by : Eliran Ben-Zikri
Welcome to the amazing world of computer
networking, I hope you’ll find this presentation
informative and interesting.
Networking – A bunch of devices with cool
green LEDs that when combined all together
allows computers to exchange data
60,000 Years ago – People started to Speak
5,000 Years ago – People started to Write
600 Years ago – Please started to publish
50 Years ago – The Internet was born
WWW was invented in 1989 by Tim Berners-
Lee. The entire World-Wide-Web used to be just
In 1999, 38M People had broadband Internet.
Today, 1.2B have in on their mobile devices
14.3 Trillion webpages are live on the Internet
2.7 Billion People (40% of the world’s
population) are Online.
Internet? Say what?
How did it all start?
Back in the 70’s, many vendors developed
many types of computers, each has it’s own
set of protocols and architecture
an IBM Computer could only talk to an IBM
No standards, No compatibility
TCP/IP & OSI model we’re combined to help
creating the world you know today
The Layers of the Internet
The Open System Interconnect Model
Divides Networking to 7 Layers
Each layer takes care of a very specific job
Each Job is not too Complicated
Passes the data onto the next layer.
Defines “What”, Not “How”
1 Model To Rule Them All
The physical layer does not understand anything but bits:
The signal comes to it in the form of pulses and is
transformed into 0's and 1's.
Physical Equipment, Cables, Connectors, NICs
Bit Sync, Work Rate
Hubs, Repeaters, USB, Bluetooth, SDH, DSL
Parallel VS. Serial
#1 - Physical Layer
Puts some sense to the bits, turning them into Frames,
Bridging between Layer 1 & 3 (LLC & MAC), Connecting
between Hosts in the LAN – No IP’s, Just MAC’s.
CRC – Error Handling
Collisions and Broadcasts
Switches, LAN, ATM, VLANs
#2 – Data-Link Layer
Responsible for packet forwarding, Routing, Transferring
data from a source to a destination host via one or more
networks, while maintaining Quality-Of-Service functions
Connecting two or more LANs all together
Inter-Networking (Internet = Collection of LANs 7 WANs)
IP Protocol (Connectionless), ICMP, IPSec, IPX
#3 – Network Layer
Provides end-to-end communication services for
applicationswithin a layered architecture of network
components and protocols, Between Ports.
Connects between Applications
Reliabile/Unreliable Connection (VoIP vs HTTP)
TCP, UDP, Segments
#4 – Transport Layer
Provides the mechanism for opening, closing and
managing a session between end-user application
#5 – Session Layer
Responsible for the delivery and formatting of information
to the application layer for further processing or display.
Encryption & Decryption
ASCII, Terminal, Telnet, AFP
#6 – Presentation Layer
The user interface, Responsible for displaying data and
images to the user in a human-recognizable format and to
interface with the presentation layer below it.
SSH, FTP, HTTP, SSL, DNS
NFS, SIP, SMB, SMTP, RDP
LDAP, POP, IMAP, SNMP
REST, Web Applications
#7 – Application Layer
DataData Link Header
#7 – Application Layer
DNS – Domain Name Server/Service
It translates easily memorized domain names
to the numerical IP addresses
www.eToro.com -> 184.108.40.206
Openbook.eToro.com -> 220.127.116.11
NAT – Network Address Translation
Private IP’s <-> Public IP’s
Source NAT: In -> Out
Destination NAT: Out -> In
VLAN – Virtual LAN
Partitioning a Switch to several virtual networks
A router is needed for Inter-LAN communication
Software rather than Hardware
Each Packet is tagged with
A VLAN number, and Only
Trunk ports or the same
VLAN ports can accept these
Frames (Layer 2)
Wi-Fi/WLAN based on IEEE 802.11 specs
Uses wireless access points (WAPs)
Usually operate in the unlicensed spectrum near 2.4 GHz.
MIMO – Multiple Input, Multiple Output
802.11a 54Mbps max, 75 feet max, uses 5 GHz band - Rare
802.11b 11Mbps max, 45 meter max, 2.4 GHz, lowest cost – The Past
802.11g 54Mbps max, 45 meter max, 2.4 GHz band – The Popular
802.11n 600Mbps max, 70 meter max, 2.4 or 5 GHz band, MIMO – Rising
802.11ac 1Gbps max, 70 meter max, 5 GHz band, MIMO – The Future
Thank You for Listening!
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