Client-server & Peer-to-Peer Networks

• Client-server networks are made up of a server and clients
• A client-server network is managed by a server. The devices connected to the server are clients
• Files and software are usually stored centrally on the server rather than on individual client devices
• Clients send requests to the server, e.g. asking for data. The server processes the request and responds. This is the client-server relationship
• The server stores user profiles, passwords and access information - it may request a password before fulfilling certain requests or deny requests to users without the right access level
• Most uses of the internet work on a client-server relationship. E.g. websites are hosted on web servers. Web browsers are client programs which send requests to web servers. Web servers fulfil requests (e.g. by sending web pages) for thousands of clients
• Pros of client-server networks

  • Easier to keep track of files as they are stored centrally
  • Easier to perform back-ups
  • Easier to install and update software
  • Easier to manage network security (e.g. anti-malware software and user access levels)
  • Servers are very reliable and are always on
• Cons of client-server networks

  • Expensive to set up and needs IT specialists to maintain the network and server
  • Server dependence - if the server goes down all clients lose access to their work
  • The server may become overloaded if too many clients are accessing it at once
• Peer-to-peer networks don't use servers
• In peer-to-peer (P2P) networks all devices are equal, connecting directly to each other without a server
• In P2P networks, you store files on individual devices and share them with others
• You may use a P2P network at home to share files between devices, or connect devices to a printer
• Pros of P2P networks

  • Easy to maintain - you don't need any expertise or expensive hardware
  • No dependence on server - if one device fails the whole network isn't lost
• Cons of P2P networks

  • No centralised management - devices need their updates and security installed individually. Back-ups are also more complicated
  • Copying files between devices creates duplicate files - it's easy to lose track of what's stored where and which files are up to date
  • Peer machines are less reliable and data may be lost if one fails
  • Machines are prone to slow down when other devices access them
• Although most internet use is client-server based, there are some common P2P applications such as cryptocurrency exchanges and file sharing (usually for illegal sharing of copyrighted material)