MAN Network

A Metropolitan Area Network (MAN) is one of a number of types of networks (see also LAN and WAN). A MAN is a relatively new class of network, it serves a role similar to an ISP, but for corporate users with large LANs. There are three important features which discriminate MANs from LANs or WANs:

1. The network size falls intermediate between LANs and WANs. A MAN typically covers an area of between 5 and 50 km diameter. Many MANs cover an area the size of a city, although in some cases MANs may be as small as a group of buildings or as large as the North of Scotland.
2. A MAN (like a WAN) is not generally owned by a single organisation. The MAN, its communications links and equipment are generally owned by either a consortium of users or by a single network provider who sells the service to the users. This level of service provided to each user must therefore be negotiated with the MAN operator, and some performance guarantees are normally specified.
3. A MAN often acts as a high speed network to allow sharing of regional resources (similar to a large LAN). It is also frequently used to provide a shared connection to other networks using a link to a WAN.
   

A typical use of MANs to provide shared access to a wide area network is shown in the figure below:

Use of MANs to provide regional networks which share the cost of access to a WAN

Local Area Network (LAN)

A local area network (LAN) supplies networking capability to a group of computers in close proximity to each other such as in an office building, a school, or a home. A LAN is useful for sharing resources like files, printers, games or other applications. A LAN in turn often connects to other LANs, and to the Internet or other WAN.

Most local area networks are built with relatively inexpensive hardware such as Ethernetcables, network adapters, and hubs. Wireless LAN and other more advanced LAN hardware options also exist.

Specialized operating system software may be used to configure a local area network. For example, most flavors of Microsoft Windows provide a software package called Internet Connection Sharing (ICS) that supports controlled access to LAN resources.

The term LAN party refers to a multiplayer gaming event where participants bring their own computers and build a temporary LAN.

Also Known As: local area network

Examples:

The most common type of local area network is an Ethernet LAN. The smallest home LAN can have exactly two computers; a large LAN can accommodate many thousands of computers. Many LANs are divided into logical groups called subnets. An Internet Protocol (IP) "Class A" LAN can in theory accommodate more than 16 million devices organized into subnets.

Wide Area Network (WAN)

The term Wide Area Network (WAN) usually refers to a network which covers a large geographical area, and use communications circuits to connect the intermediate nodes. A major factor impacting WAN design and performance is a requirement that they lease communications circuits from telephone companies or other communications carriers. Transmission rates are typically 2 Mbps, 34 Mbps, 45 Mbps, 155 Mbps, 625 Mbps (or sometimes considerably more).

Numerous WANs have been constructed, including public packet networks, large corporate networks, military networks, banking networks, stock brokerage networks, and airline reservation networks. Some WANs are very extensive, spanning the globe, but most do not provide true global coverage. Organisations supporting WANs using the Internet Protocol are known as Network Service Providers (NSPs). These form the core of the Internet.

By connecting the NSP WANs together using links at Internet Packet Interchanges (sometimes called "peering points") a global communication infrastructure is formed. NSPs do not generally handle individual customer accounts (except for the major corporate customers), but instead deal with intermediate organisations whom they can charge for high capacity communications. They generally have an agreement to exchange certain volumes of data at a certain "quality of service" with other NSPs. So practically any NSP can reach any other NSP, but may require the use of one or more other NSP networks to reach the required destination. NSPs vary in terms of the transit delay, transmission rate, and connectivity offered.

DHS Network Topology Diagram

Network Topology

Computer network topologies can be categorized in the following categories.

• bus

• star

• ring

• mesh

• Tree.

Hybrid networks are the complex networks, which can be built of two or more above mentioned topologies.

Bus Topology

Bus topology uses a common backbone to connect all the network devices in a network in a linear shape. A single cable functions as the shared communication medium for all the devices attached with this cable with an interface connector. The device, which wants to communicate send the broadcast message to all the devices attached with the shared cable but only the intended recipient actually accepts and process that message.

