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Chapter 12 Point-to-Point Access: PPP. Point-to-Point protocol PPP stack. Point-to-Point Protocol: PPP. Many Internet users use telephone lines to connect home computers to Internet providers A point-to-point link protocol is required to control and manage the transfer of data PPP defines
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Chapter 12Point-to-Point Access: PPP Point-to-Point protocol PPP stack Data Communications, Kwangwoon University
Point-to-Point Protocol: PPP • Many Internet users use telephone lines to connect home computers to Internet providers • A point-to-point link protocol is required to control and manage the transfer of data • PPP defines • The format of the frame to be exchanged between devices • How two devices negotiate the establishment of the link and the exchange of data • How network layer data are encapsulated in the data link frame • How two devices can authenticate each other Data Communications, Kwangwoon University
PPP Frame Data Communications, Kwangwoon University
Transition States Data Communications, Kwangwoon University
Protocol Stack Data Communications, Kwangwoon University
LCP Packet Encapsulated in a Frame • For establishing, maintaining, configuring, and terminating links • code: Type of LCP packet • ID: A value used to match a request with the reply Data Communications, Kwangwoon University
LCP packets Data Communications, Kwangwoon University
LCP: Common Options • Options are inserted in the information field of the configuration packets Data Communications, Kwangwoon University
Authentication • Authentication means validating the identity of a user who needs to access • PPP is designed for use over dial-up links User authentication is necessary • PPP has two protocols for authentication • Password Authentication Protocol (PAP) • Challenge Handshake Authentication Protocol (CHAP) Data Communications, Kwangwoon University
PAP Data Communications, Kwangwoon University
PAP Packets Data Communications, Kwangwoon University
CHAP Data Communications, Kwangwoon University
CHAP Packets Data Communications, Kwangwoon University
Network Control Protocol: NCP • In the networking state, PPP uses NCP • To encapsulates data from network layer protocols (such as IP, IPX, and Appletalk) • IPCP (IP Control Protocol) • Establishes and terminates a network layer connection for IP packets • After configuration, an IP packet is carried in the payload field of a PPP frame (protocol=002116) • Other protocols have their own sets of control packets Data Communications, Kwangwoon University
IPCP Packet Encapsulated in PPP Frame Data Communications, Kwangwoon University
Code Value for IPCP Packets Data Communications, Kwangwoon University
An Example Data Communications, Kwangwoon University