1. Network Configurations
Introduction to Digital Technology
Networks can be configured or organized in a variety of ways. In this lesson we will look at several of the most common configurations. We will compare and contrast each type.

2. Client/Server Network
A client/server network the server is the host computer that serves the other computers, or clients. The server controls access to the hardware, software and other resources on the network, and provides a centralized storage are for programs, date and information. The clients do not communicate with each other. Everything goes through the server.
Server is ‘host’
Clients do not communicate with each other

3. Peer-to-Peer Network Personal computers act as both client and server
Each computer has access to the others
Some restricted access available
Less expensive but...
Less efficient when large amounts of data need to be exchanged
A peer-to-peer network is made up of personal computers, each of which acts as both client and server, so that each can exchange files directly with every other computer on the network.
Each computer can access any of the others, although access can be restricted to those files that a computer's user chooses to make available
A Peer-to-peer networks are less expensive than client/server networks but less efficient when large amounts of data need to be exchanged

4. Peer-to-peer
Here is an example of a peer-to-peer network. Notice how the computers can access each one in the network. There is no central server that controls information.

5. Client/Server vs. Peer-to-Peer
Here is another illustration to compare the client/server network to the peer-to-peer network.

6. How do we choose the architecture?
Type of user
Size of the organization
Administration
Security
Network traffic
Cost
Scalability
So how do we choose which type of network or ‘architecture’ should be used?
When making this decision, network developers look at several elements or parameters to determine which would be best. SHOW LIST AND READ
Let’s look at a comparison of peer-to-peer along these parameters to see how decisions are made.

7. Comparison of … Peer-to-peer Client/Server Type of user
Homes and small businesses
Large corporations, schools, and hospitals
Size of organization
Limited number of workstations
Large number of workstations
Network traffic
Limited number of users
Large number of users
Administration
User
Central administrator
Security
Individual users
Network administrator
Cost
Inexpensive to implement
Usually more expensive than peer-to-peer
Scalability
Limited growth
High growth projected
A peer-to-peer network is used mostly by homes and small businesses, while larger corporations, schools and hospitals use the client/server networks. This is because peer-to-peer works best with limited workstations and a limited number of users. Client/server networks are efficiently used with a large number of workstations and users.
Administration and security of the network are handled by the user in peer-to-peer networks, while in the client/server network there is a central administrator that maintains the network and the security.
Obviously it costs more to set up and maintain a peer-to-peer network than a client/server network.
Also, peer-to-peer networks do not have as much capability of growing without losing its efficiency, while a client/server network can easily be increased in size with minimal cost and effort.

8. 22

9. Topology
So once a decision is made, how are the nodes of the network arranged? This refers to the ‘topology’ of the network.

10. Topology Physical arrangement of devices in a network Common types:
Bus
Star
Ring
Tree
The topology refers to how the devices are physically arranged in order to suit the user(s) of the network as well as the organization (or home) in which the network is located.
The four common topologies are: star, ring, bus and tree.

11. Bus Topology Linear configuration Broadcast message to all computers
One cable
Broadcast message to all computers
Work best in networks with just a few computers
The bus topology is a linear configuration in that a single cable connects all of the devices in a row. Each device attaches to, or taps into, the single cable with an interface connector. Devices wanting to communicate with other devices on the network send a broadcast message. The other devices can see it, but only the intended recipient actually accepts and processes the message. This network topology works best with just a few computers.

12. Bus Topology Advantages: Easy to connect Requires less cable length
Disadvantages
Entire network affected by cable issue
Difficult to identify problems
One advantage to the bus topology is that it’s very easy to connect a computer or peripheral device to the linear bus or cable. Also, this topology requires less cable length than others.
A disadvantage is that if there is a break in the main cable, the entire network shuts down, affecting all computers. This makes it difficult to identify a problem since the entire network shuts down.

13. Star Topology Central connection point Often used in home networks
hub, switch or router
Often used in home networks
Star Topology
The STAR topology features a central connection point called a "hub“. Although it could be an actual hub, it may be a switch or router.
This topology is often used in home networks. Let’s look at the advantages and disadvantages of the star topology.

14. Star Topology Advantages: Disadvantages: Easy to install
Failure in a cable will not affect other computers
Easy to detect faults and to remove parts
Disadvantages:
If the hub fails, the entire network also fails
Requires more cable than linear topology
The star topology is very easy to install as each computer is connected directly to the hub. If one of the cables or a computer fails, the other computers are not affected. Therefore it’s easy to detect where a problem lies and to repair the defect.
However, if the HUB fails, the entire network will shut down. Another disadvantage is that the star topology requires more cable than the linear bus topology discussed previously.

15. All messages travel through a ring in the same direction (either "clockwise" or "counterclockwise")
Found in some office buildings or school campuses
Used for LANs primarily
Ring Topology
The next type of topology is the RING topology. In this configuration, every device has exactly to neighbors for communication purposes. All messages travel through a ring in the same direction (either ‘clockwise’ or ‘counterclockwise’). When a computer or device sends data, the data travels to each computer on the ring until it reaches its destination.
One disadvantage to this is that if any cable or device breaks, then the entire loop will be affected.
This topology is found in some office buildings or on school campuses and is used primarily for LANs networks.

16. Ring Topology Advantages Disadvantages
Spans larger distance than bus network
Disadvantages
A failure in any cable or device breaks the loop and can take down the entire network
Difficult to install
The only real advantage to a ring topology is that it can span larger distances than the bus network. The main disadvantage is that if a cable or device breaks, then the loop is broken and the entire network is down. Also, this type of topology is difficult to install.

17. Tree Topology Combination of star and bus topologies
Hubs in bus configuration
Segments created from each hub in ‘star’ configuration
The TREE topology uses a combination of multiple star topologies with the bus topology.

18. Tree Topology Disadvantages Advantages
Point-to-point wiring for individual segments
Supported by several hardware and software venders
Easier to expand than bus or star
Disadvantages
Overall length of each segment is limited by the type of cabling used
Segments dependent on hub bus line
More difficult to configure and wire than other topologies
The tree topology uses point-to-point wiring to set up individual segments, making it easier to expand than the bus or star alone. Also this type of topology is supported by several hardware and software venders, making it easier to get additional and/or replacement parts.
Since this topology is a combination of two types, it is more difficult to configure. Also depending on the type of cabling used, the length of each segment could be limited. Finally, if the ‘bus’ line breaks, the entire segment or branch of the tree will go down.

19. Considerations When Choosing a Topology
Money
Length of cable needed
Future growth
Cable type
When considering the type of topology to use, network developers will consider the cost involved in the configuration, the length of cable needed, the capability of the network’s growth in the future, and the type of cable.