| Here we have an example frame of an L2F packet and its format. Notice that it is located inside an IP header and a UDP header. The PPP header is located just inside the packet. In the case of TCP/IP, the IP header would be next, followed by the TCP header. The payload area is located beneath all the headers. As you can see, the L2F VPN does create some overhead. Note that L2F uses registered port 1701 and only exists in version one.