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A+ Guide to Managing and
Maintaining Your PC, 7e
Chapter 17
Networking Essentials
Objectives
• Identify the different elements of a network
• Differentiate network classification according to
categories, namely, size and protocol
• Understand different networking technologies
• Differentiate the different medium used in
networking
• Identify essential hardware used in networking
• Understand what is an IP address and how it works
• Understand basic networking protocol
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Networking Definition
• What is a Computer network
– Two or more computers communicating through a
medium whether in a cable or in a wireless manner or
both.
• Three elements of a network
– Source (transmitter)
– Medium (line, circuit or cable)
– Sink (receiver)
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Category of Network according to size
and area
• Categorized by size and physical area covered
–
–
–
–
PAN (Personal Area Network)
LAN (Local Area Network)
MAN (Metropolitan Area Network)
WAN (Wide Area Network)
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Category of Network according to size
and area
WAN
MAN
LAN
PAN
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Category of Network according to size
and area
• Categorized by size and physical area covered
– PAN – devices like PDA, cellphone communicating in
very close range/proximity up to 100 meters.
– LAN – devices interconnected in a limited and closetype area like school laboratory, a building or home.
– MAN – networks that span normally wider geographic
location of up to 30 miles like a city or a metropolitan.
– WAN – networks that span beyond 30 miles a whole
country or country-to-country etc. A good example of
WAN is the Internet.
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Category of Network according to
Topology
• Topology – is the physical and logical layout of the
network that interconnects different nodes (e.g.
computer, network devices).
• Main topologies: Bus, Ring, Star, and Mesh
• Hybrid topologies: star-bus, star-ring
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Bus Topology
• Bus topology
– Consists of cables connecting PCs or file servers
– Visualizes connections as chain links
– Terminator attached to each end of bus cable segment
• Transmitting packet across bus
– Detected by all nodes on segment
– Given time limit to reach destination
• IEEE (Institute of Electrical and Electronics Engineers)
– Develops standards for network cabling, transmission
– Specifies length of bus segment
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Bus Topology (continued)
• Terminator signals end of physical segment
– Functions as resistor that absorbs signal
• Terminator critical on bus networks
– Prevents signal reflection back on to covered path
• Advantages of bus design
– Requires less cable than other topologies
– Easy to extend bus with a workstation
• Disadvantages of bus topology
– High management costs
• Single defective node can take down entire network
– Can become quickly congested with network traffic
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Ring Topology
• Ring topology: continuous data path
– Workstations attached to cable at points around ring
• Transmitting data across ring topology
– Goes around ring to reach destination
– Continues until ends at source node
• Advantages to ring topology
– Easier to manage than bus
– Handles high volume network better than bus
– Suited to transmitting signals over long distances
• Disadvantages to ring topology
– More expensive to implement than bus
– Fewer equipment options than bus
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A+ Guide to Managing and Maintaining Your PC, 7e
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Star Topology
• Star topology: multiple nodes attached to central
device (hub, switch, router)
– Cable segments radiate from center like a star
– Example: workstations connected to switch
• Advantages of star topology
–
–
–
–
Start-up costs comparable to ring topology
Easier to manage, defective nodes quickly isolated
Easier to expand by connecting nodes or networks
Offers better equipment and high-speed options
• Disadvantages of star topology
– Failure of central device may cause network failure
– Requires more cable than bus
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Hands-on Networking Fundamentals
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Mesh Topology
• Mesh topology
– Every node connected to every other node in network
– Provides network with fault tolerance
• Fault tolerance: built-in protection against failure
• If link breaks, nodes can still communicate
– Alternate communication paths increase as number of
nodes increase
• Mesh topology used less on LANs
– Expensive to implement
• Mesh topology often used in MANs and WANs
Hands-on Networking Fundamentals
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Hands-on Networking Fundamentals
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Star-Bus Hybrid Topology
• Star-bus (star-wired) topology
– Each radiating finger is separate logical bus segment
– Each segment terminated at both ends
• Advantages of star-bus topology
– No exposed terminators
– Connect multiple central devices to expand network
– Connection between central devices is a backbone
• Backbone enables high-speed communication
– Central devices have built-in intelligence
– Many equipment and high-speed options available
Hands-on Networking Fundamentals
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Star-Ring Hybrid Topology
• Star-ring (star-wired) topology
– Hub or access unit acts as linking device
– Transmission using logical communication of ring
– No need for built-in terminators
Hands-on Networking Fundamentals
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Activity - Drawing Network Topologies
• Using the blank sheet of paper that will be
provided make a hand-drawn sketch of different
network topologies, namely, Bus, Star, Ring and
Mesh.
