IP Multicasting

IP Multicasting is a technique of distributing the data across multiple servers over the WAN.  It is simply the delivery of the same data packets to the multiple destinations.  It allows the multiple recipients to receive the same data packets from a single source. Multicasting allows the distributed applications to work over the WAN with great performance.  It is an excellent alternative for the unicast and broadcast transmissions.


In Multicasting, the information is sent to only the destined recipients.   It is like the TV or radio transmission system in which only those terminals receive the information who have tuned themselves to receive it.
It is the bandwidth-conserving technology that reduces the traffic load over the network.  The ideal applications that uses the multicast technology includes video conferencing, stock quotes, distance learning, weather updates, video streaming, news and other distributed software applications in the LAN/WAN network.  IP multicasting mechanisms depends upon the two protocols i.e. group management protocol and the routing protocols.

Group Management protocols establish the multicast groups and the routing protocols routes the traffic to the destination. Multicast routing protocols makes the distribution tree for the data forwarding in the network. It is an ideal solution for the distribution applications in the TCP/IP based LAN/WAN networks.


Though it has been successful in many businesses but it is not extensively deployed and used by the average users.  Special addressing scheme is assigned while implementing the IP multicasting.  These addresses are assigned from the Class D i.e. 224.0.0.0 to 239.255.255.255.  The typical multicast applications include the following.

• Video conferencing
• Audio conferencing
• Stock Quotes
• Distributed LAN/WAN Software Applications
• Weather Updates
• Data Conferencing
• Network-based games
• Online Training
• Database replication

Multicasting applications minimize the demand of the network bandwidth while sending the information from one source to multiple destinations via same stream.
Multicasting can be implementing in the following situations.

• For better bandwidth utilization.
• Less Router/Hosts Processing.
• When sending the same data to the multiple receivers is required.
• When the recipient address is unknown.
• When a one-to-many communication systems model is required.

It has many advantages over the unicast and broadcast communication system such as the following.

• Enhanced performance.
• Optimized performance.
• One-to-many communication system.

What is a WiFi Network-How to Setup

An Introduction to the Wi-Fi (Wireless Fidelity) Here you will learn how to setup wifi network, how wireless fidelity works, hotspot security, vpn servers. Wi-Fi or wireless fidelity is meant for to be used when referring any type of 802.11 network, whether 802.11, 802.11a and dual band. Any products tested and approved as Wi-Fi certified by the Wi-Fi alliance are interoperable with each other.

