Network architecture & Organizational Networks

Network architecture

Network architecture is the design of a communication network. It is a framework for the specification of a network's physical components and their functional organization and configuration, its operational principles and procedures, as well as data formats use.

What is network topology?

Computers in a network have to be connected in some logical manner. The layout pattern of the interconnections between computers in a network is called network topology. You can think of topology as the virtual shape or structure of the network. Network topology is also referred to as 'network architecture.'

Devices on the network are referred to as 'nodes.' The most common nodes are computers and peripheral devices. Network topology is illustrated by showing these nodes and their connections using cables. There are a number of different types of network topologies, including point-to-point, bus, star, ring, mesh, tree and hybrid. Let's review these main types.

The types :-

1- Bus network each device is connected to a common

cable called a bus or backbone, and all communications

travel along this bus.

2- Ring network—each device is connected to two other

devices, forming a ring. (See Figure 8-17.) When a message

is sent, it is passed around the ring until it reaches

the intended destination.

3- Star network—each device is connected directly to a

central network switch. (See Figure 8-18.) Whenever a

node sends a message, it is routed to the switch, which

then passes the message along to the intended recipient.

The star network is the most widely used network

topology today. It is applied to a broad range of applications

from small networks in the home to very large networks

in major corporations.

4- Tree network—each device is connected to a central

node, either directly or through one or more other

devices. The central node is connected to two or more

subordinate nodes that in turn are connected to other

subordinate nodes, and so forth, forming a treelike

structure. (See Figure 8-19.) This network, also known

as a hierarchical network, is often used to share corporatewide

data.

5- Mesh network—this topology is the newest type

and does not use a specific physical layout (such as

a star or a tree). Rather, the mesh network requires

that each node have more than one connection to

the other nodes. (See Figure 8-20.) The resulting

pattern forms the appearance of a mesh. If a path

between two nodes is somehow disrupted, data can be

automatically rerouted around the failure using another

path. Wireless technologies are frequently used to build

mesh networks

strategies:

Every network has a strategy, or way of coordinating

the sharing of information and resources. Two of the

most common network strategies are client/server and

peer-to-peer.

Client/Server Networks :

use central servers to coordinate and supply services to other nodes on the network.

The server provides access to resources such as web pages, databases, application software, and hardware.

This strategy is based on specialization. Server nodes coordinate and supply specialized services, and client

nodes request the services. Commonly used server operating systems are Windows Server, Mac OS X Server, Linux, and Solaris. Client/server networks are widely used on the Internet. For example, each time you open a web browser, your computer (the client) sends out a request for a specific web

page. This request is routed over the Internet to a server. This server locates and sends the requested material back to your computer.

One advantage of the client/server network strategy is the ability to handle very

large networks efficiently. Another advantage is the availability of powerful network management software to monitor and control network activities. The major disadvantages are the cost of installation and maintenance

peer-to-peer (P2P) network : nodes have equal authority and can act as both clients and servers. The most common way to share games, movies, and music over the Internet is to use a P2P network. For example, special file-sharing software such as

BitTorrent can be used to obtain files located on another personal computer and also can provide files to other personal computers.

P2P networks are rapidly growing in popularity as people continue to share information with others around the world. The primary advantage is that they are easy and inexpensive (often free) to set up and use. One disadvantage of P2P networks is the lack of security controls or other common management functions. For this reason, few businesses use this type of network to communicate sensitive information.

Organizational Networks

Organizational network analysis (ONA) is a method for studying communication and socio-technical networks within a formal organization. This technique creates statistical and graphical models of the people, tasks, groups, knowledge and resources of organizational systems.

(i) Network technologies :

1- Intranets : a private network within an organization that resembles the Internet.

applications include electronic telephone directories, e-mail addresses, employeeites, and web pages. Typical pplications include electronic telephone directories, e-mail addresses, employee benefit information, internal job openings, and much more. Employees find surfing their organizational intranets to be as easy and as intuitive as surfing the Internet.

2- extranets : is a private network that connects more than one organization.

Many organizations use Internet technologies to allow suppliers and others limited access to their networks. The purpose is to increase efficiency and reduce costs. For example an automobile manufacturer has hundreds of suppliers for the parts that go

into making a car. By having access to the car production schedules, suppliers can

schedule and deliver parts as they are needed at the assembly plants.

In this way, operational efficiency is maintained by both the manufacturer and the suppliers.

(ii) Network security :

1- firewalls : Consists of hardware and software that control access to a company’s intranet and other internal networks.

2- proxy server : All communications between the company’s internal networks and the outside world pass through this server. By evaluating the source and the content of each communication, the proxy server decides whether it is safe to let a particular message or file pass into or out of the organization’s network.

3- intrusion detection system (IDS) : work with firewalls to protect an organization’s network.

These systems use sophisticated statistical techniques to analyze all incoming and outgoing network traffic. Using advanced pattern matching and heuristics, an IDS can recognize signs of a network attack and disable access before an intruder can do damage.

4- virtual private network (VPN) : create a secure private connection between a remote user and an organization’s internal network. Special VPN protocols create the equivalent of a dedicated line between a user’s home or laptop computer and a company server.

The connection is heavily encrypted, and, from the perspective of the user, it

appears that the workstation is actually located on the corporate network. Like organizations, end users have security challenges and concerns. We need to be concerned about the privacy of our personal information.