Network Layer

4 Layer Internet Model

• Application Layer
  • Bi-directional reliable byte stream between two applications, using application-specific semantics (e.g. Hypertext Transfer Protocol, bittorrent, SSH, FTP).
• Transport Layer
  • TCP and UDP
  • Guarantees correct, in-order delivery of data end-to-end. Congestion Control
• Network Layer
  • IP and Routing
  • No need to concern how packets are sent via link layer
  • Delivers datagrams end-to-end. Best-effort delivery, no guarantees. Must be used with the Internet Protocol.
• Link Layer
  • Ethernet or wifi
  • Delivers data over a single link between an end host and router, or between routers

7 Layer OSI Model

7 Layer OSI Model

1. Physical Layer
2. Data Link Layer
3. Network Layer
4. Transport Layer
5. Session Layer
6. Presentation Layer
7. Application Layer