Does anyone use anycast DHCP service?

Robert E. Seastrom rs at
Mon Aug 13 11:50:27 UTC 2012

An anycast solution that doesn't involve a way to promptly yank the
route when the service is unhappy is not really a full anycast
solution.  You could probably use
for health checking, wrap in a script with something to talk to bgpctl
(if you're running openbgpd) or something similar if you're talking to
bird or quagga or whatever, loop once a second...  you get the idea.
Don't forget to have a hook in your script so you can send it a signal
to yank the route and take the box offline without killing the

Having the dhcp server boxes themselves speak BGP or your favorite IGP
(I'm in favor of BGP for this because of policy knobs) may or may not
be tenable in your organization.  The optimal org chart for this sort
of setup is one wherein the routing people and the systems people are
the same folks.  I'll go out on a limb and guess that in an
organization where you're thinking of this scale of dhcp server,
you're probably reporting to different VPs.

So the SLB might be necessary for layer 9 reasons - something that the
network guys trust to speak a routing protocol to.  If you don't have
transaction load problems or layer 9 problems to solve with the load
balancer then I'm not sure what value it brings - assuring server
availability in an anycast environment is just not that valuable (so
long as the anycast environment is designed properly - see above).

hope this helps!


Joe <sj_hznm at> writes:

> hi,
> We are considering setup  reduant DHCP server clusers by using anycast.
> In our situation  customer get IP address with DHCP, DHCP server authenticate  customer by  radius.Authentication information is carried by option60 and option82.
> does anybody has some suggestion on this ?
> if anycast is suitable for our situation, does it possible to introduce load balancer in anycast node ? that is,  
> DHCP service availabilty is guaranteed by multiple anycast nodes, inside anycast node  dhcp service availability 
> is guaranteed by  server farm behind load balancer?
> Joe 		 	   		  

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