The configuration of DSL on a Cisco IOS router can be quite confusing for people who haven’t worked much with Cisco routers before or didn’t have to worry about DSL settings because the ISP provided the DSL modem. In this short lesson, I will explain the steps required to get a working DSL connection.
I will only focus on the configuration of DSL, we will not dive into other things like NAT/PAT or the configuration of DHCP.
To get a working DSL connection there are a number of things we have to deal with:
- Configure a dialer interface.
- Apply PPP configuration and layer 3 settings to the dialer interface.
- Apply the ATM configuration to the ATM interface.
- Link the ATM interface to the dialer interface.
- Configure a default route to route traffic out of the dialer interface.
Let me walk you through the configuration:
First, we will configure a dialer interface that has all PPP settings:
Router(config)#interface dialer 1 Router(config-if)#encapsulation ppp Router(config-if)#ip address negotiated Router(config-if)#dialer pool 1 Router(config-if)#ppp authentication chap callin Router(config-if)#ppp chap hostname MYUSERNAME Router(config-if)#ppp chap password SECRET
First, we will tell the dialer interface to use PPP encapsulation and that we want to receive an IP address from the ISP through PPP. The dialer pool command tells the dialer interface that when it wants to set up a connection, it has to use a member interface of the “dialer pool”. We’ll configure the ATM interface as a member of this pool in a bit.
We also configured the dialer interface to use CHAP authentication with username ‘MYUSERNAME’ and ‘MYSECRET’ as password. Not all ISPs will require authentication, but this is how to do it if required.
Now we will configure the ATM interface: