Skip to main content

Internet

Consist​

Internet Service Provider -> Packet Switch/Communication Link -> Host/End System.

Delay​

nodal = proc + queue + trans + prop: 总时延 = 产生/到达时延 + 排队时延 + 传输时延 + 传播时延.

Layer​

End-to-end principle: implement features in the end-system/hosts where possible.

tip

Congestion implemented on transport layer.

Internet layer:

  • Application layer protocol: HTTP SMTP (message, stream of data).
  • Transport layer protocol: TCP UDP (segment, segment of data).
  • Network layer protocol: IP (因特网的粘合剂) (unreliable datagram, packet of data).
  • Data link layer protocol: WiFi PPP(点对点) 以太网 (frame).
  • Physical layer protocol.

Layering principles:

  • Modularity.
  • Well defined service: simple service model provided by lower level, providing for higher level.
  • Reuse.
  • Separation of concerns.
  • Continuous improvement: change inner structure of layer independently.