An NSX gateway provides optimized distributed routing as well as centralized routing and services such as NAT, Load Balancer, DHCP server and so on. In a single tier (only Tier-0) routing topology, the Tier-0 gateway is connected to segments southbound providing E-W routing and is also connected to physical infrastructure to provide N-S connectivity. This gateway is referred to as a Tier-0 Gateway.
An Edge node can support only one tier-0 gateway or logical router. When you create a tier-0 gateway or logical router, make sure you do not create more tier-0 gateways or logical routers than the number of Edge nodes in the NSX Edge cluster.
Note: When connecting tier-0 uplinks to multi-chassis port-channel topologies such as vPC (virtual PortChannel) or VSS (Virtual Switching System) from Cisco, or MLAG (Multi-Chassis Link Aggregation) from Arista, be sure to consult with the network provider to understand the limitations of the topology when it is being used for transit routing.
