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New Member

Setting up DSL connections on a 3640 w/ ATM

We are reselling the LEC's DSL service in our area. We connect to the LEC via a ATM T3 interface. I'm looking for a solution that will let me use PPPoE for authentication for my dynamic IP customers. I found scattered information on the cisco website, but I havent found anything that matches my scenario.

Does anybody have any examples that they could share with me? Right now I have 6 VC-Class statement, 1 BVI Statement, and seperate 6 sub-interfaces setup for each class of DSL service that we offer.

I'm unclear on how to make customers authenticate via PPPoE against my RADIUS server. I've never setup a IP pool on a 3640 before but I have a good idea on how to do it. I just dont understand how the router knows who to assign the IP's to after authentication via PPPoE against the radius server. Somebody please help.



Re: Setting up DSL connections on a 3640 w/ ATM

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If anyone else in the forum has some advice, please reply to this thread.

Thank you for posting.

Cisco Employee

Re: Setting up DSL connections on a 3640 w/ ATM


PPPoe would need a bridge enviroment, don't know currently

if this is configure in your router.

If one of the sub-interface is receiving snap packet with PPPoe header the IOS will see this and submit the incoming

PPP packet to a virtual-access, of course if the PPPoE

was establish previously.

PPPoe configuration require vpdn as well as a target


This work almost the same way than l2tp except of course that

PPPoe use message like PADI, PADO, PADS,...

Once PPPoE has establish the session the PPP code takes

over, hence the ip address allocated to a remote PC would

be as if you were doing this via l2tp.

First you authenticated (local, or radius) then you discuss IPCP, if the pool as well as the virtual-template is configured

properly, when the PC start negotiating the address, it will send a confreg with seeing this the PPP code will try

to get the ip address following configuration on the virtual-template (this could even be from a dhcp server)

Hope this helps


New Member

Re: Setting up DSL connections on a 3640 w/ ATM


I am trying to use more than one ip pool and also do not have static adressing ready yet...that's my question. Maybe we can help each other. Here's my working config (relevant) on a 3620 on an ATM T1. My customers use PPPoE as well. Would you mind emailing me your config to Thanks in advance.

Current configuration : 2944 bytes


version 12.1

no service single-slot-reload-enable

service timestamps debug uptime

service timestamps log uptime

service password-encryption


hostname xxxxxxx


logging rate-limit console 10 except errors

aaa new-model


username password 7 xxxxxxxxxxx

username password 7 xxxxxxxxxxx username password 7 xxxxxxxxxxx ip subnet-zero



no ip finger

no ip domain-lookup

ip domain-name

ip name-server xx.xx.xx.xx

ip name-server xx.xx.xx.xx


vpdn enable

no vpdn logging


vpdn-group 1


protocol l2tp

virtual-template 1

terminate-from hostname xxxxxxxx

local name xxxx

lcp renegotiation always

l2tp tunnel password 7 xxxxxxxx


call rsvp-sync


interface FastEthernet0/0

ip address xx.xx.xx.xx secondary

ip address yy.yy.yy.yy

duplex auto

speed auto


interface Serial0/0

no ip address


clockrate 2000000


interface ATM1/0

no ip address

no ip mroute-cache

atm vc-per-vp 4096

no atm ilmi-keepalive

atm ilmi-pvc-discovery

no scrambling-payload


interface ATM1/0.1 point-to-point

ip address xx.xx.xx.xx

no ip mroute-cache

pvc x/xxx

encapsulation aal5snap



interface Virtual-Template1

mtu 1492

ip unnumbered FastEthernet0/0

peer default ip address pool dslpool1

ppp authentication chap


ip local pool dslpool1 xx.xx.xx.xx xx.xx.xx.xx

ip default-gateway zz.zz.zz.zz

ip classless


dial-peer cor custom



Cisco Employee

Re: Setting up DSL connections on a 3640 w/ ATM


Useally I configure pppoe as in the following url

If you question was to associate pool1 for l2tp and pool 2 for pppoe this should work just fine by configuring different virtual-template.

I am a bit confused by the config you posted, I see l2tp

as protocol in the vpdn config.

Could you please answer if you are trying to get specific

address to PPPoe users, or if you want to different pools

for l2tp and PPPoe


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