Computer Networks -Introduction · Computer Networks -Introduction Wednesday, March 5,2014 Computer...
Transcript of Computer Networks -Introduction · Computer Networks -Introduction Wednesday, March 5,2014 Computer...
Computer Networks
-Introduction
Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 1
In this Intro:
About the Instructor.
Course Contents.
Computer Networks
-Introduction
Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 2
About the Instructor:
As an Instructor.
As an Employee.
As IT Consultant.
Computer Networks
-Introduction
Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 3
As an Instructor:
More the 7 years instruction: in ComputerHardware,
Networking Administration and Software Engineering.
Teaching in Institutes and Universities: International
Horn University(2010-2011), SITCO(2005-2009),
SIDAM.
Computer Networks
-Introduction
Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 4
As an Employee:
Currently as Network Security Administrator
About 8 years, I dealt with IT infrastructure such as Computers, Servers, Networking Devices, Switches, Routers, Firewalls….etc
I also administer, Configure, Secure and Install Windows Server/Client Network Controllers know as Domain Networks.
Train IT Officers in Regional Offices when we enforce or upgrade Network Systems….
Computer Networks
-Introduction
Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 5
As an IT Consultant:
I have my Own Consulting Company Since 2012
Its for IT Services which Include:
Cabling(Electricity/Telephones/Network),
PBX systems, VSATs,
Servers Deployment, Domain Network Setup,
Poin-to-Point and Multipoint Networks,
Security and Much more….
Computer Networks
-Week1
Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 6
General Uses of Networks:
Work:
– Email, file sharing, printing, …
Home:
– Movies / songs, news, calls / video, messaging, e-commerce,
Mobile:
– Calls / texts, games, videos, maps, information access …
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Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 7
Uses of Networks
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Instructor: Ahmed Hussein Farah 8
For User Communication
From the telephone onwards:
– VoIP (voice-over-IP)
– Video conferencing
– Instant messaging
– Social networking
Computer Networks
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Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 9
For Resource Sharing
Many users may access the same underlying resource
– E.g., printers, search index, machines in the cloud
More cost effective than dedicated resources per user
– Even network links are shared via statistical multiplexing
Computer Networks
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Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 10
For Statistical Multiplexing
Sharing of network bandwidth between users according to
the statistics of their demand:
– (Multiplexing just means sharing)
– Useful because users are mostly idle and their traffic is busty.
Computer Networks
-Week1
Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 11
For Content Delivery
Same content is delivered to many users
– Videos (large), songs, apps and upgrades, web pages, …
More efficient than sending a copy all the way to each user
– Uses replicas in the network.
Computer Networks
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Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 12
For Computer Communication
To let computers interact with other computers
– E.g., e-commerce, reservations…
Enables automated information processing across different
parties
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Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 13
To Connect Computers to the Physical World:
For gathering sensor data, and for manipulating the world
– E.g., webcams, location on mobile phones, door locks, …
This is a rich, emerging usage
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Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 14
The Value of Connectivity
“Metcalfe’s Law” ~1980:
– “The value of a network of N nodes is proportional to N2”
– Large networks are relatively more valuable than small ones.
Bob Metcalfe
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Instructor: Ahmed Hussein Farah 15
Networks by Type:
WiFi (802.11)
Enterprise / Ethernet
ISP (Internet Service Provider)
Cable / DSL
Mobile phone / cellular (2G, 3G, 4G)
Bluetooth
Telephone
Satellite ...
Computer Networks
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Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 16
Networks by Scale:
Scale Type Example
Vicinity PAN (Personal Area Network) Bluetooth (e.g.,
headset)
Building LAN (Local Area Network) WiFi, Ethernet
City MAN (Metropolitan Area Network) Cable, DSL
Country WAN (Wide Area Network) Large ISP
Planet The Internet (network of all
networks)
The Internet!
Computer Networks
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Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 17
Internetworks and the Internet:
An internetwork, or internet, is what you get when you join
networks together.
– Just another network
The Internet (capital “I”) is the internet we all use
Computer Networks
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Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 18
Understanding Local Area Networks(LANs)
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Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 19
Local Area Network
a “network” is two or more computers that exchange data.
A local area network (LAN) is a group of these computers that are
confined to a small geographic area, usually one building. Setting
up a LAN requires computers with network adapters, central
connecting devices to connect those computers together, and
a numbering scheme (such as IP addresses) to differentiate
from one computer to the next.
