Computer slides

1. Network Topologies

2. What is Topology?
• The topology of a space is the definition of a
collection of sets (called the open sets) that include:
– the space and the empty set
– the union of any of the sets
– the finite intersection of any of the sets
• “Topological space is a set with the least structure
necessary to define the concepts of nearness and
continuity”

3. Types of Topologies
•
•
•
•
•
Bus Topology
Star Topology
Ring Topology
Mash Topology
Tree Topology

4. Bus Topology
• A bus topology connects all stations in a linear fashion

5. Bus Topologies
• Bus topology advantages:
– It is inexpensive
– It is easy to design and implement because the
stations are simply daisy-chained together
• Bus topology disadvantages:
– It is difficult to troubleshoot
– It requires termination

6. Star Topologies
• The star network configuration is the most popular
physical topology
• In a star configuration, all computers or stations are
wired directly to a central location:
– Concentrator (a.k.a. hub)
– Multistation Access Unit (MAU)
• A data signal from any station goes directly to this
central device, which transmits the signal according
to the established network access method for the
type of network

7. Star Topology

8. Star Topologies
• Star topology advantages:
– A break in one cable does not affect all other
stations as it does in bus technologies
– Problems are easier to locate because symptoms
often point to one station
– The second-easiest topology to design and install
– Does not require manual termination
• Instead the media is terminated in the station at the
transceiver on the NIC and in the hub or MAU

9. Star Topologies
• Star topology disadvantages:
– Hubs, which are required for a star topology, are
more expensive than bus connectors
– A failure at the hub can affect the entire
configuration and all connected stations
– Uses more cable than bus topologies

10. Star Topologies
• Bus and star topologies can be combined to form
a star/bus or bus/star physical topology
• Hubs that have connectors for coaxial cable as
well as for twisted-pair wiring are used to form
these types of networks
• When different physical topologies are applied to
a network, the result is often called a mixed
media network

11. Ring Topology
• Physical rings
– Most often seen in Fiber Distributed Data
Interface (FDDI) networks
• FDDI is a WAN technology
– Stations on a ring are wired to one another in a
circle around the entire network

12. Ring Topology

13. Ring Topologies
• Ring topology advantages:
– It prevents network collisions because of the
media access method or architecture required
– Each station functions as a repeater, so the
topology does not require additional network
hardware, such as hubs

14. Ring Topologies
• Ring topology disadvantages:
– As in a bus network, a failure at one point can
bring down the network
– Because all stations are wired together, to add a
station the network must be shut down
temporarily
– Maintenance on a ring is more difficult than on a
star topology because an adjustment or
reconfiguration affects the entire ring

15. Tree Topology
• Characters of bus and star topology
• Different groups
• Backbone cable

16. Tree Topology

17. Tree Topology
• Advantages
– It provides point to point wiring for individual
segments
– It is supported by several hardware and software
venders

18. Tree Topology
• Disadvantages
– Overall length of each segment is limited by the
type of cabling used
– If the backbone line breaks the entire segments
goes down
– It is more difficult to configure and wire than
other topologies

19. Mesh Topology
•
•
•
•
Physically connected
Improved performance and reliability
Don’t used in local area network
Used in wide area network

20. Mesh Topology

21. Mesh Topology
• Advantages
– Dedicated link guarantee that each connection
carry its own data load
– Eliminates the traffic problems
– If one link become unusable it does not harm the
entire system
– It is easy to troubleshoot

22. Mesh Topology
• Disadvantages
– Very expensive
– Difficult to install and reconfigure