Point to Point Protocol over Ethernet
Virtualizes Ethernet into multiple p2p sessions between clients and server
RFC 2516
- • Adds 8 bytes of overhead
- 2 bytes PPP
- 6 bytes PPPoE
- Change MTU on interface to 1492
- MSS is changes to 1452 bytes
- Allows for 40 bytes of TCP and IP header and 8 byte PPPoE header
- Uses dialer interface
- Pppoe-client dial-pool-number [#]
Configuration Example
Client
Int [wan] Pppoe enable Pppoe-client dial-pool-number [#] Int dialer [#] Mtu 1492 Ip tcp adjust-mss 1452 Encapsulation ppp Ip address negotiated (optional), can config with an address (optional) - ppp authentication - see above Dialer pool [#] Dialer-group 1
Server
Bba-group pppoe global Virtual-template [#] Int [wan] Pppoe enable group global Int virtual-template [#] Ip unnumbered [wan] Mtu 1492 Peer default ip address pool PPPOEPOOL Ip local pool PPPOEPOOL [ip range]
- Client negotiates PPPoE using PADo, PADi and PADr with the server, both client and server move into PPP–>LCP phase
- Client/Server negotiate authentication, other parameters
- Server asks the client for a username/password (using pap, as pap is configured before chap)
- Client sends out a username/password configured in it’s dialer
- Server authenticates this username/password against its global username/password list (alternatively a AAA/Radius server)
- Client and Server both move on to IPCP phase
- Client sends an ip address of 0.0.0.0 (asking for an ip address from the Server)
- Server hands out an IP address from its pool (in this case pppoepool)
- Client/Server finish IPCP phase and the link comes up
- PADI – PPPoE Active Discovery Initiation
- Multicast message from client to server to MAC ffff.ffff.ffff
- PADO – PPPoE Active Discovery Offer
- Reply to a PADI
- Contains MAC of the server and it’s hostname
- PADR – PPPoE Active Discovery Request
- Response from client to server of a PADO
- Confirms acceptance of the offer
- PADS – PPPoE Active Discovery Session-confirmation
- Response server to client of PADR
- Session ID is given in this response
- PADT – PPPoE Active Discovery Terminate
- Termination of connection
- Can be sent by either client or server