Explanation
The two interfaces that will be used for ingress traffic on the Edge node supporting a Single Tier topology are:
B: Tier-0 Uplink interface
C: Downlink Interface for the Tier-0 DR
The Tier-0 Uplink interface is the interface that connects the Tier-0 gateway to the external network. It is used to receive traffic from the physical router or switch that is the next hop for the Tier-0 gateway. The Tier-0 Uplink interface can be configured with a static IP address or use BGP to exchange routes with the external network.
The Downlink Interface for the Tier-0 DR is the interface that connects the Tier-0 gateway to the workload segments. It is used to receive traffic from the VMs or containers that are attached to the segments. The Downlink Interface for the Tier-0 DR is a logical interface (LIF) that is distributed across all transport nodes that host the segments. The Downlink Interface for the Tier-0 DR has an IP address that acts as the default gateway for the VMs or containers on the segments.