NETWORKS
TELECOMMUNICATIONS
Two or more computers communicating
Long distance communications
2 Network Classifications
• Client server
• Peer to Peer
Physical definitions
2 Network Classifications
• LAN
• WAN
Distance definitions
LOCAL AREA NETWORK
WIDE AREA NETWORK
NETWORKS
LAN
LOCAL AREA NETWORK
LAN Characteristics
• TOPOLOGY
Bus
Star
Ring
• Protocol
Polling
CSMA/CD
Token Ring
NETWORKS
WAN
WIDE AREA NETWORK
Long distance communication
Generally not privately owned
MAJOR FUNCTIONS
Make long distance communication seem local
Standardize network interface
Standardize procedures for sending information
Govern error transmission
Govern security
Govern integrity of data
NETWORK COMPONENTS
• Computers
• Media
• Software
• Network
connections
• Satellites
• Microwave
stations
• Multiplexer – combines many data streams into a single stream
Additional Media Type
Electromagnetic waves
A type of radio wave
Used by satellites
Used by portable computers
MICROWAVE STATIONS
Needs a direct sight line
SATELLITES
WAN TOPOLOGIES
1. Point to Point
2. Multidrop
3. Mesh
4. Star
Point to Point
Direct Connection
Between Computers
Advantage
No Waiting
Disadvantage
Expensive to connect
Adding new computer
Multidrop
C om p u ter2 C om p u ter3
C om p u ter1
Hierarchical
Between Concentrator
Advantage
No Waiting
Direct connections
Disadvantage
May find delays if going outside
the predefined connections
Adding new computer
Star
Central Point
Time Sharing Host
Advantage
Centralized control
(security)
Disadvantage
Centralized control
(delays)
Mesh
Individual Routes
Needs a router
Advantage
No Waiting
Disadvantage
Connections
(solutions – servers)
Other types of NETWORKS
Public access networks (government)
VAN – value added network
(extra feature – faxes)
Private area networks (Sears)
Public Data Network
(TYMNET)
Wide Area NetworksEnvironments
PSTNPublic Switch
Telephone Network
TYPES of Lines
Private– Direct– Expensive
Tie line– Dedicated without the use of the PSTN
Exchanges– Foreign/private
800 numbers
DDNdata digital network
Only transmits DIGITAL information
PSNpacket switching network
Sends information in groups called PACKETS
ISDNintegrated services
digital network
Sends only digital signals
Transmits HIGH VOLUME of data
Can use the Internet while using the phone line – use of two phone lines
DSLDigital Subscriber Line
Translates digital signals to analog
Transmits HIGHER VOLUME of data than ISDN
Spreads analog signal over a wide range of frequencies