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<p class="MsoNormal">Hello all,</p>
<p class="MsoNormal">We’re having a strange behavior on our network preventing several
clients from being served by a pair of servers working in failover. It seems
that the problem is related to a bug on the client that fails to increment the “seconds
elapsed” field on “request” messages. It only increments on the “discovers”. I
was hoping that you could suggest some workaround or configuration change for
this issue, because the update of all clients’ firmware might not be an immediate
option.</p>
<p class="MsoNormal">This is our scenario:</p>
<p class="MsoListParagraphCxSpFirst" style="text-indent: -18pt;"><span style=""><span style="">-<span style="font-family: "Times New Roman"; font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-size-adjust: none; font-stretch: normal;">
</span></span></span>We need to give a static IP to our clients based
on the option 82 location info received by the server;</p>
<p class="MsoListParagraphCxSpMiddle" style="text-indent: -18pt;"><span style=""><span style="">-<span style="font-family: "Times New Roman"; font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-size-adjust: none; font-stretch: normal;">
</span></span></span>to do so we created matching classes, and pools
with only one IP available. On each on those pools we accept only one mach class;</p>
<p class="MsoListParagraphCxSpMiddle" style="text-indent: -18pt;"><span style=""><span style="">-<span style="font-family: "Times New Roman"; font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-size-adjust: none; font-stretch: normal;">
</span></span></span>when the client sends the first Discover, dhcp0
ignores (I believe he thinks it will be handled by its peer), but dhcp1 writes
on the log “peer holds all free leases” (I believe dhcp1 isn’t controlling this
specific lease);</p>
<p class="MsoListParagraphCxSpMiddle" style="text-indent: -18pt;"><span style=""><span style="">-<span style="font-family: "Times New Roman"; font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-size-adjust: none; font-stretch: normal;">
</span></span></span>The client keeps trying and incrementing the “seconds
elapsed” field on the “discovers”. When it becomes greater than our configured “load
balance max seconds”, dhcp0 answers the request with the usual “offer”;</p>
<p class="MsoListParagraphCxSpMiddle" style="text-indent: -18pt;"><span style=""><span style="">-<span style="font-family: "Times New Roman"; font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-size-adjust: none; font-stretch: normal;">
</span></span></span>The problem is when the client sends the “request”,
because it sends it with “seconds elapsed” = 0! The transaction id is the same,
and all the other parameters seem to be correct except this one.</p>
<p class="MsoListParagraphCxSpLast" style="text-indent: -18pt;"><span style=""><span style="">-<span style="font-family: "Times New Roman"; font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-size-adjust: none; font-stretch: normal;">
</span></span></span>Dhcp0 ignores the request even that on the
options the client specifically states that he’s answering his offer.</p>
<p class="MsoNormal">To me it seems clear that the problem is the bug on the dhcp
client, however it looks like that the failover / loadbalancing is a lot dependent
on the good implementation of all the clients. Without failover this would work
perfectly, ignoring this bug. </p>
<p class="MsoNormal">Do you think there could be any workaround to solve this
problem in the server side? </p>
<p class="MsoNormal">Is dhcp0 working correctly when it ignores the “request”
with seconds-elapsed = 0?</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">Thanks,</p>
<p class="MsoNormal">Daniel Duarte</p>