On 2009-02-24, Rod Whitworth <[email protected]> wrote: > On Mon, 23 Feb 2009 17:52:33 -0600, Todd T. Fries wrote: > >>As a corrilary, for those ISP's who think there is only need for a >>single /30 for a client's router, the concept of failover routers >>means 1 physical IP per router, and 1 IP for the failover IP, aka >>3 IP's for the client side, dictating a /29. (sorry for this >>paragraph, but I am not happy with a particular upstream which >>thinks otherwise and is not willing to change). >> > > As a lab exercise, conducted because an upstream provider would only > provide one router IP, I set up two Soekris 4801s with their external > interfaces just "up" -ed and used the exclusive global IP for carp. It > worked like a charm. The internal interfaces could have had whatever > addresses I wanted but, just for fun, I made them work the same way as > the externals.
If the upstream connection is a /30 via something like PPP and you don't care about being able to contact the immediately adjacent addresses, there is the possible hack of setting the netmask a bit shorter than it really is, so you can use the network and broadcast addresses, giving you the two extra addresses you need for this.
