Case Study:Pat Lee’s Home PC Network

Chapter 1a

Panko’s Business Data Networks and Telecommunications, 6th edition

Copyright 2007 Prentice-Hall May only be used by adopters of the book

1a-2

Pat Lee’s Home Network

• Pat Lee is a vice president at FBP

• Wants a network in her home

– Family’s main computer is the downstairs PC

– Daughter Emily has a PC in her room

– Wants to connect both to the Internet through a broadband (high-speed) cable modem service

• Perspective

– A small LAN but has all the key network elements

1a-3

Figure 1a-1: Pat Lee’s Home Network

1.Coaxial Cable

to ISP

2.Cable

Modem

3. UTP Cord

4.AccessRouter

1a-4

Figure 1a-2: Coaxial Cable

InnerConductor

(wire) Insulation Insulation

OuterConductor(cylinder)

CommonAxis

Two conductors are required forTwo conductors are required for transmission

1a-5

Figure 1a-1: Pat Lee’s Home Network, Continued

5. UTPCord

5. UTPCord

6.B2-CD-13-5B-E4-65

PC in Study

6.A1-BD-33-6E-C7-BBPC in Emily’s Room

4.AccessRouter

1a-6

Figure 1a-5: Unshielded Twisted Pair (UTP) Cord With RJ-45 Connector

8-Pin RJ-45 Connector

4-Pair Unshielded Twisted Pair (UTP)

Industry Standard Pen

UTP Cord

1a-7

Figure 1a-1: Pat Lee’s Home Network, Continued

6.B2-CD-13-5B-E4-65

PC in Study

6.A1-BD-33-6E-C7-BBPC in Emily’s Room

7. FileSharing

1a-8

Figure 1a-1: Pat Lee’s Home Network, Continued

6.B2-CD-13-5B-E4-65

PC in Study

6.A1-BD-33-6E-C7-BBPC in Emily’s Room

8. PrinterSharing

1a-9

Figure 1a-3: Network Interface Cards (NICs)

Internal NIC. Installed inside systems unit. Plugged into expansion slot on the mother board.

PC Card NIC. Installed in PC Card slot in notebook and some PDAs.

1a-10

Internal NIC

RJ-45Jack

PCI Connector Pins

1a-11

Figure 1a-6: UTP Cord RJ-45 Connector and Jack

RJ-45 JackOn a Wall

On a Switchor

on a NIC

RJ-45Connector

UTP Cord---

About as thickas a pencil

---Rugged and

Flexible

1a-12

Computer Mother Board

• Mother BoardPCI Slots

for Expansion Boards(NICs, etc.)

Slots for RAM

Slot forMicroprocessor

(Pentium 4)

1a-13

Mother Board and Expansion Boards

ConnectorExpansion Board

(NIC)Expansion

Slots

Mother Board

1a-14

Figure 1a-4: Device Drivers

Operating System

NICDeviceDriver

Hard DriveDeviceDriver

PrinterDeviceDriver

NIC PrinterHard Drive

1a-15

Figure 1a-7: Home Network Access Router

Switch PortsUTP Cords

Run to Stations

WAN PortUTP CordRuns to

Cable Modem

About 4 inches (10 cm) Wide

PowerJack forExternalPower

1a-16

Figure 1a-9: Ethernet Switch Operation

Switching TablePort Host 10 A1-44-D5-1F-AA-4C13 B2-CD-13-5B-E4-6515 C3-2D-55-3B-A9-4F16 D4-47-55-C4-B6-9F

UTP

UTPUTPUTP

Ethernet Switch

A1-44-D5-1F-AA-4C B2-CD-13-5B-E4-65

D4-47-55-C4-B6-9F

C3-2D-55-3B-A9-4F

Frame To C3…Frame To C3…

1a-17

Figure 1a-8: Logical Functions of the Access Router

DHCPServer

Function

Router Function

NATFunction

Switch Function

Access Router

CableModem

1a-18

Figure 1a-10: Dynamic Host Configuration Protocol (DHCP)

Access Router

CableModem

A1-BD-33-6E-C7-BBPC in Emily’s Room

B2-CD-13-5B-E4-65PC in Study

ISPDHCP Server

1.IP Address =60.47.112.6

A DHCP Serverprovides User PCs witha temporary IP Address

each time the userconnects to the Internet

The ISP onlyGives each home aSingle IP address

1a-19

Figure 1a-10: Dynamic Host Configuration Protocol (DHCP)

