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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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
Andrew S. Tenenbaum, Computer Network, Prentice-Hall
Computer Networks and Internet
Douglas E. Comer, Computer Networks and Internet.
To serve various applications.
To Share Data, Messages, Graphics, Printers, Scanners, Fax, Modem,….,…
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).
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).
Protocol is a rule or a set of rules set by companies, organizations or
service providers to form a standard .
i.e. : http
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?
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.
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.
multi-port repeater (physical hardware device)
provides physical star topology (but logically bus)
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
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
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
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
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
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.
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