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Prototyping the WAN
Designing and Supporting Computer Networks – Chapter 8

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Objectives
 Describe the methods to prototype remote
connectivity support
 Prototype the WAN Connectivity
 Prototype the VPN connectivity for remote workers

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Describe the Methods to Prototype Remote
Connectivity Support
 Simulation software
 Prototype testing using simulated links
 Pilot testing in the actual environment

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Describe the Methods to Prototype Remote
Connectivity Support
Benefits of using simulation software to test remote
connectivity:
 Lower overall cost
 Flexibility
 Scalability
 Control

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Limitations of using simulation software to test the
design:
 Limited functionality
 Unrealistic performance
Describe the Methods to Prototype Remote
Connectivity Support

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Describe the Methods to Prototype Remote
Connectivity Support
Simulate WAN connectivity in a prototype lab:
 Use Ethernet connection to simulate DSL or cable
 Use CSU/DSU, serial modems, or V.35 cables to
simulate serial connectivity

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Prototype the WAN Connectivity
 Identify business goals and technical requirements from
the case study and determine which of these goals and
requirements can be tested in the prototype

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Prototype the WAN Connectivity
 Create a success criteria checklist to support business
goals and technical requirements

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Determine the elements of the simulated WAN
connection:
 Simulate the Frame Relay connection using a Cisco
router acting as a Frame Relay switch
 Simulate a crossover function using V.35 cables
 Provide the DCE function with a clock rate
Prototype the WAN Connectivity

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Prototype the WAN Connectivity
Validate the choice of WAN devices and topologies:
 Local point-to-point circuit
 Packet-switched network
 Remote point-to-point circuit

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Prototype the WAN Connectivity
 Configure the router to act as the Frame Relay switch
 Configure serial interfaces as DCE devices
 Configure Layer 3 addresses and encapsulation type

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Prototype the WAN Connectivity
Verify that the Frame Relay WAN operates as expected:
 Display the status of the interfaces
 Verify the exchange of LMI messages
 Display the status of PVCs and the Frame Relay maps

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Provide and test backup capabilities:
 Set up Ethernet connections
 Create floating static routes
Prototype the WAN Connectivity

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Prototype the WAN Connectivity
 Troubleshoot Layer 1 using the show interface serial
command
 Troubleshoot Layer 2 using the show frame-relay lmi
command
 Check Layer 3 functionality

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Prototype the WAN Connectivity
 Identify areas of risk and weakness in the design

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Prototype the VPN Connectivity for Remote
Workers
Determine which business goals and technical
requirements can be tested in the prototype:
 VPN security
 VPN server location

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Prototype the VPN Connectivity for Remote
Workers
 Create a success criteria checklist to support business
goals and technical requirements

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Prototype the VPN Connectivity for Remote
Workers
 Verify the use of Cisco EasyVPN to configure a VPN
server and set up the client software

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Prototype the VPN Connectivity for Remote
Workers
 Validate the choice of VPN technology, devices, and
topologies

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Prototype the VPN Connectivity for Remote
Workers
Prototype the Remote Worker Support:
 IPSec
 Split tunnels

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Prototype the VPN Connectivity for Remote
Workers
 Validate the placement of the VPN server and access
list filtering in the prototype network

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Prototype the VPN Connectivity for Remote
Workers
 Identify risks or weaknesses in the VPN design

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Summary
 Every Frame Relay link has three components: a local
point-to-point circuit, the packet-switched network, and
a remote point-to-point circuit.
 Frame Relay is a nonbroadcast multi-access protocol.
 One way to configure routers to use a backup link when
a primary link fails is to create floating static routes.
 VPNs have two important components: tunneling and
encryption.
 Encryption algorithms such as DES require a
symmetric, shared secret key.
 IPSec provides data confidentiality, integrity, and
authentication at Layer 3.

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