CARP and the likes rely on the presence of an L2 layer which means you get limited scale or increased risk of a global outage. An L3 design scales very well and

CARP and the likes rely on the presence of an L2 layer which means you get limited scale or increased risk of a global outage. An L3 design scales very well and is resilient (notably because of the distributed control plane and the inability to create a loop).