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Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 20
Networks are used to exchange data. But Important reasons that organizations need networks? These reasons can be divided into four categories:
Sharing: Networks permit the sharing of files, databases, and media.
Communication: Networks are critical for email, instant messaging, and faxing capabilities.
Organization: Networks centralize data and make it more accessible, which increases the efficiency and speed with which this information can be accessed.
Money: A network should ultimately save a company money, often by aiding in the budgeting process and/or increasing productivity.
Computer Networks
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Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 21
Basic LAN documentation
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Instructor: Ahmed Hussein Farah 22
In the Figure, several hosts connect to the hub, including the following:
A server: A server is used to centralize data and share it (or serve it) with other computers on the network.
A PC (personal computer): A PC usually acts as a client on the network, most likely getting its information from the server. A PC can also store information locally.
A Mac (Macintosh) computer: As another type of client computer, a Mac can store information locally or get it from the server.
A laptop: This could be a PC or a Mac. Despite its portability, a laptop stores and accesses data the same way the other network computers do.
Computer Networks
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Sunday, March 16, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 23
In this Week:
1. Network Card and Data Transfer
2. Networking Devices, UTP Cable, and Topologies.
3. LAN Architecture: (a) Peer-to-Peer, (b) Client Server,
( c) Distributed Computing and (d) Centralized
Computing.
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Network components and Terminology
Data
Node
Client
Server
Peer
Network adapter
Hub
Switch
Router
Media
Transport Protocol
Bandwidth
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1. Network Card and Data Transfer
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Instructor: Ahmed Hussein Farah 26
Computer Networks
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A network card: A network
adapter, also known as a
network interface card or
NIC,
NIC: is the device that
enables you to send and
receive data to and from
your computer.
NIC can be Wired or
Wireless.
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Instructor: Ahmed Hussein Farah 28
The network adapter might be integrated into the
motherboard or act as a separate device that connects to a
PCI slot, or perhaps a PC card slot or USB port.
An adapter can connect to the network by cable (wired) or
by air (wireless).
Network adapters also have a software component known as
a driver, which defines how the card will interact with the
operating system;
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Instructor: Ahmed Hussein Farah 29
View a Network Adapter
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Wireless Access Point
The wireless access point (WAP) acts as the central connecting device for the network
Wireless networks can consist of many types of devices other than traditional PCs:
Smart phones
PDAs
Tablet computers
Micro computers
PCs and laptops equipped with wireless network adapters can connect to these networks as well
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Instructor: Ahmed Hussein Farah 32
Wireless LAN Diagram:
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Instructor: Ahmed Hussein Farah 33
Wired LAN Documentation:
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Sunday, March 16, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 34
Demos:
Device Manager Showing Network Adapters
Network Adapter Properties
IP Address
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Sunday, March 16, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 35
Check the Driver, MAC(Physical) and IP your NIC.
1. Checking the Driver, Steps: Rclick Computer -> manage-
> device manager ->network adapters.
2. Check the MAC and IP address of your XP Computer,
Steps: start -> run-> cmd -> type: ipconfig /all -> enter.
3. Check the MAC and IP address of your Window7 PC,
Steps: start -> run-> cmd -> ipconfig /all -> enter.
4. Write down the MAC and IP of your PC.
Computer Networks
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Sunday, March 16, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 36
Serial Data Transfer
Serial data transfer is the transfer of one bit at a time—in
other words, transfer in a single-bit stream, like a one lane
highway
On the network cable, data travels in a single bit stream
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Sunday, March 16, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 37
Data Transfer Rate
Data transfer rate is the maximum bits per second (bps) that
can be transmitted over a network
Rated in bits, and signified with a lowercase b (for example,
10 Mbps)
The lowercase b is for bits and an upper case B stands for
bytes (for example 10 MB)
Types of Transfers
Broadcast sends data to every other host on the network
Unicast sends data to a specific host
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Sunday, March 16, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 38
IP Address
Most every computer and many other devices have an Internet Protocol (IP) address
An IP address uniquely identifies your device and the associated network and allows each device to send and receive information
A typical example of an IPv4 address would be 192.168.1.1
Every IP address is broken down into two parts by a subnet address
Network ID 192.168.1
Host ID 1
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Sunday, March 16, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 39
Subnet Mask
The subnet mask is a group of four numbers that define what
IP network the computer is a member of.
All of the 255s in a subnet mask collectively refer to the
network portion, whereas the 0s refer to the host portion.
