DSL static/DHCP pppoe config

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Oct 28th, 2008
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Hey guys!! Can someone one here point me to a doc or send me a config example of a c880 on DSL or cable modem? I would totally like to plagiarize your working config hahaha

thanks in advance!

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Brent Rockburn Thu, 10/30/2008 - 09:33
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Thanks for the doc but I think I'm missing something... I am on a 880 so this is what I have so far.

I guess my question is where do I input the username and password for the PADI callin. does this make sense or am I way off.

Giuseppe Larosa Thu, 10/30/2008 - 10:06
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Hello Brent,

as for PPP authentication you can:

a) use a username password command in global config mode


b) inside the dialer interface use the ppp chap username e ppp chap password or ppp chap sent-password (not sure about the command syntax but the idea is this)

you can debug the PPP process setup with

terminal monitor

debug ppp negotiation

debug ppp authentication

Hope to help


Brent Rockburn Thu, 10/30/2008 - 10:24
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yes see that's what I thought and this is what's confusing me...

when I go under the dialer1 interface all I see is this

BLKLANSTR01(config-if)#ppp chap ?

hostname Set alternate CHAP hostname

password Set default CHAP password

refuse Refuse to authenticate using CHAP

wait Wait for caller to authenticate first

and when i go further like under hostname and so on I don't see anything that implies a "username and password" to be used for pppoe authentication. So I'm thinking I must be in the wrong place. Very strange this 880 is.

Brent Rockburn Thu, 10/30/2008 - 12:18
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Giuseppe Larosa Thu, 10/30/2008 - 12:49
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Hello Brent,

actually with ppp hostname you specify how your router presents itself to the PPP peer.

ppp chap hostname

To create a pool of dialup routers that all appear to be the same host when authenticating with Challenge Handshake Authentication Protocol (CHAP), use the ppp chap hostname command in interface configuration mode. To disable this function, use the no form of this command.

ppp chap hostname hostname

no ppp chap hostname hostname

Syntax Description


The name sent in the CHAP challenge.

So the commands look like correct and you need to use the parameters that your ISP has given you.

hostname: because the PPP authentication appears between two routers the default name is the router hostname.

And the username password command in global config is used to define the other router's hostname and password is the same (but this is bidirectional authentication that happens on both side)

So actually this is the correct way to configure CHAP on an ISP connection where the caller (your router is authenticated) ppp authentication chap callin

Hope to help



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