Ring Topology

Ethernet bus topologies are easy to install and don’t require much cabling and only a main shared cable is used for network communication. 10Base-2 and 10BaseT are two popular types of the Ethernet cables used in the Bus topology. Also, Bus network works with very limited devices. Performance issues are likely to occur in the Bus topology if more than 12-15 computers are added in a Bus Network. Additionally, if the Backbone cable fails then all network becomes useless and no communication fails among all the computers. Unlike in the Star topology in which if one computer is detached from a network then there is not effect on the other computers in a network.

In ring Network, every computer or devices has two adjacent neighbors for communication. In a ring network, all the communication messages travel in the same directory whether clockwise or anti clockwise. Any damage of the cable of any cable or device can result in the breakdown of the whole network. Ring topology now has become almost obsolete.

FDDI, SONET or Token Ring Technology can be used to implement Ring Technology. Ring topologies can be found in office, school or small buildings.

Star Topology

In the computer networking world the most commonly used topology in LAN is the star topology. Star topologies can be implemented in home, offices or even in a building. All the computers in the star topologies are connected to central devices like hub, switch or router. The functionality of all these devices is different. I have covered the detail of each networking devices in the separate portion of my website. Computers in a network are usually connected with the hub, switch or router with the Unshielded Twisted Pair (UTP) or Shielded Twisted Pair Cables.

As compared to the bus topology, a star network requires more devices & cables to complete anetwork. The failure of each node or cable in a star network, won’t take down the entire network

as compared to the Bus topology.

However if the central connecting devices such as hub, switch or router fails due to any reason,then ultimately all the network can come down or collapse.

Tree Topology

Tree topologies are comprised of the multiple star topologies on a bus. Tree topologies integrate multiple star topologies together onto a bus. Only the hub devices can connect directly with the tree bus and each Hub functions as a root of a tree of the network devices. This bus/star/hybrid combination supports future expandability of the computer networks, much better than a bus or star.

Mesh Topology

Mesh topology work on the concept of routes. In Mesh topology, message sent to the destination can take any possible shortest, easiest route to reach its destination. In the previous topologies star and bus, messages are usually broadcasted to every computer, especially in bus topology. Similarly in the Ring topology message can travel in only one direction i.e clockwise or anticlockwise. Internet employs the Mesh topology and the message finds its route for its destination. Router works in find the routes for the messages and in reaching them to their destinations.The topology in which every devices connects to every other device is called a full Mesh topology unlike in the partial mesh in which every device is indirectly connected to the other devices.

Summary

Topologies are the important part of the network design theory. A better network can be built if you have the knowledge of these topologies and if you know the difference between each topology. Similarly you should have the knowledge of each network device so that you can properly use them according to your network needs. A misconfigured network can result in a waste of time and energy as well as a lots of troubleshooting methods to resolve the issue. So thebasic understanding of the network topologies and network devices is a must to build a good network.

Network Protocol

A network protocol defines rules and conventions for communication between network devices. Protocols for computer networking all generally use packet switchingtechniques to send and receive messages in the form of packets.

Network protocols include mechanisms for devices to identify and make connections with each other, as well as formatting rules that specify how data is packaged into messages sent and received. Some protocols also support message acknowledgement and data compression designed for reliable and/or high-performance network communication. Hundreds of different computer network protocols have been developed each designed for specific purposes and environments.

Internet Protocols

The Internet Protocol family contains a set of related (and among the most widely used network protocols. Besides Internet Protocol (IP)itself, higher-level protocols like TCP, UDP, HTTP, and FTP all integrate with IP to provide additional capabilities. Similarly, lower-level Internet Protocols like ARP and ICMP also co-exist with IP. These higher level protocols interact more closely with applications like Web browsers while lower-level protocols interact with network adapters and other computer hardware.

Routing Protocols

Routing protocols are special-purpose protocols designed specifically for use by network routers on the Internet. Common routing protocols include EIGRP, OSPF and BGP.

How Network Protocols Are Implemented

Modern operating systems like Microsoft Windows contain built-in services or daemons that implement support for some network protocols. Applications like Web browsers contain software libraries that support the high level protocols necessary for that application to function. For some lower level TCP/IP and routing protocols, support is implemented in directly hardware (silicon chipsets) for improved performance.

