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Computer Networks

Computer Networks


Overview

Relevant Orgs

Regional Internet Registries World Map

center


Glossary
  • Collisions: will occur when devices both:
    • Can only handle one operation at any given time
    • Are queried operations while another is in progress
  • Collision domain: link in which collisions can happen, resolved with:
  • Duplex system: two connected parties can bilaterally communicate
    • Half: a device can either send or receive at any given time
    • Full: a device can both send and receive at the same time
  • Flooding: received data is forwarded through all but the receiving port
  • Routing: process of selecting network traffic paths

center


Devices

History

Conceptual Models


Overview

OSI Model & TCP/IP Suite Layers
+------------------+-----------------+
|     OSI Model    |     IP Suite    |
+==================+=================+
|  Application - 7 |                 |
+------------------+                 |
| Presentation - 6 | 4 - Application |
+------------------+                 |
|      Session - 5 |                 |
+------------------+-----------------+
|    Transport - 4 | 3 - Transport   |
+------------------+-----------------+
|      Network - 3 | 2 - Internet    |
+------------------+-----------------+
|    Data Link - 2 |                 |
+------------------+ 1 - Link        |
|     Physical - 1 |                 |
+------------------+-----------------+

Glossary
  • Encapsulation: model layers are added around data
    • In front: header, behind: trailer
  • De-encapsulation: models layers are removed around data
  • Adjacent layer interactions: encapsulation or de-encapsulation
  • Same layer interactions: model layer to same model layer
  • PDUs (Protocol Data Units): single unit of information transmitted
    • Bits: physical layer PDUs
    • Frames: Data link / link layer PDUs
    • Packets: Network / Internet layer PDUs
    • Segments: Transport PDUs
    • Through OSI layers:
--+----------------------------------------------------------------------+
L |                      PDUs - Protocol Data Units                      |
==+===============================================+======+===============+
7 |                                               |      |               |
--+                                               |      |               |
6 |                                               |      |               |
--+                                               |      |               |
5 |                                               | Data |               |
--+                              +----------------+------+               |
4 |                              | Segment Header | Data |               |< SEGMENT
--+              +---------------+----------------+------+               |
3 |              | Packet Header | Segment Header | Data |               |< PACKET
--+--------------+---------------+----------------+------+---------------+
2 | Frame Header | Packet Header | Segment Header | Data | Frame Trailer |< FRAME
--+--------------+---------------+----------------+------+---------------+
1 |                                                                      |< BITS
--+----------------------------------------------------------------------+

OSI Model Layers

TCP/IP Connections


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