G4G0-2/Networking and Security/Week 4/Lecture 8.md

OSI	Internet 4 Layer	Protocols
Application Presentation	Application	HTTP SMTP Telnet
Session Transport	Host2Host Transport	TCP, UDP
Network	Internet	IP, ICMP
Data Link Physical	Network Access	PPP IP-over-ADSL IP-over-Ethernet

Internet Protocol Version 4

• Connectionless packet oriented service
• Unreliable service, no guarantee of delivery
• Best effort, no error recovery

All packets routed independently

• Routers examine destination IP address and choose best route to forward packet
• Big packets fragmented, fragments routed separately