Chapter14ccna
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This document provides an overview of wide area networks (WANs) and common WAN technologies. It defines WAN terminology like customer premises equipment and demarcation. It describes different WAN connection types and protocols like HDLC, PPP, Frame Relay and VPNs. PPP is examined in detail, including its components, establishment process and authentication methods. Frame Relay is also covered in depth, discussing its encapsulation, DLCI addressing, subinterfaces, mapping and monitoring. Troubleshooting tips are provided for common Frame Relay issues. Finally, an introduction to VPN technologies is given for remote access, site-to-site and extranet deployments.
Chapter14ccna
- 1. Sybex CCNA 640-802 Chapter 14: Wide Area Networks Instructor & Todd Lammle
- 2. Chapter 14 Objectives The CCNA Topics Covered in this chapter include: • Introduction to WAN’s • HDLC • PPP • Frame Relay • Introduction to VPN’s 2
- 3. Defining WAN Terms • Customer Premises Equipment (CPE) • Demarcation (demarc) • Local loop • Central Office (CO) • Toll network
- 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
- 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
- 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
- 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 RouterA & RouterB: 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 remoteremote 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
- 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
- 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
- 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?Why can’t RouterA talk to RouterB?
- 41. Troubleshooting Frame Relay Why is RIP not sent across the PVC?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. 42
- 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. 43
- 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. 44