Typically, any Wi-Fi product using the same radio frequency will work with each other even if not Wi-Fi certified. Formerly the term Wi-Fi was used only in the place of the 2.4 GHz 802.11b standard in the same way Ethernet was used. Wi-fi short for wireless fidelity refers to a set of wireless networking technologies and more specifically referred to as any type of 802.11 network, 802.11b and 802.11a and dual band. The word Wi-Fi was built by an organization named as Wi-Fi alliance. A product that undergoes the Wi-Fi alliance analyses is given the name Wi-Fi certified. Wi-Fi rapidly gained the fame in the United States with the access point. These devices tested by the “Wi-Fi alliance” are used around the world and allow users to have Wi-Fi capable device like a PDA or Laptop to connect anywhere there is availability of Wi-Fi access point. There are currently three standards that are used to signify the speed of the connection. Both the 802.11a and 802.11b are the capable of 54 Mbps with 802.11a additional features. The most common standard is 802.11b/second because it can transmit the data at 11 Mbps. All these Wi-Fi connections are fast enough to allow the broadband internet connection. Wireless Fidelity is a fastest growing wireless technology that will probably be as common as phone lines and electric devices. Wi-Fi adds great levels of convenience and high level of production. Wireless fidelity is planned to be used with the wireless devices but it is most commonly used for internet access. With Wi-Fi you can connect computers in your home, office or anywhere without the need of wires. The computers can just connect to the network that uses radio waves. How does W-Fi work? Wi-Fi is the wireless technology to handle the networking/communication. Wi-Fi allocates internet connection globally and to be transmitted by the radio waves. Radio waves are the main cause of Wi-Fi. Radio waves are transmitted from antenna and Wi-Fi receivers pick them up. When a user receives the Wi-Fi signals, a wireless internet connection is produced and a user is prompted to provide the user name and password if required to establish a wireless connection. What is Wi-Fi Security? Wi-Fi maintains certain security issues. WEP or Wired Equivalent Privacy is used in the physical and data link layers. It was planned to provide the wireless security by protecting the data, while it transmits from one point to another. Wi-Fi networking usually maintained inside a building premises. The data transmission in the Wi-Fi is protected by Wireless LANs but due to the fact that data travels over the radio waves so there are chance that data can be exposed and capture. How to secure your WiFi network? When you buy a wireless router you might find an Installation CD by vendor that CD with guide you through a wizard on setting up router. Here are some suggestions that how can you setup security on the router without using the application software. 1. Open a new browser. 2. You may now type IP address of the router in your browser. The step here is where you can get the management system of the router. Due to different vendors, you need to lookup on your router’s manual for the IP address usually it may be 10.10.10.01, 196.168.1.1 or 192.168.0.1, 100.100.100.1 or something similar to those matches and the default password of the router. Every router management console is different from each other. Try exploring around and find the appropriate section to manage. 3. You should never forget this step to setup an administrative password. The step to set here is often not located in Security section; you will need to take a look at the utilities, user management or system settings. Find it and change the password immediately for any user account. 4. Enable Wireless security. To turn on your encryption look under the wireless security tab. The step over here will need you to either use WPA or WPA-PSK and this will only appropriate if the devices on your network supported it. Otherwise you will need 128-bit WEP. For WPA or WPA-PSK, you would have to type pass phrase/password into a piece of paper and transfer to thumb drive so that you can set the password in the client’s machines. 5. Change your SSID. You should not make your SSID this will be probably a default SSID, normally those who do not configure their SSID will have their router name such as “linksys”, “belkin”, “dlink” etc. Try changing it with someone menacing, which will be threat for them to connect. Like virus geek, virus spreader. Remember that you will need this SSID when you browse through the network from your client machines. You can find these settings in the section of Channel or SSID. 6. Save your configurations and settings by pressing the save changes or save settings button. You will need to save every change that you will make to the router in order to it can take effect and probably you will have to reboot your router multiple times. Congratulations, finally you have covered the basic settings for your Wi-Fi network Wi-Fi Hotspot Security: Using VPNs There are numerous security issues regarding the use of the public wireless networks but all of which can be overcome. One of the solutions for users, as brought up in Wi-Fi Hotspot security, is to use the VPN (Virtual Private Network) to secure the real time traffic of the Wi-Fi hot spot users. Many small to large businesses provide their employees with the VPN access. Although this access is typically put in place for employees to have the remote access to the corporate network in order to access the files and documents remotely. If you don’t have access to any VPN servers, create your own. By doing this you can remotely access the files from your office as well as other devices such as Wi-Fi video camera to keep an eye on the things while away. When using the software-based VPN server features in Windows XP Pro, the PC running the server has to be powered-on to access the home network from the Wi-Fi hotspot. VPN routers can cost as low as $70 to $130 and the popular models are Linksys, WRV200 and WRV5G.

What is a Web Server?

Learn Web server software overview, how to configure, how it works, apache, tomcat. Web server is a computer including a software package that provides the specific services to the client computers. Web server delivers the web pages. Every web server has an IP address and a domain name. If you sends a request through your browser for this website http://www.networktutorials.info, the request goes to the server whose domain name is networktutorials.info.  



