Hello,
Raspberry Pi model 3 B is connected with ZigBee receiver which getting data from Wireless Sensor transmitter and via LAN port I have connected the ethernet relay board which I want to connect with Online server database using PI inbuilt wifi connection but for doing this, I want to assign the VLAN ID(Virtual LAN ID) to LAN port connection between relay board and raspberry pi for some security purpose.
Any suggestion to make this kind of solution work will be very helpful.
Take a look at the vlan package and 8021q module, here’s a link which should help https://blog.sleeplessbeastie.eu/2012/12/23/debian-how-to-create-vlan-interface/
Don’t mistake VLANs for security though! 
any sample in python for this kind of solution?
so that ill be able to modify as per my sufficiency.