Upgrade 4.2.4->4.3.5

[Bob Harold]

On Tue, Oct 2, 2018 at 8:21 PM Gregory Sloop <gregs at sloop.net> wrote:

> Re-post of my query from last week...
> Any thoughts/ideas, please share!
>
> ---
> So, several questions:
> Moving from Ubuntu 16.04, [IIRC] and dhcpd 4.2.4 to 18.04 and version
> 4.3.5
> [I'm completely rebuilding the pair of dns/dhcp boxes, so no in-place
> upgrades.]
>
> Currently use peer/load-balancing/failover.
> Will 4.2.4 communicate fine with 4.3.5? [i.e. can I convert/upgrade one of
> the peers and let it sync and then do the second, at my leisure?
>
> I don't notice any real game-changers in terms of the config files in
> looking through the change-logs. Yet it's certainly possible I've missed
> something.
> Does anyone have any warnings I ought to take to heart? :)
> Any warnings outside of the peer communications and config files?
>
> <tangent> [Is now a good time to really consider KEA, or shall I put that
> off until we're closer to widespread ipv6 deployment?] </tangent>
>
> TIA
> -Greg
>

If it were me, I would try upgrading one at a time and see if they talk to
each other ok.  If that fails, then my process for switching from one DHCP
server to another is to reduce the lease time to an hour (or less), at
least a full lease time ahead of the change.  Then at a time when few new
clients are joining the network, turn off one server and turn on the
other.  You will see clients trying the old server unicast between 1/2 and
7/8 of the lease time, then finding the new server with broadcast.  Since
clients should renew at different times, expect most to find the new server
between 3/8 and 7/8 of the lease time from when you make the switch.  Once
things are working well, turn up the lease time to 'normal'.
I would combine the two - turn down the lease times, but try changing one
server of the pair at a time.

p.s. I have not tried KEA, I am using a packaged solution that has ISC
DHCP.  From the email group, it sounds to me like KEA still has some
features missing, compared to DHCPD.  But I could be  wrong.

-- 
Bob Harold
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