Load Balance & redundancy for internet from 2 different sites?

[louis0001]

Hi,

we have 2 core sites where our servers are situated. Both sites are connected via a ptp link.
All of our clients/sites reach these two sites via our MPLS network and they never route via the ptp link which is solely used between the two core sites.

One of the sites has an ASA which goes out to our internet. We are thinking of replicating this on our other site.

How would we go about load balancing the internet connection ie 50% go out on site A & 50% go out on site B?
And if site A goes down, everything goes out via site B and vice versa?

Diagram attached....

Thank you,

Louis

[Bilal Nawaz]

Hi Louis, you could set default routes on the ASA's with tracking, and use ospf downstream to inject the default route in to the network with default information originate - this will only advertise out a default route if it has it in the routing table. With SLA you can track internet reachability by IP SLA echo to something like 8.8.8.8. Both sides can advertise this in to the network, if one goes then there is one left. Just be mindful of the policies and NAT required, you will have to duplicate the rules on the ASA's. With the NAT you have to ensure, that outgoing traffic comes back in the same path it left so it doesn't break connections.