1. NETWORK Topologies
An Introduction

2. What is a Network? Several computers linked together by a cable.
Allows users to share resources.
Allows the rapid transfer of data.
Allows users to communicate with each other.

3. Local Area Networks LANs are usually found on a single site.
May be single building, room or floor.
There are four main LAN topologies (maps).

4. Bus Network

5. Bus Network Several stations are connected to a single cable.
Terminators are used to stop data “falling off”.
Advantages of a Linear Bus Topology
Easy to connect a computer or peripheral to a linear bus.
Requires less cable length than a star topology.
Disadvantages of a Linear Bus Topology
Entire network shuts down if there is a break in the main cable.
Difficult to identify the problem if the entire network shuts down.

6. Star Network – Central Hub
Workstation 1
Workstation 2
Workstation 3
Workstation 4
Workstation 5
Central Hub

7. Star Network Stations are directly connected to a central hub.
Data on a star network passes through the hub before continuing to its destination
Advantages of a Star Topology
Easy to install and wire.
No disruptions to the network when connecting or removing devices.
Easy to detect faults and to remove parts.
Disadvantages of a Star Topology
Requires more cable length than a linear topology.
If the hub or concentrator fails, nodes attached are disabled.
More expensive than linear bus topologies because of the cost of the hub.

8. Ring Network

9. Ring Network Cable forms an endless loop.
Stations are directly connected to this loop.
Data flows in one direction around ring.
Topology is commonly implemented as token ring
Advantages of a Ring Topology
Each node in the network is able to purify and amplify the data signal before sending it to the next node.
More stations can easily be added.
Individual workstations can be isolated from the ring.
Disadvantages of a Ring Topology
A break in the ring causes the entire network to fail.

10. Mesh Network

11. Mesh Network Each station is connected to every other station.
Mesh topology's are used in critical connection of host computers (typically telephone exchanges).
Advantages of a Mesh Topology
Any failure of one computer allows all others to continue, as they have alternative paths to other computers.
Alternate paths allow each computer to balance the load to other computer systems in the network by using more than one of the connection paths available.
Disadvantages of a Mesh Topology
Difficult to add more stations.

12. Topology Comparison Features Bus topology Star Ring topology
Mesh topology
Expense
Low
Medium
High
Reliability
Good
Excellent
Geographically coverage ability
Poor
Troubleshooting ease

13. Network Card - NIC
Purpose of NIC is to physically connect computer into network
RJ-45 port
BNC port
Can have an RJ-45 connector port, a BNC connector port or both.

14. Peer–Peer Network
Allow users to share resources and files located on their computers.
They do not have a file server or a centralized management source
All computers are considered equal; they all have the same abilities to use the resources available on the network.
Designed primarily for small to medium local area networks.

15. Peer-Peer Network Advantages of a peer-to-peer network:
Less initial expense. No need for a dedicated server.
An operating system (such as Windows 95) already in place may only need to be reconfigured for peer-to-peer operations.
Disadvantages of a peer-to-peer network:
Decentralized. No central repository for files and applications.
Security. Does not provide the security available on a client/server network.

16. Client-Server Network
Allow the network to centralize functions and applications in one or more dedicated file servers
The file servers become the heart of the system, providing access to resources and providing security.
Individual workstations (clients) have access to the resources available on the file servers.
The network operating system provides the mechanism to integrate all the components of the network.
Novell Netware and Windows NT Server are examples of client/server network operating systems.

17. Client-Server Network
Advantages of a client/server network:
Centralized. Resources and data security are controlled through the server.
Scalability. Any or all elements can be replaced individually as needs increase.
Flexibility. New technology can be easily integrated into system.
Interoperability. All components (client/network/server) work together.
Accessibility. Server can be accessed remotely and across multiple platforms.
Disadvantages of a client/server network:
Expense. Requires initial investment in dedicated server.
Maintenance. Large networks will require a staff to ensure efficient operation.
Dependence. When server goes down, operations will cease across the network.

18. NETWORK Topologies
The End