1. Chapter 3 -- PPP PPP – A continuation of CCNA – Semester 4

2. DataLink (Layer 2) TCP/IP Protocols SLIP - SLIP is a standard protocol for point- to-point serial connections, using TCP/IP. SLIP was a predecessor of PPP. PPP - PPP provides router-to-router and host-to-network connections over synchronousand asynchronous circuits, which can be either dialup or leased lines.

3. PPP Supports Protocols – TCP/IP, AppleTalk, IPX Essential features such as dynamic address allocation, PAP authentication, CHAP authentication, and Multilink PPP

4. HDLC High-Level Data Link Control (HDLC) is the default encapsulation for ISDN and serial interfaces on a Cisco router. Although HDLC is a default encapsulation, Cisco's HDLC is not necessarily compatible with other vendors' HDLC implementations PPP is a standard protocol – can be used with any vendor equipment

5. PPP Specifications It is a standard – operates at OSI Layer 2 Encapsulates Layer 3 datagrams with a specialized frame. PPP defines the Link Control Protocol (LCP) Once the LCP establishes the Layer 2 connection, the Network Control Protocol (NCP) takes over– frame includes protocol field – Each Layer 3 protocol has its own NCP. For example, IP's NCP is IPCP; IPX's NCP is IPXCP, and Appletalk's NCP is ATALKCP

6. Code RTA(config)#interface async 2 RTA(config-if)#encapsulation ppp

7. Remote Connections Exec –Can dial in and take control of command line Telnet Access resources – network access –Can access printers, servers, etc. PPP encapulation via asynchronous dialup connection

8. Commands RTA(config)#interface async 1 RTA(config-if)#encapsulation ppp RTA(config-if)#async mode interactive RTA(config)#line 1 RTA(config-line)#autoselect ppp during-login –Will eliminate possibility of Exec session Router(config-if)#async mode dedicated –Will ensure PPP runs on specified line

9. Programming Interface RTA(config)#interface async1 RTA(config-if)#ip address10.1.1.1 255.255.255.0 or RTA(config-if)#ip unnumbered lo0 192.16.1.1 RTA(config-if)#peer default ip address 10.1.1.1 –Assigns an address (usually host on same subnet) to the dial-in unitor RTA(config-if)#peer default ip address pool NAME –Requires global command # ip local pool pool-name starting-address end-address.

10. LCP Configuration Options Authentication –CHAP or PAP Callback –Billing consolidation Compression –Reduces size of frame - Stacker, Predictor, and Microsoft Point to Point Compression (MPPC) Multilink PPP – load balancing functionality over multiple WAN links

11. Authentication Programming Router(config)#username Romeo password Juliet Router(config-if)#encapsulation ppp Router(config-if)#ppp authentication pap Router(config-if)#ppp pap sent-username GIN password RUMMY –Name and password are case sensitive Dialer-map command tells each router what to do (suggest it be used) – see 3.2.2

12. Configuring CHAP Router(config-if)#encapsulation ppp Router(config-if)#ppp authentication chap Router(config-if)#ppp chap hostname GIN Router(config-if)#ppp chap password RUMMY –Remember that you will also have to configure a local username/password database, or point the router to the TACACS+ or RADIUS server that has that information. –Router(config-if)#ppp authentication pap chap

13. Callback provides a client/server relationshipbetween the endpoints of a point-to-point connection can be used to control access and toll costs between hosts the calling router (the callback client) pases authentication information to the remote router (the callback server) for PPP callback server disconnects, and then places a return call Both routers on a point-to-point link must be configured for PPP callback – server/client

14. Configuration for Callback Server(config)#username Client password itsasecret Server(config)#map-class dialer DIALBACK Server(config-map-class)#dialer callback-server username Server(config-map-class)#exit Server(config)#interface async 1 Server(config-if)#ppp callback accept Server(config-if)#dialer map ip 10.1.1.2 name Client class DIALBACK modem-script hayes56k broadcast 5556002

15. Client Configuration Client(config)#interface async 1 Client(config-if)#encapsulation ppp Client(config-if)#ppp authentication chap Client(config-if)#ppp callback request Client(config-if)#dialer in-band Client(config-if)#dialer-group 1 Client(config-if)#dialer map ip 10.1.1.1 name Server modem-script hayes56k broadcast 5556001

16. Compression CPU or Memory Intensive –Can impact router performance Use only on slow lines Use commands to show impact –Show process cpu –Show processes memory

17. PPP Multilink Use MLP with applications in which bandwidth requirements are dynamic, such as remote LAN access applications for telecommuters or small office, home office (SOHO) environments Creates bundles RFC 1717 and 1990

18. MMP Features Combine multiple physical links into one logical link (bundle) Receive and reassemble upper-layer protocol data units (PDUs) Receive PDUs of a negotiated size

19. Troubleshooting Commands Show dialer –view the status of asynchronous dialup connections. Debug PPP negotiation –troubleshooting the PPP LCP activities such as authentication, compression, and MLP Debug PPP Authentication –output is limited to CHAP and PAP authentication – events.