how to use VHDL get mac address of a development kit?

I am assuming your question is to find the MAC address in your development kit. What development kit are you using?

If you can send a packet from your development kit, a great tool for Windows is Wireshark. It might work for your purposes if you can get ethernet packets to your PC.

any VHDL example about send packet or frame from Cyclone III development kit

would like to send some data to Cyclone III through USB and then send to a switch

from Cyclone III and then the switch send back to my computer

any development kit have two ethernet port?

one port is connecting to computer, one port is connecting to switch

if no, i may use a hub

as i may send data from computer to Cyclone through ethernet first