HP MSR Router Series Wan Access Configuration Manual page 81

Figure 25 NAS-initiated tunneling mode
A NAS-initiated tunnel has the following characteristics:
The remote system only needs to support PPP, and it does not need to support L2TP.
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• Authentication and accounting of the remote system can be implemented on the LAC or LNS.
Figure 26 NAS-initiated tunnel establishment process
As shown in Figure 26, the following workflow is used to establish a NAS-initiated tunnel:
1. A remote system (Host A) initiates a PPP connection to the LAC (Device A).
2. The remote system and LAC perform PPP LCP negotiation.
3. The LAC authenticates PPP user information of Host A by using PAP or CHAP.
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