Shows how TCP/IP works in a very simple way.

1. Networking Standards
Over the years these have been
written and developed by 3
organisations (mainly).

2. These organisations are:-
• International Organisation for standards,
ISO who developed OSI
– Open Systems Interconnect.
• Institute of Electrical and Electronic
Engineers defines standards for LANs
(TCP/IP).
• Internet Engineering Task Force IETF
manages the process of
creating/developing TCP/IP standards

3. IETF
• Anyone can participate in the
creating/developing of TCP/IP standards.
IETF put the standards used and new on a
web site www.ietf.org and request your
comments (RFC’s) which if useful may be
include in future developments.
• TCP/IP is made up of many standards.
• ftp, smtp, http,tcp, ip,udp + others.

4. Open System Interconnect
• This is the sort of overall standard for
networking. But because it is very large
and complex is not normally used,
however you should know its basic
structure.
• This is a layered protocol and each layer
can be used or not depending on what you
are doing.

5. OSI layers
Layer What is does.
7 Application Controls how the OS and applications interact with the
network
6 Presentation Puts the data supplied together so it can be presented
to the system. (not the user). Encryption and
decryption lives here.
5 Session Defines the connection, negotiations between nodes
etc.
4 Transport Manages the flow of information and ensures packets
are all received and put in order.
3 Network Defines how data packets get from place to place. The
IP and IPX lives here. (routers work from here)
2 Data Link Defines standards that assign meaning to the bits
carried by the physical layer. (switches work here)
1 Physical Defines the physical properties of the medium used to
make a connection.

6. How to remember this (if you want
to I look it up in a book myself)
• All People Seem To Need Data
Processing ( layer 7 to 1)
• Please Do Not Throw Sausage Pizzas
Away (layer 1 to 7)

7. OSI
• While its important to know a little about it,
in general its not used, too complex.
• What is used is a sub set of it:-
»TCP/IP

8. TCP/IP
Or
• Transfer Control Protocol/Internet Protocol
As its know by its friends. This is a 4 or 5
layer protocol depending on who you read.
This a very very important protocol, as all
computers use it for communications.
It is the English of the computer world.

9. Fit them together.
OSI Model TCP/IP TCP/IP alt
7 Application
6 Presentation Application Application
5 Session
4 Transport Transport Transport
3 Network Internetwork Internetwork
2 Data Link Network Data Link
1 Physical Interface Physical

10. But what do they do??
TCP/IP `
4 Application Protocols for specific function. ftp,
smtp http, pop3,
3 Transport Error recovery and recovery of
data. TCP, UDP.
2 Internetwork IP works here and attaches
destination and source addresses
1 Network Interface Frames are set up here. Ethernet,
Frame relay, Token ring

11. Help what does this mean??
TCP/IP `Information comes down
to be sent off
4 Application Segmented into pieces.
3 Transport Pieces numbered
2 Internetwork IP source and destination addresses
added.
1 Network
Interface
Physical source and destination
addresses added. Put into a frame,
type depending on network.

12. Put it together.
Fred
Sent “how are you”
To John
John
how
are youSegmented
Numbered
IP
Mac
Piece 1
how are you
how Piece 1IP
Mac
how
how Piece 1IP
It is now a frame send it off

13. Put it together.
Fred
Sent “how are you”
To John
John
Segmented
Numbered
IP
Mac
how Piece 1
how Piece 1IP
Mac
how
how Piece 1IP

14. Put it together.
Fred
Sent “how are you”
To John
John
are
are youSegmented
Numbered
IP
Mac
Piece 2
are Piece 2IP
Mac are Piece 2IP
It is now a frame send it off
how

15. Put it together.
Fred
Sent “how are you”
To John
John
Segmented
Numbered
IP
Mac
are Piece 2
are Piece 2IP
Mac
are
are Piece 2IP
howyou

16. Put it together.
Fred
Sent “how are you”
To John
John
you
areyouSegmented
Numbered
IP
Mac
Piece 3
you Piece 3IP
Mac you Piece 3IP
It is now a frame send it off
how

17. Put it together.
Fred
Sent “how are you”
To John
John
Segmented
Numbered
IP
Mac
you Piece 3
you Piece 3IP
Mac
you
you Piece 3IP
howyou are

18. Put it together.
Fred
Sent “how are you”
To John
John
Segmented
Numbered
IP
Mac
you how are

19. Put it together.
Fred
Sent “how are you”
To John
John
Segmented
Numbered
IP
Mac
youhow are

20. Put it together.
Fred
Sent “how are you”
To John
John
Segmented
Numbered
IP
Mac
youhow are
how are you

21. Put it together.
Fred
Sent “how are you”
To John
John
Segmented
Numbered
IP
Mac
how are you

22. There are a number of different
types of frames.
Ethernet frame
Preamble
Destination
Address
Source
address
Type Data (packet) FCS
8 Bytes 6 Bytes 6 Bytes 2 Bytes 46 - 1500Bytes 4 Bytes
Frame Check Sequence
IEEE 802.3 frame
Preamble SOF
Destination
Address
Source
address
Type
802.2 header
and data
FCS
8 Bytes 6 Bytes 6 Bytes 6 Bytes 2 Bytes 46 - 1500Bytes 4 Bytes
Start of Frame
Token ring data frame
Start
delim
End delim Frame Ctrl
Destination
Address
Source address Information
Frame
check
End delim
Frame
status
1 Bytes 1 Bytes 1 Bytes 6 Bytes 6 Bytes 0-18000 Bytes 4 Bytes 1 Bytes 1 Bytes
Different ones are used for different types of networks.