Sybex CCNA Chapter 16: Wide Area Networks Instructor & Todd Lammle

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

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

WAN Connection Bandwidth Digital Signal 0 (DS0) This is the basic digital signaling rate of 64Kbps, equivalent to one channel. Europe uses the E0 and Japan uses the J0 to reference the same channel speed. Typically used in a T-carrier transmission, this is the generic term used by several multiplexed digital carrier systems. This is the smallest capacity digital circuit. 1 DS0 = 1 voice/data line. T1 Also referred to as a DS1, this contains 24 DS0 circuits bundled together with a total bandwidth of 1.544Mbps. E1 European equivalent of the T1. Contains 30 DS0 circuits bundled together with a bandwidth of 2.048Mbps. T3 Referred to as a DS3, this has 28 DS1s bundled together, or 672 DS0s, with a bandwidth of Mbps. OC-3 Optical Carrier (OC) 3, uses fiber, is made up of three DS3s bundled together, and contains 2,016 DS0s with a total bandwidth of Mbps. OC-12 Optical Carrier 12 is make up of four OC-3s bundled together and contains 8,064 DS0s with a total bandwidth of Mbps. OC-48 Optical Carrier 48 is made up of four OC12s bundled together and contains 32,256 DS0s with a total bandwidth of Mbps.

WAN Connection Types

WAN Support Frame Relay ISDN LAPB LAPD HDLC PPP ATM PPPoE Cable DSL MPLS DWDM

Cable and DSL Comparisons –Speed –Security –Popularity –Customer satisfaction

Cable Terms Headend Distribution network DOCSIS (Data Over Cable Service Interface Specification )

Digital Subscriber Line (DSL) Symmetrical DSL Asymmetrical DSL

ADSL PPPoE RFC1483 Routing PPPoA

PPPoE with ADSL

DTE-DCE-DTE

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

HDLC Frame Format

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

Point-to-Point Protocol Stack

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

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

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

PPP Session Establishment

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

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

PPP Example 1

PPP Example 2

PPP Example 3

PPP Example 4

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

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

Before Frame Relay

After Frame Relay

Frame Relay Terminology Committed Information Rate (CIR) Access rate

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

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

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 ? Define a DLCI as part of the current subinterface RouterA(config-if)#frame-relay interface-dlci 16

DLCI’s are Locally Significant

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

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

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

Frame Relay Implementation Single Interface

Partial Meshed Networks

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

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.? Serial interface number RouterA(config)#int s0.16 ? multipoint Treat as a multipoint link point-to-point Treat as a point-to-point link

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

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 RouterA(config-if)#frame-relay map ip ietf broadcast RouterA(config-if)#frame-relay map ip broadcast RouterA(config-if)#frame-relay map ip

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

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

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

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

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. 49

Types of VPN’s R EMOTE ACCESS VPN S Remote access VPNs allow remote users like telecommuters to securely access the corporate network wherever and whenever they need to. S ITE - TO - SITE VPN S 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. E XTRANET VPN S 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. 50

Cisco IOS IPsec IPSec Transforms specify a single security protocol with its corresponding security algorithm Security Protocols –Authentication Header (AH) –Encapsulating Security Payload (ESP) 51

IpSec benefits Confidentiality Data origin authentication and connectionless integrity Anti-replay service Traffic flow 52

Encryption Symmetric encryption Asymmetric Encryption Private keys Public keys 53

Written Labs and Review Questions –Open your books and go through all the written labs and the review questions. –Review the answers in class. 54