Freedom Internet on Cisco modem

This morning I changed to another internet service provider (ISP) known as Freedom. When into tech news in the Netherlands you've must have heard about the XS4ALL story, if not head over to this page.

The transition went not as smooth as I hoped for. It took me several hours to finally identify the issue (I'm not an real networking guy). In my neighborhood there is still no fiber available, so my only option is VDSL. Freedom internet delivers the same connectivity as XS4ALL did, so my current configuration (on an Cisco 887VA modem) should have been ok. Around eight I noticed connectivity loss, so on the other end of the line the migration had taken place. I did some basic checks and found out the DSL interface was ok, but there was no PPP session.

router#show ppp all

I rememberd there was something I had to change on the Dialer interface, so I did.

conf t
interface Dialer0
ppp pap sent-username fake@freedom.nl password 0 1234
end

Still no PPP session after this change. So I had to dive deeper. Enabled PPP debugging on the topics negotiation and authentication.

debug ppp negotiation
debug ppp authentication

I discovered the PPP session in AUTHENTICATING phase chose CHAP instead of the configured PAP protocol. I'm no expert, but I suspect CHAP goes first because it's a more secure protocol and the fall-through doesn't work as expected. So I eventually came up with the following work-around.

interface Dialer0
ppp chap refuse

Now things start to look good.

Jun 22 08:36:47.433: Vi2 PPP: Phase is AUTHENTICATING, by the peer
Jun 22 08:36:47.433: Vi2 PAP: Using hostname from interface PAP
Jun 22 08:36:47.433: Vi2 PAP: Using password from interface PAP
Jun 22 08:36:47.433: Vi2 PAP: O AUTH-REQ id 1 len 25 from "fake@freedom.nl"
Jun 22 08:36:47.433: Vi2 LCP: State is Open
Jun 22 08:36:47.701: Vi2 PAP: I AUTH-ACK id 1 len 5
Jun 22 08:36:47.701: Vi2 PPP: Phase is FORWARDING, Attempting Forward
Jun 22 08:36:47.701: Vi2 PPP: Phase is ESTABLISHING, Finish LCP
Jun 22 08:36:47.701: %LINEPROTO-5-UPDOWN: Line protocol on Interface Virtual-Access2, changed state to up

And there is a PPP session active.

router#show ppp all        
Interface/ID OPEN+ Nego* Fail-     Stage    Peer Address    Peer Name
------------ --------------------- -------- --------------- --------------------
Vi2          LCP+ IPCP+            LocalT   185.93.175.225                  
router#

At this point I have got an IP address and traffic starts to flow and everybody in the house is happy again.