Have a look at the messages of Negotiation Packets Of course if one end does not support a feature or offers an alternative, the CONFREJ and CONFNAK messages. This means both send out a CONFREQ and both must send a CONFACK agreeing to the requested parameters. In order for PPP to finish LCP, both ends must agree on the way the intend to run PPP on the link. Static one IP address (not available for PPPoE!).Authentication (whether or not to do authentication).Letting the other end know that if you receive a packet of say 2,100 bytes, do not even attempt to fragments it, because I will not be able to reconstruct it. This value is the total size of the original packet.MRRU (Maximum Received Reconstructed Unit) in debug.Optionally negotiate authentication before NCP. LCP (Link Control Protocol) for the link and NCP (Network Control Protocol) for the upper layer protocols running over the link.
PPP uses two steps to negotiate a connection. The PPP header gives a total of 8 bytes of overhead! Negotiation of a Connection The Protocol field indicates whether the frame is a data or control protocol frame (type of payload) for negotiation. The Address is set to 0xFF (11111111) statically. The Flag is used to signal this is the beginning of a PPP frame (like preamble with Ethernet). PPP Frame FormatĪ quick look at the frame format for PPP.
It was originally designed for dial-up connections.Īs it is point to point there is no need for Layer 3 to Layer 2 resolution like ARP in Ethernet, because the data is only going to one destination. The other main reason is dynamic IP addressing. This is one of the main reasons why you’d use PPP to begin with. PPP is a standards based protocol that offers authentication at L2.