Networking Domain

Windows Network Domain

Windows network technology enables you to create network domains. A domain is a group of connected Windows computers that share user account information and a security policy. A domain controller manages the user account information for all domain members.

The domain controller facilitates network administration. By managing one account list for all domain members, the domain controller relieves the network administrator of the requirement to synchronize the account lists on each of the domain computers. In other words, the network administrator who creates or changes a user account needs to update only the account list on the domain controller rather than the account lists on each of the computers in the domain.

To log in to a Windows database server, a user on another Windows computer must belong to either the same domain or a trusted domain. A trusted domain is one that has established a trust relationship with another domain. In a trust relationship, user accounts are located only in the trusted domain, but users can log on to the trusted domain.

A user who attempts to log in to a Windows computer that is a member of a domain can do so either by using a local login and profile or a domain login and profile. However, if the user is listed as a trusted user or the computer from which the user attempts to log in is listed as a trusted host, the user can be granted login access without a profile.

Important:

A client application can connect to an Informix database server only if there is an account for the user ID in the Windows domain in which the database server runs. This rule also applies to trusted domains.

For more information on domains, consult your Windows operating system manuals.

Important:

The Informix trusted client mechanism is unrelated to the trust relationship that you can establish between Windows domains. Therefore, even if a client connects from a trusted Windows domain, the user must have an account in the domain on which the database server is running. For more information on how the database server authenticates clients

Red Hat Enterprise Linux 5

The world's leading open source application platform

On one certified platform, Red Hat Enterprise Linux offers your choice of:

• Applications - Thousands of certified ISV applications
• Deployment - Including standalone or virtual servers, cloud computing, or software appliances
• Hardware - Wide range of platforms from the world's leading hardware vendors

This gives IT departments unprecedented levels of operational flexibility. And it gives ISVs unprecedented market reach when delivering applications. Certify once, deploy anywhere. All while providing world-class performance, security, and stability. And unbeatable value.

This is why Red Hat is the platform of choice.

Eliminate barriers to adoption

Red Hat Enterprise Linux solutions, in combination with other Red Hat technologies-such as JBoss middleware solutions - provide the easy, no-risk path to open source cost savings. Use commodity hardware. Interoperate easily with existing UNIX and Windows infrastructure. Deploy applications you know and trust. Reduce system administration costs through high server/admin ratios and desktop-to-mainframe consistency.

Eliminate economic constraints

Basing your solution on open source technologies wherever practical - from the virtualization hypervisor to the SOA middleware to the end user application - guarantees you'll make the most of your IT budget. Despite what vendors of single solutions tell you about their product’s cost - it’s the overall total cost that matters. And open source solutions offer lower total costs:

• Lower capital expense and operational expense
• Elimination of vendor lock-in - puts the customer in control.
• Proven superior product quality - better security, higher performance
• Technology leadership - driven by industry-wide collaboration
• Flexibility - deploy what you need, when you need, how you need it

Broadest open source ecosystem

Customers using new deployment paradigms, including virtualization, need the confidence they can deploy on the widest range of hardware and applications - now and in the future. Red Hat’s open source development brings you the world's largest open source ecosystem of certified hardware and software.

Applications: Certify once-deploy anywhere

Red Hat Enterprise Linux provides a standardized environment for your applications so they can be deployed however your business requires. And Red Hat application partners need only certify their applications once.

With thousands of applications certified to run on Red Hat Enterprise Linux, you can run the application you need, where you need it, today.

Choose your preferred way to deploy

Red Hat Enterprise Linux is the most flexible operating system environment available. Enterprise Linux solutions are ideal for all of these deployment types - using the same applications. Deploy whichever environment best suits your business:

• Standalone or "bare metal" systems
  This is the most common environment for servers today. Red Hat Enterprise Linux scales from desktop and laptop systems, to small servers, to the largest SMP servers and to mainframes. And, of course, it is ideal for blade and rack environments - especially today's popular 4-CPU quad-core systems.
  • Learn more about Red Hat Enterprise Linux servers
  • Learn more about Red Hat Enterprise Linux Desktop clients

• Virtualized
  Virtualized systems, which offer improved resource management and operational flexibility through features such as live migration, dynamic resource allocation, high availability, and clustering. Enterprise Linux provides the industry’s highest performance, complete virtualization capability, for no additional charge.

