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Description PPP over Ethernet (PPPoE) provides the ability to connect a network of hosts over a simple bridging access unit to a remote access concentrator. 
With this model, each host utilizes it's own PPP stack and the user is presented with a familiar user interface.
Access control, billing and type of service can be done on a per-user, rather than a per-site, basis.

PPPoE has two distinct stages.
There is a discovery stage and a PPP Session stage.
When a Host wishes to initiate a PPPoE session, it first performs discovery to identify the ethernet MAC address of the peer and establish a PPPoE SESSION_ID. 
While PPP defines a peer-to-peer relationship, discovery is inherently a client-server relationship.
In the Discovery process, a host (the client) discovers an access concentrator (the server). 
Based on the network topology, there are more than one access concentrator that the Host can communicate with. 
The Discovery stage allows the host to discover all access concentrators and then select one. 
When Discovery completes successfully, both the host and the selected access concentrator have the information which will use to build the point-to-point connection over Ethernet.


When a capture of Wireshark shows that the ETHER_TYPE is set to 0x8863 (Discovery Stage), the cause of the error is that TLV tag's are being used. (Service-Name, AC-Name).
# config system interface
    edit portx
        set mode pppoe
        set username pppoe
        set password pppoe
        set service-name rogersBC
        set ac-name ac_abba
        set idle-timeout 60

To revert to default settings.
# config system interface
    edit portx
        set mode pppoe
        unset ac-name
        unset service-name

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Technical Note: Error with PPPoE when setting the Service and AC-name in PPOE PADI/PADO Negotiations