Watching performance on a DHCP Server

Frank Bulk - iNAME frnkblk at
Sat Feb 16 22:17:10 UTC 2008

At these volumes/rates, are people syslogging DHCP traffic to disk?


-----Original Message-----
From: dhcp-users-bounce at [mailto:dhcp-users-bounce at] On Behalf
Of sthaug at
Sent: Tuesday, February 12, 2008 3:49 AM
To: dhcp-users at
Subject: Re: Watching performance on a DHCP Server

> 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.

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, sthaug at

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