1. COS 338
Day 1 Introduction

2. Agenda Roll Call Introduction to Course WebCT Overview Syllabus Review
Introduction to Networking

3. INSTRUCTOR Tony Gauvin, Assistant Professor of E- Commerce
Contact info
216 Nadeau
(207) or ext 7519
WebCT (Tony Gauvin COS 125)

4. Instructional Philosophy
Out-Come based education
Would rather discuss than lecture
Requires student preparation
Hate grading assignments
Especially LATE assignments
Use class interaction, assignments, quizzes, labs and projects to determine if outcomes are met.

5. COS 338 Survival Primer Check WebCT Often
Read Material BEFORE the class discussion
Check WebCT Often
Use the additional resources identified in syllabus
ASK questions about what you didn’t understand in readings
DON’T do assignments and projects at last minute.
REVEIW lectures and notes
Seek HELP if you are having difficulties
OFFER feedback and suggestions to the instructor in a constructive manner

6. Computer Accounts Computer login MSDN Academic Alliance Access Cards
Sys admin
Pete Cyr (x7547) or Art Drolet (x7809)
Applications
MSDN Academic Alliance
Free Stuff
See Dr. Ray Albert
Access Cards
$10 deposit
See Lisa Fournier

7. WebCT http://webct.umfk.maine.edu Login
First name. Last Name
John Doe  John.Doe
Initial password is webct
Help with WebCT available from Blake Library staff
All quizzes and assignments will be administered from WebCT

8. COS 338 Specifics Fully WebCT enabled Market Driven Content
All Quizzes, assignments, projects
Market Driven Content
Wireless, Ethernet, QOS, Security, Frame Relay, TCP/IP, Windows XP
Cohesion Case
First Bank of Paradise
Managerial Perspectives instead of technical
Lab Components
Hands-on using OMS CIAG Lab
Students will build a SOHO LAN with working apllications
Simulations using Opnet IT Guru and ACE
Follow-up Course Cos 420 Internet and Intranet Architecture will be much more technical and will be based on TCP/IP

9. Syllabus review Requirements Grading Course outline Special Notes
Subject to change

10. Introduction
Chapter 1
Panko’s Business Data Networks and Telecommunications, 5th edition Copyright 2005 Prentice-Hall

11. The Chapter
This chapter is a survey of the key concepts we will see in this course
The rest of the book essentially fleshes out out the concepts we will see in this chapter

12. The Chapter Networking is a Head Game
There is a lot of information to master
There are many TLAs (three-letter acronyms)
For design and troubleshooting, you must know everything to do anything.

13. Learning Objectives By the end of this chapter, you should be able to
Discuss the First Bank of Paradise (FBP), our running case study for this book.
Discuss the major types of networked applications.
List the eight elements of networks.
Explain the major types of networks in businesses: LANs, WANs, internets, intranets, and extranets.

14. Learning Objectives By the end of this chapter, you should be able to
Discuss major concerns for network managers: staffing, network architecture, standards, security, wireless networking, efficiency, and quality of service (QoS).
Explain the elements and operation of a small home PC network using a LAN.

15. Learning Objectives By the end of this chapter, you should be able to
Use some key hands-on network management tools, including bandwidth measurement services, ping, ping , tracert, ipconfig, winipconfig, nslookup, and the use of Windows Calculator to compute dotted decimal notation IP addresses.

16. First Bank of Paradise (FBP)
The book’s cohesion case study
Composite mid-size bank in Hawaii
Banks are fairly “typical” firms, although they have stronger need for security
Warren Chun is the chief information officer (CIO)
Yvonne Champion is the network manager

17. First Bank of Paradise (FBP), Continued
Annual Revenues: $4 Billion
Operations
50 Branches
350 ATMs (Automated Teller Machines)
Network
500 Ethernet switches
400 Routers

18. First Bank of Paradise (FBP), Continued
Computers
2,000 desktop and notebook user PCs
200 Windows servers
30 Unix servers
10 Novell NetWare file servers
Information Systems Staff
150 people

19. Figure 1-1: Networked Applications at the First Bank of Paradise
Networked Applications are Applications Made Possible by Networking
, etc.
Users Only Care About Applications
The rest is just details to them

