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.