Subject: [dhcwg] DHCPv6 Failover 2011-09-07 meeting invitation

From: Tomasz Mrugalski <[email-masked]>
Date: Tue, 06 Sep 2011 21:35:29 +0200

Dear all,
Vacations are over and most people are back in offices. It's time to
resume failover work. I asked people who were previously participating
in those meetings about preferred schedules and the answer seems to be
Wednesday 10am PDT. The next meeting will be tomorrow then.

Agenda:

- Lease update data: during previous meetings we discussed communcation
overview between partners. We will resume this discussion by reviewing
those parameters.
- Acknowledging reception: Partner operation when receiving lease
update. Acknowledging valid update is trivial, processing rejected lease
is not.
- State machines: partner states
   - list of states
   - state descriptions
   - state machine initialization
   - state transitions
- Failure recovery

People who previously expressed interest in this work received latest
copies of the draft (check your mail from August 17th). If you are
interested in getting a copy, let me know or ask anyone who participates.

Also, a kind reminder to chairs: would it be possible to proceed with
adoption of dhcpv6-failover-requirements and annoucing WGLC on
dhcpv6-redundancy-considerations drafts? Please check following mails
from August 12nd:
http://www.ietf.org/mail-archive/web/dhcwg/current/msg11882.html and
http://www.ietf.org/mail-archive/web/dhcwg/current/msg11881.html

Thanks,
Tomek

Tomorrow's meeting details:

Topic: DHCPv6 Failover
Date: Wednesday, September 7, 2011
Time: 7:00 pm, Europe Summer Time (Berlin, GMT+02:00)
Meeting Number: 807 974 224
Meeting Password: failover

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From: "Marc Lampo" <[email-masked]>
Date: Thu, 8 Sep 2011 08:38:10 +0200 (CEST)

Hello,

For some reason this invitation for a meeting on the 7th
was sent (by IETF mailing list server) only late on the 7th
and reached "my eyes" only on the 8th ...

Anyhow, I just wanted to repeat the remark I made in Quebec :
one desire I'd have for DHCP failover is that "roles" are not
distributed per server, but per network served.

In my experience (I was initially misled myself) people assume
they can assign a role / distribute load per network,
thus achieving a (simple) setup :
- DHCP partner in location A services 100% of the local network(s),
   and 0% of the network(s) in location B.
- DHCP partner in location B services 100% of the local network(s) there,
   and 0% of the network(s) in location A
--> should either DHCP partner "die",
    the remaining partner services 100% of both locations.

DHCPv4 failover does not allow this;
the above scenario is not possible.
I translate this in :
DHCP(v4) failover is not suited for redundancy of "equivalent" partners.

The only scenario where DHCP(v4) makes sense seems (to me) :
- central site has DHCP partner which server 0% of all remote networks
- every remote site has DHCP partner that services 100% of its local 
networks
(a "star" setup)

Personally I find it a pity that "role per server" actually limits
the useful cases where the protocol can be used.

Hence my question :
What are the feelings in this WG ?
Is this worth to be included as requirement for DHCPv6 failover ?

Kind regards,

Marc Lampo

-----Original Message-----
From: Tomasz Mrugalski [mailto:[email-masked]]
Sent: 06 September 2011 09:35 PM
To: [email-masked]
Subject: [dhcwg] DHCPv6 Failover 2011-09-07 meeting invitation

Dear all,

Agenda:

Thanks,
Tomek

Topic: DHCPv6 Failover

Access code:807 974 224

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From: Ted Lemon <[email-masked]>
Date: Thu, 8 Sep 2011 11:37:39 +0000

On Sep 8, 2011, at 2:38 AM, Marc Lampo wrote:

Actually, this is not true: DHCPv4 failover does allow this exact configuration.   It's just a matter of correctly configuring the load balancing array, and setting up two peering relationships with two separate load balancing arrays, one for each network.

The problem with this, and the reason it's not typically done, is that it doesn't buy you anything.   It doesn't save you having to send traffic to both servers.   It doesn't reduce the load on either server during normal operation.   A database update is a database update whether it happens as a result of failover activity or as a result of DHCP protocol activity.   So why bother?

(This is a serious question: obviously you perceive a problem with the setup I've described.  I'd like to know what that problem is.)