Troubleshooting guide

Tip: If you are not familiar with configuring Cisco devices and would like to follow a step−by−step
configuration, click here.
Tasks to Perform
Note: A color code is used to relate tasks in this section with examples of configurations in the Configuration
section. Configurations are color−coded as follows: Dynamic Host Configuration Protocol (DHCP) Server,
Network Address Translation (NAT).
Design an IP addressing scheme for your private LAN.•
Configure an IP address and subnet mask on the Cisco DSL Router Ethernet interface.•
Configure the ATM interface (Asymetric Digital Subscriber Line (ADSL) interface) of the Cisco DSL
Router with an ATM permanent virtual circuit (PVC) and encapsulation.
•
Create and configure the Dialer interface of the Cisco DSL Router for Point−to−Point Protocol over
ATM (PPPoA) with a negotiated IP address.
•
Configure NAT on the Cisco DSL Router to allow sharing of the dynamic public IP address of the
Dialer interface.
Optional: NAT Pool, if additional IP addresses have been provided by your ISP.♦
Optional: Static NAT, if Internet users require access to internal servers.♦
•
Configure each host PC with an IP address, subnet mask, default gateway, and Domain Name System
(DNS) server(s).
Alternatively, if you want the Cisco DSL Router to assign your PC clients' dynamic IP addresses,
configure each PC to obtain an IP address and DNS server(s) automatically via DHCP.
•
Configuration
Tip: If you are not familiar with configuring Cisco devices and would like to follow a step−by−step
configuration, click here.
Cisco DSL Router with a Dynamic IP Address
!−−− Comments contain explanations and additional information.
service timestamps debug datetime msec
service timestamps log datetime msec
ip subnet−zero
!
ip dhcp excluded−address <ip address of ethernet0>
ip dhcp pool <dhcp pool name>
network <ip network address of ethernet0> <subnet mask>
default−router <ip address of ethernet0>
dns−server <ip address of dns server>
!
interface ethernet0
no shut
ip address <ip address> <subnet mask>
ip nat inside
no ip directed−broadcast
!
Cisco DSL Router Configuration and Troubleshooting Guide