The server fetches the index or main page of the website and sends it to your browser. Web-based servers are used for hosting the websites. One web server can hosts thousands for one sites. But in the hosting companies there are number of the web servers for load balancing and sharing the other services.
A computer can be act as a web server by installing and configuring the server software and connecting the computer to the Internet. Normally, web server computers have to be turn on (online) for almost all the day.


There are many software applications that are used as the web server like IIS, Apache web server, Tom Cat web server. A web server typically accepts thousands of the concurrent incoming requests for the specific domain, that it hosts.
In case if the server is down for any reason, the websites that are hosted on this server cannot be accessed. So the downtime is a biggest negative thing for the web hosting companies. Many hosting companies have to mention the uptime of their servers for the client’s satisfactions like 99.9 % uptime. You may have seen this percentage on many hosting companies’ websites.


The web servers serves the objects in the form of html documents, plain text, images, sounds, video and some other form of the data. Many of the data types may not be placed in the static form but they are shown on the run time by the software programs, that are installed on the web server and the CGI scripts are the most common form of these programs.
Web servers and the browsers such as internet explorer, Firefox, Netscape, Opera etc communicate with the web server by using the HTTP protocols (Hypertext Transfer Protocol). This is very effective method of requesting the data over the Internet. Web servers are in various shapes and sized and run under different operating systems like Windows, Linux, and Unix etc. They are also range differently in prices and working.
Apache Web Server
The Apache web server is the most popular and most commonly used web server today. Apache web server has many features and good functionality that appeals to the users and that’s major cause of its popularity. On the other end, Microsoft’s IIS still is struggling to complete fully with apache web server. IIS is a very good server on the NT platforms and Apache is compatible with the Linux/Unix platforms.
Another big reason for the worldwide acceptance of the Apache web server is its stability. Many big websites on the Internet has chosen Apache web server for their hosting needs.
Additionally, Apache web server is a relatively fast. If your website contents are static then Apache’s working is very efficient and fast and on the other end, if you are using scripts like CGI scripts or others, it usually slows down the speed of the Apache web server.
A Web server is simply a little piece of the software, it takes the file name sent in the GET command, retrieves that files and send it back to the browser.
Most servers implement some level of security on the serving process. For example login/password accessible page requires the proper login and password from the users to accept that page. Web servers have the database and login information of the entire subscriber and only a subscriber of that typical service will be able to see that page. Additionally, while doing secure transactions the web pages allows encrypted transactions between the browsers and the servers such as on the E-commerce websites and other websites where a transaction through a credit card is required.
Basic Overview How Web Server Works
A web server performs various tasks on the request from the clients. To understand the working of the web server, it is necessary to first understand that what is client and server and what is their relationship with each other. A client is a program that sends request to a server and server responds to the requests of the clients.
This generic definition covers many types of relationships between client and servers like database server & web server etc. Web server have to be connected to the internet because client computers need to access them for various needs like data, files, graphics, video and html documents access.
The client program such as browsers and typically designed for the purpose of communicating with the web servers. A browser itself has different levels of features and security. To start the communication between the client (browser) and the server, a set of rules or agreed upon way is required and that is called a protocol. To access the web pages from the server HTTP protocol is required and for the file sharing access FTP protocol is required. There are a large number of the web protocols.
A web server is configured and designed in such a way that it responds to the thousands of the concurrent incoming requests from the clients for different things like html documents, graphics, images or video etc.

OSI 7 Layers Reference Model

Here you will learn OSI Model Layer Introduction, overview of the 7 OSI reference model, applicaion, session, transport, network and physical layers. If you want to remember the sequence of the OSI layers model name then the following two sentences can help you a lot for this purpose.“All People Seems To Need Data Processing”. Open Systems Interconnection (OSI) model is developed by ISO (International organization for standardization) in 1984. OSI reference model is a logical framework for standards for the network communication.  



