In PDNAT_TABLE, we have a FIP mac match for performing FIP to internal IP translation.

cookie=0x8000004, duration=41.833s, table=25, n_packets=0, n_bytes=0, priority=10,ip,dl_dst=fa:16:3e:1c:ac:79,nw_dst=100.100.100.12 actions=set_field:60.0.0.2->ip_dst,write_metadata:0x33c20/0xfffffe,goto_table:27

But, the traffic comes from DC-gateway hits L3_LFIB_TABLE, doesn't add the FIP MAC in action as done in L3_FIB_TABLE.

cookie=0x8000002, duration=40.956s, table=20, n_packets=5, n_bytes=510, priority=10,mpls,mpls_label=106017 actions=pop_mpls:0x0800,goto_table:25
cookie=0x8000003, duration=40.956s, table=21, n_packets=0, n_bytes=0, priority=42,ip,metadata=0x33c34/0xfffffe,nw_dst=100.100.100.12 actions=set_field:fa:16:3e:1c:ac:79->eth_dst,goto_table:25

As a result, Floating IP connectivity via DC-gateway(using l3gre tunnel) fails.