Transcript Sullivan - Oregon State University

Telecommunications and Networking
Dr. V.T. Raja
Oregon State University
[email protected]
Summer 2007
Outline
• Introduction
– Why care about telecom/networking? Why
should non-IT business students learn basics
about telecom/networking?
• Some basics about Telecom/Networking
– Analogy with effective human communication
Why telecom/networking?
Some Reasons
Some Basic Characteristics of Effective Human Communication
• Sender/Receiver
• Messages (Words)
• Transmission Media
Air/Printed Page
• Speak same language or have an Interpreter
• Less noisy room (or) talk loud
Some Basic Characteristics of
Telecommunication Networks
Wired Transmission Media
• Twisted Pair Cables
• Coaxial Cables (Cable TV)
• Fiber Optic Cables
• Wavelength Division Multiplexing
Wireless Transmission
• Infrared (as in a TV remote)
• Radio Signals (as in microwave transmissions)
• Satellites
– GEOS: Geosynchronous Earth Orbiting Satellites –
stationary orbit at 22,300 miles above the Earth
– LEOS: Low Earth Orbiting Satellites
•
•
•
•
Closer to the Earth and reachable from mobile devices
200-1,000 miles above the Earth
Not stationary, goes around the Earth in about 90 minutes
60-70 LEOS are needed to cover the Earth
– http://www.orbitaldebris.jsc.nasa.gov/index.html
Communication Protocols
• Speak same language or have an
interpreter
– HTTP (Hyper Text Transfer Protocol)
– SMTP (Simple Mail Transfer Protocol)
– TCP (Transmission Control Protocol)
– IP (Internet Protocol)
– Ethernet
Communication Protocols (Continued)
• Ethernet
– Media Access Control (Traffic Cop – Who has access
to transmission media and when? How to
handle/resolve collisions?)
– Error Detection/Correction
– Message Delineation (Identifying beginning and
ending of packets – framing)
• TCP
– Packetizing (Breaking messages into smaller packets
and reassembling packets in the correct order)
– Keeping track of packet #s
Communication Protocols (Continued)
• IP
– Addressing (DHCP and DNS)
– Routing
• Tracert www.__________
• Tracert www.stfx.ca
Some Internetworking Devices
• Routers, hubs, switches
– routers use routing rules to forward packets to
the next appropriate destination
– hubs forward all packets on all connected
wires
– switches keep track of which computer is on
each line and send packets only to the
desired destination
Routers
This is how packets find their way
around the Internet
A
Router
Router
Router
Router
Router
Router
Router
B
Hubs vs. Switches:
Switching increases performance, security,
and cost
A
B? That’s not for
me, I’ll ignore it
B? So
what?
Nothing
What’s
here
this?
Switch
Hub
Oh,
Good!
I’m not
B
B
Network Design
How to support full connectivity?
• Design the most economic
internetwork between “end-user
nodes” and an existing WAN
Usernode
Usernode
Usernode
Usernode
Usernode
Usernode
Usernode
Usernode
Usernode
WAN
Usernode
Network Design (Continued)
Find an economic internetworking solution
A direct connection to
a WAN backbone node
Connection via
multiplexers
Usernode
Usernode
Usernode
Usernode
Usernode
Usernode
Usernode
Usernode
Usernode
Usernode
Usernode
Usernode
Some Network Design Issues
Major Cost Components
• A Multiplexer (MUX) consolidates network traffic from
several users on slower links and connects them to a
fast link (e.g. a WAN such as the Internet).
• Acquisition and installation costs of a MUX
• Cost of high bandwidth link between MUX
and WAN (Internet)
• Cost of low bandwidth link between end-user
node and MUX
Some Network Design Issues
(Continued)
• Find an optimal number of MUXs to interconnect all
given user nodes to some existing WAN such that ...
 All user nodes are connected
 User communication requirements are satisfied
 Capacity constraints on each MUX is not violated
 Total internetworking costs are minimized
 Topology issues are considered
Example 1
Example 2
Example 3