Post on 04-Jan-2016
transcript
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
San Francisco Executive Airport
Sacramento Army Depot
Capitol Building
Office of Public Works
MANs usually span 3-30 miles and can support data rates of100 – 1000Mbps.
Types of Networks
WAN (Wide Area Network)
Seattle
Sacramento
Los Angeles
Phoenix
Chicago
New York
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
MAN
MAN
LAN
LAN
LAN
LAN
WANs are interconnected too
WAN
WAN
WAN
WAN
WAN
ExampleTrace Route to http://www.bbc.co.uk/
IP: 212.58.240.120
What a LAN might look like:
Print Server
WebServer
File Server
Router
Circuit: The pathway through which the messages travel
ClientComputers
HUB
Data Processing on Networks
• Host-Based Architectures
• Client-Based Architectures
• Client-Server Architectures
Host-Based ArchitectureClient (user) Terminals
Host (Mainframe computer)
Presentation LogicApplication LogicData access logicData storageProblems:
-All processing is done by the host which creates a bottleneck
-Upgrades require big jumps and are expensive
Thin CLIENT
Client-based ArchitectureClient
(microcomputer)
Server (microcomputer)
Data storagePresentation LogicApplication LogicData access logic
Problem:
All data must travel between server and clients
Why is this a problem?
It creates network congestion that can cause poor network performance
FAT CLIENT
Client-Server Architecture
• More efficient
• More reliable
• Allows hardware and software from different servers to be used together.
Client (microcomputer)
Server (microcomputer)
Data Access Logic
Data storage
Presentation LogicApplication Logic
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
-Inexpensive-Easy to get-Flexible and lightweight-Easy to work with
CONS
-High interference
-Signal weakens over time
-Relatively low bandwidth
Coaxial CableInner Conductor
Insulator
Wire mesh (ground)
Outer protective shell
TV companies use coaxial cable between community site out to businesses and telephone poles between users.
Coaxial cable was invented in 1929 and first used commercially in 1941
Biggest difference between coaxial and twisted pair is that it is better shielded
Coaxial Cable
PROS
-Higher bandwidth • 350-600MHz
•Up to 10,800 voice conversations
-Easy to work with
-Less interference than Twisted Pair
CONS
-Signal strength wanes fairly quickly over distance
-Expensive over long distances
-Bulky
Fiber Optic Cable
Plastic Jacket Glass Cladding Fiber Core
Fiber in the real world
Fiber Optic Cable
PROS
-Greater Capacity
-Data rates of up to 2Gbps
-Strong signal over distance
-Small and lightweight
-Immune to electromagnetic interference
-Good security
CONS
-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?
• What are possible cons?
Flexibility!
Cost: No wires to install!
It’s fast!
Security
More Interference – what does this mean?
Satellite TransmissionPROS-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 LANRouter
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
Ron
Meg
Amy
TCP/IPTransmission 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
128.95.230.3
128.95.230.54
128.95.230.80
128.95.230.100
140.142.200.100
140.142.200.95
140.142.200.34
OSI Model
7. Application
6. Presentation
5. Session
4. Transport
3. Network
2. Data Link
1. Physical
7. Application
6. Presentation
5. Session
4. Transport
3. Network
2. Data Link
1. Physical1010001011101000111010
Suzy Rachael
Application Layer
Internetwork Layer
Hardware Layer
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