Networking 101

1
Networking 101
2
Communications Model
Source
Transmitter
Message
Receiver
Destination
Medium
3
Its All Plumbing and Highways!!
4
Point to Point (Guided)
5
MultiPoint (Unguided)
6
Period

Time
-
Amplitude
Frequency
Bandwidth
Continuous / Analog
Discrete / Digital
7
Common Terms

• Amplitude
• voltage of the signal at any moment in time
• Frequency
• number of periods of the signal in one second
  (cycles per second Hertz (Hz)
• Bandwidth
• total range of frequencies supported by the
  medium (expressed in Hz)

8
Hertz

• Hertz 1-999 hz
• KiloHertz 1000-999,999 hz
• MegaHertz 1,000,000-999,999,999 hz
• GigaHertz billions of hz
• TeraHerz trillions of hz

9
Continuous or Analog

• Radio / TV broadcasts - analog
• Amplitude --- Frequency
• AM changes amplitude
• FM changes frequency
• One stream of information

10
Discrete or Digital

• Data / Voice / Video
• Finite amplitude and finite frequency
• bit (binary 0 or 1 -- on or off)
• byte (8 bits -- represents a character)
• Mbps - Megabytes (millions)
• Information broken into packets

11
Twisted Pair (Category 5)

• Bandwidth 100 MHz
• Data Rate 100 Mbps
• Voice / Data

12
Coaxial

• Bandwidth 250 MHz
• Data Rate 500 Mbps
• Video / Data

13
Fiber Optic

• Bandwidth 2 GHz
• Data Rate 2 Gbps
• Higher potential
• Voice / Video / Data

14
Broadband vs. Baseband

• Broadband
• Frequency division multiplexing
• information is streamed
• Baseband
• Time division multiplexing
• -information is broken into packets

15
Topologies

• Bus

16
Topologies

• Star

17
SchoolNet
Data
Voice
Video In
Video Out
18
SchoolNet
Cat(egory)5 - Twisted Pair
Data
Voice
Video In
Video Out
19
SchoolNet

• Requires the wire to have the capacity to deliver
  voice, data, video-in, video-out.
• Intent of SchoolNet wiring is to place a drop in
  every classroom -- formula is
• ADM / 20 of drops
• 500 per drop
• Requires a Star Topology

20
Networks

• LocalTalk
• Token-Ring
• Ethernet
• Novell

21
Network Interface Cards

• NIC -- Network Interface Cards read the digital
  packets
• they are receivers
• each computer needs one with most
  topologies/protocols
• Apple LocalTalk does not need a card
• LocalTalk connector needed with each device on
  the network

22
Proprietary vs. Non-Proprietary

• Proprietary
• Local Talk
• Novell
• Non-Proprietary
• Ethernet
• Token-Ring

23
When everyone talks at once...

• You need RULES

24
LocalTalk

• cost effective
• slow
• Uses an RS-432 port (plug)
• Uses a Daisy Chain
• Farallon PhoneNet

25
CSMA/CA

• Carrier Sense Multiple Access with Collision
  Avoidance
• computer listens for idle
• computer says it is going to talk now
• all other computers are silent until computer
  stops talking

26
Ethernet

• Originally used Thick Ethernet Cable
• Now uses 10baseT (10Mbps baseband unshielded
  twisted pair) and fiber and thinwire coax
• RJ 45 connector

27
CSMA/CD

• Carrier Sense Multiple Access with Collision
  Detection
• computer listens to see if anyone is talking --
  if no other computers are talking, it knows it
  can talk
• Collisions occur when two computers talk at once
  -- network asks them to wait (random gneration)
  until they start talking

28
Token-Ring

• computer does not listen -- it asks for the
  token
• if the computer does not have the token, it
  cannot talk
• when the network is idle, the token passes from
  one computer to the next until a computer
  requests the token

29
LAN

• Local Area Network
• Limited area
• could be a building
• could be a district
• usually has just one or two connections to
  outside
• Relative

30
WAN

• Wide Area Network
• Has a larger topology

31
Boxes
HUB
splits 10Mb
Drop
32
Boxes

• Switch
• allows 10 Mb per line

100 Mb
10Mb
Hub
33
Boxes
T1
Hub
Router
connects to outside world
need pairs
Switch
usually 1 per building
34
WAN Example
35
Firewall

• Used for network protection
• Can prevent addresses from coming in or going out
• Proxies used to control access