Transcript WHAT IS NETWORKING? - University of Washington

WHAT IS NETWORKING?
Networking is …
How computers talk to each other
Overview of Today
• Types of Networks
• Data Processing on Networks
• Communications Circuits
• Communications Devices
• TCP/IP Protocol and Routing
Types of Networks
LAN (Local Area Network)
Local area networks usually occupy a room or building, and
typically include a group of PCs that share a circuit. Support
data rates of 10 to 100Mbps.
Types of Networks
MAN (Metropolitan Area Network)
Air Force Base
Capitol Building
Office of Public
Works
Sacramento Army Depot
San Francisco
Executive Airport
MANs usually span 3-30 miles and can support data rates of
100 – 1000Mbps.
Types of Networks
WAN (Wide Area Network)
Seattle
Chicago
Sacramento
New
York
Los Angeles
Phoenix
WANs span hundreds or even thousands of kilometers. Leased circuits or
other commercially available services are used to transmit data. Supports
data rates of 28.8 Kbps – 2Gbps.
These different types of networks
are linked together!
WAN
MAN
MAN
LAN
LAN
MAN
MAN
LAN
LAN
WANs are interconnected too
WAN
WAN
WAN
WAN
WAN
Example
Trace Route to http://www.bbc.co.uk/
IP: 212.58.240.120
What a LAN might look like:
Router
HUB
Circuit: The pathway
through which the
messages travel
Client
Computers
File
Server
Web
Server
Print
Server
Data Processing on Networks
• Host-Based Architectures
• Client-Based Architectures
• Client-Server Architectures
Host-Based Architecture
Client (user)
Terminals
Problems:
-All processing is done by the host which creates a
bottleneck
-Upgrades require big jumps and are expensive
Host
(Mainframe computer)
Presentation Logic
Application Logic
Data access logic
Data storage
Client-based Architecture
Client
(microcomputer)
Presentation Logic
Application Logic
Data access logic
Server
(microcomputer)
Data storage
Problem:
All data must travel between server and clients
Why is this a problem?
It creates network congestion that can cause poor network performance
Client-Server Architecture
Client
(microcomputer)
Presentation Logic
Application Logic
Server
(microcomputer)
Data Access Logic
Data storage
• More efficient
• More reliable
• Allows hardware and software from
different servers to be used together.
Bandwidth
WHAT IS IT?
Twisted Pair
• Most Commonly used
• WHY are they twisted?
• Two Types
– Shielded:
• Difficult to Install and use
• More expensive
– Unshielded:
• Easier to Install
• More susceptible to Interference
Twisted Pair Pros and Cons
PROS
CONS
-Inexpensive
-Easy to get
-Flexible and lightweight
-Easy to work with
-High interference
-Signal weakens over
time
-Relatively low
bandwidth
Coaxial Cable
Inner Conductor
Insulator
Coaxial cable was
invented in 1929 and
first used
commercially in 1941
Wire mesh (ground)
Outer protective shell
TV companies use coaxial cable between
community site out to businesses and
telephone poles between users.
Biggest difference
between coaxial and
twisted pair is that it is
better shielded
Coaxial Cable
PROS
CONS
-Higher bandwidth
-Signal strength wanes
fairly quickly over
distance
-Expensive over long
distances
-Bulky
• 350-600MHz
•Up to 10,800 voice conversations
-Easy to work with
-Less interference than
Twisted Pair
Fiber Optic Cable
Plastic Jacket
Glass Cladding
Fiber Core
Fiber in the real world
Fiber Optic Cable
PROS
CONS
-Greater Capacity
-Data rates of up to 2Gbps
-Strong signal over distance
-Small and lightweight
-Immune to electromagnetic
interference
-Good security
-EXPENSIVE
-Difficult to install
Fiber Optic Cable is THE FUTURE!
Want to learn more? There are tutorials on
the web:
• http://www.iec.org/online/tutorials/fiber_optic/
• http://www.arcelect.com/fibercable.htm
Wireless
To Internet
Wireless
• Balmer! 
• Popular in LAN use
• WHY?
Flexibility!
Cost: No wires to install!
It’s fast!
• What are possible cons?
Security
More Interference – what does this mean?
Satellite Transmission
PROS
-Can reach a large
geographical area
-High bandwidth
-Cheaper over long
distances
CONS
-High Installation Cost
-Interference from lots of
factors, including weather
Another look at the LAN
Router
HUB
or
Switch?
HUB
• Old technology
• Stupid, why?
Broadcasts to all computers on the network,
which creates unnecessary traffic
Switch
• Does everything a HUB can do, but it’s
smarter
• Forwarding Tables allow switches to send
messages directly to the computer who it’s
supposed to go to
Switch
Kim
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Ron
Meg
Amy
TCP/IP
Transmission Control Protocol/Internet Protocol
• What is it?
A Protocol! Yeah, but what does that mean?
A Language that computers use! We use English, they use TCP/IP
• What does it look like?
111.111.111.111  4 octet number
All computer must have an IP address to use the Internet. Why?
It’s the address of the computer, just like you have a street address
TCP/IP
140.142.200.95
128.95.230.3
128.95.230.54
128.95.230.100
140.142.200.100
140.142.200.34
128.95.230.80
OSI Model
Suzy
Rachael
7. Application
7. Application
6. Presentation
6. Presentation
Application Layer
5. Session
5. Session
4. Transport
4. Transport
Internetwork Layer
3. Network
3. Network
2. Data Link
2. Data Link
1. Physical
Hardware Layer
1010001011101000111010
1. Physical
How packets move across the
Internet
Asynchronous Packet Transfer
• Out of order
• How does the computer know what order
they should be in?
– There is a header on each packet
• Why is this good?
– Each packet can find the fastest way (not
necessarily the most direct way)
• Synchronous Packet Transfer