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List:       dhcp-users
Subject:    Re: reserved leases
From:       "David W. Hankins" <David_Hankins () isc ! org>
Date:       2006-09-16 17:19:30
Message-ID: 20060916171929.GN29172 () isc ! org
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On Sat, Sep 16, 2006 at 05:32:51PM +1000, Ray Phillips wrote:
> As I understand it this wouldn't work with failover since pools need 
> to have at least two IP numbers so each peer can be responsible to 
> half the pool?

I'm not aware of any such restriction, per se.  It certainly would not
work well, however, since only one server would have the ability to
answer.  You'd have to assume your servers always operate in normal
state.

It might be easier to use host records, which are 'failover compatible'
(in that both servers will happily answer).

> Is it possible to use 3.1.0's reserved lease feature to replace this 
> scheme?

I'm not sure.  Do you allocate multiple clients to a pool of one address,
or is it a 1:1 ratio on clients to addresses?

Reserved leases will only work in the 1:1 case.

> The man page seems to say a client can only have a reserved 
> lease if it requests an infinite lease, or if it OMAPI is used to 
> configure it.

You can also edit dhcpd.leases.  Just mark a lease "reserved;".

> Can a lease only be reserved once it's been allocated, 
> in which case it's not possible to specify in advance which IP number 
> a client with a reserved lease will get?

No, but you have to know how the client is going to identify itself
beforehand.  Client identifier or hardware address, and the contents
of those fields.

> What's the syntax for using OMAPI to reserve a lease?

I haven't had time to complete documentation to those ends...

Suffice to say you need to set a magic bit in a flags field.

-- 
ISC Training!  October 16-20, 2006, in the San Francisco Bay Area,
covering topics from DNS to DHCP.  Email training@isc.org.
-- 
David W. Hankins	"If you don't do it right the first time,
Software Engineer		you'll just have to do it again."
Internet Systems Consortium, Inc.	-- Jack T. Hankins

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