The command vmkping ++netstack=geneve -d -s 1572 <destination IP address> is used to check the VMware kernel ports for tunnel end point communication. This command uses the geneve netstack, which is the default netstack for NSX-T. The -d option sets the DF (Don't Fragment) bit in the IP header, which prevents the packet from being fragmented by intermediate routers. The -s
1572 option sets the packet size to 1572 bytes, which is the maximum payload size for a geneve encapsulated packet with an MTU of 1600 bytes. The <destination IP address> is the IP address of the remote ESXi host or VM.
Reference: : VMware NSX-T Data Center Installation Guide, page 19. : VMware Knowledge Base:
Testing MTU with the vmkping command (1003728). : VMware NSX-T Data Center Administration Guide, page 102.