• This is worth 20 points
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Networking Technologies
• Bandwidth: data transmission rate or the number of
bits that can be transmitted over a network at one
time (e.g. 56Kbps, 10Mbps, 1Gbps). It is a theoritical
or potential speed of a network.
• Data throughput: actual network transmission speed
• Latency: delays in network transmissions
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Networking Technologies (cont’d.)
• Internet Service Provider (ISP)
– Required for Internet connection
– Upload speed is slower than download speed
• Communicating devices require same protocol
– Protocol is a set of rules that governs interaction and
in a network environment it means the rule that
governs the communication between computers.
– Internet protocol: TCP/IP (group of protocols)
– Data is broken into segments, segment are put into
packets
Figure 17-1 Use an ISP to connect to the Internet
Courtesy: Course Technology/Cengage Learning
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• Networking Technologies – Speed and Common
Uses
Technology
Speed or Speed Range
Common Uses
Dial-up or regular telephone
Up to 56 Kbps
Slow access to ISP using modem and
a telephone line
ADSL (Assymetric DSL)
Up to 640Kbps upstream
and up to 8 Mbps
downstream
Commonly used by ISP today that
are more affordable for their
customers
SDSL (Symmetric DSL)
Up to 2.3 Mbps
Still used by today’s ISP but more
suited for business. Both upstream
and downstream are of the same
speed.
Fiber Optic, Optical Carrier
Level
Up to 50Mbps and Up to
160Gbps respectively
Used as dedicated line for ISP to
business and as an Internet
backbone respectively.
T1, T2 & T3
1.54Mbps, 6Mpbs and
45Mbps respectively
Used for dedicated line for
businesses like banks to ISP
802.11a, 802.11g, 802.11n
Up to 54Mbps, 54Mpbs and
160Mbps respectively
Used for wireless networking
Ethernet, Fast Ethernet,
Gigabit Ethernet
Used in Local Area Network
10Mpbs, 100Mbps and
1Gbps respectively
Table 17-1 Networking technologies
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Broadband Technologies
• Connect to the Internet
– Cable modem, DSL, fiber-optic, satellite, ISDN
(Integrated Services Digital Network)
• Cable modem communication
– Uses existing cable lines
– Always connected (always up)
– TV signals and PC data signals share same coax
cable
– Cable modem converts PC’s digital signals to analog
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Broadband Technologies (cont’d.)
• DSL (Digital Subscriber Line)
– Group of broadband technologies
• Wide range of speeds
– Uses ordinary copper phone lines and unused voice
frequencies
– Always connected
• Some DSL services offer connect on demand
– Asymmetric DSL (ADSL): one upload speed, faster
download speed
– Symmetric DSL (SDSL): equal bandwidths in both
directions
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Broadband Technologies (cont’d.)
• Cable modem and DSL
– Sometimes purchased on a sliding scale
– Cable modem shares TV cable infrastructure with
neighbors
• Service may become degraded
– DSL uses dedicated phone line
• Must filter phone line static
– Similar setup for both
– Installation completed by provider or user
– Both use PC network port or USB port to connect
cable modem or DSL box
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Broadband Technologies (cont’d.)
• Satellite provides high-speed Internet connections in
remote areas
– Available everywhere (airplanes)
– Disadvantage: latency when uploading
Figure 17-5 Communication by satellite can include television and Internet access
Courtesy: Course Technology/Cengage Learning
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Broadband Technologies (cont’d.)
