The NSX ESG comes in a virtual machine form factor that is managed solely by NSX. The ESG has many different functionalities in addition to routing, which provide the advanced functionalities of the NSX for vSphere platform. Each ESG can run one or more of these application services, but an ESG can also be deployed for a single purpose, which is very common in many enterprise deployments. This is done for many reasons, as an ESG used for load balancing in one-armed mode may be tied to the application, therefore it should be commissioned with the application and decommissioned with the application.

The services that can be run on the NSX ESG are as follows:

• DNS relay
• DHCP server
• Network Address Translation (DNAT and SNAT)
• Load Balancing (layer 4 and layer 7)
• Routing:
  • BGP
  • OSPF
  • Static
• VPN services:
  • Layer 2 VPN (L2VPN)
  • IPSEC VPN
  • SSL VPN

We will explore these core services in this chapter. For the layer 2 VPN service, which is not covered in this chapter, please refer to the NSX Administration Guide at https://docs.vmware.com/en/VMware-NSX-for-vSphere/.