DHCP code in 2.0.4+

Alan DeKok aland at deployingradius.com
Mon Jun 8 07:48:55 CEST 2009

Karl Auer wrote:
>>   It's really not that hard.  Database books describe replication
>> protocols.  They look very different from the DHCP fail-over protocol.
> Though to be fair, database replication is *not* solving the same
> problem as failover is.

  I'll have to disagree with you on that.  There's a lot of database
research on consistency.  The DHCP failover protocol is an attempt to
re-invent much of that, without using research that was well known at
the time it was created.

  I just can't see how the failover protocol is *so* special that it
falls into a class all by itself.  It's just data replication, with
certain constraints.  Big whoop...

>>   And for most enterprise sites, you *don't* need a fail-over protocol.
>>  Really.
> Well... if they have a HA arrangement for DHCP such as that described
> here recently, maybe not. Otherwise we'll have to disagree on that.

  Exactly.  HA for DHCP is needed.  Lazy replication is pretty much all
you need when new machines are rare.  And that's a *lot* easier to
implement than the failover protocol.

  I don't think there's  need for FreeRADIUS to implement a protocol
that's broken *by design*.  If failover works for you, it's likely
because Nominum is using some other protocol than the one that ISC is using.

  Alan DeKok.

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