InternalDHCPServer

Access Router

A1-BD-33-6E-C7-BBIP Address = 192.168.0.3

PC in Emily’s Room

B2-CD-13-5B-E4-65IP Address = 192.168.0.2

PC in Study

ISPDHCP Server

1.IP Address =60.47.112.6

2. IP Address =192.168.0.2

2. IP Address =192.168.0.3

The access router’sinternal DHCP server

gives private IPAddresses to each PC

1a-20

Figure 1a-11: Network Address Translation (NAT)

Access Router

CableModem

WebserverIP Address=123.7.86.285

1. Packet from192.168.0.2

InternalNAT

Module

PC in Study192.168.0.2

2. Packet from60.47.112.6

The access router’s NATmodule translates between the

private IP Addresses andthe single ISP-given IP Address

1a-21

Figure 1a-11: Network Address Translation (NAT), Continued

AccessRouter

CableModem

WebserverIP Address=123.7.86.285

4. Packet to192.168.0.2

InternalNAT

Module

PC in Study192.168.0.2

3.Packet

to60.47.112.6

1a-22

Perspective

• Pat Lee would like to serve the upstairs computer wirelessly

• This requires a wireless access point connected to the router or built into the router

• The upstairs computer must have a wireless NIC

• The downstairs computer, which is next to the access router, will still be connected via UTP

• If a separate wireless access point is used, it must be connected to the access router via UTP

1a-23

Figure 1a-12: Pat Lee’s Wireless LAN

AccessRouter

A1-BD-33-6E-C7-BBPC in Emily's Roomwith Wireless NIC

B2-CD-13-5B-E4-65PC in Study

UTP Cord

Option with Separate Wireless Access Point

UTP Cord

WirelessAccess Point

WirelessCommunication

1a-24

Figure 1a-12: Pat Lee’s Wireless LAN

Access Routerwith Built-in

Wireless Access PointFunctionality

A1-BD-33-6E-C7-BBPC in Emily's Roomwith Wireless NIC

Option with Access Router with Integrated Wireless Access Point Functionality

WirelessCommunication

1a-25

Figure 1a-13: Access Router with Wireless Access Point and Wireless NICs

Access Router withWireless

Access Point

InternalWireless

NIC

External WirelessNIC with

USB Connector

PC Card orExpressCardWireless NIC

Antenna

Antenna

1a-26

Configuration

• Each computer must be configured for communication with the outside world. See Chapter 1b for details.

• Each computer must be configured for file and print sharing. See Chapter 1b for details.

• The access router has a built-in webserver, allowing either of the two PCs to configure it using a browser.

Not in theBook

1a-27

Figure 1a-14: Peer-to-Peer Service Versus Dedicated Servers

• Peer-to-Peer Networks

– Clients serving other clients

– Inexpensive—no need to purchase a dedicated server

– Operational problems for other users if a user PC is turned off or crashes

– Poor security: No password or shared password for shared directories

1a-28

Figure 1a-14: Peer-to-Peer Service Versus Dedicated Servers

• Dedicated Servers

– Servers that are not also used simultaneously as user PCs

– Do not use standard client versions of Microsoft Windows (XP, and so forth)

– They use special server operating systems

• Known for historical reasons as network operating systems (NOSs)

• One popular NOS is Microsoft Windows (latest version is Windows Server 2003)

• Another is Unix, which has versions for PCs (Linux, BSD, etc.)

1a-29

Figure 1a-14: Peer-to-Peer Service Versus Dedicated Servers

• Dedicated Servers

– NOSs for dedicated servers are rich in functionality

• They are designed to serve many users with many services

• Have strong security

– Unfortunately, dedicated servers are very expensive

– Installation requires specialized training

– Make no sense for home use

1a-30

Figure 1a-14: Peer-to-Peer Service Versus Dedicated Servers

• Network Attached Storage (NAS) Units

– Boxes that cost $200 to $500

– Contain a large shared hard drive

– RJ-45 plugs allow the NAS to be connected to the switch in the access router via UTP

– No mouse or keyboard; has a built-in webserver that can be managed remotely by a client PC

– Do not lose availability when a user PC is turned off or crashes

– Better security than PC file service

– Backup is crucial