OSI reference model is now considered as a primary standard for internetworking and inter computing. Today many network communication protocols are based on the standards of OSI model. In the OSI model the network/data communication is defined into seven layers.
These 7 layers further divide the tasks of moving the data across the network into subtask and hence complete one communication cycle between two computers or two network devices. Each layer is assigned a task and the task is completed independently. The OSI layers have the clear and independent characteristics and tasks.


The 7 layers of the OSI models can be divided into upper and lower layers. I have defined the characteristics, tasks and features of each layer separately.
Layer 7: Application Layer
The application layer defines the interfaces for communication and data transfer.
This layer also provides and support services such as job transfer, handles network access, e-mail, supports user applications and error recovery.
Protocols: FTP, DNS, SNMP, SMTP, FINGER, TELNET, TFTP, BOOTP and SMB protocol are operated on the application layer.
Network Devices: Gateway network device is operated on the application layer.


Layer 6:Presentation Layer
The presentation layer presents the data into a uniform format and masks the difference of data format between two dissimilar systems. It also translates the data from application to the network format. Presentation layer is also responsible for the protocol conversion, encryption, decryption and data compression. Presentation layer is a best layer for cryptography.
Network Devices: Gateway Redirector is operates on the presentation layer.
Layer 5: Session Layer
Session layer establish and manages the session between the two users at different ends in a network. Session layer also manages who can transfer the data in a certain amount of time and for how long. The examples of session layers and the interactive logins and file transfer sessions. Session layer reconnect the session if it disconnects. It also reports and logs and upper layer errors.
Protocols: The protocols that work on the session layer are NetBIOS, Mail Slots, Names Pipes, RPC
Network Devices: Gateway
Layer 4: Transport Layer
Transport layer manages end to end message delivery in a network and also provides the error checking and hence guarantees that no duplication or errors are occurring in the data transfers across the network. Transport layer also provides the acknowledgement of the successful data transmission and retransmits the data if no error free data was transferred.
It also provides and error handling and connectionless oriented data deliver in the network.
Protocols: These protocols work on the transport layer TCP, SPX, NETBIOS, ATP and NWLINK.
Network Devices: The Brouter, Gateway and Cable tester work on the transport layer.
Layer 3: Network Layer
The network layer determines that how data transmits between the network devices. It also translates the logical address into the physical address e.g computer name into MAC address. It is also responsible for defining the route, managing the network problems and addressing. Router works on the network layer and if a sending device does not break the data into the similar packets as the receiving device then network layer split the data into the smaller units and at the receiving end the network layer reassemble the data.
Network layer routes the packets according to the unique network addresses. Router works as the post office and network layer stamps the letters (data) for the specific destinations.
Protocols: These protocols work on the network layer IP, ICMP, ARP, RIP, OSI, IPX and OSPF.
Network Devices: Network devices including Router, Brouter, Frame Relay device and ATM switch devices work on the network layer.
Layer 2:Data Link Layer
Defines procedures for operating the communication links
Frames packets
Detects and corrects packets transmit errors
Protocols: Logical Link Control
• error correction and flow control
• manages link control and defines SAPs
802.1 OSI Model
802.2 Logical Link Control
Media Access Control
• communicates with the adapter card
• controls the type of media being used:
802.3 CSMA/CD (Ethernet)
802.4 Token Bus (ARCnet)
802.5 Token Ring
802.12 Demand Priority
Network Devices: Bridge
Switch
ISDN Router
Intelligent Hub
NIC
Advanced Cable Tester
Layer 1: Physical Layer
Physical layer defines and cables, network cards and physical aspects. It defines raw bit stream on the physical media. It also provides the interface between network and network communication devices. It is also responsible for how many volts for 0 and how many for 1. Physical layer also checks the number of bits transmitted per second and two ways or one way transmission. Physical layer also dealing with the optical, mechanical and electrical features.
Protocols: Protocols that work on the physical layer are ISDN, IEEE 802 and IEEE 802.2
Network Devices: Hubs, Repeaters, Oscilloscope and Amplifier works on the network devices.

