[GRE] The concept of GRE flow by using vlan

WiFi send a package(P) to eth0.100 (vlan number of eth0 is 100).
P pass through to Gre interface, because eth0.100 and Gre are bridge together.

P flow to Happy 0.100 by GRE tunnel.
P pass through to eht2 interface, because Happy 0.100 and eth2 are bridge together.
When P go out of eth2 will take off vlan number 100, then send a normal packet to DHCP Server.