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CCNA 4 v3.1 Module 3

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CCNA 4 v3.0 Module 3 PPP

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Objectives

• Serial point-to-point links

• PPP authentication

• Configuring PPP

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Introduction to Serial Communication

Some of the many serial communications standards include the following:

RS-232-E V.35 High-Speed Serial Interface (HSSI)

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Time-Division Multiplexing

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Demarcation Point

The point in the network where the responsibility of the service provider or "telco" ends.

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DTE-DCE

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Serial Connection Options

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HDLC Encapsulation

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Configuring HDLC Encapsulation

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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.

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PPP Layered Architecture

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PPP and the Data Link Layer

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PPP and the Network Layer

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Establishing a PPP Session

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PPP Operation

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LCP Options

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PPP Configuration Options

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NCP

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PPP Authentication Protocols

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PPP Authentication

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Password Authentication Protocol (PAP)

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Challenge Handshake Authentication Protocol (CHAP)

CHAP provides protection against playback attack through the use of a variable challenge value that is unique and unpredictable.

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PPP Encapsulation and Authentication Process

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CHAP Authentication Process

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Configuring PPP

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Configuring PPP Authentication

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PAP Configuration

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CHAP Configuration

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Verifying PPP

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PPP Configuration Commands

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Debug PPP Authentication