failover compatibility

[Glenn Satchell]

(b) copy the leases file is preferable. Do this after shutting down dhcpd.

The clients hold the lease information too, so they need to match up.

It's been a while since I've done this, but essentially you need to copy
each one.

1. Shut down old1
2. Copy dhcpd.conf and dhcpd.leases to new1.
3. Start new1
4. Shut down old2
5. Copy dhcpd.conf and dhcpd.leases to new2
6. Start new 2

May need to swap steps 3 and 4.

Are you using new dhcp servers? Will they have the same or new IPs? If the
new servers are running on new ip addresses then all clients will need to
wait for their lease to expire, then they will go back to discover the new
dhcp servers. On the other hand if the new servers have the same IP
addresses as the old servers then the clients will contact them directly
to renew existing leases. Either works ok as long as the leases file is
copied to the new server so that it can issue the same IP address the
client had before.

regards,
-glenn

On Wed, September 5, 2012 2:30 pm, Campbell.ColinD at police.qld.gov.au wrote:
> Hi,
>
> Thanks for that. That brings a new quandary.
>
> I can't upgrade both servers simultaneously. I have to do one at a time.
> In doing so, I plan on shutting one down, upgrading it, restoring the
> configs, shutting down the other old server and doing something with the
> leases on the new server. That something could be:
>
> a) let the new server create a new leases file, or
> b) copy the leases file from the still-active old server
>
> Is (a) or (b) preferable? If neither, what is the correct procedure?
>
> Colin
> --
> Colin Campbell
> Security Specialist
> Public Safety Network Management Centre
> p: (07) 3008 4851
> f: (07) 3008 4799
> e: campbell.colind at police.qld.gov.au
>
>
>> -----Original Message-----
>> From:
> dhcp-users-bounces+campbell.colind=police.qld.gov.au at lists.isc.org
>>
> [mailto:dhcp-users-bounces+campbell.colind=police.qld.gov.au at lists.isc.o
> rg]
>> On Behalf Of Glenn Satchell
>> Sent: Wednesday, 5 September 2012 2:11 PM
>> To: Users of ISC DHCP
>> Subject: Re: failover compatibility
>>
>> No. The failover protocol changed somewhere in the 3.1 to 4.x range.
>> Details would be in the RELNOTES file distributed with the source.
>>
>> Essentially you need to shutdown and upgrade both failover hosts at
> the
>> same time. You can pre-check the format of dhcpd.conf and dhcpd.leases
>> using dhcpd -t and dhcpd -T to see if there are any issues wit the new
>> version. In general, the files *should* be compatible with all newer
>> versions.
>>
>> regards,
>> -glenn
>>
>> On Wed, September 5, 2012 8:24 am, Campbell.ColinD at police.qld.gov.au
> wrote:
>> > Hi,
>> >
>> > Will a 3.0.5 server form a failover pair with a 4.x server? This
> would
>> > be a temporary arrangement during a server pair upgrade.
>> >
>> > Colin
>> > --
>> > Colin Campbell
>> > Security Specialist
>> > Public Safety Network Management Centre
>> > p: (07) 3008 4851
>> > f: (07) 3008 4799
>> > e: campbell.colind at police.qld.gov.au
>> >
>> >
>> >
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