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The ESG is used primarily to provide north-south routing between the physical network and internal logical networks in NSX. The physical network connection is typically a VLAN-backed Portgroup connection mapped to the ESG as an uplink Port. This provides the north-south physical connection, at which point the ESG can either use the default gateway, static routes, dynamic routing protocol (BGP/OSPF), or a combination of the three.

It is generally recommended only to run a single routing protocol (instance) per ESG in production networks and to treat NSX logical networks as stub networks. In this topology, it is also recommended that the ESG learn as few routes as possible to complete its function of routing traffic north-south; therefore, if a single default route (0.0.0.0/0) is sufficient, that should be all that is advertised to the ESG. All other routes would not be beneficial and only increase CPU cycles on the ESG. This is also considered good network design.