Type of
Address
First Octet Second Octet Third Octet Fourth Octet
IP Address 192 168 1 1
Subnet Mask 255 255 255 0
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Sunday, March 16, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 40
Host
IP addresses are usually applied to your network adapter, but
they can also be applied to other devices like switches,
routers, and so on
The fact that a device or computer has an IP address is what
makes it a host
Computer Networks
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Sunday, March 16, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 41
LAN: Computers and other devices are connected using
copper-based twisted-pair cables or wireless equipment.
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Instructor: Ahmed Hussein Farah 42
Network Topology
A network topology defines the physical connections of hosts
in a computer network.
There are several types of physical topologies including:
Bus
Ring
Star
Mesh
Tree
Computer Networks
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Sunday, March 16, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 43
Star
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Instructor: Ahmed Hussein Farah 44
Mesh
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Instructor: Ahmed Hussein Farah 45
Ring
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Instructor: Ahmed Hussein Farah 46
Star Topology
Most Common topology
Each computer is
individually wired to a
central connecting device
(hub, switch or SOHO
router) with twisted-pair
cabling
Computer Networks
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Instructor: Ahmed Hussein Farah 47
Mesh Topology
Every computer connects to every other computer; no
central connecting device is needed.
Computer Networks
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Sunday, March 16, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 48
Ring Topology
In a LAN environment,
each computer is
connected to the network
using a closed loop
Used by Token Ring and
Fiber Distributed Data
Interface (FDDI)
Computer Networks
-Week2
Sunday, March 16, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 49
Token Ring
A Token Ring network sends data logically in a ring fashion,
meaning that a token goes to each computer, one at a time,
and continues on in cycles
Namely, all computers in a Token Ring network are
connected to a central connecting device known as a
Multistation Access Unit (MAU or MSAU)
Computer Networks
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Sunday, March 16, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 50
Ethernet
Institute of Electrical and Electronics Engineers (IEEE)
standard (802.3) that defines how information is sent and
received between network adapters, hubs, switches, and
other devices
Ethernet is the de facto standard and is the most widely-
installed local area network technology
Common types of Ethernet include:
802.3u or Fast Ethernet that runs at 100 Mbps
802.3ab or Gigabit Ethernet
Computer Networks
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Sunday, March 16, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 51
Frames
Computers on Ethernet networks communicate via frames
A frame is a sequence of bits containing a detectable
beginning and end of a packet in the stream of bits
A frame is a data packet residing on Layer 2 of the OSI model
Computer Networks
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Sunday, March 16, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 52
Twisted Pair Cable
Computer Networks
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Sunday, March 16, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 53
Twisted-Pair Cable
the most commonly used cable type in local area
networks
relatively easy to work with, flexible, efficient, and fast
contains eight wires grouped into four twisted pairs,
typically blue, orange, green, and brown
The twisted wires reduce crosstalk and interference
Computer Networks
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Sunday, March 16, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 54
Twisted-Pair Cable with the Wires Exposed
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Instructor: Ahmed Hussein Farah 55
568B, 568A, and BOGB standards
Computer Networks
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Instructor: Ahmed Hussein Farah 56
Twisted Pair Categories
Twisted-pair cables are categorized according to the
frequency at which they transmit signals and their data
transfer rate
Cable Type Speed
Category 3 (Cat-3) 10 Mbps
Category 5 (Cat-5) 100 Mbps
Category 5e (Cat-5e) 100 Mbps and 1000 Mbps+
Category 6 (Cat-6) 1000 Mbps+
Computer Networks
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Sunday, March 16, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 57
Tools For Twisted Pair Cables
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Sunday, March 16, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 58
Twisted-Pair Patch Cable
Computer Networks
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Sunday, March 16, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 59
Types of Patch Cables
Straight through cable Most common type of patch cable
Used to connect a computer to a central connecting device like a switch
Crossover cable Used to direct connect similar devices without the use of a hub
Computer Networks
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Sunday, March 16, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 60
Patch Panel and RJ45 Wall Jack
Computer Networks
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Sunday, March 16, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 61
Network Documentation
Network documentation helps describe, define, and explain
the physical and logical method for connecting devices
The documentation phase occurs before a network is built,
or when changes are made to the network
Microsoft Visio is a tool that can be used to document
networks
Computer Networks
