Network Protocols and Layers

Network Layers and Protocols

Protocols

There are billions of network connected devices on the planet, each made at different times by different companies. In order for all these devices to communicate successfully with each other they all need to send, receive and process data in an agreed manner – a protocol (a protocol can be considered like a rule)

Common Networking Protocols

IP / TCP – Internet Protocol / Transfer Control Protocol - This protocol defines how packets are send over IP based networks.

IPV4 vs IPV6 – When Internet Protocol was designed very few institutions had networks or computers and so an address system of 32 bits was chosen as it was thought there would be enough addresses. (4,2 Billion addresses).With the exponential growth of the internet and internet enabled devices, we are now running out of addresses available. A new system (IPV6) is being introduced that contains far more available addresses. 3.4×10³⁸

HTTP / HTTPS – Hyper-Text Transfer Protocol / Hyper-Text Transfer Protocol Secure - This protocol defines how servers handle web requests from users. This includes how to handle get/ post requests, as well as how to format error messages (such as 404 not found messages)

SMTP – Simple Mail Transfer Protocol - This is the protocol used when sending emails across the internet.

POP / POP3 – Post Office Protocol - This is the protocol used when retrieving emails - POP involved mail being sent to the email server and then the data is removed once the email has been downloaded to a device. This means the email once downloaded will only be accessible on the device that originally requested the data from the server.

IMAP - This is a protocol used for both sending and receiving email. (Instant message access protocol) this means that the email is always stored on the email server and can be retrieved by requesting the data from the server. This will result in you being able to access the same email from many devices.

FTP – File Transfer Protocol / File Transfer Protocol Secure - This protocol is used when sending and receiving files over the internet

The TCP/IP model

The TCP/IP model consists of four layers, with each layer responsible for a small part of the communication process.

TCP/IP consists of two separate protocols. A protocol is a set of agreed rules and signals used by computers for exchanging data.

TCP (transmission control protocol) defines how messages are broken up into packets and reassembled at the destination. The

IP (internet protocol) identifies the location of a device on the Internet and routes the individual packets from source to destination via routers.

I remember it by using the Mnemonic (can you come up with better?)

Application = Angry

Transport = Terrorists

Internet/Network = Irritate

Link/Data = Llamas

So what does each of the layers do? Let's take a look at the TCP/IP Stack in a bit more detail

The TCP/IP model consists of four layers, with each layer responsible for a small part of the communication process

TCP/IP consists of two separate protocols. A protocol is a set of agreed rules and signals used by computers for exchanging data.

TCP (transmission control protocol) defines how messages are broken up into packets and reassembled at the destination. The IP (internet protocol) identifies the location of a device on the Internet and routes the individual packets from source to destination via routers.

Application Layer: encodes the data being sent so that it will be understandable by the recipient. This means formatting data and adding an appropriate heater. It uses the protocol HTTP.

Transport Layer: splits the data into packets and adds packet information such as packet number specifying that packet’s order and the total number of packets so they can be reassembled correctly. It uses the protocol TCP.

Internet/Network Layer: attaches the IP address of the sender so the recipient will know who sent it. It also attaches the address of the host that is sending the data, and the destination IP address. It uses the protocol IP.

Link / Data Layer: attaches the MAC addresses of the sender and the recipient, allowing the packet to be directed to a specific device on a local area network.

Activity - Protocols and Layers

• read the webpage and the lesson presentation from your teacher carefully then answer the questions using the link below:

• Teacher Presentation

• Student questions (you will need to make a copy) or alternatively use the resource in Google Classrooms

• Using the same presentation from the student questions create your own example of how the TCP/IP stack works (you may need to watch this video for further help) here is an example of some past student's work.