Transition Phases

A PPP connection goes through phases  which can be  shown in a transition phase .

Dead: In  the dead phase  the link is not  being used. There is  no active  carrier at the  physical  layer and the  line is quiet.

Establish : When  one of the  nodes  starts the  communication the  connections goes into this  phase in this  phase  options are  negotiated between  the two  parties. If  the negotiation is successful the system goes to the authentication phase( if authentication  is required) r directly to the networking  phase. The link control protocols packets discussed shortly are used  for this  purpose. Several  packets  may be  exchanged  here.

Authenticate: The authentication phase  is  optional the two nodes may decide during  the establishment phase not to skip  this phase. However  if they  decide to proceed with  authentication they send several authentication packets  it goes  to the  termination phase.

Network : In  the network phase negotiation for the network  layer protocols   takes  place  PPP specifies that two  can be exchanged. The reason is that PPP supports  multiple protocols at  the network  layer. If a node  is running multiple protocols  simultaneously at the network layer the receiving  node  to know  which  protocols  will receive at the data.

Open: In the  phase data transfer  takes  place. When a  connection reaches this  phase  the exchange of data  packets  can be  started. The connection  remains in this  phase until  one of the  end points wants  to terminate the connection.

Terminate : In  the termination phase  the connection is terminated. Several packets are exchanged  between  the two  ends for house  cleaning and  closing  the link.