Computer Networks

Introduction

• Overview
• Examples of networks

The OSI 7-Layer Model:

Seven layers, created for different abstractions. Each layer does well-defined functions

Minimises info flow across layer interfaces.

Layers:

1. Physical — sends bits as analog signals

   1. Physical: Basis for data communication

   2. Physical: Transmission Media

   3. Physical: Modulation & multiplexing

2. Data Link — sends frames of information

   1. Data Link: Overview & framing

   2. Data Link: Error detection/correction

   3. Data Link: Protocols

   4. Medium Access Control Sublayer

      1. MAC: Overview & allocation methods

      2. MAC: Protocols

      3. MAC: Use in Ethernet

      4. MAC: Use in Wifi & Broadband

      5. MAC: use in Bluetooth & RFID

3. Network — sends packets over multiple data links

   1. Network: overview

   2. Network: routing

   3. Network: providing service

   4. Network: internet protocols

4. Transport — provides end-to-end packet delivery

   1. Transport: overview

   2. Transport: elements of transport protocols

   3. Transport: internet transport protocols

5. Session — manages task dialogs using tokens

6. Presentation — converts different representations

7. Application — provides functions needed by users