/etc/modprobe.conf (insert last 2 lines)

alias scsi_hostadapter mptbase
alias scsi_hostadapter1 mptspi
alias scsi_hostadapter2 ata_piix
alias eth0 pcnet32
alias eth1 pcnet32
alias dummy0 dummy
options dummy numdummies=1
!
!
info :

eth0 is core
eth1 transit

Preload the dummy network driver on the machine. If this command is successful,
you do not receive any messages from the server :

modprobe -a dummy

Find the last address in the last usable network range.

/etc/sysconfig/network-scripts/ifcfg-dummy0

DEVICE=dummy0
BOOTPROTO=static
ONBOOT=yes
IPADDR
NETMASK=255.255.0.0


Before we bring up dummy interface. Need to :

rmmod dummy =  removes dummy modules
modprobe dummy =  re-creates the dummy modules
ifup dummy0 =  bring up dummy0

LINUX GENTOO ADD DUMMY INTERFACE

# /etc/conf.d/net
config_dummy0=(‘10.1.2.100 netmask 255.255.255.255 broadcast 10.1.2.100’)

!

I actually added both forwarded ip addresses and make the dummy interface start up by default

cd /etc/init.d
ln -s net.lo net.dummy0
rc-update add net.dummy0 default
/etc/init.d/dummy0 start

!

I added this to my /etc/sysctl.conf
net.ipv4.conf.all.arp_ignore=1
net.ipv4.conf.eth0.arp_ignore=1
net.ipv4.conf.all.arp_announce=2
net.ipv4.conf.eth0.arp_announce=2

Then refresh the sysctl settings:
sysctl -p

!

Bring up interface :

/etc/init.d/net.dummy0 stop
/etc/init.d/net.dummy0 start