20. Figure 1-1: Networked Applications at the First Bank of Paradise, Continued
E-Commerce
Buying and selling on the Internet
Users typically interact with databases
Customers will soon be able to talk to customer representatives while online

21. Figure 1-1: Networked Applications at the First Bank of Paradise, Continued
Transaction Processing
Simple, highly-structured, and high-volume interactions, such as check processing
Built around databases
External settlement networks

22. Figure 1-1: Networked Applications at the First Bank of Paradise, Continued
Transaction Processing
Back-office transaction processing applications
Accounting, payroll, purchasing, human resources, etc.
Functional databases in individual departments

23. Figure 1-1: Networked Applications at the First Bank of Paradise, Continued
Office Applications
Word processing, spreadsheeting, etc.
, instant messaging (IM), and Web access

24. Figure 1-2: Elements of a Network
Message (Frame)
Application
Application
Client
Station
Switch
Server
Station
Networks connect
applications on different stations.
Applications are all users care about
Switch
Trunk
Line
Access
Line
Switch
Trunk
Line
Outside
World
Mobile Client
Station
Switch
Router
Mobile Client
Station

25. Figure 1-2: Elements of a Network, Continued
Message (Frame)
Application
Application
Client
Station
Switch
Server
Station
Networks connect stations:
clients (fixed and mobile) and servers
Switch
Trunk
Line
Access
Line
Switch
Trunk
Line
Outside
World
Mobile Client
Station
Switch
Router
Mobile Client
Station

26. Figure 1-2: Elements of a Network, Continued
Message (Frame)
Application
Application
Client
Station
Switch
Server
Station
The path
a frame takes
is called its data link
Stations (and routers)
usually communicate
by sending messages
called frames
Switch
Trunk
Line
Access
Line
Switch
Trunk
Line
Outside
World
Mobile Client
Station
Switch
Router
Mobile Client
Station

27. Figure 1-2: Elements of a Network, Continued
Message (Frame)
Application
Application
Client
Station
Switch
Server
Station
Switch
Trunk
Line
Access
Line
Switches move frames
to or closer to the destination station
Switches handle a packet sequentially
Switch
Trunk
Line
Outside
World
Mobile Client
Station
Switch
Router
Mobile Client
Station

28. Figures 1-6 and 1-7: Workgroup and Core Switches
19 inches (48 cm) wide
19 inches (48 cm) wide
Small Switches
(Stacked):
Workgroup Switches
To Link Stations
To Network
Central Core Switch

29. Figure 1-2: Elements of a Network, Continued
Message (Frame)
Application
Application
Client
Station
Switch
Server
Station
Routers connect networks
to the outside world;
Treated just like stations
Switch
Trunk
Line
Access
Line
Switch
Trunk
Line
Outside
World
Mobile Client
Station
Switch
Router
Mobile Client
Station

30. Figure 1-2: Elements of a Network, Continued
Message (Frame)
Application
Application
Access lines
connect stations
to switches
Trunk lines
connect switches
to switches (and routers)
Client
Station
Switch
Server
Station
Switch
Trunk
Line
Access
Line
Switch
Trunk
Line
Outside
World
Trunk
Line
Mobile Client
Station
Switch
Router
Mobile Client
Station

31. Figure 1-2: Elements of a Network (Recap)
Applications (the only element that users care about)
Stations
Clients
Servers
Switches
Routers
Transmission Lines
Trunk lines
Access Lines
Messages (Frames)
Never talk about an
Innovation “reducing cost,” “increasing speed,” etc.
without specifying
which element is cheaper or faster.
For example, multiplexing
only reduces the cost of
trunk lines; other
costs are not decreased

32. Figure 1-3: Multiplexing in a Packet-Switched Network
Trunk line
multiplexes the
messages of
different
conversations AC AC
Client
Station A AC
Server
Station C AC AC BD AC
Trunk Line
This reduces
trunk line
costs through
cost sharing
by users BD
Access
Line BD BD
Router D
Mobile Client
Station B

33. LANs and WANs LANs transmit data within corporate sites
WANs transmit data between corporate sites
Each LAN or WAN is a single network
WAN

34. DAY 2 Agenda Questions? Assignment 1 due next class
8 elements of a network?
Differences between LAN and WAN
Assignment 1 due next class
Opnet Lab 1 next class
Read Home PC Network Lab Manual.pdf loaded in WebCT
Today
Finish Introduction
Some Hands on Computer stuff

