ISC DHCP server failover

Dan White dwhite at olp.net
Wed Mar 17 14:22:06 UTC 2010


On 17/03/10 10:01 -0400, Summers, William wrote:
>Greetings Nanog members,
>
>I am wondering if anyone has implemented the failover features of ISC DHCP? And if so, how successful has failover been in your environment? 

We've been running version 4 in a failover scenario for a couple of years.
It's worked very well for us in an ISP environment. We serve several
networks from a pair of servers.

We've experienced two types of problems from time to time:

   The servers stop balancing their addresses, and one server starts to
exhibit 'peer holds all free leases' in its logs, in which case we need to
restart the dhcpd process(es) to force a rebalance.

   In some cases, and I'm not sure which equipment may be to blame, if one
server goes down then the other server will not hand out addresses to
clients which had originally received addresses from the failed server.
We've dealt with that by balancing our lease times with our MTTR for a
failed server.

-- 
Dan White




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