General Questions about PPPOE between Client and Provider

Unanswered Question
Jul 31st, 2008


I'm currently doing a project to successfully end my apprenticeship.

I have some problems now.

In general, I want to simulate an DSL-connection between two routers.

Therefore I would need two DSL-Lines which I don't have available.

So I must at least simulate something like Internet an DSL.

I thought of an PPPOE-connection as a good candidate, as it allready is the real DSL-protocol type, which is used... but I can't work out the provider-side.

First of all you could take a look at the attachment.

As you can see I added a third router to the scenario, for simulation WAN or simply the internet.

Now I want to use PPPOE on both sides of this router and the WANrouter should provide static ip-addresses to his clients (llrouter, mlrouter).

Now I have several options which I can't figure out.

First, I created a dialer interface on both client-routers, set the MTU-size etc. including the ppp encapsulation.

I also have an vpdn-group with "request-dialin" set and protocol pppoe defined.

One question here is, how these both configurations are connected together.

I do understand the basic purpose of a "Virtual Private Dialup Network" but I don't see how the vpdn configuration does affect the overall configuration.

On which point of connection-establishment and traffic is the vpdn config actually used ?

Next questions would be the dialer pools and groups I defined in the dialer interface.

All I did was configuring "dialer pool 1" and "dialer-group 1".

But where can I configure further details to the pool or the group ?

Both configurations link to someplace called "1" which has never been defined anywhere.

Whats the purpose of that ?

Another thing which I don't get is the "ip address negotiated" configuration.

For my understanding its purpose is to automaticly assign an IP-adress from a server.

Just like DHCP, but over PPP.

So far, so good.

But here the trouble starts again:

How do I get the wan-router to distribute IP-Adresses over PPP ?

DHCP works fine: I have my defined pool and certain settings and everything works.

For PPP I can't find similar settings... what do I have to do ?

I have no idea how to configure the wanrouter to be "provider"-like.

And theres nothing I could find about that.

The hardware I used:

llrouter - 2621XM

wanrouter - 7204VXR

mlrouter - 1641

Can anyone help me with that ?

I have this problem too.
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Giuseppe Larosa Wed, 08/06/2008 - 09:14

Hello Jens,

PPPoE is PPP emulation over ethernet.

You just need to configure one side as a client and one as a server.

All the VPDN and dialer stuff is used in order to have the client to make a logical call.

Think of DDR on ISDN the concepts are the same: the client needs a reason to perform a call, then the PPP negotiation starts.

Here you needs to trigger PPP negotiation, during this phase and the IPCP phase for IPV4 one side can ask an IP address to the other part (this is the meaning of ip address negotiated) . This is the way how IP addresses assignment works on PPP, PPPoX

You can use debug ppp negotation to see the whole process. It is very instructive.

The server can assign IP addresses from a pool to the current clients.

Negotiation includes ip address and possibly a default route on the point-to-point logical link.

Notice that you should need to use physical interfaces if the pppoe commands are not accepted on subinterfaces.

Hope to help


Lagerhaus_Jonny Thu, 08/14/2008 - 03:52

The main problem is, that I have no idea of how to configure one router as a server.

So i was stuck there.

Luckily I asked in another forum.

Refering me to global documentations (which only provide client configurations) or tell me to configure a client and a server won't help.


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