Cisco Router 850 Series Software Configuration Guide

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Configuring PPP over ATM with NAT
The Cisco 857, Cisco 876, Cisco 877, and Cisco 878 access routers support Point-to-Point Protocol over 
Asynchronous Transfer Mode (PPPoA) client s and network address translation (NAT). 
Multiple PCs can be connected to the LAN behind the router. Before traffic from the PCs is sent to the 
PPPoA session, it can be encrypted, filtered,...

 
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Chapter 4      Configuring PPP over ATM with NAT
  
In this scenario, the small business or remote user on the Fast Ethernet LAN can connect to an Internet 
service provider (ISP) using the following protocols on the WAN connection:
 Asymmetric digital subscriber line (ADSL) over plain old telephone service (POTS) using the 
Cisco
 857 or Cisco 877 router
 ADSL over integrated services digital network...

 
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Chapter 4      Configuring PPP over ATM 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. It is also used for cloning 
virtual access. Multiple PPPoA client sessions can be configured on an ATM interface,...

 
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Chapter 4      Configuring PPP over ATM with NAT
  Configure the Dialer Interface
Repeat these steps for any additional dialer interfaces or dialer pools needed.
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)#...

 
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Chapter 4      Configuring PPP over ATM with NAT
  Configure the ATM WAN Interface
Configure the ATM WAN Interface
Perform these steps to configure the ATM interface, beginning in global configuration mode.
CommandPurpose
Step 1interface type number
Example:
Router(config)# interface atm 0Router(config-if)# 
Enters interface configuration mode for the ATM 
interface (labeled ADSLoPOTS or G.SHDSL on 
the...

 
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Chapter 4      Configuring PPP over ATM with NAT
  Configure DSL Signaling Protocol
Configure DSL Signaling Protocol
DSL signaling must be configured on the ATM interface for connection to your ISP. The Cisco 857 and 
Cisco
 877 routers support ADSL signaling over POTS, the Cisco 876 supports ADSL signaling over 
ISDN, and the Cisco
 878 supports SHDSL signaling. Based on the router you are configuring,...

 
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Chapter 4      Configuring PPP over ATM with NAT
  Configure DSL Signaling Protocol
If you wish to change any of these settings, use one of the following commands in global configuration 
mode.
 dsl operating-mode (from the ATM interface configuration mode)
 dsl lom integer
 dsl enable-training-log
See the Cisco IOS Wide-Area Networking Command Reference for details of these commands.
Verify the...

 
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Chapter 4      Configuring PPP over ATM with NAT
  Configure DSL Signaling Protocol
NoteIf you are integrating your Cisco router into a European network, use the dsl dsl-mode shdsl symmetric 
annex {A | B} command to choose annex B. The router uses annex A by default (United States).
Verify the Configuration
You can verify that the configuration is set the way you want by using the show controllers dsl...

 
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Chapter 4      Configuring PPP over ATM with NAT
  Configure Network Address Translation
Receiver Gain: 22.5420 dBSNR Sampling: 36.8590 dB
Dying Gasp: Present
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...

 
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Chapter 4      Configuring PPP over ATM with NAT
  Configure Network Address Translation
Step 4ip nat {inside | outside}
Example:
Router(config-if)# ip nat insideRouter(config-if)# 
Applies NAT to the Fast Ethernet LAN interface 
as the inside interface.
For details about this command and additional 
parameters that can be set, as well as information 
about enabling static translation, see the 
Cisco IOS...