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Computer Networks. Marwan Al- Namari Week 1. Unit Guide: Computer N etworks . Teaching Plan: Weeks 1 – 14 . Week 1-6 (In week 4 you will have a Quiz No.1 ) . Mid Term Holiday Mid-Term Exam . Week 7-14 (In week 10 you will have a Quiz No.2) .

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Computer Networks

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Computer networks

Computer Networks

Marwan Al-Namari

Week 1

Unit guide computer n etworks

Unit Guide: Computer Networks

TeachingPlan: Weeks 1 – 14.

Week 1-6 (In week 4 you will have a Quiz No.1) .

Mid Term Holiday

Mid-Term Exam .

Week 7-14 (In week 10 you will have a Quiz No.2).

Mode of Assessment : Final Exam (50 %)+Mid-Term Exam(20%) + Presentation (10%)+ Quizzes(10%) +Attendance (10%)



Computer Networking: A Top Down Approach 6th edition Jim Kurose, Keith RossAddison-WesleyMarch 2012

Computer Networks

Andrew S. Tenenbaum, Computer Network, Prentice-Hall

Computer Networks and Internet

Douglas E. Comer, Computer Networks and Internet.

What is networking

What is computer network?

What is networking?

It is two computers(smart devices) or more connected by cables, repeaters ,switches hubs, access point(wirelessly).

It is the process of sharing and exchanging information or data in the network.

Why networks

To improve our lives.

To serve various applications.

  • To communicate via emails and voice (VoIP).

    To Share Data, Messages, Graphics, Printers, Scanners, Fax, Modem,….,…

Why Networks?

What is Internet?

It is the largest engineered network system ever created by mankind, with hundreds of millions of connected computers, communication links, and

switches; with billions of users who connect via laptops, tablets, and smartphones.

End systems connect to Internet via access ISPs (Internet Service Providers).

Internet structure

Internet Structure

Internet structure network of networks

Internet structure: network of networks

How many classes of networks

How many Classes of Networks?

LAN: Local Area Network: Network in small geographical Area (Room, Building or a Campus).

MAN: Metropolitan Area Network: Network in a City.

WAN: Wide Area Network: Network spread geographically (Country or across Globe).

Network classes cont

Network Classes cont.

What is a protocol

What is a Protocol?

Protocol is a rule or a set of rules set by companies, organizations or

service providers to form a standard .

i.e. : http





Some of the many standards bodies

Some of the many standards bodies:

2 kinds to networks

2 Kinds to Networks :

Peer- to-Peer : 2 computers or more connected to each other, each node is a client and server.

Clint-Server: a node(workstation, terminal) or more connected to a dedicated server .

Find out the advantages and disadvantages of both types?

Type of connections

Type of connections

  • Point-to-point

    • One-to-one communication

    • Unicasting

  • Point-to-multipoint

    • Communication channel shared among nodes

    • One-to-many

    • Broadcasting (ALL)

    • Multicasting (SOME)

  • Multipoint-to-point

    • Many-to-one

Bandwidth and latency

Bandwidth and Latency

Bandwidth is a data transmission rate; the maximum amount of information measured in bits per second

(bits/second) that can be transmitted along a channel.

Latency (delay) : how much time it takes for transmission from one point to another.

Data communication

Data communication

Direction of data flow transmission mode

Direction of data flow (Transmission Mode)

Network design topology

Network Design (Topology)

The network topology defines the way in which computers, printers, and other devices are connected. A network topology describes the layout of the wire and devices as well as the paths used by data transmissions.

Standard Topologies:

Network devices elements

Network Devices & Elements

Network devices elements cont hub

Network Devices & Elements cont.Hub

multi-port repeater (physical hardware device)

provides physical star topology (but logically bus)

no intelligence

no separations of collision domains

all the hosts compete for the shared bandwidth

Active central element of star layout

Each station connected to hub by two lines

Transmit and receive

When single station transmits, hub repeats signal on outgoing line to each station

Transmission from any station received by all other stations

If two stations transmit at the same time, collision

Network devices elements cont repeater

Network Devices & Elementscont.Repeater:

works at the Physical layer

Regenerates received bits before it sends them out

connects different half-duplex network segments

either extends the number of users or the total span (by improving the quality of the transmitted signal)

no separation of collision domains

Network devices elements cont bridge

Network Devices & Elementscont.Bridge:

works at layer 2 (requires software)

connects two networks of the same type

LAN to LAN (example: WLAN to Fast Ethernet)

forwards data (1 packet @ the time) depending on the destination address in the data packet (not the IP address, but the physical (MAC) address that is unique for every Network Interface Card (NIC))

all computers are in the same sub-network

packet filtering

separates collision domains – larger network spans

a stand alone device or a PC with the special NIC and the accompanied software

can connect different Ethernet types

transparent (“plug-and-play”): no configuration necessary

Network devices elements cont switch

Network Devices & Elementscont.Switch:

basically a multi-port bridge

provides a better network performance

forwards more than a single packet at a time

separates collision domains – larger total network span

Incoming frame from particular station switched to appropriate output line

Unused lines can switch other traffic

More than one station transmitting at a time

Multiplying capacity of LAN

Network devices elements cont switches vs hubs

Network Devices & Elementscont. Switches Vs Hubs

Hubs are half-duplex while switches are full-duplex, this means that only one station can send when connected by a hub while more than one can send when connected via a switch. And this is because:

Switches separate collision domains while hubs not.

A station connected with a switch can send with the maximum possible speed while with hub can send only with the speed of the slowest station speed, for example if we have many station with different speed (1, 10, and 100 mbps), if they are connected using a switch (100mbps) a two station with 100mbps speed can send with this rate while with hub they can send data only with 1 mbps.

Network devices elements cont layer 2 switch v bridge

Network Devices & Elementscont.Layer 2 Switch v Bridge:

Layer 2 switch can be viewed as full-duplex hub

Can incorporate logic to function as multiport bridge

Bridge frame handling done in software

Switch performs address recognition and frame forwarding in hardware

Bridge only analyzes and forwards one frame at a time

Switch has multiple parallel data paths

Can handle multiple frames at a time

Bridge uses store-and-forward operation

Switch can have cut-throughoperation

Bridge suffered commercially

New installations typically include layer 2 switches with bridge functionality rather than bridges

Layer 2 switch and hub

Layer 2 Switch and Hub

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