Computer Networking — A Top-Down Approach Chpt 1

CHAPTER 1

Overall introduction to “Computer” network and Internet.

1. Network Edge — wire, wireless; DSL, Cable, FTTH, …; twisted-pair copper wire, Coaxial Cable, Fiber Optics, …;

2. Network Node — Packet Switching(queue, forwarding) vs Circuit Switching(frequency-division multiplexing (FDM) or time-division multiplexing (TDM))

3. Network of Network — tier-1 ISPs, lower-tier ISPs

4. Packet Switching — Delay, Loss, and Throughput

5. Nodal delay = nodal processing delay + queuing delay + transmission delay + propagation delay

6. Comparing Transmission and Propagation Delay:

The transmission delay is the amount of time required for the router to push out the packet

The propagation delay is the time it takes a bit to propagate from one router to the next

7. Queuing Delay — La/R; L bit-long packet; R rate transmission; a packet per sec

8. Packet Loss

9. End-to-End Delay — d = N * (d_proc + d_trans + d_prop)

10. Traceroute — Because of Queuing delay; round-trips_delay[i+1] < rtd[i] is possible

11. Throughput — instantaneous throughput

12. Protocol layers; Layered architecture

a. Each layer performs certain action

b. Each layer uses service provided by the layer below it directly

13. Application Layer — Protocols: HTTP, SMTP

14. Transport Layer — TCP; UDP

15. Network Layer — Moving packets; datagrams

16. Link Layer — Ethernet; packet -> frames

17. Physical Layer — actual bit transmission; medium of the link/bits

18. OSI — Application Layer, Presentation Layer, Session Layer, Network Layer, Data Link Layer, Physical Layer

19. Presentation Layer — Data compression, data encrytion, data description

20. Session Layer — delimiting & synchronization of data exchange

21. Router VS Switches — $1 is able for IP protocol (3 layers); $2 only for 2 layers

22. DoS — Denial of Service