This chapter discusses wide area network (WAN) technologies including HDLC, PPP, Frame Relay, and virtual private networks (VPNs). It defines WAN terminology and components. PPP is described as a protocol used to transport layer 3 packets across point-to-point links. Frame Relay is introduced as a high-performance WAN encapsulation method that provides a connection-oriented data link layer. VPNs allow remote access, site-to-site, and extranet connectivity over public networks like the internet.

1. Instructor & Todd Lammle Sybex CCNA 640-802 Chapter 14: Wide Area Networks

2. Chapter 14 Objectives The CCNA Topics Covered in this chapter include: Introduction to WAN’s HDLC PPP Frame Relay Introduction to VPN’s

3. Defining WAN Terms Customer Premises Equipment (CPE) Demarcation (demarc) Local loop Central Office (CO) Toll network

4. WAN Connection Types

5. DTE-DCE-DTE

6. WAN Support Frame Relay ISDN LAPB LAPD HDLC PPP ATM

7. HDLC Protocol Bit-oriented Data Link layer ISO standard protocol Specifies a data encapsulation method No authentication can be used

8. HDLC Frame Format

9. Point-to-Point Protocol (PPP) Purpose: Transport layer-3 packets across a Data Link layer point-to-point link Can be used over asynchronous serial (dial-up) or synchronous serial (ISDN) media Uses Link Control Protocol (LCP) Builds & maintains data-link connections

10. Point-to-Point Protocol Stack

11. PPP Main Components EIA/TIA-232-C Intl. Std. for serial communications HDLC Serial link datagram encapsulation method LCP Used in P-t-P connections: Establishing Maintaining Terminating NCP Method of establishing & configuring Network Layer protocols Allows simultaneous use of multiple Network layer protocols

12. LCP Configuration Options Authentication PAP CHAP Compression Stacker Predictor Error detection Quality Magic Number Multilink Splits the load for PPP over 2+ parallel circuits; a bundle

13. PPP Session Establishment Link-establishment phase Authentication phase Network-layer protocol phase

14. PPP Session Establishment

15. PPP Authentication Methods Password Authentication Protocol (PAP) Passwords sent in clear text Remote node returns username & password Challenge Authentication Protocol (CHAP) Done at start-up & periodically Challenge & Reply Remote router sends a one-way hash ~ MD5

16. Configuring PPP Step #1: Configure PPP on Router A & Router B : Router__# config t Router__(config)# int s0 Router__(config-if)# encapsulation ppp Router__(config-if)#^ Z Step #2: Define the username & password on each router: RouterA: RouterA(config)# username RouterB password cisco RouterB: RouterB(config)# username RouterA password cisco NOTE: (1) Username maps to the remote router (2) Passwords must match Step #3: Choose Authentication type for each router; CHAP/PAP Router__(Config)# int s0 Router__(config-if)# ppp authentication chap Router__(config-if)# ppp authentication pap Router__(config-if)#^Z

17. PPP Example 1

18. PPP Example 2

19. PPP Example 3

20. PPP Example 4

21. Frame Relay Background High-performance WAN encapsulation method OSI Physical & data Link layer Originally designed for use across ISDN Supported Protocols IP, DECnet, AppleTalk, Xerox Network Service (XNS), Novell IPX, Banyan Vines, Transparent Bridging, & ISO

22. Before Frame Relay

23. After Frame Relay

24. Frame Relay Purpose Provide a communications interface between DTE & DCE equipment Connection-oriented Data Link layer communication Via virtual circuits Provides a complete path from the source to destination before sending the first frame

25. Frame Relay Terminology

26. Frame Relay Encapsulation Specified on serial interfaces Encapsulation types: Cisco (default encapsulation type) IETF (used between Cisco & non-Cisco devices) RouterA(config)# int s0 RouterA(config-if)# encapsulation frame-relay ? ietf Use RFC1490 encapsulation <cr>