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Sunday, March 16, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 62
Hub
A Hub is the most basic
central connecting device
Hubs enable computers on
a network to communicate
A host sends data to the
hub. The hub sends the data
to all devices connected to
the hub
•
•
Computer Networks
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Sunday, March 16, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 63
Switch
Switches work the same
was as a hub, but they can
identify the intended
recipient of the data
Switches can send and
receive data at the same
time
•
•
Computer Networks
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Sunday, March 16, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 64
Router
Routers enable computers to communicate and allow communication between two networks – such as your home network and the Internet
This communications link between the one network and the other is where the LAN ends
192.168.1.1
Internet
24.136.72.110
Computer Networks
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Sunday, March 16, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 65
3. LAN Architectures
Computer Networks
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Sunday, March 16, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 66
Peer-to-Peer Networking
Peer-to-peer networking distributes applications or
workloads between computers
Peers are both service providers and service requestors
Computer Networks
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Sunday, March 16, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 67
Client/Server Networking
The client/server model is an architecture that distributes
applications between servers and client computers
Server: System that provides services such as Windows
Server 2008 R2
Client: Device that requests services such as Windows 7
Computer Networks
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Sunday, March 16, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 68
Distributed Computing
Distributive computing includes both client-server and peer-
to-peer networks
Every device or workstation has its own processing power
Computer Networks
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Sunday, March 16, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 69
Centralized Computing
Computing is done at a central location using terminals that
are attached to this main system
Mainframes are a powerful computer and the rest of the
devices connected to the computer are known as terminals
(or dumb terminals)
Each terminal consisted solely of a keyboard and display with
no processing power
Computer Networks
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Sunday, March 16, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 70
Servers
More powerful computers that provide centralized services:
File
Database
Network controller
Messaging/Email
Web
Computer Networks
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Sunday, March 16, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 71
Client and Server Operating Systems
Client Operating Systems Server Operating Systems
Windows 8 Windows Server 2012
Windows 7 Windows Server 2008 R2
Windows Server 2008
Windows Vista
Windows XP
Windows Server 2003
Windows 2000 Professional Windows 2000 Server
Windows NT 4.0 Workstation
Windows ME/98/95
Windows NT 4.0 Server
Computer Networks
-Week2
Sunday, March 16, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 72
Summary of What We Covered in Week2:
Understand local area networks (LANs), including but not
limited to LAN elements, design, IP addressing, and LAN
types
Understand network topologies , including topologies such
as star, mesh, and ring; Ethernet architecture; and the client-
server and peer-to-peer networking models
Computer Networks
-Week2
Sunday, March 16, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 73
In Week3 (Next Class) We Will:
Cover All Important Concepts in Week1 and Week2.
Explain What you Should know and Remember in Past 2
weeks.
DON’T MISS.
Computer Networks
-Week3
Sunday, March 23, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 74
In Week3 We Will:
Cover All Important Concepts in Week1 and Week2.
Explain What you Should know and Remember in Past 2
weeks.
Makin LAN Connections(UTP Cable).
Computer Networks
-Week3
Sunday, March 23, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 75
In Week1:
Give 3 Examples for the general use of Networks in each of
the following:
1. Home.
2. Work.
3. Mobile (on the go)
Computer Networks
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Sunday, March 23, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 76
Examples are:
Work:
– Email, file sharing, printing, …
Home:
– Movies / songs, news, calls / video, messaging, e-commerce,
Mobile:
– Calls / texts, games, videos, maps, information access …
Computer Networks
-Week3
Sunday, March 23, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 77
Categorize the following uses of Networks as user
communication and Resource Sharing:
VoIP (voice-over-IP) , Sharing Printers, Video conferencing
Sharing Machines in the cloud, Instant messaging, Content
Delivery. Social networking, Statistical Multiplexing. ….
Computer Networks
-Week3
Sunday, March 23, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 78
List 5 Different Types of Networks we use our daily
life
Computer Networks
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Sunday, March 23, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 79
List 5 of these networks…
WiFi (802.11)
Enterprise / Ethernet
ISP (Internet Service Provider)
Mobile phone / cellular (2G, 3G, 4G)
Bluetooth
Telephone
Satellite ...
Computer Networks
-Week3
Sunday, March 23, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 80
List 4 Type of Networks by Scale with examples:
Computer Networks
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Sunday, March 23, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 81
Define LAN, what are the reasons for building Local Area
Networks?
