PPPOE confusion

[a.azab]

Dear Experts,

I have been reading PPPOE and know that it is being used to send PPP over Ethernet. This is mainly seen in ISPs.

My question(s):

- The PPPOE username/password, is it is used to authenticate out PPP connections between the Modems or to be authenticated at the ISP side.

- Are the username/password encrypted when sent?

-I still don't get what is the benefit exactly of running PPP over Ethernet (PPPOE)? I read it helps to increase the number of users, but does not make sense. Can't we use PPP to connect our modem to a route, and connect that router to a switch via Ethernet?

Our Network >>>> Over Ethernet >>>> Switch >>> Over Ethernet >>>Router >>>> PPP >>>> Modem >>>> PPP >>> Modem >>> PPP >>> ISP router.

Thanks,

Ahmad

[Julio E. Moisa]

- The PPPOE username/password, is it is used to authenticate out PPP connections between the Modems or to be authenticated at the ISP side.

To be honest I have just used authentication with the ISP, but it should be same equal with the modems. 

- Are the username/password encrypted when sent?

CHAP provides a secure approach to authentication and more robust than PAP.

-I still don't get what is the benefit exactly of running PPP over Ethernet (PPPOE)? I read it helps to increase the number of users, but does not make sense. Can't we use PPP to connect our modem to a route, and connect that router to a switch via Ethernet?

PPPoE provides the ability to connect a network of hosts over a simple bridging access device to a remote access concentrator where each host utilizes its own PPP stack. It also gives users a familiar interface. PPP is basically used to create a virtual dial up connection between to devices. 

I recommend this link

http://packetlife.net/blog/2009/apr/20/configuring-pppoe/

Hope it is useful

:-)

[Masoud Pourshabanian]

Hello,

PPP is a WAN protocol. It is a point to point protocol and provides authentication. ISPs used to provide dial up connection to their customers using PPP(some may still do). It needs serial interface so kind of slow. You need to connect a modem through a serial connection to your computer in order for dial-up connection.

With DSL,  there should be a way to separate different customers on a shared link and also be able to authenticate customers. It is done through ppp emulation.

Computer-->Ethernet>>>DSL modem----------------phone line--------DSLAM-->> ethernet--->>PPPOE server.

You computer encapsulates PPP packets into Ethernet and forwards them to DSL modem. DSL modem sends them over phone line to DSLAM(using ATM). DSLAM decapsulates Ethernet frame and send them to PPPOE server(shared link). PPPOE server receives ethernet frames and able to separate and authenticate different customer through PPP. PPP is inside the Ethernet frame,

As Julio mentioned, if CHAP is used, credentials are sent encrypted. PAP sends them clear text.

Masoud