• Fiber optic dedicated point-to-point (PTP)
– No line sharing
– Broadband fiber-optic cable
• Television, Internet data, voice communication
– Verizon technology: Fiber Optic Service (FiOS)
– Cabling endpoints: carrier dependent
– Upstream and downstream speeds and prices vary
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Wireless Technologies
• Use radio waves or infrared light
– Useful in places where cables difficult to install
• 802.11 wireless (Wi-Fi or Wireless Fidelity)
– 802.11g and 802.11b
• 2.4 GHz frequency Range, 100m distance
– 802.11n: Multiple input/multiple output (MIMO)
• 2.4 GHz and 5 GHz range, 600 Mbps speed possible
– 802.11a: no longer widely used
– 802.11k and 802.11r
• Manage connections between wireless devices and
access points
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Wireless Technologies (cont’d.)
• Security methods required
– Encrypt data
• WEP (Wired Equivalent Privacy), WPA (Wi-Fi Protected
Access), WPA2 (Wi-Fi Protected Access 2)
– Disable SSID broadcasting
• SSID: name of the wireless access point
– Filter MAC addresses
• MAC (Media Access Control) address: 6-byte number
uniquely identifying network adapter
• Prevents uninvited guests from using wireless LAN
• Does not prevent others from receiving data in the air
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Activity – Checking ISP Broadband
prices and speed
• Using the blank sheet of paper that will be
provided make a table for the speed and prices
from FSM telecom for the technologies listed
below
– ADSL
– SDSL
– T1,T2,T3 (if any)
• Check out from FSM Telecom website
www.telecom.fm
• This is worth 20 points
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Media used in Networking
• Two types of Medium
– Wireless or Unguided
– Wired or Guided Media
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Different types of Guided Media or Cable
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Table 17-2 Variations of Ethernet and Ethernet cabling
32
Figure 17-17 The most common networking cable for a local network is UTP cable
using an RJ-45 connector. Courtesy: Course Technology/Cengage Learning
Figure 17-18 Coaxial cable and a BNC connector are used with ThinNet Ethernet.
Courtesy: Course Technology/Cengage Learning
Figure 17-19 Fiber-optic cables contain a glass core for transmitting light.
Courtesy: Course Technology/Cengage Learning
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Most Common Cable for LAN
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Table 17-2 Variations of Ethernet and Ethernet cabling
34
Connector Used for Twisted Pair
RJ-45 Connector
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Unshielded Twisted Pair
• Unshielded Twisted-Pair Cable (UTP)
– Consists of wire pairs within insulated outer covering
– Has no shielding between wires and encasement
• UTP is most frequently used network cable
• Reducing EMI (Electro Magnetic Interference) and
RFI (Radio Frequency Interference)
– Twist interior strands (like STP)
– Build media filter into network equipment, workstation,
and file connection servers
A+ Guide to Managing and Maintaining Your PC, 7e
Table 17-2 Variations of Ethernet and Ethernet cabling
36
UTP Cable Types/Category
• UTP cables used in 10BaseT networks
–
–
–
–
Category 3: transmission rates up to 16 Mbps
Category 4: transmission rates up to 20 Mbps
Category 5 UTP has 100 Mbps transmission rate
Category 5e (enhanced) UTP vs. Category 5 UTP
• 1 Gbps transmission rate
• Uses better-quality copper
• Has higher twist ratio for better EMI/RFI protection
– Category 6 UTP
• Wire pairs wrapped within insulating foil
• Has fire resistant plastic sheath
• 1 Gbps transmission rate
A+ Guide to Managing and Maintaining Your PC, 7e
Table 17-2 Variations of Ethernet and Ethernet cabling
37
Standard in Twisted Pair Cabling
• Recommended by EIA/TIA
– EIA/TIA 586A and EIA/TIA 586B
– Either of the standards above could be used
– Use Color Coding for Correct Wiring combination
A+ Guide to Managing and Maintaining Your PC, 7e
Table 17-2 Variations of Ethernet and Ethernet cabling
38
Standard in Twisted Pair Cabling (cont’d)
A+ Guide to Managing and Maintaining Your PC, 7e
Table 17-2 Variations of Ethernet and Ethernet cabling
39
Types of Twisted Pair connections
• Straight connection
– When two different type of nodes are connected. For
example a desktop PC to a hub or a switch.
