Networking Summary and Supplemental

Networking Hardware

Hub:

Connects computers and other hardware

Switch: Like a hub, but with an intelligent design

Firewall:

  • Can be either hardware or software
  • Prevents unauthorized communication via a set of predetermined rules

Router

  • Exists between networks

  • Commonly a LAN and the Internet

  • Uses a routing configuration table

  • Different types for different environments

Router that shows ADSL line and Ethernet connections (for LAN/WAN0

Internet Connection Sharing

  • Home broadband Routers
  • Office Network Routers
  • Major Traffic Routers

Wired Media

Ethernet Cable

  • 2 pairs of cables
  • CAT5 and CAT6 wire, RJ-45 connector
  • 100 m (320 ft) without signal loss

Coaxial Cable

  • Copper wire; Durable and insulated
  • 500 m without signal loss
  • Single direction data transfer

Fiber Optics

  • Uses pulses of light
  • Travels at the speed of light
  • 145 km without signal loss
  • Primarily choice for telecommunication industry
  • Example: Verizon Fios, Google Fiber, ATT Fiber

Wireless Media

  • Wi-Fi
    • Standardized by the IEEE
    • 802.11 groups: a, b, g, n
  • MIMO (Multiple Input Multiple Output)
  • Bluetooth
  • Cell phones
Bluetooth symbol
Wi-Fi Symbol

Network Topology

Area networks

LAN – WAN – MAN and VLAN

Classification of Networks by Scale (Reference link)

VLAN is virtual LAN (setting up a LAN, but with software). Think of a ‘virtual switch’.

Configurations

DescriptionAdvantageDisadvantage
Tree:collections of star networks arranged in a hierarchyReduces wiringA failed node will fragment the network
Star:computers are connected by one central device known as a concentratorHigh wire usageConcentrator failure disables the network
Bus:set of clients is connected using a single shared connection line known as a bus. The single connection line  uses CSMACheapest and easiestLine break drops network
Ring:Nodes are connected in a circular configuration. Data travels in one directionLine breaks doesn’t completely disable computersIsolation issues can occur if a device fails

Layers

LayerExample
Link LayerEthernet
Internet LayerInternet Protocol (IP)
Transport LayerTransmission Control Protocol (TCP)
Application LayerHyperText Transfer Protocol (HTTP)
Internet layers with example protocols

Domain Name Server

  • Why domain names?
  • user friendly
  • no need to remember IP address
  • load balancing
  • same name maps to changing IP address
  • decoupling
  • can move server to different network, ISP, etc.

Domain names are hierarchical!

SSH

  • Program that enables a computer to log into another computer over a network
  • Works securely due to tunneling and encryption
  • Secure against:
    • Spoofing
    • Source Routing
  • No protection from root access