CenturyLink DSL Setup on a Cisco 1720

I turned up a 7Mbps DSL connection with CenturyLink this evening. Here’s the configuration I used to get the circuit working. The ‘debug ppp authentication command’ helped a lot, too.

Note: To get the username and password I had to call CenturyLink technical support. The CenturyLink provisioned modems must have some mechanism to get the necessary information automatically.

interface ATM0
 no ip address
 no atm ilmi-keepalive
 dsl operating-mode auto
 pvc 0/32
  dialer pool-member 1
  protocol ppp dialer
interface Dialer0
 ip address negotiated
 ip nat outside
 ip nbar protocol-discovery
 encapsulation ppp
 dialer pool 1
 ppp pap sent-username USERNAME password PASSWORD
int FastEthernet0
 ip nat inside
ip nat inside source list 111 interface Dialer0 overload
ip route Dialer0

Layer 2 Protocols on Serial Links

Earlier today I was tasked with getting two serial interfaces to talk with each other. Frame-relay is far from my strong suit, so I question-marked my way through the FR commands, making up DLCIs, adding map statements, etc. After several minutes with no luck I looked at the solution. As it turns out, Frame-relay was entirely unnecessary! And so began my Layer 2 serial interface education.

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