Cisco Systems Router 1800 Series User Manual

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Sample Network Deployments
This part of the software configuration guide presents a variety of possible Ethernet- and Digital 
Subscriber Line (DSL)-based network configurations using Cisco
 1800 series routers. Each scenario is 
described with a network topology, a step-by-step procedure that is used to implement the network 
configuration, and a configuration example that shows the results...

 
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Chapter 2      Sample Network Deployments
   

CH A P T E R
 
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Configuring PPP over Ethernet with NAT
The Cisco 1811 and Cisco 1812 integrated services fixed-configuration 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 en crypted, filtered, and so forth....

 
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Chapter 3      Configuring PPP over Ethernet with NAT
  Configure the Virtual Private Dialup Network Group Number
PPPoE
The PPPoE Client feature on the router provides PPPoE client support on Ethernet interfaces. A dialer 
interface must be used for cloning virtual access. Multiple PPPoE client sessions can be configured on 
an Ethernet interface, but each session must use a separate dialer interface and a...

 
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Chapter 3      Configuring PPP over Ethernet with NAT
  Configure the Fast Ethernet WAN Interfaces
Configure the Fast Ethernet WAN Interfaces
In this scenario, the PPPoE client (your Cisco router) communicates over a 10/100-Mbps Ethernet 
interface on both the inside and the outside. 
NoteThe Cisco 1800 series integrated services fixed-configuration routers have a hardware limitation on the 
Fast Ethernet...

 
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Chapter 3      Configuring PPP over Ethernet with NAT
  Configure the Fast Ethernet WAN Interfaces
Perform these steps to configure the Fast Ethernet  WAN interfaces, starting in global configuration 
mode: 
CommandPurpose
Step 1interface  type number
Example:
Router(config)# interface fastethernet 0
Router(config-if)# 
Enters interface configuration mode for a 
Fast
 Ethernet WAN interface.
The Cisco...

 
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Chapter 3      Configuring PPP over Ethernet with NAT
  Configure the Dialer Interface
Configure the Dialer Interface
The dialer interface indicates how to handle traffic from the clients, including, for example, default 
routing information, the encapsulation protocol, and the dialer pool to use. The dialer interface is also 
used for cloning virtual access. Multiple PPPoE client sessions can be...

 
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Chapter 3      Configuring PPP over Ethernet with NAT
  Configure the Dialer Interface
Step 7dialer-group group-number
Example:
Router(config-if)# dialer group 1Router(config-if)# 
Assigns the dialer interface to a dialer group 
(1–10).
TipUsing a dialer group controls access to 
your router.
Step 8exit
Example:
Router(config-if)# exit
Router(config)# 
Exits the dialer 0 interface configuration.
Step...

 
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Chapter 3      Configuring PPP over Ethernet with NAT
  Configure Network Address Translation
Configure Network Address Translation
Network Address Translation (NAT) translates packets from addresses that match a standard access list, 
using global addresses allocated by the dialer interface. Packets that enter the router through the inside 
interface, packets sourced from the router, or both are checked...

 
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Chapter 3      Configuring PPP over Ethernet with NAT
  Configure Network Address Translation
NoteIf you want to use NAT with a virtual-template interface, you must configure a loopback interface. See 
Chapter 1, “Basic Router Configuration,” for information on configuring a loopback interface.
Step 5no shutdown
Example:
Router(config-if)# no shutdownRouter(config-if)# 
Enables the configuration changes...