so i figured out some topology.
i can insall layer2 line between DCs and transfer the vlan that will be between the internet GW and the router that will be connected to 2 internet lines. there will be a router on each site with it's own internet lines. i want to configure the internet GW (cluster) that 1. if the active member is in site a it will route traffic with priority to site a, and use site b as a backup. and the opossite if the active member now in site b. and i also want that the checkpoint will know to return the packet from the same interface/next hop the packet arrived from (for incoming connections).
i know that isp redundancy is build for this purpose, but it has it's limitations. for example i can't priorities isp based on latency/bandwidth. i need to configure one priority per the whole cluster, and not per member. and also i can't use third isp (which is my case may be helpful as a 3rd option)
how can i accomplish this with dynamic routes/pbr or other features? thx