Roles of TCP/IP Layers Application Transmission Network Link Layer Harry Graham
Application layer • Handles the details of a particular networking application, e.g a web browser using HTTP. The protocols associated with the application layer are typically: • HTTP: hypertext transfer protocol; used for web browsers. There is HTTPS for secure transactions online. The typical The port number for http(s) is 80/8080. • FTP: file transfer protocol; for transferring data (files) over a netoworking application. Typical port number is 20/21. • POP3: post office protocol (v3); email client – deals with receiving emails. Port number is 25 • SMTP: simple mail transfer protocol; deals with the sending of emails. Port number is 100.
Transmission Layer • The transmission layer manages the transfer of data by monitoring connections between networked applications. -The protocol involved with this layer is the TCP.(The transmission control protocol). TCP enables applications executing on two hosts to establish a connection and exchange streams of data. TCP guarantees delivery of data and also guarantees that packets will be delivered in the order they were sent (packet sequence number). TCP is responsible for dividing the data passed to it from the application layer into chunks for the network layer
Network Layer • This layer ADDS source and destination addresses to packets on their way from the transmission layer to the link layer. ALSO removes source and destination IP addresses from packets on their way from the link layer to the transmission layer. (The reverse process when the data is at the other host). • The protocol that deals with this layer is the IP; Internet Protocol.
Link Layer • Handles all the physical details of interfacing with the cable, including the network interface card and a device driver. • The link layer ADDS source and destination Hardware address to packets that it receives from the network layer then dispatches the packets onto the local cable. The destination address is the Gateway’s hardware address. • This layer provides the error checking of the data.
Networking Application such as web browser (HTTP) Application Network Link Transmission TCP splits the data (sent to it from the application layer) and divides it into packets for the network layer. Data Packets Organises packets for dispatch Source Destination Sort number Checksum IP adds source and destination IP addresses to packets and organises them for dispatch in the link layer. Adds source and destination hardware addresses and dispatches onto the cable. Along the local area network cable. To the other host gateway and then the destination link layer