35. Figure 1-4: The First Bank of Paradise’s Wide Area Networks (WANs)
North Shore
Operations
OC3 Private Line T3 T3
Bank has multiple
facilities connected
by multiple WANs
Headquarters

36. Figure 1-5: Local Area Network (LAN) in a Large Building
Multi-floor
Office Building
The bank has multiple
LANs—one at each site

37. Figure 1-5: Local Area Network (LAN) in a Large Building, Continued
Wall Jack
Workgroup Switch
Workgroup Switch To
WAN
Core Switch
Router

38. Internets Most firms have multiple LANs and WANs.
They must create internets
An internet is a collection of networks connected by routers so that any application on any host on any single network can communicate with any application on any other host on any other network in the internet.
Application
Application
LAN
WAN
LAN
Router
Router

39. Figure 1-8: Internet with Three Networks
Host A R1
Packet
Network X
A packet goes all the
way across the internet;
It’s path is its route
Network Y
Route A-B
Network Z R2
Host B

40. Figure 1-8: Internet with Three Networks, Continued
Messages in single networks (LANs or WANs) are called frames
Message in internets are called packets
Travel from the source host to the destination host across the entire internet
Within a single network, the packet is encapsulated in (carried in) the network’s frame
Package
(Packet)
Truck
(frame)
Packet
Frame

41. Figure 1-8: Internet with Three Networks, Continued
Frame X
Details in
Network X
Packet
Data Link
A-R1
Switch
Host A
Switch
Server
Host
Switch X1
Mobile Client
Host
Switch X2
Route
A-B
Router R1
Network X

42. Figure 1-8: Internet with Three Networks, Continued
Details in
Network Y To
Network X
Route
A-B
Router R1
Frame Y
Data Link
R1-R2
Packet To
Network Z
Router R2
Network Y

43. Figure 1-8: Internet with Three Networks, Continued
Details in
Network Z
Packet
Data Link
R2-B
Frame Z
Switch Z1
Host B
Switch
Router R2
Switch Z2
Mobile Client
Hosts
Switch
Router
Network Z

44. Figure 1-8: Internet with Three Networks, Continued
In this internet with three networks, in a transmission,
There is one packet
There are three frames (one in each network)
If a packet in an internet must pass through N networks,
How many packets will be sent?
How many frames must carry the packet?

45. Figure 1-8: Internet with Three Networks, Continued
Lower-case internet is any internet
Upper-case Internet is the global Internet

46. NAP = Network Access Point
Figure 1-11: The Internet
Webserver
User PC
The Internet Backbone
(Multiple Carriers)
Access
Line
Access
Line
Router
NAP
NAP
ISP 2
NAP
ISP 4
ISP 1
ISP 3
Internet
Service
Provider
For User PC
Internet Service
Provider
For Webserver
NAP = Network Access Point

47. Figures 1-9 and 1-10: Routers
19 inches (48 cm) wide
19 inches (48 cm) wide
Small Routers
Stacked
For Branch Offices
Large Routers
for Large Sites and ISPs

48. Figure 1-12: The Internet, internets, Intranets, and Extranets
internets versus the Internet
Intranets
Internal internet for use within an organization
Based on the TCP/IP standards created for the Internet
Extranets
Connect multiple firms
Only some computers from each firm are on the extranet
Use TCP/IP standards

49. Recap Switches versus Routers Messages
Switches move frames through single networks (LANs or WANs)
Routers move packets through internets
Messages
Messages in single networks are called frames
Messages in internets are called packets
Packets are encapsulated within frames

50. Figure 1-13: Major Network Technical Concerns
Network Architecture
A broad plan for how the firm will connect all of its computers within buildings (local area networks), between sites (wide area networks), and to the Internet
New systems must fit the rules of the architecture
Undisciplined growth in the past
No overall plan

51. Figure 1-13: Major Network Technical Concerns, Continued
Network Architecture
Legacy networks
Use obsolete technologies that do not fit the long-term architecture
Many exist in the bank
Too expensive to replace quickly; must live with many for awhile

52. Figure 1-13: Major Network Technical Concerns, Continued
Network Architecture
Scalability
The ability of selected technologies to be able to handle growth efficiently
Poor
Scalability
Cost
Per
Bit
Good
Scalability
Demand

