font-size:10.0pt;font-family:"Tahoma","sans-serif";
color:black'>UNCLASSIFIED</span><o:p></o:p></p>
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