• Cross-over connection
– When two the same type of nodes are connected. For
example a desktop PC is to connected to another
desktop PC.
A+ Guide to Managing and Maintaining Your PC, 7e
Table 17-2 Variations of Ethernet and Ethernet cabling
40
Two Basic Networking Setup
• Peer-to-Peer
– Two (or more) computers communicating each other
in which either computer could act as a Server or a
Client.
• Client and Server
– One computer act as a Server or the computer who is
solely responsible for distributing resources (like
Database, Web connection) among the network and
the rest act as a client or the who request resources
from the Server.
A+ Guide to Managing and Maintaining Your PC, 7e
Table 17-2 Variations of Ethernet and Ethernet cabling
41
Hardware Used by Local Networks
• Hardware devices creating and connecting to
networks
–
–
–
–
–
–
Desktop and laptop devices
Cables and their connectors
Hubs
Switches
Wireless access devices
Routers
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Networking Adapters and Ports
• Ethernet network adapters and ports
– Network adapter: direct connection to a network
• Takes the form of a network interface card (NIC)
• External devices connect using USB port
• Provides RJ-45 port
– Network cards provide status light indicators
• Useful in troubleshooting
– MAC (Media Access Control) address
• Unique 48-bit (6-byte) number hard-coded on card by
manufacturer
• Identifies adapter on the network
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Networking Adapters and Ports
(cont’d.)
• WI-FI wireless adapters
– 802.11b/g/n connections use a variety of devices
– Laptops sold today have antenna embedded inside
Figure 17-16 Four different types of wireless
network adapters: (a) wireless NIC that fits in a
PCI slot; (b) onboard wireless with an antenna
that can be moved; (c) PC Card wireless NIC
with embedded antenna; and (d) wireless NIC
that uses a USB port on a desktop or notebook
computer. Courtesy: Course
Technology/Cengage Learning
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Cables and Connectors
• Types of Ethernet cabling:
– Twisted-pair
• Unshielded (UTP) and shielded twisted pair (STP)
• Coaxial cable: single copper wire with braided shield
– Fiber-optic: glass strands inside protective tubing
• Ethernet types (categorized by speed):
–
–
–
–
10-Mbps Ethernet
100-Mbps or Fast Ethernet
1000-Mbps or Gigabit Ethernet
10-Gigabit Ethernet
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Hubs and Switches
• Star topology: nodes connected to a centralized hub
or switch
• Hub: pass-through device
– No regard for data
• Switch: keeps a table of all devices connected to it
– Determines path when sending packets
• Network cables
– Patch cable (straight-through cable): connects
computer to hub or switch
– Crossover cable: connects two like devices
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Hubs and Switches (cont’d.)
• Some switches have uplink port for patch cable use
• Some switches use auto-uplinking
Figure 17-24 An Ethernet network with three switches
Courtesy: Course Technology/Cengage Learning
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Wireless Access Points
• Allows wireless device connection to LAN
– Devices communicate through access point
– May double as a router
Figure 17-26 Nodes on a
wireless LAN connect to a
wired network by way of an
access point. Courtesy:
Course
Technology/Cengage
Learning
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Routers
Figure 17-27 A router stands between a local network and the Internet and
manages traffic between them. Courtesy: Course Technology/Cengage Learning
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Routers (cont’d.)
• DHCP (dynamic host configuration protocol) server
– Provides IP addresses to network computers
– Dynamic IP addressing
• No need to assign, keep up with unique IP addresses
• Router functions
–
–
–
–
–
Router
Switch
DHCP server
Wireless access point
Firewall with or without NAT redirection
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Windows on a Network
• Client/server applications
– Two computers and two applications involved
– Communication occurs three levels
• Hardware, operating system, application
• Dependent on one computer addressing the other
Figure 17-31 A Web browser (client software) requests a Web page from a Web
server (server software); the Web server returns the requested data to the client
Courtesy: Course Technology/Cengage Learning
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Layers of Network Communication
• Level 1: Hardware level
– Root level of communication
• Wireless or network cables
• Phone lines or TV cable lines
– Includes the network adapter and MAC address
– Communication protocols used
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Figure 17-32 Network communication happens in layers
Courtesy: Course Technology/Cengage Learning
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Layers of Network Communication
(cont’d.)
