11.6.2.3 know the features of the client-server model
Model "Client-Server" vs model "Peer-To-Peer"
LANs and WANs can be peer-to-peer, client-server, or mixed networks (which use both peer-to-peer and dedicated server technologies).
Model "Client-Server"
The client-server model is a relationship between two computers in which one, the client, makes a request to a server that responds to the client's requests.
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All computers connected to the network and directly participating in the exchange of data are considered nodes or hosts. Hosts are so-called endpoints. Hosts play a role in the operation of the network. Some hosts are responsible for security, others are for providing web services. There are also a number of legacy or integrated systems that are responsible for performing specific tasks, such as working with files or printing. The hosts responsible for providing services are called servers. Hosts that use such services are called clients.
A client is a hardware or software component of a computing system that sends requests to a server.
The server processes the client's request, searches for the required data and sends it to the client.
Advantages
Disadvantages
All files are stored in a centralized storage. This makes it easier to manage and back up data since it's all located in one place.
Requires a dedicated network operating system. Implementing a centralized storage system often requires specialized network operating systems and software.
Network peripherals are centrally managed. This allows for easier configuration, monitoring, and maintenance of network peripherals such as printers, scanners, and storage devices.
The server is expensive. Setting up and maintaining a robust server infrastructure can be costly, especially for smaller organizations or those with limited budgets.
Backup and network security are centrally controlled. This makes it easy to regularly back up all your important data, reducing the risk of data loss in the event of hardware failure or other disasters.
Requires trained personnel with expertise in network administration (system administrator)
Users can access shared data from any connected device on the network, which is controlled centrally.
If the server fails, then all computers on the network lose access to the data.
Computers in peer-to-peer networks can act as both clients and servers.
Peer-to-peer networks do not have centralized control over resource sharing.
Any of the computers can share their resources with any computer on the same network. Peer-to-peer relationships also mean that no computer has a higher priority for access or increased responsibility for sharing resources.
Client-server
P2P
Security
The server controls security of the network.
No central control over security.
Management
The server manages the network. Needs a dedicated team of people to manage the server.
No central control over the network. Anyone can set up.
Dependency
Clients are dependent on the server.
Clients are not dependent on a central server.
Performance
The server can be upgraded to be made more powerful to cope with high demand.
If machines on the network are slow they will slow down other machines.
Backups
Data is all backed up on the main server.
Each computer has to be backed up. Data can easily be deleted by users.
Questions:
What is the purpose of the Client-Server model in computer networks?
Describe the roles of the client and server in the Client-Server model.
What are the key characteristics of client-server interaction?
How does the client-server model contribute to the scalability of networked systems?
What benefits does the client-server model offer in terms of centralized management and resource sharing?
Discuss the concept of fault tolerance in the context of the client-server model. How can redundancy be provided to improve reliability?
Exercises:
Ex. 1
Ex. 2
Exam questions:
Question. A school with 20 stand alone PCs is considering networking them together and adding a file server. Consider four possible benefits of doing this. (Marks: 4)
Answer.
All 20 computers will be able to print to a single printer. Without the network you would need 20 printers, or each student would have to wait until the computer with the printer attached was free.(1)
All 20 computers will be able to share an Internet connection, giving all the students access to the Internet.(1)
Students can have their own space on the file server, improving security when compared to storing the files locally on each computer.(1)
The file server can be backed up to tape every night keeping the students' documents safe.(1)
