1 © 2003, Cisco Systems, Inc. All rights reserved. CCNA 4 v3.0 Module 3 PPP

222 © 2003, Cisco Systems, Inc. All rights reserved. Objectives Serial point-to-point links PPP authentication Configuring PPP

333 © 2003, Cisco Systems, Inc. All rights reserved. Introduction to Serial Communication Some of the many serial communications standards include the following: RS-232-E V.35 High-Speed Serial Interface (HSSI)

444 © 2003, Cisco Systems, Inc. All rights reserved. Time-Division Multiplexing

555 © 2003, Cisco Systems, Inc. All rights reserved. Demarcation Point The point in the network where the responsibility of the service provider or "telco" ends.

666 © 2003, Cisco Systems, Inc. All rights reserved. DTE-DCE

777 © 2003, Cisco Systems, Inc. All rights reserved. Serial Connection Options

888 © 2003, Cisco Systems, Inc. All rights reserved. HDLC Encapsulation

999 © 2003, Cisco Systems, Inc. All rights reserved. Configuring HDLC Encapsulation

10 © 2003, Cisco Systems, Inc. All rights reserved. Troubleshooting a Serial Interface Five possible problem states can be identified in the interface status line of the show interface serial display: Serial x is down, line protocol is down. Serial x is up, line protocol is down. Serial x is up, line protocol is up (looped). Serial x is up, line protocol is down (disabled). Serial x is administratively down, line protocol is down.

11 © 2003, Cisco Systems, Inc. All rights reserved. PPP Layered Architecture

12 © 2003, Cisco Systems, Inc. All rights reserved. PPP and the Data Link Layer

13 © 2003, Cisco Systems, Inc. All rights reserved. PPP and the Network Layer

14 © 2003, Cisco Systems, Inc. All rights reserved. Establishing a PPP Session

15 © 2003, Cisco Systems, Inc. All rights reserved. PPP Operation

16 © 2003, Cisco Systems, Inc. All rights reserved. LCP Options

17 © 2003, Cisco Systems, Inc. All rights reserved. PPP Configuration Options

18 © 2003, Cisco Systems, Inc. All rights reserved. NCP

19 © 2003, Cisco Systems, Inc. All rights reserved. PPP Authentication Protocols

20 © 2003, Cisco Systems, Inc. All rights reserved. PPP Authentication

21 © 2003, Cisco Systems, Inc. All rights reserved. Password Authentication Protocol (PAP)

22 © 2003, Cisco Systems, Inc. All rights reserved. Challenge Handshake Authentication Protocol (CHAP) CHAP provides protection against playback attack through the use of a variable challenge value that is unique and unpredictable.

23 © 2003, Cisco Systems, Inc. All rights reserved. PPP Encapsulation and Authentication Process

24 © 2003, Cisco Systems, Inc. All rights reserved. CHAP Authentication Process

25 © 2003, Cisco Systems, Inc. All rights reserved. Configuring PPP

26 © 2003, Cisco Systems, Inc. All rights reserved. Configuring PPP Authentication

27 © 2003, Cisco Systems, Inc. All rights reserved. PAP Configuration

28 © 2003, Cisco Systems, Inc. All rights reserved. CHAP Configuration

29 © 2003, Cisco Systems, Inc. All rights reserved. Verifying PPP

30 © 2003, Cisco Systems, Inc. All rights reserved. PPP Configuration Commands

31 © 2003, Cisco Systems, Inc. All rights reserved. Debug PPP Authentication