Computer Networks
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Sunday, March 23, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 82
Reasons include:
Sharing Resources:
Example:……………………..
Communication:
Examples:………………..
Organization and User Management:
Examples:
Computer Networks
-Week3
Sunday, March 23, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 83
Define each of the Following:
Server.
PC.
Mac.
Terminal
Computer Networks
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Sunday, March 23, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 84
What is most important component(device) in our
Computers that enables to send and receive data.
What is the name of the software component, which defines
how the card will interact with the operating system
What are the Types of Network adapters.
Computer Networks
-Week3
Sunday, March 23, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 85
What is the device we should have in order for Wireless
Devices to Communicate.
Computer Networks
-Week3
Sunday, March 23, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 86
How data travels in the network cable?
What is the unit for the data transfer(speed) of the cable?
Define these types of data transfers:
Unicast and
Broadcast.
Computer Networks
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Sunday, March 23, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 87
Why we assign IP address to a computer ?
What makes a device a host?
Computer Networks
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Sunday, March 23, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 88
What are the Characteristics of these Network Topologies:
Ring
Star
Mesh
Computer Networks
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Sunday, March 23, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 89
What are the 4 Colors(BOGB) of the UTP cable?
When we should use :
Straight-through cable
Cross-over Cable
Computer Networks
-Week3
Sunday, March 23, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 90
Understand and Define the following:
Hub
Switch
Router
Peer to Peer Network.
Client/Server Network.
Computer Networks
-Week3
Sunday, March 23, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 91
What are the Important Services that Servers Provide?
Computer Networks
-Week3
Sunday, March 23, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 92
Main Services are
File
Database
Network controller
Messaging/Email
Web
Computer Networks
-Week3
Sunday, March 23, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 93
List three examples of each :
Client Operating System
Server Operating System
Computer Networks
-Week3
Sunday, March 23, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 94
Making LAN Connections:
Straight-through and Cross-over UTP Cables:
Typically, when connecting different types of devices, use a
straight-through cable. And when connecting the same type
of device, use a crossover cable.
Computer Networks
-Week3
Sunday, March 23, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 95
Straight-through UTP Cables
A straight-through cable has connectors on each end that are
terminated the same in accordance with either the T568A or
T568B standards.
Use straight-through cables for the following connections:
Switch to a router Ethernet port
Computer to switch
Computer to hub
Computer Networks
-Week3
Sunday, March 23, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 96
Computer Networks
-Week3
Sunday, March 23, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 97
Crossover UTP Cables
To achieve this type of connection with a UTP cable, one end must be terminated as T568A pinout, and the other end terminated with T568B pinout,
To summarize, crossover cables directly connect the following devices on a LAN:
Switch to switch
Switch to hub
Hub to hub
Router to router Ethernet port connection
Computer to computer
Computer to a router Ethernet port
Computer Networks
-Week3
Sunday, March 23, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 98
Computer Networks
-Week3
Sunday, March 23, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 99
Build Straight-through and Cross-over Cable UTP
cables.
Computer Networks
-Week3
Sunday, March 23, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 100
Computer Networks
-Week3
Sunday, March 23, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 101
Computer Networks
-Week3
Sunday, March 23, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 102
Computer Networks
-Week4-8
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 103
In these Weeks:
