Network Types
Networks fall into two major
types: peer-to-peer and client/server (sometimes called server-based).
Peer-to-Peer Networking
This is a simple network
configuration that requires some basic know-how to set up. Each of the
interconnected machines share dual capability and responsibility on the
network. That is to say, that each machine serves a dual purpose or role,
i.e. they are both clients and servers to some extent.
The server capability of the
machines is very basic. The services provided by each, is no more than the
ability to share resources like files, folders, disk drives and printers.
They even have the ability to share Internet access.
However, the server
functionality of these machines stops there. They cannot grant any of the
benefits mentioned previously, since these are functions provided only by a
dedicated server operating system.
Because all machines on the
network have equal status, hence the term peers, there is no centralised
control over shared resources. Sharing is endorsed or repealed by each
machine's user. Passwords can be assigned to each individual shared resource
whether it is a file, folder, drive or peripheral, again done by the user.
Although this solution is
workable on small networks, it introduces the possibility that users may
have to know and remember the passwords assigned to every resource, and then
re-learn them if the user of a particular machine decides to change them!
Due to this flexibility and individual discretion, institutionalised chaos
is the norm for peer-to-peer networks.
Security can also be a major
concern, because users may give passwords to other unauthorised users,
allowing them to access areas of the network that the company does not
permit. Furthermore, due to lack of centralisation, it is impossible for
users to know and remember what data lives on what machine, and there are no
restrictions to prevent them from over-writing the wrong files with older
versions of the file. This of course cripples attempts to organise proper
backups.
It may appear that peer-to-peer
networks are hardly worthwhile. However, they offer some powerful
incentives, particularly for smaller organisations. Networks of this type
are the cheapest and easiest to install, requiring only Windows95, a network
card for each machine and some cabling. Once connected, users can start to
share information immediately and get access to devices.
As a result, networks of this
type are not scalable and a limit of no more than 10 machines is the general
rule.
Advantages
· Easy to install and configure.
· No dedicated server required.
· Users control their own
resources.
· Inexpensive to purchase and
operate.
· No specialist software
required.
· No dedicated administrator to
run the network required.
Disadvantages
· Difficult to employ security.
· Too many passwords for shared
resources.
· Backups difficult to manage.
· No centralisation.
· Limited users.
Client/Server Networks
Server based networks, or
client/server networks as they are properly called, has a machine at the
heart of its operations called the server. A server is a machine that
provides services over a network by responding to client requests. Servers
rarely have individuals operating it, and even then, it is usually to
install, configure or manage its capabilities. The server's essential role
on the network is to be continuously available to handle the many requests
generated by its clients.
Server-based networks provide
centralised control of the entire network environment. The computer systems
used for this role are generally more powerful than end-user machines,
incorporating faster CPUs, more memory, larger disk drives and other drive
types installed, like a tape drive for backup purposes. These are required,
because servers are dedicated to handling multiple simultaneous requests
from their client communities.
Server based networks provide
centralised verification of user accounts and passwords. Only valid account
name and password combinations are allowed access to the network.
Client/Server networks typically require a single login to the network
itself, meaning that users need to remember long password lists to access
various resources. Concentrations of resources on a single server, mean that
they are easier to find, as opposed to the peer-to-peer model, were
resources were distributed throughout the network since they were attached
to multiple machines. The server being a central data repository, means that
not only is data more accessible to users, but it also makes life much
easier in terms of performing backups, since the data is in a location know
to the administrator.
Server-based networks are easier
to scale. Peer-to-peer networks bog down seriously as they grow beyond ten
users, and serious slow up with 20 users. On the other hand, client/server
networks can handle a few users, up to a thousand users as such networks
grow to keep pace with an organisations growth and expansion.
Unlike peer-to-peer networks,
client/server networks don't come cheap. The server machine itself may cost
several thousands of pounds, along with the software to make it run; another
thousand pounds. Because of the complex nature of this kind of networking
environment, a dedicated administrator is required to be on site at all
times to be involved in the day to day running of the network. Hiring an
individual of this nature adds considerably to the cost of client/server
networks.
Lastly, because the networks
operability is so dependant upon the server, this introduces a single point
of failure, if the server goes down the network goes down. There are
measures available, that can legislate for such failures, however these
techniques add even more cost to this solution.
Advantages
· Centralised user accounts,
security and access controls simplify network administration.
· More powerful equipment means
more efficient access network resources.
· Single password login, means
access to all resources.
· Supports greater numbers of
users, or networks where resources are heavily used.
Disadvantages
· More costly to install and
maintain.
· Single point of failure,
server goes down, the network goes down.
· Complex special-purpose
software requires appointment of expert staff, increasing costs.
· Dedicated hardware and
software increases costs. |
