Categorizing Networks by
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
- 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
- data sources
- 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
||Some Advantages of
|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.
Disadvantages of Peer-to-Peer Networks
Disadvantages of Client/Server Networks
|Does not scale well to larger networks
||Requires more expensive network operating
|Administration easily becomes unmanageable
as network grows
||Requires more expensive powerful hardware
||Requires a professional administrator
|Having a lot of machines sharing resources
||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
- 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
- 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
- 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.
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
- 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
- each user is responsible for the
administration of their own computer
- creating shares
- assigning access permissions
- there is no central database where user account
information is kept
- all security is local
- user accounts must be created on each individual
- Share Level versus User Level
|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
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
- 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