Types of Networks

Types of Networks:
LANs (Local Area Networks)
A network is any group of independent computers that transfer with one another over a shared network medium. LANs are networks usually limited to a geographic area, such as a single building or a college campus. A Local Area Network (LAN) is basically a smaller network that does connect to a small area.

Metropolitan Area Networks
A Metropolitan Area Network (MAN) connects two or more computers (LANs) together but not the limits of a city, town, or metropolitan area. Within this type of network is also the Campus Area Network, which is generally smaller than a MAN, connecting LANs within a limited specific area, like a university campus, military base, or industrial complex.
WANs (Wide Area Networks)
Wide area networking chains multiple LANs that are geographically distinct. This is able by connecting the different LANs using services such as dedicated leased phone lines, fiber links, and satellite links. Wide Area Networks (WAN) connect larger areas. Often, smaller LANs are interconnected to large WAN. For instance, an office LAN in India may be connected to office LANs for the same company in US to form a WAN spanning the whole company. The individual offices are no longer part of individual LANs, they are instead part of a worldwide WAN. The connection of this type of network is complex. WANs are normally connected using multiplexers connect local and metropolitan networks to global communications networks like the Internet.

Internet
The Internet is a system of joined networks that are worldwide in scope and enable data communication services such as remote login, file transfer, electronic mail, the World Wide Web and newsgroups. Now a day the Internet has become a communications highway for millions of users. The Internet was initially restricted to military and academic institutions, but now it is a complete conduit for any and all forms. Internet websites now provide personal, educational, political and economic resources to every corner of the globe.

Intranet
With the developments made in browser-based software for the Internet, many private organizations are implementing intranets. An intranet is a private network utilizing Internet-type tools, but accessible only within that organization. For large organizations, an intranet provides an easy access mode to business information for employees.

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What is a Computer Network? Understanding Networking

What is a Network?

A network consists of two or more units or items sharing resources and information.

What is a Computer Network?

A computer network consists of two or more computing devices connected to each other to share resources and information. 
The network becomes a powerful tool when computers communicate and share resources (files, Peripherals such as printers, CD ROMS, Modems, Tape Backup drivers) with other computers on the same network or entirely distinct networks. At multiple places are connected with network people can send e-mail, share links to the global Internet, or video conferences to remote users.

Understanding Networking

Network - A set of computers connected together in a way that allows information to be exchanged between the computers.

Node – Any devices that is connected to the network. While a node is typically a computer, it can also be something like a printer…

Segment - Any section of a network that is divided, by a switch, bridge or router, from other section of the network.

Backbone - The major cabling of a network that all of the segments connect to. Typically, the backbone is capable of carrying more information than the individual segments. For example, each segment may have a transfer rate of 100 Mbps (megabits per second: 1 million bits a second), while the backbone may operate at 1 Gbps.

Topology - The way that each node is physically connected to the network.

Basic Networking Components

Most networks consist of at least two computers, network interface cards,Cabling, network operating system software, and a hub or switch.

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Basic Concept in Communication

Basic Concept in Communication  

Communications – activity related with distributing or exchanging information between source and destination.

Telecommunications– Technology of communications at a distance that allows information to be produced anywhere and used everywhere with slight delay.

Today it, engages 

• Data: digital and analog
• Voice: spoken word
• Video: telecommunication imaging

Essentials for Communications

• Message or resources to be share
• Source or Transmitter 
• Destination or Receiver
• Communication medium (Transmission system)

1. Input Message
2. Input data digital bit stream
3. Transmitted analog signal
4. Received analog signal
5. Output data digital bit stream 
6. Output Message

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IaaS (Infrastructure as a Service) - Segments or Sections of Cloud Computing

Segments or Sections of Cloud Computing

IaaS (Infrastructure as a Service)

Brings utility computing capability, typically as raw virtual servers, on demand that customers configure and manage.  Here Cloud Computing delivers grids or clusters or virtualized servers, networks, storage and systems software, usually (but not always) in a multi-tenant architecture.

• IaaS is planned to enlarge or replace the purposes of an entire data center. This saves cost (time and expense) of capital equipment deployment but does not reduce cost of configuration, integration or management and these tasks must be executed remotely.
• IT infrastructure through virtualization. Virtualisation allows the splitting of a single physical portion of hardware into independent, self-governed environments, which can be scaled in terms of CPU, RAM, Disk and other elements.
• The infrastructure includes servers, networks and other hardware appliances delivered as either Infrastructure “Web Services”, “farms” or "cloud centers". These are then interlinked with others for resilience and additional capacity. 

Examples are Amazon.com (Elastic Compute Cloud [EC2] and Simple Storage), IBM and other traditional IT vendors.

