I assume you either have a stretched cluster or two site local clusters in VCF but in both cases your intention is to span a Tier-0 GW across the two sites.
For redundancy and performance reasons I would create an Edge cluster with 4 Edge nodes total, two per site. Depending if your uplink VLANs are stretched across both sites or if they are only available within each site:
- All Edges in AZ1 and AZ2, in essence the Tier-0 GW, have their uplink interfaces in the two stretched uplink VLANs. All Edge nodes peer with a router in AZ1 and AZ2 through both uplink VLANs, 4 peers in total.
- Each pair of Edge nodes, in essence the Tier-0 GW, have their uplink interfaces in the two site local uplink VLANs in AZ1 and AZ2 respectively. Edge nodes in AZ1 peer with a router in AZ1 and Edge nodes in AZ2 respectively, 4 peers in total.
For both cases: Depending on how you wan't your traffic carried to your physical network, you might use traffic steering options in BGP like local preferences and AS path prepending to have e- and ingress traffic though AZ1 primarily. Or you don't steer your traffic but you'll have asymmetric routing (which doesn't need to be negative).
