DHCP Redundancy

Simon Hobson dhcp1 at thehobsons.co.uk
Sat Nov 27 17:44:26 UTC 2010

Dan Letkeman wrote:

>I'm using ISC DHCP with webmin for management, and I'm wondering what
>the best way is to build some redundancy into the DHCP server.  Is it
>best just to have two?  Is there a way that I can use Webmin to manage
>both at the same time?

Don't know about Webmin, never used it for managing DHCP.

For IPv4 you would probably want to use two servers with failover. In 
this mode, the two server cooperate over which one is giving what IPs 
to which client. If one fails, the other can take over and manage the 
full address space.

There isn't failover for IPv6, but then the address space is large 
enough that you should have no problems running multiple servers 
allocating out of different ranges. That is an option for IPv4, but 
many people don't have the address space for that.

If you run two servers on a network, then you must do one of two things :

1) Run them as a failover pair so they can manage one set of client 
addresses between them.


2) Run them with separate and non-overlapping address ranges so that 
they don't interfere with each other.

Simon Hobson

Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed
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