What is Network Routing

You will be able to find the basic network routing overview, router configuration, router working, simulations static routes and routing table. Routing is the process of defining routes for the packets to its destination through an internetwork and this is performed by the router.
Routing is consist of two separate tasks.


1. Defining paths for the packets through and internetwork.
2. Forwarding data packets based on their predefined paths.
Generally, there are two types of routing.

STATIC AND DYNAMIC ROUTING
Routing can be performed by manually defining the routes or paths for packets to reach its destination. This is called static routing.


Stating routing works well for the small networks and when using the static routing, the routing table of the each router should be updated each time there is any change in the network configuration or topology. A router, whose routing table is not regularly updated, cannot communicate with the other routers.
While on the other end in most of the networks, routing is accomplished through the use of the dynamic routing. In the dynamic routing, routing protocols, such as RIP, OSPF etc create and maintain the routing tables of each router. Practically, dynamic routing functions very well than the static routing


ROUTING TABLE
A routing table is a set or rules, viewed in a tabular format and this used to define the routes of the data packets. All the network devices, which have IP, enabled functionality such as routers and switches use the routing tables. Routing table stores the information and configurations of every router in the IP enabled network. A routing table contains the information necessary to transmit the packets toward its destination.
When a packet is received, the network devices matches the information contained in the packets and the information in the routing tables and then it defines the shortest possible route for the transmission of the packets towards its destination.
Each packet contains the information of its origin and destination and the routing table contains the following information.
• Destination: The IP address of the packet’s final destination (next hop). Next hop: The IP address to which the packet is forwarded
• Metric: It assigns the cost to each route so that most-effective paths can be picked up.
• Routes: It includes directly attached direct subnets, indirect subnets, that are not directly connected to the device but it can be accesses through one ore more hops
• Interface: The outgoing network interface the device should use when forwarding the packet to its final destination.
Routing tables can be maintained manually by the network administrator or by dynamically (automatically). The static network tables do not change unless the network administrator changes them. Routing tables can be maintained manually or dynamically. Tables for static network devices do not change unless a network administrator manually changes them. In the dynamic routing, the network devices such as routers and switches maintain the routing tables dynamically by using the routing protocols, such as RIP, OSPF etc. In the dynamic routing, the network devices listen and detect any network or devices failure and packet congestions.
Routing in the Internet
Routing is the method in which data finds its destination from one computer to the next. In the Internet there are 3 major aspects of routing.
1. Physical Address Finding
2. Determination of inter-network gateways
3. Numeric and symbolic Addresses
Physical address finding is the method of the Internet Routing and is used when datagram is transmitted from a computer. It is necessary to encapsulate the IP datagram. This encapsulation requires the local network or physical address.
If a computer wishes to transmit IP datagram it needs to encapsulate the physical address of the destination network device in the frame. This address can be achieved by using the table that will map the IP address with the physical address. Such table can be configured into a file that can be read into the memory at the boot up time. Computer normally uses the Address Resolution Protocol (ARP), which operates dynamically to maintain the translation table.
The second method is necessary because the Internet consists of a large number of local networks, which are interconnected with each other by gateways. Such gateways are known as routers, which has physical as well as logical connectivity with many networks.
The determination of the best suitable gateway and port for a particular IP address is called routing.
The third method generally involves the translation of the human friendly form (names) to the number address (IP Address). IP address can’t be remembered due to its numeric form but the simplest names (domain names) are easy to remember e.g www.yahoo.com, www.google.com, www.msn.com are easiest to remember as compared to the IP addresses 122.11.22.34, 223.45.66.76, 155.44.55.120. DNS translates the domain names into the IP address and IP address into the domain name. This domain to IP translation is a must for communicating on the Internet because communication on the Internet is performed by the IP addresses.
Communication between routers
The Internet is a network of networks. The Internet consists of large number of autonomous systems, each of which further consists of routing domains. Such autonomous systems are usually run by the larger companies or universities. Within the Autonomous system, a router communicates with the other router using the best intra domain routing protocols, which are known as interior gateway protocols. Autonomous system are connected via gateways, these exchange information using inter domain routing protocol, which are also called exterior gateway protocols.
The RIP or (Routing Information Protocol) is the commonest interior gateway protocol and the recent protocol such as open shortest path first (OSPF). The purpose of these protocols is to enable routers to exchange locally so that all the routers in the autonomous system must a have coherent and up to date information.
When a host receives the new routing information, it is likely to update not only to it but also sends this new updated information to all the connected hosts so that they can updated themselves. Hence these changes propagate across the entire network.

