The OSI model is a framework for standardizing communications.OSI defines the communications process as a set of SEVEN layers with specific functions isolated and associated with each layer.
When was the OSI model developed?
Who developed the OSI model?
The International Standards Organization
Why are there layers, what do they do?
Each layer performs a set of functions necessary to provide a set of services to the layer above itself. Layer isolation allows a given layer to change without affecting the rest of the model.
How can the SEVEN layers of the OSI model be remembered and what are they?
Physical - Please
Datalink - Do
Netowork - Not
Transport - Throw
Session - Sausage
Presentation - Pizza
Application - Away
What does the PHYSICAL LAYER do?
The PHYSICAL LAYER is defines data transmission between devices.
It is involved in :
TRANSPORT MEDIA &
LAYER1 - Essentially everything you can TOUCH such as cabling and connectors.
What is the DATALINK LAYER?
The DATALINK LAYER is involved in:
Flow Control &
of the Data.
(FRAMES are sent at LAYER 2)
What does the NETWORK LAYER do?
The NETWORK LAYER is responsible for Logical Addressing. It translates Logical ~ to Physical Addresses.
(Prioritizing of Data is done at Layer 3)
What is a Logical Address?
A Logical Address is a 48 bit address that is burned into the ROM of a NIC (Network Interface Card,which is of course part of Layer 1). The first 24 bits are for VENDOR CODE and the next 24 bits make the SEQUENTIAL ADDRESS. This address is commonly referred to as the MAC (Media Access Control) address.
REMEMBER - IP is where you are.
MAC is who you are.
What is a Physical Address?
A Physical Address is a 32 bit address assigned to each system in a network. It is also known as the IP Address.
Elaborate on the PHYSICAL LAYER.
1. The PHYSICAL LAYER provides for TX of info between two endpoints (1's and 0's)