Scenario:
Office network consists of two internet facing SRX firewalls (FW1 and FW2) and L3 main switch (CORE-SW1). Core switch can be from any vendor, in our case, its a cisco device. Firewalls are connected to two different ISPs, FW1 is connected to ISP1 and FW2 is connected to FW2. CORE-SW1 has L3 uplinks to each SRX and has a couple of different VLAN L3 interfaces where users live, it is a default gateway for LAN.
Both firewall have IPsecVPN links to the datacenter network, which consists of actually two datacenters connected via 10g DCI. Clients/Users of the remote office need to be able to connect to the internet and also to the datacenter. We need to be able to fail over to the secondary ISP should the primary fail. Active/Active scenario is preferred.