    Amazon EC2

• Amazon EC2 is one large complex web service.
• EC2 provided an API for instantiating computing instances with any of the operating systems supported.
• It can facilitate computations through Amazon Machine Images (AMIs) for various other models.
• Signature features: S3, Cloud Management Console, MapReduce Cloud, Amazon Machine Image (AMI)
• Excellent distribution, load balancing, cloud monitoring tools

Advantages

•     Pay per use
•     Instant Scalability
•     Security
•     Reliability
•     APIs

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PaaS (Platform as a Service) - Segments or Sections of Cloud Computing

Segments or Sections of Cloud Computing

PaaS (Platform as a Service)

Brings virtualized servers on which customers can run present applications or develop new ones without having to burden about keeping the operating systems, server hardware, load balancing or computing capacity.

•   A cloud computing platform dynamically supplies, configures, re-configures and de-provisions servers as needed to manage with increases or decreases in demand. This in certainty is a distributed computing model, where many services collected to deliver an application or infrastructure demand.
• These vendors deliver APIs or development platforms to create and run applications in the cloud – e.g. using the Internet.
•   Managed Service providers with application services delivered to IT departments to monitor systems and downstream applications such as virus scanning for e-mail are frequently included in this kind.

Examples are Microsoft's Azure, SalesForce.com, Google Maps, ADP Payroll processing, and US Postal Service offerings.

  Microsoft's Azure

•       Enterprise-level on-demand capacity builder

•       Fabric of cycles and storage available on-request for a cost

•       You have to use Azure API to work with the infrastructure offered by Microsoft

•       Significant features: web role, worker role , blob storage, table and drive-storage

 Advantages

•          Pay per use

•          Instant Scalability

•          Security

•          Reliability

•          APIs

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SaaS (Software As A Service) - Segments or Sections of Cloud Computing

Segments or Sections of Cloud Computing 

SaaS (Software As A Service)

The most broadly known and extensively used form of cloud computing.  It provides all the purposes of a classy traditional application to many customers and often thousands of users, but through a Web browser, not a “locally-installed” application.

• SaaS removes customer concerns about application servers, storage, application development and related, common concerns of IT.
• SaaS is a model of software deployment where an application is hosted as a service delivered to customers across the Internet.
• SaaS is usually used to refer to business software rather than consumer software, falls under Web 2.0!
• By eliminating the need to install and run an application on a user’s own computer it is seen as a way for businesses to get the same proceeds as commercial software with smaller cost expenditure.
• Saas lessens the problem of software maintenance, support, but users surrender control over software versions and requirements.

Examples are Salesforce.com, Google's Gmail and Apps, instant messaging from AOL, Yahoo and Google, and VoIP from Vonage, MS Live/Exchange Labs, IBM, Quicken Online, Zoho, Cisco  and Skype. 

Advantages

• Pay per use 
• Instant Scalability
• Security
• Reliability
• APIs

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Basics of Cloud Computing

What is Cloud Computing?

Cloud computing is Internet-based computing, whereby shared resources, software and information are provided to computers and other devices on-demand, like the electricity grid.

In other words, this is a collection/group of integrated and networked hardware, software and Internet infrastructure (called a platform).

(Move towards delivering “computing” to masses similar to other utilities (electricity and voice communication).

The cloud computing is a conclusion of many attempts at large scale computing with seamless access to virtually unlimited resources.

  * Using the Internet for communication and transport provides hardware, software and networking services to clients.

  * on-demand computing, utility computing, ubiquitous computing, autonomic computing, platform computing, edge computing, elastic computing, grid computing, …

The on-demand, self-service, pay-by-use model

The on-demand, self-service, pay-by-use nature of cloud computing is also an addition of established trends. From an enterprise viewpoint, the on-demand nature of cloud computing helps to support the performance and capacity features of service-level objectives. The self-service nature of cloud computing allows organizations to create elastic environs that expand and contract based on the workload and target performance limits. And the pay-by-use nature of cloud computing may take the form of equipment lease that assurance a minimum level of service from a cloud provider.

Virtualization is a key feature of this model. IT organizations have agreed for years that virtualization permits them to quickly and easily create copies of present locations —sometimes involving multiple virtual machines — to support test, development, and staging activities. The cost of these environments is minimal because they can coexist on the same servers as production environments because they use little resources.

Benefits of Cloud Computing

~ The platform provides on demand services that are always on anywhere, anytime and anyplace.

~  Pay for use and as needed, elastic (scale up and down in capacity and functionality).

~  The hardware and software services are available to the general public, enterprises, corporations and businesses markets.

 ~ It hides the complexity and details of the original infrastructure from users and applications by providing very simple graphical interface.

Segments or types of Cloud Computing

         Cloud computing has three main segments which are as follows:

o   Applications  or software (SaaS)

o   Platform (PaaS)

o   Infrastructure  (IaaS)

•       A cloud computing environment can provide one or more of these requirements for a cost

•       Pay as you go model of business, when using a public cloud the model is similar to renting a property than owning one.

•       An organization could also maintain a private cloud and/or use both.

Cloud Computing Architecture

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