Installing

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Maintaining and Troubleshooting Networks

Chapter 16

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Overview

• In this chapter, you will learn to– Install and configure wireless networks

– Configure security

– Recognize and fix basic network problems

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Getting the Right Sound CardInstalling and Configuring

a Wireless Network

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Introduction

• Wireless networks are growing in popularity

• Wireless networks use radio waves or beams of infrared light to communicate with each other

• Two primary types of wireless networks– Based on IEEE 802.11 standard – Based on Bluetooth technology

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Wireless Networking Components

• Many capabilities built-in today

– Infrared transceiver ports standard in laptops, PDAs, and high-end printers

– Infrared not usually included in desktop PCs

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Wireless Networking Components

• Wireless Ethernet and Bluetooth often integrated or can easily be added– USB, PCI, PCI Express, or PC Card adapters

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Wireless Networking Components

• Wireless access point (WAP)– Acts like a hub to the wireless hosts in the area

• Bluetooth– Built-in option on many newer PCs

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Wireless Networking Software

• Wireless devices use same networking clients and protocol as wired networks

– Use CSMA/CA (CA stands for collision avoidance)

• Another option is using Request to Send/Clear to Send (RTS/CTS)

• Sending node issues an RTS to the receiving node as a request

• Receiving node replies with a CTS when it’s clear

• Once data is received, receiving node sends an ACK (acknowledge)

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Wireless Configuration Utility

• Configure wireless networking software– Use a utility to configure parameters

• Windows built-in utility or vendor provided• Set parameters like network name

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Wireless Networking Modes

• Ad-hoc mode

– Each wireless node is in direct contact with every other node in a decentralized free-for-all

– Form an Independent BasicService Set (IBSS)

– Called peer-to-peer mode

– Good for a few computers or temporary network such as study groups or business meetings

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Wireless Networking Modes

• Infrastructure Mode

– Use one or more WAPs to connect wireless nodes to a wired network segment

– A single WAP servicing an area is called a Basic Service Set (BSS)

– Additional WAPs create an Extended Basic Service Set (EBSS)

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Wireless Networking Security

• Three methods used to enhance security

1. Configure SSID

2. Filter by MAC address

3. Use encryption

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Wireless Networking Security

• Service Set Identifier (SSID)– Configure a unique SSID or network name

• Default is often name of vendor such as “LinkSys”• Widely known so easy to guess

– Each node needs to have the same SSID– Turn off SSID broadcasting

● MAC filtering– Filtering based on each host’s MAC address– Creates a type of accepted user

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Wireless Networking Security

• Wireless Equivalency Privacy (WEP)– Encrypts data using 40-bit or 104-bit encryption

– Provides authentication based on MAC addresses

– Significant flaws

• Wi-Fi Protected Access (WPA)– Interim upgrade to WEP– Uses encryption key integrity-checking through Extensible Authentication Protocol (EAP)

• WPA2 (IEEE 802.11i )– Full upgrade to WEP – Significant improvements– Current wireless security standard

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Speed and Range Issues

• Wireless speeds range from 2 Mbps to54 Mbps

• Speed affected by range– Speed dynamically negotiated– Maximum throughput at approximately 25 feet or less

– At edge of range, throughput may decrease to 1 Mbps

– Range not exact• Often listed as around 150 feet or 300 feet

– Dead spots and interfering devices can affect signal

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Wireless Networking Standards

• 802.11-based wireless networking– Three primary standards– All can work in ad-hoc or infrastructure modes

802.11a 802.11b 802.11gMaxthroughput

54 Mbps 11 Mbps 54 Mbps

Max range 150 feet 300 feet 300 feetFrequency 5 GHz 2.4 Ghz 2.4 GhzSecurity SSID, MAC,

WEP, WPASSID, MAC, WEP, WPA

SSID, MAC, WEP, WPA

Compatibility 802.11a 802.11b 802.11b, 802.11g

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Wireless Networking Standards

• Infrared wireless networking– Simple way to share data without adding any additional hardware or software

– Uses the Infrared Data Association (IrDA) protocol

– Line-of-sight required– No authentication or encryption

• You can’t be more than 1 meter away

Infrared (IrDA)Max throughput Up to 4 MbpsMax range 1 meter (39 inches)Security NoneCompatibility IrDACommunication mode Point-to-point ad-hoc

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Wireless Networking Standards

• Bluetooth

– Designed to create small wireless personal area networks (PANs)

– Typically used for peripherals• Mice, keyboards, PDAs, etc.

