Network Layers Flashcards
Application Layer Purpose
Header -
Port Number, Packet Number
Suite of different protocols designed to manage communication between different types of programs
Application Protocols
SSH POP3 SMTP IMAP
FTP DHCP HTTP(S) DNS
Transport Layer Purpose
IP Address (reciever and sender)
Accepts message from the application layer as application data, Breaks data into segments(TCP) or datagrams (UDP)
Sequence numbers allocated. - source and destination port numbers are added to header
Transport protocols
TCP
UDP
Network layer purpose
MAC Address (sender and receiver)
Encapsulates segments from transport layers by IP to create IP packets
Each IP packet given header containing source and destination IP address
Source address is allocated to computer sending IP packet
Destination Address locked up via DNS
Network Protocols
IP
Link Purpose
No protocols
Error Checking (checksum)
Operates across a physical connection (e.g Ethernet)
IP packet further encapsulated by Ethernet frames
Header of frames contain MAC address and type field to indicate what payload carrying
DHCP
Pool of unused IP address
When a new device wants to join a network the DHCP recognises the request and allocated a temporary IP address
When device is no longer on network IP address is returned to DHCP
POP3
Download emails stored on a remote server to a local client ( remove after download)
IMAP
manages emails on a server so multiple clients can access same email account in synchronity
SMTP
Used to send emails and forward them between mail servers to their destinations
HTTP(S)
Data requested is transferred and stored in a database. Sent to a crud application and then a SQL command
Used when interacting with web server, rendering web pages, handling user data
FTP
Protocol used to transfer files
SSH
Remote log in to another device