• Level 2: Operating system level
– Manages communication between itself and another
computer using TCP/IP
– Uses IP addressing
Figure 17-33 Computers on the same LAN use MAC addresses to communicate,
but computers on different LANs use IP addresses to communicate over the Internet
Courtesy: Course Technology/Cengage Learning
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Layers of Network Communication
(cont’d.)
• Level 3: Application level
– Client communicates with another Internet application
– Port number
• Uniquely identifies computer application
– Socket
• IP address followed by a colon and port number
• E-mail example: 36.60.30.5:25
• Web server example: 136.60.30.5:80
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Table 17-3 Common TCP/IP port assignments for client/server applications
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Understanding IP Addresses and How
They Are Used (cont’d.)
• IP address identifies network and host
– Classes are based on the number of possible IP
addresses in each network within each class
Table 17-4 Classes of IP addresses
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Understanding IP Addresses and How
They Are Used (cont’d.)
• Class D addresses: octets 224 through 239
– Multicasting
• Class E addresses: octets 240 through 254
– Research
Figure 17-36 The network portion and host portion for each class of IP addresses
Courtesy: Course Technology/Cengage Learning
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Understanding IP Addresses and How
They Are Used
• IP address: 32 bits long, made up of 4 bytes, each 8
bits long
– Four decimal numbers separated by periods
• 190.180.40.120
– Largest possible 8-bit number
• 11111111 (255 decimal)
– Largest possible decimal IP address
• 255.255.255.255
• 11111111.11111111.11111111.11111111 binary
– Octet: each of the four decimal numbers
• 0 to 255, 4.3 billion potential IP addresses
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Understanding IP Addresses and How
They Are Used
• Converting a Decimal IP address to Binary:
– Example
• 192.168.5.1
– Use the 8 bits Octet per decimal number
• 11111111 (255 decimal)
– Use the Number system in Binary:
• 27
26
• 128 64
25
32
24
16
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8
22
4
21
2
20
1
60
Converting IP address to binary
• For example in the IP Address 192.168.5.1 we want
to convert first the 1st Octet which is 192
– Simply Go to the nearest number below and subtract:
• 27
26
25
24
23
22
21
20
• 128 64
32
16
8
4
2
1
– From above the nearest number for 192 is 128 so we have 192128=64
– So, we put 1 under that
– 128
64
32
16
8
4
2
1
– 1
– And then the nearest number of 64 is simply 64. So we put 1
under 64 also.
– 128
64
32
16
8
4
2
1
– 1
1
– And since 64-64 =0 then we put 0 on the rest
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Converting IP address to binary
• So we have finally:
– 128
64
32
16
8
4
– 1
1
0
0
0
0
– Hence the Binary format for 192 is 11000000
2
0
1
0
• How about the 168 in the 2nd Octet.
• How about the 5 in the 3rd Octet and the 1 in the 4th Octet.
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Checking IP Address
• To check in your own IP Address go to StartRun
then type cmd and press enter.
• On DOS Command prompt type ipconfig then press enter.
• To check the different IP Addresses on a certain
domain name, say www.facebook.com
• Type tracert www.facebook.com
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Activity on IP Addressing
• Convert the IP address on your PC to a binary
format.
• Using Tracert command trace the following domain:
– Set A : www.facebook.com
– Set B : www.twitter.com
• On each given IP address identify what Class each
IP address it belongs to.
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Understanding IP Addresses and How
They Are Used (cont’d.)
• Subnet masks
– Group of ones followed by a group of zeros
– Classful subnet masks: all ones, all zeros in an octet
– Classless subnet mask: mix of zeros and ones
Table 17-5 Default subnet masks for classes of IP addresses
– Take note that the one in 1s is the Network Portion
and the one in 0s is the Host portion.
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Understanding IP Addresses and How
They Are Used (cont’d.)
