Cisco 850 Series, Configuration Manual, Page: 37 / 196

C H A P T E R
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Cisco 850 Series and Cisco 870 Series Access Routers Software Configuration Guide
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Configuring PPP over Ethernet with NAT
The Cisco 851 and Cisco 871access routers support Point-to-Point Protocol over Ethernet (PPPoE)
clients and network address translation (NAT).
Multiple PCs can be connected to the LAN behind the router. Before the traffic from these PCs is sent
to the PPPoE session, it can be encrypted, filtered, and so forth.
Figure 3-1 shows a typical deployment
scenario with a PPPoE client and NAT configured on the Cisco router.
Figure 3-1 PPP over Ethernet with NAT
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Internet
1 Multiple networked devices—Desktops, laptop PCs, switches
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Fast Ethernet LAN interface (inside interface for NAT)
3 PPPoE client—Cisco 851 or Cisco 871 access router
4 Point at which NAT occurs
5 Fast Ethernet WAN interface (outside interface for NAT)
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Cable modem or other server (for example, a Cisco 6400 server) that is connected to the Internet
7 PPPoE session between the client and a PPPoE server