[CentOS] Making FORWARD_IPV4=YES permanent / DHCP multiple routers

Thu Feb 14 15:09:51 UTC 2008
nate <centos at linuxpowered.net>

Tim Alberts wrote:

> So how do I do this?

easiest way is to put it in /etc/rc.d/rc.local . I'm sure that's
not the "proper" way though.

> so that if one is down, the network PC's can fail over to another?

No PC will do that even if the DHCP server supported it. What you want
is VRRP, so the backup router will assume the IP and MAC address
of the failed router. There are other protocols that can accomplish
the same thing, OpenBSD uses pf carp, some older cisco gear have
HSRP. Lots of firewall vendors have their own proprietary protocols
for fail over. I run ESRP in my environment to provide layer 3
router fault tolerance as well as layer 2 loop prevention in a single
protocol(that doesn't require any protocols be installed on downstream
equipment unlike (R|M)STP)

nate