• Classless subnet masks
– Uses Default Subnet Mask for Class A to C
Class
Default
subnet Mask
No. of
possible
Networks
No. of
possible
Hosts
A
255.0.0.0
127
16Millions
B
255.255.0.0
16,000
65,000
C
255.255.255.0 2 Million
254
Table 17-5 Default subnet masks for classes of IP addresses
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Understanding IP Addresses and How
They Are Used (cont’d.)
• Public IP addresses: available to the Internet
• Private IP addresses: used on private intranets
– Use router with NAT redirection for Internet access
– IEEE recommendations
• 10.0.0.0 through 10.255.255.255
• 172.16.0.0 through 172.31.255.255
• 192.168.0.0 through 192.168.255.255
Table 17-6 Reserved IP addresses
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Subnetting
• Separates network
– Multiple logically defined segments (subnets)
• Geographic locations, departmental boundaries,
technology types
• Subnet traffic separated from other subnet traffic
• Reasons to separate traffic
– Enhance security
– Improve performance
– Simplify troubleshooting
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Classful Addressing in IPv4
Figure 4-8 IP addresses and their classes
• First, simplest IPv4 addressing type
• Adheres to network class distinctions
• Recognizes Class A, B, C addresses
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Classful Addressing in IPv4 (cont’d.)
• Network information (network ID)
– First 8 bits in Class A address
– First 16 bits in Class B address
– First 24 bits in a Class C address
• Host information
– Last 24 bits in Class A address
– Last 16 bits in Class B address
– Last 8 bits in Class C address
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Classful Addressing in IPv4 (cont’d.)
Figure 10-1 Example IPv4 addresses with classful addressing
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Classful Addressing in IPv4 (cont’d.)
• Drawbacks
– Fixed network ID size limits number of network hosts
– Difficult to separate traffic from various parts of a
network
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IPv4 Subnet Masks
• Identifies how network subdivided
• Indicates where network information located
• Subnet mask bits
– 1: corresponding IPv4 address bits contain network
information
– 0: corresponding IPv4 address bits contain host
information
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IPv4 Subnet Masks (cont’d.)
Table 10-1 Default IPv4 subnet masks
• Network class
– Associated with default subnet mask
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IPv4 Subnet Masks (cont’d.)
Table 10-2 ANDing
• ANDing
– Combining bits
• Bit value of 1 plus another bit value of 1 results in 1
• Bit value of 0 plus any other bit results in 0
– ANDing logic
• 1: “true”, 0: “false
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IPv4 Subnet Masks (cont’d.)
Figure 10-2 Example of calculating a host’s network ID
• ANDing example
– Address’s fourth octet
• Any combination of 1s and 0s
• Results in network ID fourth octet of 0s
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Reserved Addresses
• Cannot be assigned to node network interface; used
as subnet masks
• Network ID
– Bits available for host information set to 0
– Classful IPv4 addressing network ID ends with 0 octet
– Subnetting allows network ID with other decimal
values in last octet(s)
• Broadcast address
– Octet(s) representing host information equal all 1s
– Decimal notation: 255
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IPv4 Subnetting Techniques
• Subnetting breaks classful IPv4 addressing rules
– IP address bits representing host information change
to represent network information
• Reduce usable host addresses per subnet
• Hosts, subnets available after subnetting related to host
information bits borrowed
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IPv4 Subnetting Techniques (cont’d.)
Table 10-3 IPv4 Class B subnet masks
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IPv4 Subnetting Techniques (cont’d.)
Table 10-4 IPv4 Class C subnet masks
• Class C network
– Fewer subnets than Class B
– Less hosts per subnet than Class B
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Calculating IPv4 Subnets
• Formula: 2n −2=Y
– n: number of subnet mask bits needed to switch
• From 0 to 1
– Y: number of resulting subnets
• Example
– Class C network
• Network ID: 199.34.89.0
• Want to divide into six subnets
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Calculating IPv4 Subnets (cont’d.)
Table 10-5 Subnet information for six subnets in an example IPv4
Class C network
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Calculating IPv4 Subnets (cont’d.)
