DHCP failover without shared-network.

Hi.

I'm using ISC's dhcpd 3.0.3 on a Gentoo box in an office environment
with multiple VLANS through a set of Cisco layer 3 switches. The VLANs
define real networks, and each VLAN has a subnet clause in the
dhcpd.conf file. It's working exactly as I want it to.

I need to set up a failover peer. According to the documentation, a
failover peer has to be defined within a shared-network clause. The
server follows this rule, I've tried to set up failover without
shared-network and it won't start. I don't want the shared-network
because it's not a shared network. According to the documentation,
shared-network combines all the address pools into one and hands them
out indiscriminately. That's exactly what I can't have. Everything
the documentation says about shared-network constructs defies my whole
network design. The more I RTFM the more certain I am that
shared-network will trash my network.

I'd like some input from somebody who has done this. Is there a way to
set up REAL failover without a shared-network construct?

Maybe the more appropriate question would be, how to set up genuine
failover peers in an environment which has real subnets? The server
has only one NIC, and the switches have defined an IP helper address
that points to the server.

Thanks.