The centralized, distributed and distributed central network operating system models rate a mention here from a topology perspective as well. However, let us start with the peer-to-peer and client/server network operating system models and the gambit of possible topologies that they potentially encompass.

Network Operating System (NOS) Topology

To keep things simple we will initially look at computer networks from the fundamentalist perspective where we will assume that all network operating systems and network operating system models are able to implement the following topologies, in some form or another.

Two Categories of Network Topology

The two categories of network topology that we are going to discuss are:

1. The Network Physical Topology

   This refers to the configuration of cables, computers, and other peripherals

2. The Network Logical Topology

   This describes the method used to pass the information between workstations

Network Operating System Network (NOS) Topology Types

Just as there are different, categories of NOS topologies so to there are different types of network operating system topologies. These topologies apply equally to networking, communications, client/server networks, converged Unified Communications (UC) networks and to a lesser degree to the peer-to-peer network.

Here are some of the topologies that we will be discussing: Direct Link Topology, Linear Bus Topology, Ring Topology, Star Topology, Mesh Topology, Tree Topology, Hybrid Topology, Hierarchal Network Topology, Centralized Computing Topology, Distributed Computing Topology, and Distributed Centralized Hybrid Computing Topology

Direct Link Topology

The direct link networking topology is without doubt the simplest of all. It is very easy to setup (install, implement, configure and maintain).

The basic minimal requirements necessary for the successful implement of a production environment network based around the direct link network topology are as minimal as it gets.

The entire setup depends on every machine to be connected having the appropriate number of Network Interface Cards (NIC) installed. With this taken care of the only, other requirement is a special type of network cable known as a crossover cable.

Details about making your own crossover cable are located in the Networking and Communications section. I will update this article with the correct link immediately upon publication of this article. You also have the option of purchasing a crossover cable. They are relatively inexpensive in today's market place.

Direct Link Networking Implementation

Simply connect both ends to the devices (computers, printers etc) that you wish to network.

Ensure that both machines are members of the same subnet. Then either create a new shared folder or share an existing one. Configure the appropriate permissions and security descriptors. You will need to perform this procedure on both machines. Add the content that you wish to share and you are up and running.

Ad hoc peer-to-peer network scenarios are the most common implementations of the direct link network topology. It is easy to setup but becomes impracticable when more than three devices are to be connected primarily due to the extra costs of having to purchase a Network Interface Card (NIC) for every machine you want to connect with.

• Suppose you want to network three computers then each computer will need two network interface cards (one NIC for each connection)
• Now consider the scenario where you want to connect four computers. Each machine will still require one NIC for each machine to which it wishes to connect. This means that each machine will need at least three NICs giving us 12 NICs all up.
• Five networked machines using the Direct Link Network Topology will require 20 NICs (Four per machine). I do not think I need to go any further as the impracticality of this system increases exponentially as the number of devices to be networked increases.
• The name given to this type of network topology is “physical mesh” topology

Exclusive Dedicated Links

In its simplest form a Direct Link Network Topology is comprised of exclusively dedicated links. Each member of each pair can use their own networking components of the Direct Link Network; cable, NIC etc to communicate directly and exclusively with its associated pair peer, to the exclusion of all other nodes.

Today we find that the main implementation scenario using a Direct Link Network Topology is with networks containing small numbers of devices. This includes the peer-to-peer network operating system.

More recent implementations of the Direct Link Topology involves external devices such as print devices, scanners, Multi-Function Centers (MFC), USB flash drives and other more robust external drives based upon the “normal” array of Hard Disk Drives (HDD).

Having introduced network operating system topologies and look into the Direct Link Topology we are now ready to move on to discussing more network operating system topologies such as the Linear Bus Topology, Ring Topologies and Star Topologies. This is where “Network Operating System Linear Bus Topology” takes up the story. Until then enjoy!

Network Operating System Models

To keep things simple we will look at computer networks from the fundamentalist perspective where we can say that there are two models for networks:

The Peer-To-Peer Network Model

In the Peer-To-Peer network operating system, model (see Fig. NOS-1), all nodes are equal. There is no hierarchy and there are no dedicated “servers”.

All of the computers must have Network Interface Cards (NIC) and other network connectivity infrastructure such as cables, hubs and switches just like in the client/server network operating system model. Both the peer-to-peer and the client/server network operating system models use the same cabling, NIC, hubs, switches etc.

Every node/computer on a peer-to-peer network must handle network security and administration for themselves. Yes, this does mean that you will need to perform exactly the same task multiple times, once for each machine. Automation is not the peer-to-peer network operating system model's strong point.

Every user must make the decisions about who gets access to what individually on a machine-to-machine basis (remember no automated administration).

The Client/Server Network Model

With the Client/Server Network Operating System Model a new device known as a server, joins the network. Another difference here is that for most implementations of the client/server network operating system all nodes will need to access the server before resources including internet connectivity become available to them.

In Figure NOS-3 above you can see that logically speaking for the Client/Sever Network Operating System model all roads lead to the server. This is the most basic fundamental difference between the peer-to-peer and client/server network operating system models.

Network Operating System Model Differences

As already stated the biggest difference between the peer-to-peer and the client/server network operating system models is the SERVER. All roads lead to the server (in the logical sense). The server performs the security and administrative duties for the entire network.

Another major difference between the two types of network operating systems is the manner in which the network is constructed. Peer-to-peer networks tend to be ad hoc in the manner of their construction. That is machines join the peer-to-peer network more or less randomly, they will come and go and generally the other machines really could not care less.

The client/server network operating system model is the opposite. Structure usually in some form of hierarchy is the order of the day here. Machines are “aware” of the presence or absence of network members. This become very important when we introduce a special type of server called a domain controller or a name server into the mix.

The manner in which both network operating system models arrange their members is another difference and this is where we will take up the story in “Network Operating System Topologies”. Until then enjoy!