Silly config or bug?

Dean, Barry B.Dean at
Fri Apr 24 14:29:31 UTC 2009

Thanks all. My report to the Pointy Haired Boss will be:

1) Stop using secondary IPs on a VLAN interface (because we would like to do this anyway!)

The alternative is to add a "special case" into the scripts that generate the dhcp config for these PCs, yuk!

I guess if there is a bug in DHCPD, it's in the older 3.0.1rc11 version in that it accepts the DISCOVER  when it should probably fail like 4.0.0 does.

Like most things, this is one of those "inherited systems" that was designed to scale to 20 PCs in 2 rooms and now supports nearly 2000 PCs in dozens of rooms! The scripts all need re-writing, but not now!

Barry Dean
Networks Team

> -----Original Message-----
> From: dhcp-users-bounces at [mailto:dhcp-users-
> bounces at] On Behalf Of David Farmer
> Sent: 24 April 2009 15:09
> To: Users of ISC DHCP
> Subject: Re: Silly config or bug?
> That is incorrect, you must use the "shared network" config option to
> tell
> the DHCP server which subnets are on the same subnet.
> We have hundreds of, maybe even a thousand, VLANs set up this way
> On Apr 24 2009, A.L.M.Buxey at wrote:
> >hi,
> >
> >if I recall correctly, you cannot operate DHCP on a
> >secondary interface range on cisco kit with ip helper
> >
> >ie the DHCP server must have a leg on that VLAN and be listening
> >for that range if you want to do it.
> >
> >yet another reason to avoid a secondary interface on a VLAN
> >(unless its only for static hosts I guess) - they are widely
> >condemned s being bad things (tm) - only useful in migration
> >states (eg moving static hosts from a public IP range to a private
> >range so they can still be routed without messing with VLANs
> >at switch-level)
> >
> >alan
> >_______________________________________________
> >dhcp-users mailing list
> >dhcp-users at
> >
> >
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