Computer Networks

Computer Networks
An Introduction
• Network is defined as: A group of two or
more computer systems linked together
• local-area networks (LANs) : The
computers are geographically close
together (that is, in the same building).
• wide-area networks (WANs) : The
computers are farther apart and are
connected by telephone lines or radio
• metropolitan-area networks MANs): A
data network designed for a town or city.
• In addition to these types, the following characteristics
are also used to categorize different types of networks:
• topology : The geometric arrangement of a computer
system. Common topologies include a bus, star, and
ring. See the Network topology diagrams in the Quick
Reference section of Webopedia.
• protocol : The protocol defines a common set of rules
and signals that computers on the network use to
communicate. One of the most popular protocols for
LANs is called Ethernet. Another popular LAN protocol
for PCs is the IBM token-ring network .
• architecture : Networks can be broadly classified as
using either a peer-to-peer or client/server architecture.
Peer to Peer Network
Ethernet Packets
• Think of a packet as a
suitcase, tagged to
travel to a different
city, moving along a
conveyor belt in an
airport: In addition to
the data itself, each
packet carries a
destination address
and your computer's
"home" address.
Network Equipment
• Inside the LAN, packets flow along wires; the
arrangement of the wires and connected computers is
called the topology of the network. Though the Ethernet
specification accounts for many topologies, the most
popular configuration is called the star topology. In this
kind of network, each computer (or node) connects
directly to a centralized device (or hub). Hubs receive
packets from one node and distribute them to other
nodes. Passive hubs simply pass every incoming packet
out to every connected node; switched hubs send
packets to only the node to which the packet is
Cable that carries the signal
CAT5- 100 MBPS
CAT5E- 1000 MBPS
CAT6- 10 gig
Fiber- No Maximum found yet, they have
pushed over a Terabyte in one second
over single strand fiber.