An Overview of the Wireless Networking

Here you will find wireless networking tutorials, what is wifi, general security overview, wlans, wpans, wmans, wep and wireless access control overview. Whether you want to make a phone call from your mobile, received a message on your pager, checked your email from a PDA we have come across a wireless data or voice network.  



If a user or a company wants to make a data portable then Wireless networking is the answer. A wireless networking system can avoid the downtime, which may be caused in the wired network. A wireless network is also save your time and efforts in installing the lot of cables.
Also, if you need to relocate a client machine in your office, you only need to move the computer with wireless network card.

Wireless networking is very useful in the public places, libraries, hotels, schools, airports, railway stations where one might find wireless access to the internet. A drawback in the wireless internet is that quality of service (QOS) is not guaranteed if there is any interference then the connection may be dropped.


Wireless Network Types
Wireless Local Area Networks (WLANS)
WLANS allow users in local area, such as in a university or a library to form a network and gain wireless access to the internet. A temporary network can be formed by a small number of users without the need of access point; given that they do not need to access the resources.
Wireless Personal Area Networks (WPANS)
There are two current technologies for wireless personal network Bluetooth and Infra Red. These technologies will allow the connectivity of personal devices within an area of 30 feet. Infra Red requires a direct line and the range is less as compared to Bluetooth technology.
Wireless Metropolitan Area Networks (WMANS)
WMANS allow the connectivity of multiple networks in a metropolitan area such as building in a city. The network connectivity is the alternative of copper or fiber cabling.
Wireless Wide Area Networks (WWANS)
WWANS or Wireless Area Networks can be maintained over large areas such as in different cities or between different countries, via multiple satellite systems or antenna sites. The types of system are called 2G systems.
The following table shows the range those different types of wireless network covers.
Network Meter
Personal Area Network 0-10
Local Area Network 0-100
Wide Are Network 0-10000
Security in Wireless Networking
The following different types of security methods are available in the wireless networking.
Wired Equivalent Privacy (WEP)
Wired Equivalent Privacy is intended to stop the interference of radio frequency that is signaled by unauthorized users and this security measure is most suitable for the small networks. There is not key management protocol and each key is entered manually into the clients that’s why this is very time consuming administrative task. The WEP security method is based on the RC4 encryption algorithm. In the WEP all the client computers and Access points are configured with the same encryption and decryption keys.
Service Set Identifier (SSID)
Service Set Identifier (SSID) acts a simple password by allowing WLAN network to be split up into different networks and each having a unique identifier. These identifiers are configured in the multiple access points. To access any of any networks, a computer is configured in such a way that each is having a corresponding SSID identifier for that network. If the SSID match between the two computers or networks then access is granted to each other.
Media Access Control filtering (MAC Access Control)
A list of the MAC addresses of the client computers can be inputted into an Access point and only those computers are granted to give the access to the network. When a computer makes a request, its MAC address is compared to the list of the MAC addresses to the Access point and based on this access permission granted to deny.
This is a good security method but it is mainly involved in the small wireless networks because there is more manual work is involved of entering the MAC address into the Access point.
Bluetooth
Bluetooth is a simple type of the wireless networking that operates in the digital devices, like mobiles phones, personal computers, PDA, Laptops, digital camera, MP3 players and other Bluetooth enabled devices to form a small network. In the Bluetooth technology eight devices can be connected to each other at the same time. Bluetooth can also be found in the headsets, hands-free kits, wireless keyboards and mouse. Bluetooth technology was invented by Ericsson in 1994 and after four years in 1998 some major mobile phone companies such as Nokia, Ericsson, Intel and Toshiba formed a group to promote this technology.
Bluetooth technology falls in the category of personal area networking because it operates in the range of 30 to 300 feet. Bluetooth uses the radio waves technology, which is not very expensive and has low power consumption. Many different companies are intended to add the Bluetooth chip in their digital devices. Bluetooth technology is getting very popularity because of its low cost and portability.
The Future of Wireless Networking
WLANS wireless networking type is very popular in home networking and more than 20 percent homes with broadband internet are using WLANS and this number is increasing. In a general estimate worldwide hotspots have now reached more than 30,000 and will grow about 210,000 in the next few years. Most large hotels already offer Wi-Fi and the business travelers are willing to pay wireless access. 802.11 is the next Wi-Fi speed standard is set to offer bandwidth around 108Mbps and is still under development. With the speed of 70 Mbps and a range up to 30 miles, the 80216 standard, known as WiMAX is sure to get boost.
Some Tips & Tricks
• When purchasing a wireless NIC card try to get one that is having external antenna. When you are out and using Wi-Fi enabled laptop, disable Microsoft file and sharing, which enables other computers in a network to access data and resources on your computer. In this way, your computer or laptop will be saved from hackers.
• If you are concerned about the interference from the other wireless access point set the AP and wireless computers to use a non-overlapping channel.
• Change the configuration interface password of the access point before you enable it.
• Only buy an access point that is having upgradeable capabilities. By this way you can take the advantage of security enhancements.
• Keep the access point up to date.

