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

2. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 11.2 11-7 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:

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

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

5. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 12.2 PPP Stack Link Control Protocol (LCP) Authentication Protocols Network Control Protocol (NCP) Bit Padding Digital Signals (DS) Services

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

7. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 11.7 Figure 11.34 Multiplexing in PPP

8. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 12.10 An example PAP: C023 16 CHAP: C223 16 IPCP: 8021 16 LCP: C021 16 IPCP: 8021 16

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

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

11. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Table 12.1 LCP packets and their codes CodePacket TypeDescription 01 16 Configure-request Contains the list of proposed options and their values 02 16 Configure-ack Accepts all options proposed 03 16 Configure-nak Announces that some options are not acceptable 04 16 Configure-reject Announces that some options are not recognized 05 16 Terminate-request Requests to shut down the line 06 16 Terminate-ack Accepts the shut down request 07 16 Code-reject Announces an unknown code 08 16 Protocol-reject Announces an unknown protocol 09 16 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

12. 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

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

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

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

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

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

18. 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

19. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 11.19 An example

20. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 11.20 An example (continued)