Before exchanging network data over a point-to-point link, the link must be established, configured, and tested. A protocol is needed to negotiate link parameters and manage the connection lifecycle.
A protocol within the PPP suite responsible for establishing, configuring, testing, and terminating the data link connection.
- Link Establishment: Exchange LCP packets to open the connection
- Parameter Negotiation: Negotiate options like MRU (Maximum Receive Unit), authentication method
- Authentication: Optionally run PAP or CHAP to verify user identity
- Link Maintenance: Monitor link quality, handle echo requests/replies
- Link Termination: Gracefully close the connection with LCP terminate packets
- Part of PPP protocol suite
- Negotiates link parameters before network-layer setup
- Provides echo mechanism for link testing
- Handles authentication phase
- Built from: PPP Protocol — LCP is a component of PPP
- Related: NCP — follows LCP for network-layer configuration
- Related: Authentication — PAP and CHAP integrated
- Related: MRU — Maximum Receive Unit negotiated by LCP
- Negotiation failure: if peers can’t agree on parameters, link isn’t established
- Authentication failure terminates the connection
- LCP is layered on top of the bare serial link (no framing — PPP provides framing)