Cisco 1800 Router PPPOE Authentication

[mtnvictory69]

What commands do I need to enter to correctly authenticate with my DSL PPPOE provider? I need to have the ID and Password entered into the router.

Thanks

mtnvictory69

[paolo bevilacqua]

You can search this forum or Cisco.com for answers on your questions, that has been discussed many, many times.

[Peter Paluch]

Hi Michael,

If your router is configured for PPPoE access, it should have a Dialer interface configured. On this interface, enter these commands:

ppp chap hostname YOUR_LOGIN

ppp chap password YOUR_PASSWORD

ppp pap sent-username YOUR_LOGIN password YOUR_PASSWORD

These commands configure your router for both PAP and CHAP authentication mechanisms. If you know exactly which authentication mechanism you will be using, use just the appropriate command(s) and you may omit the configuration of the other mechanism. If in doubt, use all three commands.

Best regards,

Peter

[mtnvictory69]

Here is my current configuration without the PPPOE lines added.

Thanks

[Peter Paluch]

Michael,

Your router does not appear to be configured for any PPPoE at all. It is currently configured for plain IP conectivity. Are you sure you're using PPPoE? Can you describe how this router is connected to a DSL service? If there is another DSL router at your premises then it is that router which has to be configured for PPPoE, not this one.

Best regards,

Peter

[mtnvictory69]

I do not have a Dialer interface configured on this router. How would that be done please?

Thanks

[Peter Paluch]

Michael,

First, I need to understand your network topology, i.e. what devices you have, what is their function and how they are interconnected. Only then I can suggest how you should configure your router. Please try to describe in as much detail as possible how this Cisco router is connected to the surrounding network and to the DSL service provider.

Best regards,

Peter

[mtnvictory69]

The remote office just installed a DSL line and we have 5 dedicated IP's from CenturyLink with a modem. I am configuring this router for VPN to HQ. I know that the DSL modem needs to be setup as a bridge which has been done. Now I need to configure the router to use PPPOE authentication but not sure how since I have never used DSL in front. Hopefully this will help you.

Thanks

[Peter Paluch]

Hello Michael,

Now I have a better insight into your situation. Thank you for the additional explanation. Can I assume that the current configuration of the router is a remainder of some previous deployment and can be freely modified as needed? In particular, is the IP addressing of the Fa1 interface valid or not?

Your configuration should be modified as follows (you should paste the following commands into your global configuration mode directly, as they will perform the necessary modifications):

interface FastEthernet1
 no crypto map VPN
 no service-policy output VOIP
 no ip access-group FIREWALL in
 no ip nat outside
 no ip inspect FIREWALL out
 no ip address
 pppoe-client dial-pool-number 1
 exit
!
interface Dialer1
 dialer pool 1
 encapsulation ppp
 ppp chap hostname YOUR_LOGIN
 ppp chap password YOUR_PASSWORD
 ppp pap sent-username YOUR_LOGIN password YOUR_PASSWORD
 ip address negotiated
 ip mtu 1492   
 ip tcp adjust-mss 1452
 ip nat outside
 ip inspect FIREWALL out
 ip access-group FIREWALL in
 service-policy output VOIP
 crypto map VPN
!
no ip route 0.0.0.0 0.0.0.0
ip route 0.0.0.0 0.0.0.0 Dialer1

This configuration is not guaranteed to work out of the box. In particular, I am not sure how will the ip address negotiated command work - I do not know if the provider will assign IP addresses to you automatically or if you are supposed to configure static addressing yourself.

It is supposed that the DSL modem is set to bridge mode and that the Cisco router is connected to the DSL modem via its Fa1 interface.

In any case, after applying this configuration and waiting a minute or so, please post the output of the following commands:

show ip interface brief

show ip route

show pppoe session

These commands will help me find out if the configuration worked at least partially.

Best regards,

Peter

[mtnvictory69]

We have 5 dedicated IP's from the ISP. Yes the FastEthernet1 is configured correctly which is one of our dedicated IP's from the ISP. Yes the current config is the remainder of previous config and updates that I have done already. This router can be freely modified. I am also doing VOIP via QOS across the VPN.

I saw that you said no ip for the FastEthernet1 interface Why?

[Peter Paluch]

Hello Michael,

Yes the FastEthernet1 is configured correctly which is one of our dedicated IP's from the ISP.

Hmmm, I understand but I have to verify if this is the way the ISP wants you to configure your router. It is possible that the provider will assign some sort of private address on the Dialer interface dynamically and that these addresses are supposed to be located "behind" your router. We'll see that easily - either the Dialer1 interface will negotiate its IP address dynamically, or it will remain address-less, in which case we will configure it with a static IP address.

I saw that you said no ip for the FastEthernet1 interface Why?

Because the FastEthernet1 interface is not supposed to send IP packets directly. Instead, the IP packets have to be first encapsulated into PPP+PPPoE headers and only then sent via the Fa1 interface. Therefore the Fa1 interface will no longer be configured with any IP settings, and instead, they will all move to the Dialer interface that represents the "end", or the termination, of the PPPoE session.

Best regards,

Peter

[mtnvictory69]

here is the new config that I am using now after making the changes you gave. I will be connecting the router here soon and then do the show statements after awhile.

Thanks

Michael

[mtnvictory69]

Well that didnt work since my VOIP or vpn does not work. Here are the show statements.

Thanks

Michael

[Peter Paluch]

Hello Michael,

I believe we are not far from having the issue solved completely. The command outputs I have requested show that the Dialer1 interface is up and running and has been dynamically assigned the IP address 70.58.191.198. Also, the show pppoe session confirms that the PPPoE session has been successfully established. The show ip route also confirms that the ISP's IP address is 184.99.0.201.

What I missed is the NAT configuration: currently, you have this line in your configuration:

ip nat inside source route-map DYNAMIC interface FastEthernet1 overload

It is currently wrong as it tries to perform NAT to the IP address of the Fa1 interface - which does not have any IP address anymore. Please paste the following lines into your configuration:

interface Fa1
 no ip virtual-reassembly
 exit
!
no ip nat inside source route-map DYNAMIC interface FastEthernet1 overload
ip nat inside source route-map DYNAMIC interface Dialer1 overload

Please let me know the result. Thank you!

Best regards,

Peter

[mtnvictory69]

Here are the new results and my VOIP and DNS is not working.

Thanks

Michael