PPPoE

Most of Internet Providers use PPPoE (Point to Point Protocol Over Ethernet) to provide internet connections to individual users. All the mainstream routers and ONTs support PPPoE functionality.

PPPoE and Dial-Up?

It is quite different from the old dial-up connections. We can elaborate this different by the example of a conversation between you and your Manager.

In Dial Up connection, only two persons are involved at both ends of the line. If the manager wants to communicate with all team of 10 members, then you have to gather all of them near to the earpiece of your phone. It may lead to an ineffective conversation.

While on the other end, in PPPoE your manager is communicating with all team. But you don’t need to gather all of them near you. In this case, you have a loudspeaker so that everyone can easily listen to your manager.

PPPoE Working

Internet Providers assigns a unique PPPoE user name and PPPoE password to each user. While dialing in the router, a user only enters that PPPoE user name and password. If the authentication is successful, then the RADIUS server at ISP end allows the user to use the internet services. In case, PPPoE authentication failed then the RADIUS server block the user to connect and restrict its connectivity over the internet. You can find the Mikrotik radius server configurations at systemzone.

Internet Providers use this protocol to implement and monitor the AAA functionality at the BRAS end. In AAA functionality, ISP is able to perform the following things

Authentication– To authenticate the user
Authorization– Allows user to use a certain package
Accounting– Monitor data usage and keep a check on the billing process

TP Link PPPoE Settings — PPPoE settings in Tplink

Internet Service Providers use this protocol to extend their connection in a shared mode for multiple users such as multiple connections in a hotel and a firm. DSL modems on the old telephone lines support this protocol in DSL mode. ONT and routers provide this connectivity on ethernet card.

PPPoE encapsulate PPP frames inside the ethernet frames. There are two stages in PPPoE connectivity, discovery and session.

Discovery Stage

While initializing a Point to Point Protocol over Ethernet session, A host must identify the MAC address of the peer device. While connecting to a server, there are multiple sessions, PADI, PADO, PADR, and PADS

PADI

PPPoE Active Discovery Initiation, here at this stage client request a PADI packet over the LAN and request a service. The host sends PADI message to the destination address set to the broadcast address. This message shares the requirement about which service is required.

PADO

In response to the PADI packet, one or more routers or access concentrators sends an Offer message PPPoE Active Discovery Offer to the respective device on the LAN. Here the destination address is the unicast address of the host, who requested PADI. This message contains, own name of the device, unicast address of the client, and the requested service. As PADI was a broadcast message, so there may be more than one access concentrators may offer PADO. But the PADI host accepts only one offer.

PADR

At the first stage of PADI, destination address was a broadcast address. In returns, at PADO destination address was a unicast address. Usually, the host may receive more than one offers but it accepts only one depends upon the service offered. In response to the PADO, the host responds with a PADR message, PPPoE Active Discovery Request. Here the destination address is the unicast address of the Access Concentrator.

PADS

In response to the PADR, the router sends a confirmation message PADS, PPPoE Active Discovery Session-Confirmation. Upon receiving the PADR, the access concentrator starts to begin a PPP session, generates a unique ID for that session and replies to the host with PADS. Here the destination address is the unicast address of the Host that generated PADR and PADI.

PADT

At the PADS step PPPoE connectivity gots completed. If it is desired to break this session at any stage after the connection establishment, then a termination message is sent either by the router or the host. This message is called PADT, PPPoE Active Discovery Termination.

Session Stage

At this stage, peers transmit Point to Point Protocol data to each other and start data transmission. All the packets that we transmit in session stage keep the session id, that was generated in the Discovery Stage.

PPPoE Errors

Following are the major errors related to this protocol.

Error 676

While establishing a PPPoE connection, this error gives a message “line is busy”. In such a case, delete the connection and recreate it.

Error 678

This error usually occurs, when you place a router for PPPoE connectivity on DSL, instead of placing a DSL modem. In this error, your traffic is unable to en route through the DSL modem. Check the physical connections and make sure that the modem is properly connected and receiving DSL signal.

Error 691

It is one of the most famous errors, this occurs if PPPoE username or PPPoE password is incorrect. In such case, always refer to your ISP and confirm the credentials.

Error 651

This error occurs because of the windows operating system. It means the window is unable to find and run the desired file that is essential for PPPoE connectivity. This error can be removed by the instructions given at the following link error 651 solutions.

Error 718

When the PPPoE conversation is started but gets terminated because the remote server is not able to respond back in the defined time period. This may occur due to bad line parameter. Maybe you have entered valid credentials, but the ISP server is unable to communicate, in that case restarting the modem may be quite helpful in this regard.