1. CCNA Guide to Cisco Networking Fundamentals Fourth Edition
Chapter 11
PPP and HDLC

2. Objectives Describe PPP encapsulation
Configure PPP encapsulation and its options
Describe and enable PPP multilink
Understand Frame Relay standards and equipment
CCNA Guide to Cisco Networking Fundamentals, Fourth Edition

3. Objectives (continued)
Describe the role of virtual circuits and performance parameters in Frame Relay
Understand the Frame Relay topologies
Understand the difference between multipoint and point-to-point configurations
Configure and monitor Frame Relay
CCNA Guide to Cisco Networking Fundamentals, Fourth Edition

4. PPP
PPP
Internet standard protocol defined in RFCs 2153 and 1661
Provide point-to-point, router-to-router, host-to-router, and host-to-host connections
Considered a peer technology based on its point-to-point physical configuration
Commonly used over dial-up or leased lines to provide connections into IP networks
Serial Line Internet Protocol (SLIP) was the predecessor to PPP
CCNA Guide to Cisco Networking Fundamentals, Fourth Edition

5. PPP (continued)
PPP can be used over several different physical interfaces, including the following:
Asynchronous serial
ISDN synchronous serial
High-Speed Serial Interface (HSSI)
CCNA Guide to Cisco Networking Fundamentals, Fourth Edition

6. PPP in the Protocol Stack
You can use PPP over both asynchronous and synchronous connections
At the Physical layer of the OSI reference model
Link Control Protocol (LCP)
Used at the Data Link layer to establish, configure, and test the connection
Network Control Protocols (NCPs)
Allow the simultaneous use of multiple Network layer protocols and are required for each protocol that uses PPP
CCNA Guide to Cisco Networking Fundamentals, Fourth Edition

7. PPP in the Protocol Stack (continued)
CCNA Guide to Cisco Networking Fundamentals, Fourth Edition

8. Frame Format
PPP is based on the High-Level Data Link Control (HDLC) protocol
The difference between PPP frames and HDLC frames is that PPP frames contain protocol and Link Control Protocol (LCP) fields
LCP
Described in RFCs 1548, 1570, 1661, 2153, and 2484
Describes PPP organization and methodology, including basic LCP extensions
CCNA Guide to Cisco Networking Fundamentals, Fourth Edition

9. CCNA Guide to Cisco Networking Fundamentals, Fourth Edition

10. Frame Format (continued)
LCP field of the PPP packet can contain many different pieces of information, including the following:
Asynchronous character map
Maximum receive unit size
Compression
Authentication
Magic number
Link Quality Monitoring (LQM)
Multilink
CCNA Guide to Cisco Networking Fundamentals, Fourth Edition

11. Frame Format (continued)
LCP link configuration process
Modifies and enhances the default characteristics of a PPP connection
Includes the following actions:
Link establishment
Authentication (optional)
Link-quality determination (optional)
Network layer protocol configuration negotiation
Link termination
CCNA Guide to Cisco Networking Fundamentals, Fourth Edition

12. Establishing PPP Communications
Involves the following actions:
Link establishment
Optional authentication
Network layer protocol configuration negotiation
The link establishment phase involves the configuration and testing of the data link
The authentication process can use two authentication types with PPP connections: PAP and CHAP
CCNA Guide to Cisco Networking Fundamentals, Fourth Edition

13. Establishing PPP Communications (continued)
PPP is an encapsulation type for serial interface communications
To configure a PPP connection, you must access the interface configuration mode for the specific interface you want to configure
After LCP has finished negotiating the configuration parameters
Network layer protocols can be configured individually by the appropriate NCP
CCNA Guide to Cisco Networking Fundamentals, Fourth Edition

14. Establishing PPP Communications (continued)
CCNA Guide to Cisco Networking Fundamentals, Fourth Edition

15. Establishing PPP Communications (continued)
Configuring PPP Authentication
Using authentication with PPP connections is optional
You must specifically configure PPP authentication on each PPP host in order for the host to use it
You can choose to enable CHAP, PAP, or both on your PPP connection, in either order
CCNA Guide to Cisco Networking Fundamentals, Fourth Edition

16. Establishing PPP Communications (continued)
Once you set the authentication type
You must still configure a username and password for the authentication
You must exit interface configuration mode and enter global configuration mode
Type username followed by the host name of the remote router
Then type password followed by the password for that connection
Confirming PPP Communications
With the show interface command
CCNA Guide to Cisco Networking Fundamentals, Fourth Edition

17. CCNA Guide to Cisco Networking Fundamentals, Fourth Edition

18. Establishing PPP Communications (continued)
CCNA Guide to Cisco Networking Fundamentals, Fourth Edition