D-NASA-Lec01b-IP_Protocol_Stack

Application Layer

Function:

1. Contain the actual message the application want to send
2. Protocols in this layer define how application communicate between two devices

Application:

1. HTTP: Provide Web document request and transfer
2. SMTP: For e-mail messages transfer

Transport Layer

Function:

1. Turn message from application layer into segment, which specifies what application is this message for by specifying the destination port
2. Provides delivery service with reliability (TCP) or speed (UDP)

Application:

1. TCP
2. UDP

Network Layer

Function: Responsible for moving segments from one host to another. It adds headers to segment which turns them into datagrams/packets

Application:

1. IP protocols: Specify end systems addresses
2. routing protocols: Help decide next stop in intermediate routers

Link Layer

Function: Responsible for moving datagrams from one node to another by wrapping them with specific headers based on the protocol used between two nodes, which we’ll name it a frame

Application:

1. Ethernet
2. WiFi

Nodes here can be hosts, routers, switches... (all devices connected to a network)

Physical Layer

Function: Link between two nodes can be twisted-pair copper wire, fiber optics… The physical layer is responsible for moving every bit in the frame to the destination node with the given link medium

Application:

1. twisted-pair copper wire
2. fiber optics