Which protocol is responsible for negotiating and maintaining Point-to-Point Protocol (PPP) connections?

A.
LCP

B.
NCP

C.
BRI

D.
ISDN

Explanation:
Link Control protocol (LCP) has the primary responsibility of negotiating and maintaining a PPP connection.
LCP, defined in Request for Comments (RFCs) 1548 and 1570, has the primary responsibility to establish,
configure, authenticate, and test a PPP connection. LCP negotiates the following when setting up a PPP
connection:
Authentication method used (PAP or CHAP), if any
Compression algorithm used (Stacker or Predictor), if any
Callback phone number to use, if defined
Multilink; other physical connections to use, if configured
The ability to utilize compression, authentication, and multilink are three options that make PPP a popular
choice for Layer 2 encapsulation over a WAN link.
Network Control Protocol (NCP) defines how the two PPP peers negotiate with network layer protocols, such as
IP and IPX, will be used across the PPP connection. LCP is responsible for negotiating and maintaining a PPP
connection whereas NCP is responsible for negotiating upper-layer protocols that will be carried across the
PPP connection.
In summary, the three steps in the establishment of a PPP session are:
Link establishment phase
Optional authentication phase
Network layer protocol phase
Basic Rate Interface (BRI) and Integrated Services Digital Network (ISDN) are not components of PPP, so
these options are incorrect. BRI is a type of ISDN connection that contains three circuits, two 64K B or bearer
channels, and one D or Delta channel. ISDN circuits are a type of WAN connection.
Objective:
WAN Technologies
Sub-Objective:
Configure and verify PPP and MLPPP on WAN interfaces using local authentication

Cisco > Internetworking Technology Handbook > Point-to-Point Protocol
Cisco > Support > Technology Support > WAN > Point-to-Point Protocol (PPP) > Design > Design TechNotes >
Understanding and Configuring PPP CHAP Authentication > Document ID: 25647