Failover + PXE

[Todd Snyder]

Thanks for the information!  Much appreciated, esp the tip on TFTP, I
hadn't thought of mirroring that source yet.

A quick question regarding the failover methodology.  From what I've
read on the subject, it would appear that this set is more about load
balancing than HA (in my understanding).  Since it splits the pool in 2
and each server hands out a limited range, this seems to be less about
HA.  Does each server keep track of what the other server has handed
out, so when the other fails it keeps things organized?  Is it possible
to run one as a 'cold' standby, that keeps a copy of the leases but
doesn't actively respond to anything unless the other one is down for XX
seconds?

Just curious - we're setting this up in an HA environment, and I would
like to understand the behaviour a little more before I write the
document on how it behaves and what our options are.

(wow, that appears to be a lot less quick than I'd hoped for, but the
answer should be easy, I hope)

Cheers,

Todd. 

-----Original Message-----
From: dhcp-users-bounce at isc.org [mailto:dhcp-users-bounce at isc.org] On
Behalf Of Daniel Johnson
Sent: Thursday, November 22, 2007 6:47 PM
To: dhcp-users at isc.org
Subject: Re: Failover + PXE

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Todd Snyder wrote:
 > I am looking to setup failover, but I found a line in the man  > page
that might throw that right out:
 >
 >        Dynamic BOOTP leases are not compatible with failover,
 > and, as such, you need to disallow BOOTP in pools that you  > are
using failover for.
 >
 > I am using the DHCP server to PXE boot servers to do installs  > -
does this fall in to the previous statement?
 >
 > Does v4 do things differently?

As I read things, PXE doesn't use BOOTP.  I've denied dynamic BOOTP in
all of my pools, and PXE is working fine.  (Thanks David!)

The only failover-snag I hit setting up PXE was that my primary DHCP
server was (at the time) our only TFTP server.  If it goes down, PXE
goes with it.  The simple fix was to put a mirrored TFTP service on the
secondary DHCP server and have them hand out their own addresses.

Daniel Johnson
Progman2000 at usa.net
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