Network Communication Devices

In this tutorial you will learn get the basic introduction to network devices such as nic adapters, routers, hubs, switches, modems, communication cables, lan/wan routers, gateway and other devices. A network is consists of a larger number of the communication devices. The simplest device that is used in the communication is the NIC adapter which is attached with the every computer in a network. If you want to build a LAN, you will need to have computers, hubs, switches, network adapters, UTP/STP cables, routers, internal/external modems, connectors, cable testers and clipping tool.

On the other hand if you need to build WAN, you will need to have routers, switches, dedicated or leased telephone lines such as ISDN lines, frame relay connection and other types of wan communication connections. There are different communication mediums such as Ethernet cables, copper wire, coaxial cable, fiber optic cables, leased telephone lines and ever air is also a communication medium for the satellite communication. The most common networking medium is the LAN is the Ethernet cable (UTP/STP), which is used in the star topology. Hub is a central device of a network and every computer in a network is directly connected with the hub. If the hub fails to work, the communication between the computers stops till the hub again starts working. Hub broadcasts the data to its every port, and then finding the destined computer, the data sent toward it. The switch is an advance form of the hub similar in functions but the advanced switches has a switching table in them. A advanced switch stores the MAC address of every attached computer and the data is only sent to the destined computer, unlike the hubs where data is sent to all ports. A router is a key device in the internet communication and wan communication system. A router has software called routing table and the source and destination addresses are stored in the routing table. A router connects two logically and physically different networks. Router finds the IP address of the next hop (next router) and the data is sent toward it and so on. The well known routers developing companies are Cisco systems, Nortel, DLink and others. Every ISP, banks, corporate offices and multinational companies use routers for LAN and WAN communications and communication in their private networks. A gateway can be device or software in a network. A gateway device connects the LAN with the internet. A gateway is directly exposed to the internet so it should be securely configured and in and out traffic should be monitored. If you are using DSL connection, you must need a DSL modem in your network. The telephone line is connected with the DSL modem and UTP/STP cable attaches your computer with the DSL modem. Modems are the devices that are used to modulate and demodulate the data. They convert analogue signals to digital and digital signals to analogue so that signals can travel on the telephone lines. There are certain types of the cables that are used to connect two or more computers in a network. Fiber optic cable acts as a backbone between the ISPs and corporate offices. Data travels at the speed of light on the fiber optic cables. The cost and the installation cost of the fiber optic cable is very high but it is becoming very popular in the home networking and LANs also. In the local area networking, 10baseT/CAT5 cable is most commonly in use. A server is a computer in network that provides services to the client computers such as logon requests processing, files access and storage, internet access, printing access and many other types of services. Servers are mostly equipped with extra hardware such as plenty of external memory (RAM), more data store capacity (hard disks), high processing speed and other features.