53. Figure 1-13: Major Network Technical Concerns, Continued
Standards
Standards govern message interactions between pairs of entities (Figure 1-14)
For example, HTTP request and response messages for WWW access
Webserver
HTTP Request Message
Browser
Client
Program
Webserver
Application
Server
Program
HTTP Response Message
Client PC

54. Figure 1-13: Major Network Technical Concerns, Continued
Standards
Standards create competition
This reduces costs
It also stimulates the development of new features
Protects the business if the main vendors go out of business

55. Figure 1-13: Major Network Technical Concerns, Continued
Standards
Competing standards organizations create incompatible standards
FBP will standardize to save money
LANs: FBP will standardize on Ethernet (some legacy LAN technologies are still in use)
WAN standards: will have fewer but still two to four
Internetworking: will standardize on TCP/IP

56. Figure 1-13: Major Network Technical Concerns, Continued
Security
A Major Problem
Many attacks
Growing trend toward criminal attackers

57. Figure 1-15: Firewalls Allowed Legitimate Packet Border Firewall
Attacker
Hardened
Server
Border firewall
should pass
legitimate packets
Legitimate
Packet
Hardened
Client PC
Legitimate
Host
Log File
Internal
Corporate
Network

58. Figure 1-15: Firewalls, Continued
Border
Firewall
Attack Packet
Attacker
Border firewall
should deny (drop)
and log
attack packets
Hardened
Server
Denied
Attack
Packet
Hardened
Client PC
Legitimate
Host
Log File
Internal
Corporate
Network
Network Management
Console

59. Figure 1-13: Major Network Technical Concerns, Continued
Security
Virtual Private Networks (VPNs) (Figure 1-16)
Provide communication over the Internet with added security
Cryptographic protection for confidentiality (eavesdroppers cannot read)
Cryptographic authentication (confirms sender’s identity)

60. Figure 1-16: Virtual Private Networks (VPNs)
Site-to-Site VPN
Using Gateway
VPN
Gateway
Client
PC 1
VPN
Gateway
Remote Access
VPN Using
Gateway
Corporate
Site B
Internal
Server
Internet
Remote
Client PC 2
Host-to-Host
VPN
Corporate
Site A
Remote Client PC 3

61. Figure 1-13: Major Network Management Concerns, Continued
Wireless Communication
To improve mobility
Drive-by hackers can eavesdrop on internal communication
Drive-by hackers can break into the network bypassing firewalls
Drive-By Hacker

62. Figure 1-13: Major Network Technical Concerns, Continued
Need for Efficiency
User demand is growing rapidly
Budgets are growing slowly if at all
For projects, need burning justification
Still add new services by squeezing maximum payback from each dollar
User Demand
Money/
Demand
Budget
Time

63. Figure 1-13: Major Network Technical Concerns, Continued
QoS
Quality of Service (QoS)
Numerical objectives for performance
Transmission speed in bits per second (bps)
A bit is a single one or zero
NOT bytes per second
Increase by factors of 1000, not 1024
kilobits per second (kbps)—lower-case k
Megabits per second (Mbps)
Gigabits per second (Gbps)
Terabits per second (Tbps)

64. Figure 1-13: Major Network Technical Concerns, Continued
Quality of Service
For Transmission Speed, have 1 to 3 places BEFORE the decimal point.
Example
.5 Mbps is wrong
500 kbps is correct
2,300 Mbps is wrong
2.3 Gbps is correct
473.2 Mbps is correct
New
Not in the Book

65. Figure 1-13: Major Network Technical Concerns, Continued
Quality of Service
Typical transmission speeds in most firms:
LANs: 100 Mbps to each desktop
WANs: most site-to-site links only are 56 kbps to a few megabits per second because long-distance transmission is very expensive and so must be used more sparingly
LANs: 100 Mbps
WANs:
56 kbps
to a few
Mbps

66. Figure 1-13: Major Network Technical Concerns, Continued
Quality of Service
Congestion, Throughput, Latency, and Response Time
Congestion: when there is too much traffic for the network’s capacity
Throughput: The speed users actually see (often much less than rated speed)
Individual throughput is less than total throughput on shared-speed links

