Configure a Cisco Router as a PPPoE Client for DSL connectivity (credit to Zaher Hamiyah)

 

Note: I noticed that on some books no one mentioned the configuration of IP domain lookup command and ISP DNS options in DHCP server configuration. Without these DSL connection will not work. Also pay attention if DSL connection did not work, to check the state of all interfaces by using show ip interface brief and make sure to issue no shutdown command on all of them.

 

There are two configuration options with integrated DSL functionality in the CPE:

 

1. PPPoE on Ethernet interfaces—PPPoE functionality is configured on a CPE router with two Ethernet  interfaces. One Ethernet interface is subscriber-facing, the other provider facing.

 

2. PPPoE on ATM interfaces—PPPoE functionality is configured on a CPE router with one Ethernet interface and one ATM interface. The Ethernet interface is subscriber-facing whereas the ATM interface is provider-facing.

 

 

A. PPPoE on Ethernet interfaces

 

DSL configuration brief steps:

 

1. Internal Ethernet interface configuration
2. External Ethernet interface configuration
3. Dialer interface configuration
4. Configuring Access List
5. NAT/PAT configuration
6. Configuring IP domain Lookup
7. DHCP server services configuration
8. Static default route configuration

 

DSL configuration detailed steps:

 

1. Internal Ethernet interface configuration

 

interface FastEthernet 0/1

 description internal interface

 ip address 172.16.1.1 255.255.255.0

 ip nat inside

 no shut

 

OR (incase you are using Cisco 877 router)

 

interface Vlan1

description internal interface

 ip address 172.16.1.1 255.255.255.0

 ip nat inside

 no shut

 

2. External Ethernet interface configuration

 

Interface FastEthernet 0/0

 Description DSL interface

 no ip address

 pppoe enable

 pppoe-client dial-pool-number 1

 no shut

 

3. Dialer interface configuration

 

interface Dialer1

 ip address negotiated

 ip mtu 1492

 ip nat outside

 encapsulation ppp

 dialer pool 1

 ppp authentication chap pap callin

 ppp pap sent-username USERNAME password P@ssw0rd (this is the password that ISP gave it       to you

 ppp chap hostname HOSTNAME (This is the username that ISP gave it to you)

 ppp chap password P@ssw0rd

 no shut

 

4. Configuring Access List

 

ip access-list extended DSL_ACCESSLIST

100 permit ip 10.10.10.0 0.0.0.255 any

 

5. Configuring NAT/PAT

 

ip nat inside source list DSL_ACCESSLIST interface dialer 1 overload

 

6. Configuring IP domain Lookup

 

ip domain lookup

ip name-server Primary DNS IP address (obtained from your ISP)

ip name-server Secondary DNS IP address (obtained from your ISP)

 

7. DHCP server services configuration

 

ip dhcp pool DSL_DHCP

 network 10.10.10.0 /29

 dns-server Primary DNS IP address Secondary DNS IP address (obtained from your ISP)

 default-router 10.10.10.1 (internal VLAN or Ethernet interface Ip address)

 import all

 

8. Static default route configuration

 

Finally, configure a static default route. It should point to the dialer interface rather than an IP address as in the below example.

 

ip route 0.0.0.0 0.0.0.0 dialer 1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

B. PPPoE on ATM interfaces

 

DSL configuration brief steps:

 

1. Internal Ethernet interface configuration
2. External ATM interface configuration (in case you are using Cisco 877 Router)
3. Dialer interface configuration
4. Configuring Access List
5. NAT/PAT configuration
6. Configuring IP domain Lookup
7. DHCP server services configuration
8. Static default route configuration

 

DSL configuration detailed steps:

 

1. Internal VLAN interface configuration (using Cisco 877 Router)

 

interface Vlan1

description internal interface

 ip address 172.16.1.1 255.255.255.0

 ip nat inside

 no shut

 

OR (if you are using configurable internal Ethernet interface)

 

interface FastEthernet 0/1

 description internal interface

 ip address 172.16.1.1 255.255.255.0

 ip nat inside

 no shut

 

2. External ATM interface configuration

 

interface ATM 0

 description DSL interface

 ip directed-broadcast

 ip mask-reply

 ip route-cache flow

 no ip address

 dsl operating-mode auto

 pvc 8/35

 no shutdown

pppoe-client dial-pool-number 1

 

3. Dialer interface configuration

 

interface Dialer1

 ip address negotiated

 ip mtu 1492

 ip nat outside

 encapsulation ppp

 dialer pool 1

 ppp authentication chap pap callin

 ppp pap sent-username USERNAME password P@ssw0rd (this is the password that ISP gave it to you

 ppp chap hostname HOSTNAME (This is the username that ISP gave it to you)

 ppp chap password P@ssw0rd

 no shut

 

4. Configuring Access List

 

ip access-list extended DSL_ACCESSLIST

100 permit ip 10.10.10.0 0.0.0.255 any

 

5. Configuring NAT/PAT

 

ip nat inside source list DSL_ACCESSLIST interface dialer 1 overload

 

6. Configuring IP domain Lookup

 

ip domain lookup

ip name-server Primary DNS IP address (obtained from your ISP)

ip name-server Secondary DNS IP address (obtained from your ISP)

 

7. DHCP server services configuration

 

ip dhcp pool DSL_DHCP

 network 10.10.10.0 /29

 dns-server Primary DNS IP address Secondary DNS IP address (obtained from your ISP)

 default-router 10.10.10.1 (internal VLAN or Ethernet interface Ip address)

 import all

 

8. Static default route configuration

 

Finally, configure a static default route. It should point to the dialer interface rather than an IP address as in the below example.

 

ip route 0.0.0.0 0.0.0.0 dialer 1

I apologize if any errors found in the document. If you see any please correct them. No one is perfect.