1 © 2004, Cisco Systems, Inc. All rights reserved. CCNA 4 v3.1 Module 3 PPP

222 © 2004, Cisco Systems, Inc. All rights reserved. Objectives

333 © 2004, Cisco Systems, Inc. All rights reserved. Introduction to Serial Communication Transmission system encodes bits into electrical voltage using methods like NRZ-L or AMI Some of the many serial communications standards include the following: RS-232-E V.35 High-Speed Serial Interface (HSSI)

444 © 2004, Cisco Systems, Inc. All rights reserved. Time-Division Multiplexing

555 © 2004, Cisco Systems, Inc. All rights reserved. Demarcation Point The point in the network where the responsibility of the service provider or "telco" ends.

666 © 2004, Cisco Systems, Inc. All rights reserved. DTE-DCE

777 © 2004, Cisco Systems, Inc. All rights reserved. Serial Connection Options

888 © 2004, Cisco Systems, Inc. All rights reserved. DTE/DCE Interface The DTE/DCE interface for a particular standard defines the following specifications: Mechanical/physical - Number of pins and connector type Electrical - Defines voltage levels for 0 and 1 Functional - Specifies the functions that are performed by assigning meanings to each of the signaling lines in the interface Procedural - Specifies the sequence of events for transmitting data

999 © 2004, Cisco Systems, Inc. All rights reserved. HDLC Encapsulation

10 © 2004, Cisco Systems, Inc. All rights reserved. Configuring HDLC Encapsulation

11 © 2004, Cisco Systems, Inc. All rights reserved. Troubleshooting a Serial Interface

12 © 2004, 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.

13 © 2004, Cisco Systems, Inc. All rights reserved. PPP Layered Architecture

14 © 2004, Cisco Systems, Inc. All rights reserved. PPP and the Data Link Layer

15 © 2004, Cisco Systems, Inc. All rights reserved. PPP and the Network Layer

16 © 2004, Cisco Systems, Inc. All rights reserved. Establishing a PPP Session

17 © 2004, Cisco Systems, Inc. All rights reserved. PPP Operation

18 © 2004, Cisco Systems, Inc. All rights reserved. Link Control Protocol Options

19 © 2004, Cisco Systems, Inc. All rights reserved. PPP Configuration Options

20 © 2004, Cisco Systems, Inc. All rights reserved. Network Control Protocol

21 © 2004, Cisco Systems, Inc. All rights reserved. PPP Authentication Protocols

22 © 2004, Cisco Systems, Inc. All rights reserved. PPP Authentication Protocols

23 © 2004, Cisco Systems, Inc. All rights reserved. Password Authentication Protocol (PAP)

24 © 2004, 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.

25 © 2004, Cisco Systems, Inc. All rights reserved. PPP Encapsulation and Authentication Process

26 © 2004, Cisco Systems, Inc. All rights reserved. CHAP Authentication Process

27 © 2004, Cisco Systems, Inc. All rights reserved. Configuring PPP

28 © 2004, Cisco Systems, Inc. All rights reserved. Configuring PPP Authentication

29 © 2004, Cisco Systems, Inc. All rights reserved. PAP Configuration

30 © 2004, Cisco Systems, Inc. All rights reserved. CHAP Configuration

31 © 2004, Cisco Systems, Inc. All rights reserved. Verifying PPP

32 © 2004, Cisco Systems, Inc. All rights reserved. PPP Configuration Commands

33 © 2004, Cisco Systems, Inc. All rights reserved. Debug PPP Authentication

34 © 2004, Cisco Systems, Inc. All rights reserved. Summary