1. There are three basic configurations used to connect
computers they are the
Bus
Ring
Star

2. NETWORKING &
TOPOLOGIES

3. Bus topology
This type of network was widely used in the
1980’s
 In this configuration every computer (node)
shares the networks total bus capacities.
 In this configuration adding more computers will
reduce the access speed on the network.
 Each computer communicates to other computers
on the network independently this is referred to as
PEER-TO-PEER networking


4. How a Bus Peer to Peer
Network Works
All computers on a network have a
distinct address just like your house
does
 a message would be send from one
computer with the address of another
computer attached to the message
 The message is broadcasted to all the
computers on the network until the
addressed PC accepts the message


5. Problems

One of the main problems with this type
of network is that it is not very fault
tolerant, a break or defect in the bus
would affect the whole network

6. Ring Topology
In Ring topology each node is connected to the
two nearest nodes so the entire network forms
a circle
 Data only travels in one direction on a Ring
network


7. How this Topology works
a node has information to send to another
computer on the network so it sends the
information out on the network to the PC it
is connected to, if the information is for this
PC (the recipients NIC address is attached
to the message, which is like putting an
address on an envelope) then the PC
accepts the data
 otherwise it passes the information on to
the next PC by repeating the data back out
on the line
 This method of repeating the data helps
keep the integrity of the data readable by
other computers


8. How it Works
As it is better to have computers take
turns using the connecting Data cable,
Ring topologies incorporated a system
called Token passing
 In this topology, to transmit on the wire
your computer must have control of the
token or wait for the token to be free
 Larger Token Ring networks use
multiple tokens


9. Problems and Solutions






The drawback to this type of topology is that a
single malfunctioning workstation can disable the
whole network
To make sure all the information is sent the
receiving PC sends the token back to the sending
PC after it has received all the data
If the sending PC is finished sending it passes the
token to the next PC
This type of network was also widely used in the
1980’s
This type of network used Thinnet cable joining
nodes.
In the mid 1980’s Thinnet cable was replaced by
Category 3 Ethernet cable capable of handling up
to 10Mbps

10. Star topology
HUB
In a Star topology every node is connected
through a central device such as a Hub, Switch
or Router
 Compared to a Ring or Bus topology a Star
topology requires that more thought be put into
its setup


11. The Good and Bad of a
Star Network
The upside of a star network is that if
any one cable fails then only the node
connected on that cable would be
affected
 Another positive point to this type of
network is that it is very simple to join
two star networks together by
connecting their central devices to each
other


12. The Good and Bad of a
Star Network
As each computer is connected to a
central device (Hub) the location of the
Hub must be made as central as
possible, so as to reduce cable lengths
 The drawback to this type of topology is
if a central device was to fail then all
computers connected to that device
would not be able to see the network


13. What is a Hub?
A hub is usually a small rectangular box,
often made of plastic, which receives its
power from an ordinary wall outlet
 A hub joins multiple computers (or other
network devices) together to form a
single network segment
 On this network segment, all computers
can communicate directly with each
other


14. What is a Hub?
Ethernet hubs are by far the most
common type, but hubs for other types
of networks such as USB also exist
 A hub includes a series of ports that
each accepts a network cable
 Small hubs can network four computers
together
 They contain four or sometimes five
ports


15. What is a Hub?
Many times the fifth port is reserved for
"uplink" which is the connecting of one
hub to another hub or similar device
(joining two segments together).
 Larger hubs contain eight, 12, 16, and
even 24 ports


16. Key Features of Hubs
Hubs classify as Layer 1 devices in the OSI
model
 OSI stands for :
The Open Systems Interconnection Basic
Reference Model
 At the physical layer, hubs can support little
in the way of sophisticated networking
 Hubs do not read any of the data passing
through them and are not aware of their
source or destination


17. Key Features of Hubs
Essentially, a hub simply receives
incoming packets, possibly amplifies the
electrical signal, and broadcasts these
packets out to all devices on the network
- including the one that originally sent
the packet!
 a packet is a formatted block of data
carried by a computer network


18. Different Types of Hubs

Technically speaking, three different
types of hubs exist
Passive
Active
Intelligent

19. Passive hubs
 Passive hubs do not amplify the electrical
signal of incoming packets before broadcasting
them out to the network
Active hubs

amplify the electrical signal of incoming
packets back to their original level before
broadcasting them back out on the network

20. What is a Network Switch?
A network switch is a small hardware
device that joins multiple computers
together within one local area network
(LAN)
 Technically, network switches operate at
layer two (Data Link Layer) of the OSI
model


21. What is a Router?
Routers are physical devices that join
multiple wired or wireless networks
together
 Technically, a wired or wireless router is
a Layer 3 gateway, meaning that the
wired/wireless router connects networks
together
 A Gateway is a device that acts like a
security guard and only allows data in or
out if it has the right network headers


22. Routers
Home “networkers” often use an Internet
Protocol (IP) wired or wireless router
 IP is the most common OSI network layer
protocol
 Protocols are the rules governing the
transfer of data information, it can also be
compared to how humans use languages
(to get your point across you must talk in
the same language as the person you are
speaking to).


23. Routers
An IP router such as a DSL or cable
modem are broadband routers and joins
the home's local area network (LAN) to
the wide-area network (WAN) of the
Internet
 A Broadband Router is a device that
allows multiple PC’s to access the
Internet using only one address.
