instructor & todd lammle
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Instructor & Todd Lammle. Sybex CCNA 640-802 Chapter 14: Wide Area Networks. 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) - PowerPoint PPT PresentationTRANSCRIPT
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Sybex CCNA 640-802 Chapter 14: Wide Area Networks
Instructor & Todd Lammle
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Chapter 14 Objectives
The CCNA Topics Covered in this chapter include:
• Introduction to WAN’s• HDLC• PPP• Frame Relay• Introduction to VPN’s
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Defining WAN Terms
• Customer Premises Equipment (CPE)
• Demarcation (demarc)
• Local loop
• Central Office (CO)
• Toll network
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WAN Connection Types
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DTE-DCE-DTE
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WAN Support
• Frame Relay
• ISDN
• LAPB
• LAPD
• HDLC
• PPP
• ATM
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HDLC Protocol
• Bit-oriented Data Link layer ISO standard protocol
• Specifies a data encapsulation method
• No authentication can be used
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HDLC Frame Format
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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
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Point-to-Point Protocol Stack
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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
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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
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PPP Session Establishment
• Link-establishment phase
• Authentication phase
• Network-layer protocol phase
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PPP Session Establishment
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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
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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/PAPRouter__(Config)#int s0
Router__(config-if)#ppp authentication chap
Router__(config-if)#ppp authentication pap
Router__(config-if)#^Z
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PPP Example 1
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PPP Example 2
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PPP Example 3
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PPP Example 4
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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
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Before Frame Relay
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After Frame Relay
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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
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Frame Relay Terminology
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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>
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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
• ConfigurationRouterA(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
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DLCI’s are Locally Significant
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Local Management Interface (LMI)
• Background
• Purpose
• LMI Messages– Keepalives– Multicasting– Multicast addressing– Status of virtual circuits
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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
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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
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Partial Meshed Networks
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Creating Sub-interfaces
Configuration:#1: Set the encapsulation on the serial interface
#2: Define the subinterfaceRouterA(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
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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
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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
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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
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Congestion Control
• Discard Eligibility (DE)
• Forward-Explicit Congestion Notification (FECN)
• Backward-Explicit Congestion Notification (BECN)
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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
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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
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Troubleshooting Frame Relay
Why can’t RouterA talk to RouterB?Why can’t RouterA talk to RouterB?
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Troubleshooting Frame Relay
Why is RIP not sent across the PVC?Why is RIP not sent across the PVC?
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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.
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Types of VPN’s
• REMOTE ACCESS VPNSRemote access VPNs allow remote users like telecommuters to securely
access the corporate network wherever and whenever they need to.
• SITE-TO-SITE VPNSSite-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 VPNSExtranet 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.
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Written Labs and Review Questions
– Open your books and go through all the written labs and the review questions.
– Review the answers in class.
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