Bluetooth High-powered BluetoothMax throughput 1 Mbps 2 MbpsMax range 10 meters 300 feetCompatibility Bluetooth BluetoothCommunication mode

PAN PAN

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Wireless Networking Standards

• Cellular

– Many PDAs and phones today allow connection to Internet

– Can add this to laptop withPC Card

– Downloads as quick as 400 to 700 Kbps

– Cellular networks have their own protocols

– Downside is the price

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Configuring Wireless Networks

• Physically installing a wireless NIC is the same as installing a wired NIC

• Wireless network configuration utility– Used to configure additionalparameters

– Configure SSID and encryption

– Configure communication mode• Ad-hoc• Infrastructure

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Configuring Wireless Networks

• Wi-Fi– Ad hoc

• Each wireless node needs to be configured with the same network name (SSID)

• May need to select a common channel• Configure unique host IP addresses• Configure File and Printer Sharing

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Configuring Wireless Networks

NETGEAR wireless configuration utility

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Configuring Wireless Networks

• Wi-Fi– Infrastructure mode

• Requires a wireless access point (WAP)• All nodes need to be configured with the same SSID• Configure the WAP with clients that match the chosen options

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Configuring Wireless Networks

• Configuring a wireless access point is often done through a Web browser

– Enter the WAP’s default IP address (see your documentation or try 192.168.1.1) in your browser

– Enter the default administrative password (in your documentation) to log in

• The next few slides show some screenshots of the configuration pages

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Configuring Wireless Networks

• Sample home page

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Configuring Wireless Networks

Configuring MACaddress filtering

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Configuring Wireless Networks

Configuring encryption

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Configuring Wireless Networks

• Infrared– Not much to configure

– Confirm the IrDA protocol is installed

– To transfer files• Use Wireless Link applet• Use Windows Explorer

– To network two computers• Choose Connect Directly to Another Computer

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Configuring Wireless Networks

• Bluetooth– Completely plug and play

• May need to use vendor-supplied drivers

– Bluetooth devices seek each other out• Establish a master/slave relationship

– PANs sometimes have specialized software utility

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Troubleshooting Networks

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Troubleshooting Networks

• Networked and non-networked situations differ drastically– Networked situations add complexity

Routeror switch

`

```

CPU1

Print server

If a user can’t print from CPU1, it could be due to many possible problems on the network.

Networked printer

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Troubleshooting Networks

1. Verify the symptom– Talk with the user to try to get a precise

description of the symptoms

2. When did it happen?– Does it happen during boot, when the OS

loads, or after the system has been running for a while?

3. What has changed?– Try to find out if anything has changed– Even recent changes before the problem

began occurring

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Troubleshooting Networks

4. Check the environment– Heat, humidity, dirt– What OS? What applications? Do others use

the computer?

5. Reproduce the problem– If a problem happens only once, it’s not a

problem– Otherwise, try to make the problem happen

again

6. Isolate the symptom– Hardware—remove suspect parts – Software—remove background programs or

boot into Safe Mode

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Troubleshooting Networks

7. Separate hardware from software– Replace the suspect hardware with known

good hardware – Uninstall the suspect software and

reinstall it– Install the latest patch or upgrade– Check for viruses

8. Research– Use search engines on the Internet

9. Make the fix and test– Keep track of what you did so you may

return to the previous state if the fix does not work

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OSI Seven-Layer Model

• Use as a guide in troubleshooting

Layer Number Name DescriptionLayer 1: Please Physical NICs (link light), cables,

switches, hubs, etc. 1s, 0sLayer 2: Do Data Link MAC addresses and CSMA/CD

Layer 3: Not Network IP operates hereLayer 4: Throw the

Transport TCP/UDP operate here

Layer 5: Sausage Session Manages connections

Layer 6: Pizza Presentation Describes how to present data

Layer 7: Away Application Interacts with user

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Mike’s Four-Layer Model

• Hardware– Check the hardware starting with the physical layer

• Protocols– Is it installed and configured properly?

• Network– Servers and clients– Check users and groups and share names

• Shared resources– Make sure the resource has been properly shared

– Check the access allowed

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