1. Standards.
2. OSI and TCP/IP Models
3. Understanding Internet Protocol & TCP/IP Tools
4. Network Services and Wide Area Networks
5. Network Infrastructure and Security
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 104
Standards
Standards are sets of rules that ensure hardware and software
released from different companies work together
Examples of Organizations that Coordinate Standards:
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 105
Examples of Organizations that Coordinate Standards:
International Organization for Standardization (ISO) – Federation of standards organizations from multiple nations
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 106
Open Systems Interconnection (OSI)
The Open Systems Interconnection (OSI) reference model is used to define
how data communication occurs between devices
The model is divided into 7 layers, each layer providing services to the layers
above and below
Layer Defines
Layer 7 – Application Layer Enables users and applications to access network services
Layer 6 – Presentation Layer Translates data into a common format
Layer 5 – Session Layer Establishes a communication session between devices
Layer 4 – Transport Layer Manages message fragmentation and reassembly
Layer 3 – Network Layer Manages data routing and creating sub networks
Layer 2 – Data Link Layer Provides error-free transfer of data frames
Layer 1 – Physical Layer Physical network media and signal methods
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 107
OSI Model Layers
Layer Protocol Data
Unit (PDU)
Application Data
Presentation Data
Session Data
Transport Segment
Network Packet
Data Link Frame
Physical Bits
Layer Protocol Data
Unit (PDU)
Application Data
Presentation Data
Session Data
Transport Segment
Network Packet
Data Link Frame
Physical Bits
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 108
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 109
OSI and TCP/IP MODEL
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 110
OSI Model and Data Packet Units
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 111
OSI , TCP Models and Protocols
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 112
The two Groups of OSI Layers
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 113
The lower layers
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 114
The Transport layer can provide connection orientation
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 115
Transport Layer Protocols (TCP and UDP)
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 116
User Datagram Protocol (UDP)
Applications that use UDP include:
Domain Name System (DNS)
Video Streaming
Voice over IP (VoIP)
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 117
Transmission Control Protocol (TCP)
Applications that use TCP are:
Web Browsers
File Transfers
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 118
LAYERS OF NETWORK COMMUNICATION
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 119
Port Addressing
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 120
The Internet Assigned Numbers Authority (IANA) assigns
port numbers
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 121
TCP Ports
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 122
UDP Ports
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 123
TCP/UDP Common Ports
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 124
Three-way handshake Process:
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 125
Windowing
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 126
Layer 7 – Application Layer
Serves as a the window for users and application processes to
access network services
This layer is where message creation begins
End-user protocols such as FTP, SMTP, Telnet, and RAS work
at this layer
This layer is not the application itself, but the protocols that
are initiated by this layer
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 127
Layer 6 – Presentation Layer
This layer translates the data format from sender to receiver
in the various OSes that may be used
Presentation Layer concepts include: character code
conversion, data compression, and data encryption
Redirectors work on this layer, such as mapped network
drives that enable a computer to access file shares on a
remote computer
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 128
Layer 5 – Session Layer
The Session Layer manages session establishment,
maintenance and termination between network devices
Example: when you log on and log off
This layer controls the name and address database for the OS
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 129
Layer 4 – Transport Layer
This layer ensures messages are delivered error-free, in
sequence and with no losses or duplications
Protocols that work at this layer segment messages, ensure
correct reassembly at the receiving end, perform message
acknowledgement and message traffic control
The Transport Layer contains both connection-oriented and
connectionless protocols.
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 130
Connection Oriented Communications:
Require both devices involved in the communication
establish an end-to-end logical connection before data can be
sent
These communications are considered reliable network
services
Packets not received by the destination device can be resent
by the sender
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 131
Hello! I am a
PCHello! I am a
Server!
Ok, I will
watch for it!
I want to send
you something
important!
Connection Oriented Communications:
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 132
Layer 3 – Network Layer
Controls the operations of routing and switching information
to different networks
Translates logical addresses or names to physical addresses
Internet Protocol (IP) is a Network Layer protocol
Devices that work at the network layer are routers and IP
switches
Network Layer components: IP addresses, subnets
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 133
Packets
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 134
Layer 2 – Data Link Layer
Establishes, maintains, and decides how transfer is
accomplished over the physical layer and ensures error-free
transmission over the physical layer
Physical addresses (the hexadecimal address that is burned
into the ROM of the NIC), known as the MAC address
uniquely identify each hardware device work at the Data Link
Layer
Data Link Layer components: network interface cards and
bridges
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 135
Layer 2 Switches
Layer 2 switches are hardware-based and use the MAC
address of each host computer’s network adapter when
deciding where to direct data frames
Ports on the switch are mapped to the specific MAC address
of the device attached
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 136
Media Access Control Address
Network adapters on an Ethernet network have unique
Media Access Control (MAC) addresses
MAC addresses are unique identifiers assigned to network
adapters by the manufacturer
MAC address is written in hexadecimal
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 137
Layer 1 – Physical Layer
Defines the physical and electrical medium for data transfer
Physical layer components: cables, jacks, patch panels, punch
blocks, hubs…
Physical layer concepts: topologies, analog versus
digital/encoding, bit synchronization, baseband versus
broadband, multiplexing, and serial data transfer
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 138
Ethernet Standards
LAN standard providing a communication method for high speed data exchange among devices
Defined Physical and Data Link Layer
100BASE-T 100 for 100 Mbps BASE for baseband T for twisted-pair cabling
Baseband refers to the fact that devices on the network use digital signaling over a single frequency
Broadband systems use analog signaling over a range of frequencies enabling multiple channels over the same physical medium
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 139
Communications Subnetwork:
The communications subnetwork consists of layers 1 through
3
Physical
Data Link
Network
Regardless of what type of data transmission occurs in a
computer network, the communication subnetwork is used
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 140
3. Understanding Internet Protocol & TCP/IP
Tools
IPV4
Internet Protocol version 4 (IPv4) is the fourth version
of the Internet Protocol and the first version to be
widely deployed
IPv4 is a frequently used communications protocol and is
one of the core protocols for the Internet
IP resides on the network layer of the OSI model
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 141
IP Addresses
IP addresses consist of four octets (8-bits), each between 0 and
255.
