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-------- Original Message --------<br>
Subject: Re: Watching performance on a DHCP Server<br>
From: <a class="moz-txt-link-abbreviated" href="mailto:sthaug@nethelp.no">sthaug@nethelp.no</a><br>
To: <a class="moz-txt-link-abbreviated" href="mailto:dhcp-users@isc.org">dhcp-users@isc.org</a><br>
Date: Tuesday, February 12, 2008 3:48:48 AM<br>
<blockquote cite="mid:20080212.104848.41672666.sthaug@nethelp.no"
type="cite">
<blockquote type="cite">
<pre wrap="">You may want to review the thread from the beginning. My network
currently has 10,000+ DHCP clients (and I plan on accommodating double
that within the lifetime of this server). I have a beefy server (4x
3.0GHz Xeon, 2x 15k RAID1) and it was only able to reliably handle 10 to
20 4-way discover handshakes a second, 2-way handshakes were maybe
double or triple those numbers. When pounded by DHCP requests, it's
possible that even less are processed in a timely manner due to
collisions, timeouts, etc.
</pre>
</blockquote>
<pre wrap=""><!---->
I really don't understand the numbers people are quoting here. We use
a Dell 1850 with one 3.2 GHz CPU, one Gig of memory and two SCSI disks
in battery backed hardware RAID 1. We use this to serve 100K customers
with 24 hour leases. No problems whatsoever, and we feel we have plenty
of room to grow.
(Some calculations: Clients are expected to renew after half the lease
time has passed. So we can expect 100.000 renewals in 43200 seconds, or
a little over 2 renewals per second. Monitoring the actual DHCP traffic
on the server shows numbers which are consistent with this. We have run
with considerably shorter lease times - down to one hour in connection
with planned network reconfigurations - and again the increased DHCP
traffic has been no problem whatsoever.)
Steinar Haug, Nethelp consulting, <a class="moz-txt-link-abbreviated" href="mailto:sthaug@nethelp.no">sthaug@nethelp.no</a>
</pre>
</blockquote>
Th numbers I'm quoting are performance figures from the dhcperf testing
tool. If your 100k users were to be down 24 hours (due to regional
power failure, massive server/network failure), how would your DHCP
server cope with 100K requests at once? This thread is not about
'normal' conditions, it is about the extreme cases that administrators
(at least good ones) are expected to design for and accommodate ahead
of time.<br>
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