67. Figure 1-13: Major Network Technical Concerns, Continued
Quality of Service
Congestion, Throughput, Latency, and Response Time
Latency: delay (usually measured in milliseconds or ms)
Within corporations, latency is typically under 60 ms 90% of the time
On the Internet, typically 30 ms to 150 ms

68. Checking latency
Use Ping
Start -> Run-> cmd
Try ping

69. Checking throughput Use an available bandwidth tester on the Internet

70. Other XP Command line networking tools
Start -> run -> cmd
ipconfig /all /release /renew
Show tcp/ip settings
Tracert
Shows path of packet through Internet
nslookup
Does DNS testing

71. Figure 1-13: Major Network Technical Concerns, Continued
Quality of Service
Congestion, Throughput, Latency, and Response Time
Response Time
The time to get a response after a user issues a command
A quarter second or less is good

72. Figure 1-13: Major Network Technical Concerns, Continued
Availability
Availability is the percentage of time a network can be used
Downtime: when the user cannot use the network
Want 24x7 availability
Telephone network gives % availability
Typical networks reach 98% today

73. Figure 1-13: Major Network Technical Concerns, Continued
Error Rate
Measured as the percentage of messages damaged or lost
Substantial error rates can disrupt applications
Substantial error rates generate more network traffic because of retransmissions

74. 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

75. Figure 1-18: Pat Lee’s Home Network2.
Cable
Modem 1.
Coaxial Cable
to ISP
3. UTP Cord 4.
Access
Router

76. Figure 1-22: Home Network Access Router
About 4 inches (10 cm) Wide
Switch Ports
UTP Cords
Run to Stations
Power
Jack for
External
WAN Port
UTP Cord
Runs to
Cable Modem

77. Figure 1-18: Pat Lee’s Home Network, Continued6.
A1-BD-33-6E-C7-BB
PC in Emily’s Room
5. UTP
Cord
5. UTP
Cord 6.
B2-CD-13-5B-E4-65
PC in Study

78. Figure 1-18: Pat Lee’s Home Network, Continued6.
A1-BD-33-6E-C7-BB
PC in Emily’s Room
7. File
Sharing 6.
B2-CD-13-5B-E4-65
PC in Study

79. Figure 1-18: Pat Lee’s Home Network, Continued6.
A1-BD-33-6E-C7-BB
PC in Emily’s Room
8. Printer
Sharing 6.
B2-CD-13-5B-E4-65
PC in Study

80. Figure 1-19: Network Interface Cards (NICs) (Photo)
PC Card NIC. Installed in PC Card slot in notebook and some PDAs.
Internal NIC. Installed inside systems unit. Plugged into expansion slot on the mother board.

81. Internal NIC
RJ-45
Jack
PCI Connector Pins

82. Computer Mother Board Mother Board PCI Slots for Expansion Boards
(NICs, etc.)
Slot for
Microprocessor
(Pentium 4)
Slots for RAM

83. Mother Board and Expansion Boards
(NIC)
Connector
Expansion
Slots
Mother Board

84. 4-Pair Unshielded Twisted Pair (UTP)
Figure 1-20: Unshielded Twisted Pair (UTP) Cord With RJ-45 Connector (Photo)
4-Pair Unshielded Twisted Pair (UTP)
Industry Standard Pen
8-Pin RJ-45 Connector
UTP Cord

85. Figure 1-21: UTP Cord RJ-45 Connector and Jack
RJ-45 Jack
On a Wall
On a Switch or
On a NIC
UTP Cord
---
About as thick
as a pencil
Rugged and
Flexible
RJ-45
Connector

86. Figure 1-23: Logical Functions of the Access Router
Cable
Modem
Access Router
Router Function
DHCP
Server
Function
NAT
Function
Switch Function

87. Figure 1-24: Ethernet Switch Operation
Switching Table
Port Host
A1-44-D5-1F-AA-4C
B2-CD-13-5B-E4-65
C3-2D-55-3B-A9-4F
D C4-B6-9F
Ethernet Switch
UTP
D C4-B6-9F
UTP
UTP
UTP
Frame To C3…
Frame To C3…
C3-2D-55-3B-A9-4F
A1-44-D5-1F-AA-4C
B2-CD-13-5B-E4-65

