The NSX Tier-1 Gateway provides downlink connection to segments. In the context of a vSphere with Tanzu deployment, a Tier-1 Gateway’s primary role is to connect to logical segments, which are essentially network segments that can be used by workloads. Tier-0 gateways, on the other hand, are responsible for north-south routing and connecting to physical networks, while Tier-1 gateways focus on internal east-west traffic within the logical segments.