CCNA Cisco Certified Network Associate Study Guide - FTP Server

Point-to-Point Protocol (PPP)
Point-to-Point Protocol (PPP) 483
PPP (Point-to-Point Protocol) is a data-link protocol that can be used
over either asynchronous serial (dial-up) or synchronous serial (ISDN)
media and that uses the LCP (Link Control Protocol) to build and maintain
data-link connections.
The basic purpose of PPP is to transport layer-3 packets across a Data
Link layer point-to-point link. Figure 10.3 shows the protocol stack compared
to the OSI reference model.
FIGURE 10.3 Point-to-point protocol stack
OSI layer
3
2
1
PPP contains four main components:
Upper-layer Protocols
(such as IP, IPX, AppleTalk)
Network Control Protocol (NCP)
(specific to each Network-layer protocol)
Link Control Protocol (LCP)
High-Level Data Link Control Protocol (HDLC)
Physical layer
(such as EIA/TIA-232, V.24, V.35, ISDN)
EIA/TIA-232-C A Physical-layer international standard for serial communication.
HDLC A method for encapsulating datagrams over serial links.
LCP A method of establishing, configuring, maintaining, and terminating
the point-to-point connection.
NCP A method of establishing and configuring different Network layer
protocols. PPP is designed to allow the simultaneous use of multiple Network
layer protocols. Some examples of protocols here are IPCP (Internet
Protocol Control Protocol) and IPXCP (Internetwork Packet Exchange
Control Protocol).