INF3190 - Data Communication Summary (part 2)€¦ · INF3190 - Data Communication Summary (part 2) Carsten Griwodz Email: [email protected] . University of Oslo INF3190 – Data Communication

INF3190 – Data Communication University of Oslo

INF3190 - Data Communication

Summary (part 2)

Carsten Griwodz Email: [email protected]

INF3190 – Data Communication University of Oslo

§  Recap protocol terminology −  several OSI terms are not

introduced by Tanenbaum

§  Remember the functions of the OSI model −  very brief in the book −  but terminology persists and is

used in unexpected contexts

Basics

INF3190 – Data Communication University of Oslo

Baseband transmission schemes (very brief in Tanenbaum pp. 145) §  presented −  binary encoding /

NRZ (non-return-to-zero) −  NRZI −  Manchester −  Differential Manchester

Passband transmission (Tanenbaum pp. 110) §  approximating digital signals §  definition of bandwidth and wavelength §  bits vs. bauds

−  amplitude, frequency, phase

§  bitrate of a perfect channel (Nyquist’s theorem) §  capacity of a noisy channel (Shannon’s theorem)

−  reasons for noise

Physical layer

0!

Am

plitu

de (V

)!

f! 3f! 5f!

INF3190 – Data Communication University of Oslo

Framing (Tanenbaum pp. 217) §  What are the options? Error correcting codes (Tanenbaum pp. 224) §  Hamming distance §  CRC

−  generator polynomial −  modulo-2-arithmetic: subtraction = XOR

Flow control (Tanenbaum pp. 235) §  Protocol examples

−  stop-and-wait, go-back-n, selective repeat

§  Sequence number ranges §  Maximum link utilization

(very brief in Tanenbaum)

Data Link Layer

INF3190 – Data Communication University of Oslo

DNS (Tanenbaum pp. 629) §  recursive and iterative queries §  not in Tanenbaum

−  caching −  aliasing −  zoning and load balancing

HTTP (Tanenbaum pp. 664) Email / SMTP (Tanenbaum pp. 641)

Application layer

www.google.com

mpg.ndlab.net

records.sigmm.org

drammen.ndlab.net

simula080.simula.no

INF3190 – Data Communication University of Oslo

Multimedia (not in Tanenbaum) §  classes and characteristics of continuous media §  UDP or TCP? §  basic challenges

−  delay, loss, jitter −  jitter compensation −  loss compensation

RTP (Tanenbaum pp. 564) §  wrong section! not a transport protocol! §  relation between RTP and Application

layer framing / Integrated layer processing §  role of RTCP §  mixers and translators (not in Tanenbaum)

Application layer

packets

time

packetsgenerated

packetsreceived

loss

rp p'

playout schedulep - r

playout schedulep' - r

INF3190 – Data Communication University of Oslo

Signaling protocols §  RTSP (briefly mentioned in Tanenbaum p.733) §  SIP (Tanenbaum pp.749)

−  proxy mode and redirect mode

Quality adaptation (not in Tanenbaum) §  Loss-Delay Adjustment Algorithm §  Blurriness, noise and motion flicker

HTTP Adaptive Streaming (not in Tanenbaum) §  comparison to RTP streaming §  handling of bandwidth fluctuations

Application layer

INF3190 – Data Communication University of Oslo

Content Delivery Networks (Tanenbaum pp. 761) Modeling popularity (not in Tanenbaum) §  use and misuse of

the Zipf distribution

Peer-to-peer networks (briefly discussed in Tanenbaum pp. 766) §  Distributed Hash Tables

(DHT) §  Chord – where most things

are O(log(n))

Application layer

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Actual popularity

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Actual number of hits