  Virtualization is the fastest growing method of deployment - up to 15% of all servers are expected to be virtualized in the next five years. Virtualization lets you maximize your resources and increase deployment flexibility and responsiveness.
  

  • Learn more about Red Hat Enterprise Linux virtualization

• Software as a Service
  Software-as-a-Service, or cloud computing deployments, allows customers to extend their compute resources outside the walls of the data center - providing an on-demand infrastructure that can scale to up or down to meet business requirements. Red Hat Enterprise Linux is available as a certified and supported platform deployed on Amazon’s Elastic Computing Cloud - EC2.
  • Learn more about Red Hat and Amazon

• Appliances
  Red Hat Enterprise Linux-based appliances allow ISVs to distribute applications pre-packaged as complete solutions, including the operating system, simplifying deployment, management, and maintenance. Red Hat's appliance strategy covers a wide range of deployment opportunities, including:
  • Fully featured application stacks available through Red Hat Exchange
  • Lightweight portable media solutions - self-contained, easily provisioned tokens such as USB keys and live CDs providing a portable, low-cost application environment.

Network Administrator

Network Administrator

A Network Administrator is a professional in charge of the maintenance of the computer hardware and software systems that make up a computer network. This includes activities such as the deployment, configuration, maintenance and monitoring of active network equipment.

The Network Administrator is typically a mid to senior level of technical/network staff in an organization and is not typically involved with direct user support. The Network Administrator will concentrate on the overall health of the network, server deployment, security, ensuring network connectivity throughout and company's LAN/WAN infrastructure, and all other technical considerations at the network level of an organizations technical hierarchy. Network Administrators are considered Tier 3 support personnel that only work on break/fix issues that could not be resolved at the Tier1 (helpdesk) or Tier 2 (desktop/network technician) levels.

In some companies, the Network Administrator may also design and deploy networks. Usually, though, these tasks would be assigned to aNetwork Engineer if the company is large enough.

The actual role of the Network Administrator will vary from company to company, but usually includes tasks such as network address assignment, assignment of routing protocols and routing table configuration as well as configuration of authentication and authorization – directory services. It often includes maintenance of network facilities in individual machines, such as drivers and settings of personal computers as well as printers and such. It sometimes also includes maintenance of certain network servers: file servers, VPN gateways, intrusion detection systems, etc.

Windows Server 2008

Server Core installation provides a minimal environment for running specific server roles, which reduces the maintenance and management requirements and the attack surface for those server roles. A server running a Server Core installation supports the following server roles:

• Active Directory Domain Services (AD DS)
• Active Directory Lightweight Directory Services (AD LDS)
• DHCP Server
• DNS Server
• File Services
• Print Services
• Streaming Media Services
• Internet Information Services (IIS)
• Windows Virtualization
• The Server Core installation option of Windows Server 2008 requires initial configuration at a command prompt. A Server Core installation does not include the traditional full graphical user interface. Once you have configured the server, you can manage it locally at a command prompt or remotely using a Terminal Server connection. You can also manage the server remotely using the Microsoft Management Console (MMC) or command-line tools that support remote use.

• The Server Core installation option of Windows Server 2008 provides the following benefits:

  • Reduced maintenance - Because the Server Core installation option installs only what is required to have a manageable server for the AD DS, AD LDS, DHCP Server, DNS Server, File Services, Print Services, and Streaming Media Services roles, less maintenance is required than on a full installation of Windows Server 2008.
  • Reduced attack surface - Because Server Core installations are minimal, there are fewer applications running on the server, which decreases the attack surface.
  • Reduced management - Because fewer applications and services are installed on a server running the Server Core installation, there is less to manage.
  • Less disk space required - A Server Core installation requires only about 1 gigabyte (GB) of disk space to install and approximately 2 GB for operations after the installation.
  • Lower risk of bugs - Reducing the amount of code can help reduce the amount of bugs.

