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Chapter 10 VPN
9.1.2 Packet Flow - PPTP Client
Figure 9-2 PPTP Packet Flow
As shown in Figure 9-2, during the PPTP tunnel establishment and data transmission
processes, the packet flow through the PPTP client can be summarized as follows:
After the PPTP tunnel parameters are configured properly, the PPTP client
automatically creates a virtual interface for the new tunnel to listen for user data ((1)
in Figure 9-2).
The PPTP client’s virtual interface listens for the user packets destined for the remote
LAN ((3) in Figure 9-2).
The PPTP client initiates the PPTP tunnel setup request ((4) in Figure 9-2).
The PPTP client receives the user authentication request from the PPTP server, and
then responds to the request ((7) in Figure 9-2).
The PPTP client negotiates with the PPTP server to establish a PPTP tunnel ((8) in
Figure 9-2).
The PPTP client receives the user data (i.e., original packets) and encapsulates them
in
the
PPP
frames
((9)
in
Figure
9-2).