27. Data Link Connection Identifiers (DLCIs) Frame Relay PVCs are identified by DLCIs IP end devices are mapped to DLCIs Mapped dynamically or mapped by IARP Global Significance: Advertised to all remote sites as the same PVC Local Significance: DLCIs do not need to be unique Configuration RouterA(config-if)# frame-relay interface-dlci ? <16-1007> Define a DLCI as part of the current subinterface RouterA(config-if)# frame-relay interface-dlci 16

28. DLCI’s are Locally Significant

29. Local Management Interface (LMI) Background Purpose LMI Messages Keepalives Multicasting Multicast addressing Status of virtual circuits

30. LMI Types Configuration: RouterA(config-if)# frame-relay lmi-type ? cisco ansi q933a Beginning with IOS ver 11.2+ the LMI type is auto-sensed Default type: cisco Virtual circuit status: Active Inactive Deleted

31. Sub-interfaces Definition Multiple virtual circuits on a single serial interface Enables the assignment of different network-layer characteristics to each sub-interface IP routing on one sub-interface IPX routing on another Mitigates difficulties associated with: Partial meshed Frame Relay networks Split Horizon protocols

32. Partial Meshed Networks

33. Creating Sub-interfaces Configuration: #1: Set the encapsulation on the serial interface #2: Define the subinterface RouterA(config)# int s0 RouterA(config)# encapsulation frame-relay RouterA(config)# int s0.? <0-4294967295> Serial interface number RouterA(config)# int s0.16 ? multipoint Treat as a multipoint link point-to-point Treat as a point-to-point link

34. Mapping Frame Relay Necessary to IP end devices to communicate Addresses must be mapped to the DLCIs Methods: Frame Relay map command Inverse-arp function

35. Using the map command RouterA(config)# int s0 RouterA(config-if)# encap frame RouterA(config-if)# int s0.16 point-to-point RouterA(config-if)# no inverse-arp RouterA(config-if)# ip address 172.16.30.1 255.255.255.0 RouterA(config-if)# frame-relay map ip 172.16.30.17 16 ietf broadcast RouterA(config-if)# frame-relay map ip 172.16.30.18 17 broadcast RouterA(config-if)# frame-relay map ip 172.16.30.19 18

36. Using the inverse arp command RouterA(config)# int s0.16 point-to-point RouterA(config-if)# encap frame-relay ietf RouterA(config-if)# ip address 172.16.30.1 255.255.255.0

37. Congestion Control Discard Eligibility (DE) Forward-Explicit Congestion Notification (FECN) Backward-Explicit Congestion Notification (BECN)

38. Committed Information Rate (CIR) Definition: Provision allowing customers to purchase amounts of bandwidth lower than what they might need Cost savings Good for bursty traffic Not good for constant amounts of data transmission

39. Monitoring Frame Relay RouterA> sho frame ? ip show frame relay IP statistics lmi show frame relay lmi statistics map Frame-Relay map table pvc show frame relay pvc statistics route show frame relay route traffic Frame-Relay protocol statistics RouterA# sho int s0 RouterB# show frame map Router# debug frame-relay lmi

40. Troubleshooting Frame Relay Why can’t RouterA talk to RouterB?

41. Troubleshooting Frame Relay Why is RIP not sent across the PVC?

42. Introduction to VPN’s VPNs are used daily to give remote users and disjointed networks connectivity over a public medium like the Internet instead of using more expensive permanent means.

43. Types of VPN’s REMOTE ACCESS VPNS Remote access VPNs allow remote users like telecommuters to securely access the corporate network wherever and whenever they need to. SITE-TO-SITE VPNS Site-to-site VPNs, or, intranet VPNs, allow a company to connect its remote sites to the corporate backbone securely over a public medium like the Internet instead of requiring more expensive WAN connections like Frame Relay. EXTRANET VPNS Extranet VPNs allow an organization’s suppliers, partners, and customers to be connected to the corporate network in a limited way for business-to-business (B2B) communications.

44. Written Labs and Review Questions Open your books and go through all the written labs and the review questions. Review the answers in class.