THOMSON SpeedTouch, Configuration Manual, Page: 77 / 110

Chapter 8
PPTP-to-PPPoA relaying
E-DOC-CTC-20051017-0167 v1.0
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8 PPTP-to-PPPoA relaying
Introduction
A client establishes a PPP session with the ISP’s PPP server (BRAS). However, the
client is a PPP/PPTP client, establishing a local PPTP tunnel and encapsulating IP
packets into PPP frames. Instead of the Bridge, a PPP relay is used, forwarding the
PPP frames undisturbed from the local PPTP tunnel towards a virtual channel.
Conceptually, one might say that the local PPTP tunnel extends the ATM virtual
channel up to the client.
Features
PPTP-to-PPPoA relaying has the following features:
A Dial-In access method through a PPTP tunnel.
Platform and Operating System independent towards the SpeedTouch™
Protocol stack
The figure below shows the PPPoA-to-PPTP protocol stack.
DSLAM
SpeedTouch
operating as
PPPoA-to-PPTP relay PPP/PPTP client
on PC terminates
the PPP connection
Virtual Channel with:
ATM Encapsulation Type: VC-MUX
Connection Service Name: PPPoA
Connection Service Type: PPPoA
BRAS
Internet
Local PPTP Tunnel,
initiated by the PC, and
terminated in the SpeedTouch
ip
mac
eth
adsl
CPE
DSLAM
PC
Service
Gateway
PPPoA
AAL5/ATM
PHY
ppp
IP
PPP
Public IP
ip
PPTP/L2P
Local IP