1. Network Protocol Layers
Networks
Network Protocol Layers

2. Network Standards
Standards have been developed so all hardware and software on networks can function as a unit.
These standards ensure that each device can safely and reliably send and receive information
The International Organization for Standardization (ISO) has worked to establish these standards world wide

3. OSI Model The OSI model is made up of seven layers.
Each layer uses the resources from the layer below it
Layers:
Application
Presentation
Session
Transport
Network
Data Link
Physical

4. Application Layer
Determines the FORMAT in which the information is sent and how received information is processed
Example: SMTP (Simple Mail Transfer Protocol)
Specifies the format of mail headers
This allows hotmail to send messages to gmail

5. Presentation Layer
Handles things such as text compression or format conversion between types of computers
Not usually used in most systems
Would allow the older Apple Talk packets to be transferred to a Microsoft computer

6. Session Layer Establishes connections between different hosts
Also not used in TCP/IP based systems
Aids in login/shopping website browsing

7. Transport Layer
Provides an error-free connection between two computers.
Ensures packets of data will be transmitted in the correct order
Ensures complete transfer
Ensures data has not been corrupted

8. Network Layer Routes the packet to the correct destination
Uses transport layer packet and attaches a header that contains the address of the receiving computer
Example: TCP/IP (transmission control protocol / internet protocol) routing

9. Data Link Layer Splits packets into small pieces called frames
Each frame is given its own header and is then sent out on this layer.
Example: Ethernet standard (how information is physically bundled to travel over the wires)
Example: Wireless standard n (how information is physically converted to wireless signal)

10. Physical Layer
Sends the bits of data in a frame to the destination computer
The actual method used to transmit the data also depends on the transmission medium
Example IEEE (the Institute of Electrical and Electronic Engineers) and ANSI (the American National Standards Institute)