Attached is a diagram of our network. Currently we're fully-meshed with MPLS between sites (A, B, C, and D) and a link out to the Internet (ISP1). However were looking to add an additional internet connection (ISP2).
We use BGP at each site to talked to the service provider, and on top of that are multi-point VPNs that are routed with OSPF.
The BGP AS is not public, and we have a a /25 IP assignment from each ISP.
What would be the best way to setup the new internet connection to allow for some load balancing, but more importantly, fail-over for the sites?