PPP Link Control Protocol LCP

PPP (Point-to-Point Protocol) Link Control Protocol (LCP) is a component of the PPP protocol suite that establishes, configures, and tests the data-link connection between two PPP endpoints. It operates at the data-link layer of the OSI model and is responsible for negotiating and configuring link parameters.

PPP LCP defines a set of messages that are exchanged between the two endpoints during the link establishment phase. These messages are used to negotiate options such as the maximum transmission unit (MTU), authentication protocols, and compression algorithms.

The PPP LCP packets are sent as payloads in PPP frames and contain fields such as Code, Identifier, Length, and Data. The Code field specifies the type of message, while the Identifier field is used to match requests and replies. The Length field indicates the length of the LCP packet, and the Data field contains any options negotiated during the link establishment phase.

Once the link is established, the PPP LCP continuously monitors the quality of the link and can take corrective action if necessary. If the quality of the link deteriorates, the LCP can request that the link be terminated or renegotiate the link parameters to improve the link quality.