Re: [dhcwg] Load Balancing for DHCPv6

Andre Kostur <akostur@incognito.com> Tue, 18 September 2012 16:04 UTC

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Date: Tue, 18 Sep 2012 09:04:06 -0700
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From: Andre Kostur <akostur@incognito.com>
To: "Bernie Volz (volz)" <volz@cisco.com>
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Cc: "dhcwg@ietf.org" <dhcwg@ietf.org>, Ted Lemon <Ted.Lemon@nominum.com>
Subject: Re: [dhcwg] Load Balancing for DHCPv6
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On Wed, Sep 12, 2012 at 8:15 PM, Bernie Volz (volz) <volz@cisco.com> wrote:
>
> One comment on the draft is that I think it needs to be clear that load
> balancing is ONLY used for DHCPv6 client messages that do not include a
> server-identifier option (this is Solicit, Information-Request (if no
> server-identifier option), Rebind, and Confirm). Load balancing MUST NOT be
> used if a server-identifier option exists in the client's message, as then
> only that server should respond.

I've been mulling this over for a while in the context of the following problem:

Let us assume that there are two cooperating (through some additional
mechanism external to load balancing) DHCPv6 servers A and B.  At some
point, server A goes away for a while and the entire population
eventually binds to server B (whether rebooting, or Rebinding to it).
 Now server A returns to service.  Until the members do a reboot or
Rebind, server A will not be handling any traffic (other than about
1/2 of the new clients) as server B is receiving and answering all of
the Renews.  What I'd like is that over time, the population will
migrate around to splitting between server A and server B again.

I think for this reason we shouldn't force the server to answer (well,
consider) every request aimed at it.

--
Andre Kostur