[BBLISA] Telecommunications Recommendations...

[Brian O'Neill]

On 7/14/2010 1:22 PM, Rob Taylor wrote:
> I would guess an issue with dual wan routers is the different IP
> address's that both external interfaces would have. If you use NAT, then
> outbound traffic shouldn't be much of an issue, as it could just get
> NAT'ed to the other link(sessions going at the time of the cutover will
> break when that happens), but inbound might be.
>
> I would guess that you could have off-site dns with a low ttl, and have
> it give one of IP's of either wan interface, and when one fails, update
> it to use the other interface.
>
> Anyone have any other ideas on how to do it?
>

We have a Radware Linkproof at our location, although for various 
reasons we are planning to remove it.

The Linkproof acts as the DNS server for whatever hosts you delegate to 
it (although I was unable to delegate a base domain name - I could do 
"host.foobar.com" but not "foobar.com"). You give the LP a permanent IP 
on each attached network, and delegate the hosts RR to both of them. It 
uses a TTL of 0 (perhaps settable), and will serve out the appropriate 
IP (round robin, priority, etc. based on if the link is considered up).

It was a total pain to get configured the way you wanted it though, and 
asymmetric routing could be a pain if you aren't careful.

-Brian