How to Configure a Network

In this section you will learn how to configure a network, peer to peer, client server, workstation, server, basic data communication. Peer to Peer network model Before configuring a computer network, you have to decide that, which networking model you require. There are two main types of network models. Peer to peer and client-server network model. In the peer to peer network model you simply use the same Workgroup for all the computers and a unique name for each computer.

Additionally, you will have to give a unique IP address of the same class A, B, or C for all the computers in your network and its related subnet mask e.g if you decide to use class A IP address for your three computers in your Peer to Peer network then your IP address/Subnet mask settings can be as follows. Computer Name IP Address Subnet Mask Workgroup PC1 100.100.100.1 255.0.0.0 Officenetwork PC2 100.100.100.2 255.0.0.0 Officenetwork PC3 100.100.100.3 255.0.0.0 Officenetwor Please note that the above example is for only illustration purpose so you can choose any IP address, computer name and workgroup name of your interest. For doing this right click on My Computer and then click Properties then go to the Network Identification section and set these. In a peer to peer network all computers acts as a client because there is not centralized server. Peer to peer network is used where not security is required in the network. If a computer fails to work then all other computers work normally in peer to peer network. Client/Server Network Model In the client/server network model a computer plays a centralized role and is known as a server all other computers in the network are known as clients. All client computers access the server simultaneously for files, database, docs, spreadsheets, web pages and resources like hard diver, printer, fax modem, CD/DVD ROM and others. In other words, all the client computes depends on the server and if server fails to respond or crash then networking/communication between the server and the client computes stops. If you want to configure a client-server network model then first prepare the server. Install Windows 2000 or Windows 2003 Server from the CD on the server computer and make a domain. You can create a domain by this command on the Run “DCPROMO”. You can give this command once you install the server successfully. After you give the DCPROMO command you will be asked for a unique domain name. All the client computers will use the same unique domain name for becoming the part of this domain. This command will install the active directory on the server, DNS and other required things. A step by step wizard will run and will guide you for the rest of the steps. Make sure that a network cable is plugged in the LAN card of the server when you run the DCPROMO.exe command. When the Active directory is properly installed on the server, restart the server. You can create network users on the server computer and also name/label the network resources like computers/printers etc. Once you install the server successfully now come to the client computers. Install Windows 2000 professional on your all client computers. Once you install the Windows 2000 professional on the clients the next step is to make this computer (client computer) a part of the network. Configuration Steps 1. Choose a unique name for each client computer 2. Choose unique IP address for each computer and relevant. 3. Use the same domain name for all client PCs. Network/System administrators are required to do these administrative tasks on the server and client computers. Any shared resources on the network either on the server or the clients can be access through the My Network Places in the Windows 2000 platform. There is another way to connect to the shared resources by giving this command in the run \\ComputerName\SharedDriveLetter. Network configurations steps can be implemented by right clicking the My Computer>Properties> For giving the IP address you will have to right click on the My Network places>properties>Local Area Connection>Properties>Internet Protocols (TCP/IP)>Properties and then give the IP address and subnet mask of the same range and class for all the computers in the network.