Cisco 800 Series Routers

Configuring a Cisco 827 Router With NAT, a DHCP Server, and Easy IP Using PPPoA (aal5mux ppp)

Document ID: 12888

Updated: Nov 23, 2007



This sample configuration shows a Cisco 827 Digital Subscriber Line (DSL) Router connecting to a Cisco 6130 Digital Subscriber Line Access Multiplexer (DSLAM) and terminating on a Cisco 6400 Universal Access Concentrator (UAC). The Cisco 827 has been configured with PPP over ATM (PPPoA) with Network Address Translation (NAT) and IP address negotiation turned on. The Cisco 827 is also functioning as a server for its local Ethernet clients.

Before You Begin


For more information on document conventions, see the Cisco Technical Tips Conventions.


There are no specific prerequisites for this document.

Components Used

The information in this document is based on the software and hardware versions below.

  • Cisco 827-4V customer premises equipment (CPE) IOS® Software Release 12.1(1)XB

  • Cisco 6400 UAC-NRP IOS Software Release 12.0(7)DC

  • Cisco 6400 UAC-NSP IOS Software Release 12.0(4)DB

  • Cisco 6130 DSLAM-NI2 IOS Software Release 12.1(1)DA

The information presented in this document was created from devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If you are working in a live network, ensure that you understand the potential impact of any command before using it.


In this section, you are presented with the information to configure the features described in this document.

Note: To find additional information on the commands used in this document, use the Command Lookup Tool (registered customers only) .

Network Diagram

This document uses the network setup shown in the diagram below.



This document uses the configurations shown below.

Cisco 827
version 12.1 
service timestamps debug datetime msec 
service timestamps datetime msec 
hostname R1 
ip subnet-zero 
ip dhcp excluded-address 
ip dhcp pool pool name
interface Ethernet0 
 ip address 
 no ip directed-broadcast 
 ip nat inside 
 no ip mroute-cache
interface ATM0 
 no ip address 
 no ip directed-broadcast 
 no ip mroute-cache 
 no atm ilmi-keepalive
 pvc 1/150 
  encapsulation aal5mux ppp dialer 
  dialer pool-member 1 
 hold-queue 224 in 
interface Dialer0 
 ip address negotiated 
 no ip directed-broadcast 
 ip nat outside 
 encapsulation ppp 
 dialer pool 1 
 dialer-group 1 
 ppp pap sent-username username password password
ip nat inside source list 101 interface Dialer0 overload
ip classless 
ip route Dialer0 
no ip http server 
access-list 101 permit ip any 
dialer-list 1 protocol ip permit
voice-port 1 
 timing hookflash-in 0
voice-port 2
 timing hookflash-in 0 
voice-port 3
 timing hookflash-in 0 
voice-port 4 
 timing hookflash-in 0 

Cisco Access 6400 NRP1
username username password password

!--- The username and password values must  
!--- match the username and password values 
!--- of the remote device.
interface ATM0/0/0.200 point-to-point 
 no ip directed-broadcast
 no ip route-cache
 pvc 1/301
  encapsulation aal5mux ppp Virtual-Template11 
interface Virtual-Template11 
 ip unnumbered Ethernet0/0/0 
 no ip directed-broadcast 
 peer default ip address pool pool name
 ppp authentication pap 
ip local pool pool name


There is currently no verification procedure available for this configuration.


There is currently no specific troubleshooting information available for this configuration.

Related Information

Updated: Nov 23, 2007
Document ID: 12888