Day 1:

[25th February 2020]

1. We were able to understand what the course about, the Course Introduction is.

2. Purpose of course design.

3. about the student blog.

4. Assessments.

5. OSI model.

6. Subnetting. 

Started with the OSI (Open System Interconnection) model:

This model is most commonly used in networking. It’s a theoretical construction and visual description to understand as to what is going on with a particular networking system. This assists network managers to simplify and narrow down problems (assists in identifying whether it is a physical issue or something wrong with the application),This also assists computer programmers (when developing an application, OSI helps in identifying as to which other layers it needs to work with).

Rather than memorizing all layers if we understand and know the fundamentals, it’s easier to figure out how it works.

OSI model goes from top to bottom, with the numbers going from Layer 7 down to Layer 

1. Given below are the Layers, and what they represent:

Source: webopedia

Quick Tip if you want to memorize the 7 layers use this Code

Please Do Not Throw Sausage Pizza Away  

01.Physical 02.Data Link 03.Network 04.Transport 05.Session 06.Presentation 07.Application

Layer 7 or Application
Layer 7 or Application layer is the most visible layer one at the top. Where the users directly interact with. (Using IP address and connect to the Internet such as web browsers, Applications like outlook).

Layer 6 or Presentation

Layer 6 or the Presentation Layer’s comes after the application layer and it act as a translator. In general its main purpose is to prepare or translate application formats to network formats, or vice versa. In simple words, the presentation layer “presents” data for the application or the network for further processing or display. One simple example of the presentation layer is data been encrypted and decrypted for secure transmission.

Layer 5 or Session

The Layer 5 or the Session layer assists in opening new sessions, managing them and closing the sessions between end user application processes. In simple words in order to communicate between any two devices, servers or computers, a session needs to be created.  (For example the session layer decides on the maximum amount of time to wait for a response and termination between the applications at each end of the session).

Layer 4 or Transport

Layer 4 or the Transport Layer coordinates the transfer of data between end systems and hosts. It coordinates details such as to how much of data to is to be sent, at what rate it should be sent and where it has to go. A classic example of Layer 4 is the Transmission Control Protocol, which is built on top of the Internet Protocol, which is commonly known as TCP/IP. Transmission Control Protocol and User Datagram Protocol port numbers work at Layer 4.

Layer 3 or Network

Layer 3 or Network is responsible for packet forwarding, including routing via different routers. Routers at this layer assists to enable this task much efficiently. IP addresses work at Layer 3. 

Layer 2 or Data Link

Layer 2 or the Data Link Layer provides the transfer of data from node-to-node (between two nodes that are connected directly), and this layer also handles the correction of errors from the physical layer.

In the world of networking, most switches are operated at Layer 2.

Layer 1 or Physical

First and lowest layer is Layer 1 or Physical Layer, which consists of the electrical and physical representation of the system. This includes almost everything from the types of cables to the layout of pins, voltages and every other physical requirement.