Issues with Server Core installation and upgrading from previous versions

Since Server Core is a special installation of Windows Server 2008, the following limitations are present:

• There is no way to upgrade from a previous version of the Windows Server operating system to a Server Core installation. Only a clean installation is supported.
• There is no way to upgrade from a full installation of Windows Server 2008 to a Server Core installation. Only a clean installation is supported.
• There is no way to upgrade from a Server Core installation to a full installation of Windows Server 2008. If you need the Windows user interface or a server role that is not supported in a Server Core installation, you will need to install a full installation of Windows Server 2008.

Server Core versions

Server Core comes in Standard, Enterprise and Datacenter editions for i386 and x64 platforms. Most companies will probably go for the Standard edition because most of the differences found in the Enterprise and Datacenter editions of Windows Server 2008 won't be present in Server Core. The Enterprise Server Core will, however, allow you to utilize more processor and memory support, as well as clustering. Datacenter adds the whole Datacenter hardware program and 99.999 percent reliability.

Computer Hardware

Hardware (computer) components, equipments involved in the function of a computer. Computer hardware consists of the components that can be physically handled. The function of these components is typically divided into three main categories: input, output, and storage.

Components in these categories connect to microprocessors, specifically, the computer's central processing unit (CPU), the electronic circuitry that provides the computational ability and control of the computer, via wires or circuitry called a bus.

Software, on the other hand, is the set of instructions a computer uses to manipulate data, such as a word-processing program or a video game. These programs are usually stored and transferred via the computer's hardware to and from the CPU.

Software also governs how the hardware is utilized; for example, how information is retrieved from a storage device. The interaction between the input and output hardware is controlled by software called the Basic Input Output System software (BIOS).

Although microprocessors are still technically considered to be hardware, portions of their function are also associated with computer software. Since microprocessors have both hardware and software aspects they are therefore often referred to as firmware.

Structure of Motherboard

MOTHERBOARD

The motherboard is the main circuit board in a PC. It contains all the circuits and components that run the PC.

Major Components found on the motherboard are:

• CPU - the Central Processing Unit is often an Intel Pentium or Celeron processor. It is the heart of every PC. All scheduling, computation and control occurs here.
  
  
• BIOS - Basic Input Output System is a non-volatile memory that contains configuration information about the PC. It contains all the code required for the CPU to communicate with the keyboard, mouse video display, disk drives and communications devices.
  
  
  When a PC is powered on it uses the BIOS 'boot code' to set up many required functions that bring the PC to a point where it is ready to work.
  
  
• RTC - the Real Time Clock chip keeps date, day and time in a 24 hour format just like your watch. The PC uses this clock to 'time stamp' files as they are created and modified. When you print a file it time stamps the pages as they are printed.
  
  
• Chip Set - these are large chip(s) that integrate many functions that used to be found in separate smaller chips on the motherboard. They save space and cost.
  
  
  The functions performed by these chip sets often broken into two devices with one providing an interface from the CPU to the memory and the other providing controllers for IDE, ISA, PCI and USB devices (see below).
  
  

Primary Connectors found on the motherboard are:

• Power - A 20 pin connector accepts a plug from the power supply. This plug carry DC power to all the circuits on the motherboard.
  
  
• Keyboard - A Mini-din 6-pin (round) connector found at the back of the motherboard is where the keyboard plugs in.
  
  
• Mouse - A Mini-din 6-pin connector found next to the keyboard connector is where the where the mouse plugs in.
  
  
• Display - This connector is not integrated into the motherboard but is included in this list since its function is absolutely necessary. It is a 15-pin, D-shell type connector found on a video card that plugs into the AGP connector of the motherboard (see below).
  
  
• IDE - stands for Integrated Drive Electronics. These are 40 pin connectors that provide a place to connect the ribbon cables from the drives (hard and CD/DVD). All data between the motherboard and the drives is carried in these cables. They are not accessible unless the PC cover is removed.
  
