I deploy the sfc topology:

client->sf->server.

The client vm , sf vm ,server vm are in the different  compute nodes. The vxlan_tool.py is running in the sf and execute the command "python vxlan_tool.py --do=forward --interface=eth0"

Then client ping server and the reply packet is duplicated. Then stop the ping  and I tcpdump on the tap of sf and find the vlxan_tool still keep on sending the packets circularly.