1. Networking 101
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

2. Networking 101
History
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

3. Networking 101
History
WWW was invented in 1989 by Tim Berners-
Lee. The entire World-Wide-Web used to be just
one computer

4. Networking 101
Facts
In 1999, 38M People had broadband Internet.
Today, 1.2B have in on their mobile devices

5. Networking 101
Facts
14.3 Trillion webpages are live on the Internet
2.7 Billion People (40% of the world’s
population) are Online.

6. 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
computer
No standards, No compatibility
TCP/IP & OSI model we’re combined to help
creating the world you know today

7. OSI Model
The Layers of the Internet
The Open System Interconnect Model
Wait, What?

8. OSI Model
Key Principles
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”

9. OSI Model
1 Model To Rule Them All
Application
Presentation
Session
Transport
Network
Data Link
Physical
‫האפליקציה‬ ‫שכבת‬
‫התצוגה‬ ‫שכבת‬
‫השיחה‬ ‫שכבת‬
‫התובלה‬ ‫שכבת‬
‫הרשת‬ ‫שכבת‬
‫הערוץ‬ ‫שכבת‬
‫פיזית‬ ‫שכבה‬

10. 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.
Examples:
Physical Equipment, Cables, Connectors, NICs
Bit Sync, Work Rate
Hubs, Repeaters, USB, Bluetooth, SDH, DSL
Encoding
Parallel VS. Serial
OSI Model
#1 - Physical Layer
RCVTRS
…110100101110010011101…

11. 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.
Examples:
CRC – Error Handling
ARP Table
Collisions and Broadcasts
MAC Addresses
Switches, LAN, ATM, VLANs
OSI Model
#2 – Data-Link Layer
1
2
3 6
5
4

12. 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
Examples:
Inter-Networking (Internet = Collection of LANs 7 WANs)
IP Protocol (Connectionless), ICMP, IPSec, IPX
QOS, Routing
Packets, WAN
OSI Model
#3 – Network Layer

13. Provides end-to-end communication services for
applicationswithin a layered architecture of network
components and protocols, Between Ports.
Examples:
Connects between Applications
Reliabile/Unreliable Connection (VoIP vs HTTP)
Flow Control
Multiplexing
TCP, UDP, Segments
OSI Model
#4 – Transport Layer

14. Provides the mechanism for opening, closing and
managing a session between end-user application
processes
Examples:
Full/Half Duplex
Sync
RPC, SCP
OSI Model
#5 – Session Layer

15. Responsible for the delivery and formatting of information
to the application layer for further processing or display.
Examples:
Data Conversion
Encryption & Decryption
ASCII, Terminal, Telnet, AFP
OSI Model
#6 – Presentation Layer
Value Code
A 65
B 66
C 67
D 68
E 69
F 70

16. 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.
Examples:
SSH, FTP, HTTP, SSL, DNS
NFS, SIP, SMB, SMTP, RDP
LDAP, POP, IMAP, SNMP
REST, Web Applications
OSI Model
#7 – Application Layer

17. OSI Model
Encapsulation
Application
Presentation
Session
Transport
Network
Data Link
Physical
Data
Data
Data
DataTransport Header
DataNetwork Header
DataData Link Header
Data

18. OSI Model
#7 – Application Layer
Application
Presentation
Session
Transport
Network
Data Link
Physical
Application
Presentation
Session
Transport
Network
Data Link
PhysicalPhysical
Data Link
Network

19. Networking 101
DNS
DNS – Domain Name Server/Service
It translates easily memorized domain names
to the numerical IP addresses
Hierarchical!
www.eToro.com -> 91.220.30.150
Openbook.eToro.com -> 91.220.30.151
Client
Local
Name
Server
Root
Name
Server
IP
IP
Name
Name

20. Networking 101
DNS
Client
Local
Name
Server
Root
Name
Server
IP
IP
Name
Name

21. Networking 101
NAT
NAT – Network Address Translation
Private IP’s <-> Public IP’s
One-to-One, One-to-Many
Source NAT: In -> Out
Destination NAT: Out -> In

22. Networking 101
VLAN
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)

23. Networking 101
Wireless
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

24. Networking 101
The END
Thank You for Listening!
Wanna know more? Just ask.
Contact me @
eliranbz@etoro.com