  
• FDD connector - it is similar in function to the IDE connector. It is a 34 pin ribbon connector that carries data between the motherboard and any floppy drive installed in the PC. Not accessible with PC cover on.
  
  
• DRAM - Dynamic Random Access Memory connectors for SIMM and DIMM type memory modules. Not accessible with chassis cover on.
  
  
• Serial Connectors
  
  
  • Standard Serial Connector - This connector has been around in PCs since they first appeared. It was originally located on ISA expansion type cards (see below). Today it is an integral part of newer motherboards. It is a 9- pin, D-shell connector that allows you to connect external devices with serial ports to your PC. The maximum data rate is 115 KB/s.
    
    
  • USB - Universal Serial Bus This is a relatively new serial bus. Originally specified as low speed, 1.2 Mb/s, it was enhanced to full speed, 12Mb/s. The latest version 2.0 is specified as high speed, 400 MB/s.
    
    
    Someday USB will completely replace the standard serial connector that has been the workhorse serial port in earlier PCs. USB is now a standard connector on all new motherboards.
    
    
    Unlike serial and parallel ports, the USB port is designed to power devices connected to it. The devices must be low power devices and must be able to reduce their current draw to less than 0.5uAmps when commanded to do so by the PC.
    
    
• Parallel Connectors
  
  
  • Centronix or Standard Parallel - This connector has been around in PCs since they first appeared. It has 37-pins and is now integrated on new motherboards. It is usually used to connect your printer to the PC and moves data at about 1MB/s.
    
    
  • SCSI - Small Computer System Interface moves data at a maximum of up to 80Mb/s. It not integrated into most PC motherboards. It can be added to a PC as an Expansion card (see below). Some printers and hard disk drives use SCSI interfaces.
    
    
• Expansion Card Connectors - The CPU connects to expansion card connectors through one of the chip set ICs mentioned above. They are located on the motherboard near the rear of the PC. These connectors allow special function cards to plug into and work with the PC.
  
  
  Before motherboards integrated the serial and centronix connectors they were found on expansion boards that plugged into ISA slots.
  
  
  Most PCs have the following expansion connector types:
  
  
  • ISA - Industry Standard Architecture connectors have been around since 1980 and first appeared in the IBM XT PC. This type of slot still appears on some newer motherboards so that older expansion boards can still be used. However, many motherboards no longer have ISA connectors on them.
    
    
  • PCI - Peripheral Component Interconnect is a newer and faster interface that accepts all expansion cards that have a PCI interface.
    
    
  • AGP - Accelerated Graphics Port is a connector that is designed to work with video cards. Your video display plugs into and is controlled by one of these video cards. Many modern video cards offer enhanced 3D-graphics and fast, full motion video.
  
  

Networking Tools

Networks can be categorized in several different ways. One approach defines the type of network according to the geographic area it spans. Local area networks (LANs), for example, typically reach across a single home, whereas wide area networks (WANs), reach across cities, states, or even across the world. The Internet is the world's largest public WAN.

Network Design

Computer networks also differ in their design. The two types of high-level network design are calledclient-server and peer-to-peer. Client-server networks feature centralized server computers that store email, Web pages, files and or applications. On a peer-to-peer network, conversely, all computers tend to support the same functions. Client-server networks are much more common in business and peer-to-peer networks much more common in homes.

A network topology represents its layout or structure from the point of view of data flow. In so-called bus networks, for example, all of the computers share and communicate across one common conduit, whereas in a star network, all data flows through one centralized device. Common types of network topologies include bus, star, ring and mesh.

Network Protocols

In networking, the communication language used by computer devices is called theprotocol. Yet another way to classify computer networks is by the set of protocols they support. Networks often implement multiple protocols to support specific applications. Popular protocols include TCP/IP, the most common protocol found on the Internet and in home networks.

Wired vs Wireless Networking

Many of the same network protocols, like TCP/IP, work in both wired and wireless networks. Networks with Ethernet cables predominated in businesses, schools, and homes for several decades. Recently, however, wireless networking alternatives have emerged as the premier technology for building new computer networks.