• Class A, Class B, and Class C networks
– Can be subnetted
• Each class has different number of host information bits
usable for subnet information
• Varies depending on network class and the way
subnetting is used
• LAN subnetting
– LAN’s devices interpret device subnetting information
– External routers
• Need network portion of device IP address
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Figure 10-3 A router connecting several subnets
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Activity on Classless IP addressing
• Imagine you are the Network administrator in an
organization and you have 2 Departments and each
department has a maximum of 60 computers what
would be the range of IP addresses that could be used
for each subnetwork and what would be its
corresponding subnet mask?
• Refer to slide 80-84 as reference for your format for
your answer.
85
CIDR (Classless Interdomain Routing)
• Also called classless routing or supernetting
• Not exclusive of subnetting
– Provides additional ways of arranging network and
host information in an IP address
– Conventional network class distinctions do not exist
• Example: subdividing Class C network into six
subnets of 30 addressable hosts each
• Supernet
– Subnet created by moving subnet boundary left
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CIDR (cont’d.)
Figure 10-4 Subnet mask and supernet mask
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CIDR (cont’d.)
Figure 10-5 Calculating a host’s network ID on a supernetted network
• Example: class C range of IPv4 addresses sharing
network ID 199.34.89.0
– Need to greatly increase number of default host
addresses
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CIDR (cont’d.)
• CIDR notation (or slash notation)
– Shorthand denoting subnet boundary position
– Form
• Network ID followed by forward slash ( / ), followed by
number of bits used for extended network prefix
– CIDR block
• Forward slash, plus number of bits used for extended
network prefix
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Slash Notation in CIDR
Class C
CIDR Block
/14
/15
/16
/17
/18
/19
/20
/21
/22
/23
/24
/25
/26
/27
/28
/29
Binary Supernet Mask
11111111.11111100.00000000.00000000
11111111.11111110.00000000.00000000
11111111.11111111.00000000.00000000
11111111.11111111.10000000.00000000
11111111.11111111.11000000.00000000
11111111.11111111.11100000.00000000
11111111.11111111.11110000.00000000
11111111.11111111.11111000.00000000
11111111.11111111.11111100.00000000
11111111.11111111.11111110.00000000
11111111.11111111.11111111.00000000
11111111.11111111.11111111.10000000
11111111.11111111.11111111.11000000
11111111.11111111.11111111.11100000
11111111.11111111.11111111.11110000
11111111.11111111.11111111.11111000
11111111.11111111.11111111.11111100
Supernet Mask
Number of Class C
Networks
Number of Hosts
255.252.0.0
1024
262144
255.254.0.0
512
131072
255.255.0.0
256
65536
255.255.128.0
128
32768
255.255.192.0
64
16384
255.255.224.0
32
8192
255.255.240.0
16
4096
255.255.248.0
8
2048
255.255.252.0
4
1024
255.255.254.0
2
512
255.255.255.0
1
254
255.255.255.128
1/2
126
255.255.255.192
1/4
62
255.255.255.224
1/8
32
255.255.255.240
1/16
16
255.255.255.248
1/32
8
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Understanding IP Addresses and How
They Are Used (cont’d.)
• Dynamic IP address
– Assigned for current connection only (lease)
– Managed by DHCP server
• DHCP client: workstations working with DHCP server
• DHCP software resides client and server
• Configuring a DHCP server
– IP address ranges available for clients
• Automatic Private IP Address (APIPA) service
– Used if attempt fails
• Address range 169.254.x.y
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Summary
• A network is a system interconnecting two or more
PCs
– Basic network types
• PAN, LAN, Wireless LAN, MAN, or WAN
• There are many broadband technologies
– Cable and DSL popular
• Major issue for wireless networks is security
• Types of hardware
– Adapters, routers, hubs, switches
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Summary (cont’d.)
• Three layers of communication
– Hardware, operating system, application
• An IP address is a 32-bit address identifying network
node
• TCP/IP protocol suite uses protocols at the
application level
• Connecting to a wired network
• Connecting to a wireless networks
– Public, unsecured hotspots or private, secured
hotspots
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