Networking Standards Over the years these have been written and developed by 3 organisations (mainly).
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Networking Standards
Over the years these have been written and developed by 3
organisations (mainly).
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
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.
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.
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.
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)
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
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.
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
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
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.
Put it together.
FredSent “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
Put it together.
FredSent “how are you” To John
John
Segmented
Numbered
IP
Mac
how Piece 1
how Piece 1IP
Mac
how
how Piece 1IP
Put it together.
FredSent “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
Put it together.
FredSent “how are you” To John
John
Segmented
Numbered
IP
Mac
are Piece 2
are Piece 2IP
Mac
are
are Piece 2IP
howyou
Put it together.
FredSent “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
Put it together.
FredSent “how are you” To John
John
Segmented
Numbered
IP
Mac
you Piece 3
you Piece 3IP
Mac
you
you Piece 3IP
howyou are
Put it together.
FredSent “how are you” To John
John
Segmented
Numbered
IP
Mac
you how are
Put it together.
FredSent “how are you” To John
John
Segmented
Numbered
IP
Mac
youhow are
Put it together.
FredSent “how are you” To John
John
Segmented
Numbered
IP
Mac
youhow are
how are you
Put it together.
FredSent “how are you” To John
John
Segmented
Numbered
IP
Mac
how are you
There are a number of different types of frames.
Ethernet frame
PreambleDestination
AddressSource address
Type Data (packet) FCS
8 Bytes 6 Bytes 6 Bytes 2 Bytes 46 - 1500Bytes 4 BytesFrame Check Sequence
IEEE 802.3 frame
Preamble SOFDestination
AddressSource address
Type802.2 header
and dataFCS
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 CtrlDestination
AddressSource address Information
Frame check
End delimFrame 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.
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