Here are the steps to create the VTEP and map the VNI to the VLAN:

Enter Configuration Mode:

SwitchA# configure terminal

Create VTEP Interface:

SwitchA(config)# interface vtep1

SwitchA(config-if-vtep1)# ip address 10.10.10.1/24

SwitchA(config-if-vtep1)# exit

Map VNI 400 to VLAN 40:

SwitchA(config)# vlan 40

SwitchA(config-vlan)# vn-segment 400

SwitchA(config-vlan)# exit

Enable ARP Neighbor Suppression:

SwitchA(config)# interface Vlan40

SwitchA(config-if-Vlan40)# ip address 192.168.40.254/24

SwitchA(config-if-Vlan40)# vxlan arp-suppression

SwitchA(config-if-Vlan40)# exit

Save Configuration:

SwitchA# write memory

Enter Configuration Mode:

Begin by entering the global configuration mode to make changes to the switch configuration.

Create VTEP Interface:

Enter the interface configuration mode for the VTEP interface named vtep1 using interface vtep1.

Assign the IP address 10.10.10.1/24 to the VTEP interface using the ip address command.

Exit the interface configuration mode.

Map VNI 400 to VLAN 40:

Enter the VLAN configuration mode for VLAN 40 using vlan 40.

Map the VNI 400 to VLAN 40 using the vn-segment 400 command.

Exit the VLAN configuration mode.

Enable ARP Neighbor Suppression:

Enter the interface configuration mode for VLAN 40 using interface Vlan40.

Assign the anycast IP address 192.168.40.254/24 to the VLAN interface using the ip address command.

Enable ARP neighbor suppression using the vxlan arp-suppression command.

Exit the interface configuration mode.

Save Configuration:

Save the configuration to ensure the changes persist after a reboot using the write memory command.

References:

Dell Technologies Networking - SONiC

Dell Enterprise SONiC Deployment Guide

These steps provide a comprehensive guide to configure a VTEP and map the VNI to VLAN 40 on Switch A, ensuring the specific requirements for IP addressing and ARP neighbor suppression are met.