The LCP functions within the data link layer and has a role in establishing, configuring, and testing the data-link connection. The LCP establishes the point-to-point link. The LCP also negotiates and sets up control options on the WAN data link, which are handled by the NCPs.
The LCP provides automatic configuration of the interfaces at each end, including:
- Handling varying limits on packet size
- Detecting common misconfiguration errors
- Terminating the link
- Determining when a link is functioning properly or when it is failing
After the link is established, PPP also uses the LCP to agree automatically on encapsulation formats such as authentication, compression, and error detection.