88. Figure 1-25: Frames and Packets
A1-BD-33-6E-C7-BB
IP address =
PC in Emily’s Room
Cable
Modem
Packet in
DOCIS
Frame
Internal
Router
Packet in
Ethernet Frame
Access Router
Packet is always
carried (encapsulated)
in a frame
B2-CD-13-5B-E4-65
IP address =
PC in Study

89. Figure 1-26: Dynamic Host Configuration Protocol (DHCP)
A1-BD-33-6E-C7-BB
PC in Emily’s Room
Cable
Modem 1.
IP Address =
The ISP only
Gives each home a
Single IP address
ISP
DHCP
Server
B2-CD-13-5B-E4-65
PC in Study
Access Router
A DHCP Server
provides User PCs with
a temporary IP Address
each time the user
connects to the Internet

90. Figure 1-26: Dynamic Host Configuration Protocol (DHCP), Continued
A1-BD-33-6E-C7-BB
IP address =
PC in Emily’s Room
Cable
Modem 1.
IP Address =
Internal
DHCP
Server
ISP
DHCP
Server
2. IP Address =
Access Router
2. IP Address =
The access router’s
Internal DHCP server
Gives private IP
Addresses to each PC
B2-CD-13-5B-E4-65
IP address =
PC in Study

91. Figure 1-27: Network Address Translation (NAT)
2. Packet from
Cable
Modem
Internal
NAT
Module
Webserver
IP address=
1. Packet from
Access Router
The access router’s NAT
module translates between the
private IP addresses and
the single ISP-given IP address
PC in Study

92. Figure 1-27: Network Address Translation (NAT), Continued3.
Packet to
Cable
Modem
Internal
NAT
Module
Webserver
IP address=
4. Packet to
Access Router
PC in Study

93. Figure 1-28: The Domain Name System (DNS), Continued
DNS Table
Host Name IP Address
… …
Voyager.cba.hawaii.edu
Originating
Host’s DNS
Resolver
DNS Request Message
“The host name is Voyager.cba.hawaii.edu”
DNS Response Message
“The IP address is ”
DNS
Host

94. Other XP Command line networking tools
Start -> run -> cmd
nslookup
Does DNS testing
Try nslookup mail.maine.edu

95. Figure 1-29: Converting Binary IP Addresses to Dotted Decimal Notation
8-Bit Segments
Convert Segments to Decimal
127
171 17 13
Dotted Decimal Notation

96. Figure 1-30: Windows Calculator
1. Open Calculator, which is in
the Program Group Accessories
2. Select View,
Scientific

97. Figure 1-30: Windows Calculator
4. Enter data on keypad
(Limit is 8 bits for Binary)
3. Enter initial
data type here
Dec = Decimal
Bin = Binary

98. Figure 1-30: Windows Calculator
6. Observe answer
Initial zeros are dropped,
so answer is
5. Enter final
data type here,
observe results

99. Topics Covered The First Bank of Paradise Networked Applications
Packet switching and Multiplexing
LANs versus WANs
Within a site versus between sites

100. Elements of a Network Message (Frame) Application Application Client
Station
Switch
Server
Station
Switch
Trunk
Line
Access
Line
Switch
Trunk
Line
Outside
World
Mobile Client
Station
Switch
Router
Mobile Client
Station

101. Topics Covered Internets Categories Routers
Packets carried within frames
Categories
The Internet: ISPs and NATs
Intranets
Extranets
Package
(Packet)
Truck
(frame)

102. Topics Covered Network Architecture The Need Legacy Networks
Scalability
Standards
Need for Efficiency

103. Topics Covered
Security
Firewalls
VPNs
Wireless Communication

104. Topics Covered Quality of Service (QoS)
Numerical objectives that must be met
Speed and throughput
Latency
Response time
Availability
Error rate

105. Topics Covered: Pat Lee’s Home Network2.
Cable
Modem 6.
A1-BD-33-6E-C7-BB
PC in Emily’s Room 1.
Coaxial Cable
to ISP
3. UTP Cord
5. UTP
Cord
7. File
Sharing 4.
Access
Router
5. UTP
Cord 6.
B2-CD-13-5B-E4-65
PC in Study
8. Printer
Sharing

106. Topics Covered: Pat Lee’s Home Network
DHCP
NAT
DNS