lectures.alex.balgavy.eu

Lecture notes from university.
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      1 +++
      2 title = "Overview"
      3 +++
      4 
      5 # Overview
      6 Network types:
      7 
      8 - Personal Area Network: range of a person
      9 - Local AN: home/office building
     10 - Metropolitan AN: over e.g. city (like cable tv)
     11 - Wide AN: over a country (an ISP is a WAN, so is a VPN)
     12 
     13 Protocol layers
     14 
     15 - each protocol instance talks to its peer, using only the layer below
     16 - lower level services are accessed through interface.
     17 - at bottom, medium carries messages
     18 - each lower layer adds a header with ctrl info
     19 - example protocol stack:
     20 
     21 ![screenshot.png](c8050940fc41972164af6d5b72ec210d.png)
     22 
     23 - base stations remove headers that are not relevant:
     24 
     25 ![screenshot.png](f7f49be91a74e710095beef7affd4192.png)
     26 
     27 - connection-oriented layer service has to be set up for ongoing use, in connectionless service messages are handled separately (like postal service)
     28 
     29 Services & protocols
     30 
     31 - service is provided to higher layer as primitives
     32     - LISTEN, CONNECT, SEND, RECEIVE…
     33     - example of communication:
     34 
     35 ![screenshot.png](143cf1f67448a436383fca24f5ea75f7.png)
     36 
     37 - a layer provides service to one above (vertical)
     38 - a layer talks to its peer using a protocol (horizontal)
     39 
     40 OSI reference model (international standard)