Examples include:
12.5.24.2
127.0.0.1
192.168.3.54
208.32.56.232
In order for an IP address to function, there must be a properly
configured IP address and compatible subnet mask
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 142
Classful Network Architecture
The IPv4 classification system is known as a classful network
architecture broken down into five sections: Classes A, B, and C
are commonly used
An Class A IP address, the first octet is the “network” portion
Class IP Range
(1st Octet)
Default Subnet
Mask
Network ID / Host ID
A 0 – 127 255.0.0.0 Net.Host.Host.Host
B 128 - 191 255.255.0.0 Net.Net.Host.Host
C 192 – 223 255.255.255.0 Net.Net.Net.Host
D 224 - 239 N/A N/A
E 240 - 255 N/A N/A
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 143
Loopback Testing
The range for Class A is 0–127
The 127 network number isn’t used by hosts as a logical IP address
Instead, this network is used for loopback IP addresses, allowing
for testing
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 144
Usable Addresses
The first and last addresses cannot be used
For network 172.24.3.X
The 0 (in binary) for the host address is the entire network
172.24.3.0
The 1s (in binary) for the host address is the broadcast address
172.24.3.255
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 145
IP Conflict
IP conflicts occur when two devices have been assigned the same
IP address
Windows Error:
There is an IP address conflict with another system on the
network
If there is an IP address conflict, the devices will have problems
sending and receiving data
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 146
Public and Private Addresses
IPv4 addresses are further classified as either public or private.
Public IP addresses are ones that are exposed to the Internet
Devices connected to the Internet can potentially communicate
with them
Private IP addresses are hidden from the Internet and any other
networks
Usually behind an IP proxy or firewall device
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 147
Static and Dynamic Addresses
Static IP address are addresses that are manually assigned to a host
Dynamic IP addresses are more common than static IP addresses,
whereas they automatically obtain an IP address (and other IP
information)
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 148
Common TCP/IP Tools
command prompt
ipconfig
ping
Tracert
Netstat
Pathping
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 149
Command Prompt
The Windows command prompt is Microsoft’s version of a
command-line interface or CLI
Running the command prompt as an Administrator is also known
as running it in elevated mode
Tools can be run using the command prompt
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 150
Ipconfig
Displays the current configuration of the installed IP stack on
a networked computer using TCP/IP
The /all switch can be used to view additional details about
each adapter
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 151
Ping
verifies IP-level connectivity to another TCP/IP device by
sending Internet Control Message Protocol (ICMP) Echo
Request messages
A number of switches can accommodate different testing
scenarios
Can be used to test IPv4 and IPv6 connectivity
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 152
Ping Process
Hey, are you awake?
Why yes, yes I am...
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 153
Tracert
Determines the path taken to a destination by sending
Internet Control Message Protocol (ICMP) Echo Request
messages to the destination with incrementally increasing
Time to Live (TTL) field values
Used to “trace” a network path from sending to receiving
device
Useful if the local device is testing ok but connectivity can’t
be established
Computer Networks
-Week4
Wednesday, March 26, 2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 154
Tracert in Action
Hey, how do I get
there?
First you go
through me...Second you go
through me...
Then you re here!
Computer Networks
-Week4-8
Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 155
4. Network Services and Wide Area Networks
Computer Networks
-Week4-8
Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 156
DNS
Domain Name System (DNS) is a worldwide service that
resolves host names to IP addresses
DNS is part of the application layer of the TCP/IP reference
model
DNS servers use port 53 to accept name resolution requests
Computer Networks
-Week4-8
Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 157
DHCP
Dynamic Host Configuration Protocol (DHCP) is a
client/server protocol that enables configured client
computers to obtain IP addresses automatically.
