Categorizing Networks by Interaction Style


Introduction.  One of the main issues to resolve in any sort of computer networks is how are shared resources managed or delegated?  The some authors equate this to categorizing relative to administrative method.  The two main types of network interactions are
  • Client/Server - administration is more centralized on a computer running specialized server software.  The clients access the server and/or network for particular sorts of interactions.
    • various degrees of centralized authentication and authorization
    • data sources
  • Peer-to-Peer - each computer functions as both client and server and each user administers their own resources

It really isn't this simple.  But these two archetypes can be used to gain insight into how various not really able to be typed networks actually work administratively.

The following table lists some of the advantages for Peer-to-Peer networks and for Client/Server Networks.


Some Advantages of Peer-to-Peer Networks Some Advantages of Client/Server Networks
Less expensive to implement Easier to implement stronger security
Does not require network operating system software Easier to administer when larger
Does not require a dedicated network administrator Administration is centralized
  All data can be accessed up on one central location
  All data can be backed up on one central location


The next table lists some of the disadvantages for each of these categories of network.


Some Disadvantages of Peer-to-Peer Networks Some Disadvantages of Client/Server Networks
Does not scale well to larger networks Requires more expensive network operating system software
Administration easily becomes unmanageable as network grows Requires more expensive powerful hardware for server
Less secure Requires a professional administrator
Having a lot of machines sharing resources decreases performance It has a single point of failure depending on topology and if there is only one server


Servers and Clients.  A server is a computer that makes its resources (data, software, or attached peripherals) available for access by other computers on the network.  The following list outlines some of the major functions a server may perform.
  • File servers are servers on which data is stored.  Users save their application data to a hard disk on the server instead.
  • Print servers are machines that control one or more printers to which users can send documents to be printed.
  • Application servers are computers on which network applications are installed.  Users can run these applications on the server even though it is not installed on their machine.
  • Logon servers hold a security database , which contains information comprising user accounts.  The server checks user credentials against the database and controls access to the network and its resources.
  • Web servers run software that enable the computer to serve web pages to clients on the world wide web.
  • Mail servers provide e-mail and other related services to users.  This e-mail can be stored on the server and/or downloaded to the client's machine depending on the software and the settings.
  • Remote access servers enable dial-in connections so that other computers can access the server or the entire network from a distant location usually using telephone lines.
  • Terminal servers run software that enables client applications to be run on the server so that "thin client" computers can function as terminals rather than as independent systems.  The server provides a multi-session environment and runs the application programs being used on the clients.
  • Telephony servers provide answering machines and voice mail services.  They may also route calls.
  • Cluster servers run software that enables multiple servers to be joined in clusters so that they can work together as a single system to ensure that mission critical applications and resources remain available to clients.
  • Proxy servers act as intermediaries between workstation users and the Internet to ensure security and provide administrative control and caching services.
  • Fax servers provide a central point on the network to send and receive faxes and distribute them to the appropriate users.
  • BOOTP servers use the bootstrap protocol to enable client computers to boot an operating system and receive IP configuration information over the network.
  • DHCP- Dynamic Host Configuration Protocol servers assign IP addresses and TCP/IP configuration information to computers configured to be DHCP clients.  This keeps administrators from having to manually assign IP addresses.
  • Name resolution servers  provide mapping of friendly network names which allows users to identify computers without having to remember numerical identifiers.  These servers include DNS - Domain Name System servers which map host names to IP addresses on the internet.

A client is a computer that accesses the resources of a server.  The term client can also refer to software programs that interact with server programs.  For example, SQL Server typically has its databases and datasources on a server.  But it is also the case that there are some client side management tools to do things like develop queries, add tables and modify records that run on the client and access the source on the server.  The client operating system is typically something like Windows or Linux.

Characteristics of Peer-to-Peer Networks.  The following outlines some of the major characteristics of peer-to-peer networks.

  • Peer-to-Peer structure is best on smaller networks where strict security is not required.
    • most texts recommend a maximum of 10
    • relatively inexpensive with modern operating systems
    • to join one must configure to join a workgroup
    • locating resources can be very difficult even in small networks
  • Administration is decentralized.
    • every computer can act as both client and server
      • each user is responsible for the administration of their own computer
      • creating shares
      • assigning access permissions
  • Security
    • there is no central database where user account information is kept
    • all security is local
    • user accounts must be created on each individual machine
  • Share Level versus User Level


Share Level Security User Level Security
Used by Microsoft Windows products Used by Windows NT products
Passwords for each shared resource Passwords assigned to each individual user
To access resource across network the user must enter the resource's password To access the resource the use's account must have permissions assigned to access that resource
Users must remember multiple passwords Users must remember only one password


Characteristics of Server Based  Networks.  In server based networks, control tends to be much more centralized.  In these networks at least one machine is running a network operating system such as some variant of Windows NT, NetWare, UNIX or LINUX.  User accounts are created on this server and the sys admin can control the entire network from this location.

Generally, performance and throughput are better on server based networks rather than peer-to-peer.

Server based networks can be implemented to allow for additional servers that provide additional services.  Many of these sorts of servers were described above.

  • Administration is centralized
    • much more likely to require sys admin
    • sys admin provides expertise
  • Security
    • inherently more secure than for peer-to-peer
    • centralized authorization and authentication ultimately creates one access point
    • sys admin can assign permission levels for each resource for each user