McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Chapter 12 Point-to-Point Access: (PPP)

McGraw-Hill©The McGraw-Hill Companies, Inc., 2004McGraw-Hill©The McGraw-Hill Companies, Inc., POINT-TO-POINT PROTOCOL Although HDLC is a general protocol that can be used for both point-to-point and multipoint configurations, one of the most common protocols for point-to-point access is the Point-to-Point Protocol (PPP). PPP is a byte-oriented protocol. Framing Transition Phases Protocol Stack Topics discussed in this section:

McGraw-Hill©The McGraw-Hill Companies, Inc., 2004McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Transition states

McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 PPP frame

McGraw-Hill©The McGraw-Hill Companies, Inc., PPP Stack Link Control Protocol (LCP) Authentication Protocols Network Control Protocol (NCP) Bit Padding Digital Signals (DS) Services

McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Protocol Stack Frame Header Frame TrailerPacket ชุดการทำงานต่างๆของ Protocol ถูกควบคุมและจัดการโดยผ่าน Frame format ต่างๆที่ถูกออกแบบไว้

McGraw-Hill©The McGraw-Hill Companies, Inc., Figure Multiplexing in PPP

McGraw-Hill©The McGraw-Hill Companies, Inc., An example PAP: C CHAP: C IPCP: LCP: C IPCP:

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Link Control Protocol (LCP)

McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 LCP Packet Encapsulated in a Frame Frame Header LCP Packet

McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Table 12.1 LCP packets and their codes CodePacket TypeDescription Configure-request Contains the list of proposed options and their values Configure-ack Accepts all options proposed Configure-nak Announces that some options are not acceptable Configure-reject Announces that some options are not recognized Terminate-request Requests to shut down the line Terminate-ack Accepts the shut down request Code-reject Announces an unknown code Protocol-reject Announces an unknown protocol Echo-request A type of hello message to check if the other end is alive 0A 16 Echo-reply The response to the echo-request message 0B 16 Discard-request A request to discard the packet

McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Table 12.2 Common options OptionDefault Maximum receive unit1500 Authentication protocolNone Protocol field compressionOff Address and control field compressionOff

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Authentication Protocol

McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 PAP packets Frame Header PAP packet

McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 CHAP packets Frame Header CHAP packet

McGraw-Hill©The McGraw-Hill Companies, Inc., 2000 Network Protocol IPCP

McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 IPCP packet encapsulated in PPP frame Frame Header IPCP packet

McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Table 12.3 Code value for IPCP packets CodeIPCP Packet 01Configure-request 02Configure-ack 03Configure-nak 04Configure-reject 05Terminate-request 06Terminate-ack 07Code-reject

McGraw-Hill©The McGraw-Hill Companies, Inc., An example

McGraw-Hill©The McGraw-Hill Companies, Inc., An example (continued)