The IP information obtained might include the following:
IP addresses
Subnet masks
Gateway addresses
DNS server addresses
Other advanced options
Computer Networks
-Week4-8
Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 158
The DHCP Server service provides the following
benefits:
Reliable IP address configuration
Reduced network administration
Computer Networks
-Week4-8
Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 159
DHCP Server
Computer Networks
-Week4-8
Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 160
How Does DHCP Server Word?
Computer Networks
-Week4-8
Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 161
Wide Area Networks (WAN)
Wide area networks (WANs) connect multiple local area networks together
WANs connect multiple LANs that can include a home, school, or buildings
WANs enable network to function without concern to a location
WAN technologies can include:
Packet Switching: Devices transport packets via shared links
Leased Line: Dedicated point to point connection
Circuit Switching: Dedicated circuit path is created between end points (dial up)
ISDN, DSL, Broadband Cable, POTS/PSTN….
Computer Networks
-Week4-8
Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 162
Routing
Routing is the process of managing the flow of data between
network segments and between hosts or routers
Data is sent along a path according to the IP networks and
individual IP addresses of the hosts
A router is a network device that maintains tables of information
about other routers on the network or internetwork
Computer Networks
-Week4-8
Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 163
Static and Dynamic Routing:
A static route is a path that is manually configured and remains
constant throughout the router’s operation
A dynamic route is a path that is generated dynamically by using
special routing protocols
Computer Networks
-Week4-8
Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 164
WAN Technologies:
Integrated Services Digital Network (ISDN) is a set of
communication standards enabling simultaneous digital
transmission of data, fax, voice and video .
ISDN can be broken down into two major categories:
Basic rate ISDN (BRI):
Primary rate ISDN (PRI):
Computer Networks
-Week4-8
Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 165
DSL
Digital subscriber line (DSL) is a family of technologies that
provides data transmissions over local telephone networks
DSL allows for voice and data to be run over the same line
DSL uses higher frequency bands to transmit data
Computer Networks
-Week4-8
Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 166
Broadband Cable:
Broadband cable is used for cable Internet and cable television
using the cable television network
It operates at a higher speed than DSL and rates can range from
384 kbps to 20 Mbps +
Computer Networks
-Week4-8
Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 167
POTS/PSTN
POTS/PSTN stands for plain old telephone system/public
switched telephone network.
This is what we use now for “regular” phone lines, and it has been
around since the 1940s.
POTS/PSTN is now digital at the switching office and some
central offices, but there analog lines run to people’s homes.
Computer Networks
-Week4-8
Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 168
5. Network Infrastructure and Security
Internet
Computer Networks
-Week4-8
Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 169
Internet
The Internet is a worldwide system of connected computer
networks
Devices that connect to the Internet use the TCP/IP protocol
suite
The Internet contains a lot of information, resources and services:
World Wide Web (WWW) servers hosting content
Supporting infrastructure for email
Connectivity for peer-to-peer networks
Computer Networks
-Week4-8
Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 170
World Wide Web
The World Wide Web (WWW) is an enormous system of
interlinked hypertext documents that can be accessed by using a
web browser
Interlinked hypertext documents can contain text, graphics and
videos
Currently, the World Wide Web is in a stage known as Web 2.0
Web 2.0 is an interactive type of web experience compared to the
previous version 1.0
Computer Networks
-Week4-8
Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 171
An intranet is a private computer network or single Web site that
an organization implements in order to share data with employees
around the world
User authentication is necessary before a person can access the
information in an intranet
Ideally, this keeps the general public out, as long as the intranet
is properly secured
Computer Networks
-Week4-8
Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 172
Accessing Company Data
A company can present information to different groups:
Intranet – For internal employees
Extranet – For partners
Web Server – For the public
Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 173
Partner Public Remote Users
Computer Networks
-Week4-8
Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 174
VPN
A virtual private network (VPN) is a connection between two or
more computers or devices that are not on the same private
network
In order to ensure that only the proper users and data sessions
cross to a VPN device, data encapsulation and encryption are used
A “tunnel’ is created, through the LANs and WANs that are being
used
/ISP
Computer Networks
-Week4-8
Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 175
Firewalls
Firewalls are used to help protect a network from malicious attack
and unwanted intrusion
Computer Networks
-Week4-8
Wednesday, March 5,2014 Computer Networks: STS/MTA/Coursera/Cisco
Instructor: Ahmed Hussein Farah 176
END OF THE COURSE:
Summary
Concepts you Should Know and Understand.