>[!quote] In a Nutshell >Conceptual communication protocol framework derived from the more general [[OSI Model - Open Systems Interconnection|OSI model]]. Widely used in modern communication, e.g. internet. ![[Pasted image 20250417155348.png]] --- >[!info] Application Layer >The application layer is the highest layer of the model. It’s what you, as a user, see and interact with when sending and receiving data. > >It is responsible for ... >- Generating the data >- Requesting connections > >Some example protocols are ... >- **[[HTTP and HTTPS - Hypertext Transfer Protocol]]** >- **[[SSH - Secure Shell]]** >- **[[LCM - Lightweight Communications and Marshalling]]** >- ... >[!info] Transport Layer >It establishes a reliable and error-free data connection between the application or device and the destination. > >It is responsible for ... >- Establishing the connection (error-free) >- Splitting the data into smaller packets and numbering them into a sequence. This is based on the amount of data, the destinations and the transmission rate >- Obtaining acknowledgment that packets have been received > >The protocols in this layer are ... >- **[[TCP - Transmission Control Protocol]]** >- **[[UDP - User Datagram Protocol]]** >[!info] Internet Layer >The internet layer, also called the IP or network layer (though not to be confused with the network access layer, see below), is responsible for ... >- Sending the packets >- Ensuring that the data is transferred as accurately as possible. >- Routing the data to the correct network > The protocols belonging to this layer are: > >- **[[IP Address, IPv4, IPv6, ULA and Subnet Mask|Internet protocol versions 4 and 6 (IPv4/IPv6)]]**. Used for routing the data across the network. It’s responsible for packets delivery from the host source to the destination host by looking at the [[IP Address, IPv4, IPv6, ULA and Subnet Mask|IP addresses]] in the [[IP Packets|packet]]. >- [**Internet control message protocol**](https://www.cloudflare.com/en-gb/learning/ddos/glossary/internet-control-message-protocol-icmp/) **(ICMP)**. Used to provide information to the hosts in case of network problems. >- [**Address resolution protocol**](https://blog.cloudflare.com/ddos-attack-trends-for-2021-q4/) **(ARP)**. Used to find the hardware address of a host from a known IP address. >[!info] Network Access Layer >All protocols and technologies required to deliver data across a physical medium, also refered to as physical layer or data link layer. > >It is responsible for ... >- Adding a destination [[MAC - Media Access Control Address|MAC address]] > >Examples are ... >- Ethernet Cables >- Wi-Fi networks >- ...