DATA COMMUNICATION AND NETWORK ISSUES INTRODUCTION Data Communication Transmission Duplex Analog And Digital Signal Network Introduction Type Of Computer Computer Network Topologies Network Issues DATA COMMUNICATION Data communication refers to the exchange of data between a source and a receiver via form of transmission media such as a wire cable


DATA COMMUNICATION AND NETWORK ISSUES

INTRODUCTION
Data Communication
Transmission Duplex
Analog And Digital Signal
Network Introduction
Type Of Computer
Computer Network Topologies
Network Issues

DATA COMMUNICATION
Data communication refers to the exchange of data between a source and a receiver via form of transmission media such as a wire cable. Data communication is said to be local if communicating devices are in the same building or a similarly restricted geographical area.

The meanings of source and receiver are very simple. Source is the device that transmits the data and receiver is the the device that receives the transmitted data. Data communication aims at the transfer of data and maintenance of the data during the process but not the actual generation of the information at the source and receiver. 
The facts information statistics or the like derived by calculation or experimentation is called Datum. The information and facts so gathered are processed in accordance with defined systems of procedure. There are data in various forms, such as numbers, text, bits and bytes. A example for a simple data communication system is the figure.

Example for simple data communication system

The data transmission system can add data from remote locations through the transmission circuits, and then implement it to remote locations. The figure provides a wide range of data communications networks. Different types of data communication technologies have been developed to improve existing data communication techniques, or systematically remodel with alternatives and features. Thereafter, in communication systems, data communication jargons are available for data communication to contend such as (radar, modem, routers, LAN, WAN, TCP / IP, ISDN). Therefore, these rules and data communication systems are required to be gradually improved.

OSI model layers
Open System Interconnect is an open standard for all communication systems. OSI model is established by International Standard Organization. This model has seven layers:

Application Layer: This layer is responsible for providing interface to the application user. This layer encompasses protocols which directly interact with the user.
Presentation Layer: This layer defines how data in the native format of remote host should be presented in the native format of host.

Session Layer: This layer maintains sessions between remote hosts. For example, once user or password authentication is done, the remote host maintains this session for a while and does not ask for authentication again in that time span.
Transport Layer: This layer is responsible for the end-to-end delivery between hosts.
Network Layer: This layer is responsible for address assignment and uniquely addressing hosts in a network.
Data Link Layer: This layer is responsible for the reading and writing data from and onto the line. At this layer link errors are detected.
Physical Layer: This layer defines as the hardware, cabling, wiring, power output, pulse rate etc.

Analog and Digital Signal
Digital-to-Analog Conversion
When sending data from one computer to another via some analog carrier, it is first converted into analog signals.

Analog signals are modified to reflect digital data. An analog signal is characterized by its amplitude, frequency, and phase. There are three kinds of digital-to-analog conversions:
Amplitude Shift Keying
The amplitude of analog carrier signal is modified to reflect binary data in this conversion technique,
Frequency Shift Keying
In this conversion technique, the frequency of the analog carrier signal is modified to reflect binary data.

Phase Shift Keying
In this conversion scheme, the phase of the original carrier signal is altered to reflect the binary data.
Quadrature Phase Shift Keying
The QPSK changes at a glance to two binary numbers simultaneously. This is done in two stages. The main current of the two data is equally divided into sub-projects. The serial data pairs are simultaneously translated. Each flow is then converted to a digital signal using NRZ technology. The digital signals are then combined.
Analog-to-Analog Conversion
Analog signals are modified to represent analog data. This interpretation is called Analog Modulation. Analog modulation is needed when band pass is used. Analog to analog conversion can be done in three ways:

Network Introduction

Type of network
Local Area Network
A Local Area Network is a personal computer network covering a small Networks geographical area, like a home, office, or groups of buildings example for a school Network. LANs are used to connect the computers and other network devices and resources can be exchanged so that they can be shared with each other. A hardware device, such as a shared resource like printer, software like an application program or data. The LAN’s size is usually small. The various devices in LAN are connected to central devices called Hub or Switch using a cable.

LAN has been installed using wireless technology. An access system or AP is used to transmit and receive data through such a system. All the rest of the computers that a computer hosts on a network is provided by one server.For example, there are wireless or wireless LANs for users to connect libraries to networked devices.
The LAN speeds up communication of data rates of 4 to 16 megabits per second. IEEE has projects investigating the standardization of 100 G bit/s, and possibly 40 G bit/s. LANs Network may have connections with other LANs Network via leased lines, leased services.

Metropolitan Area Networks
MAN is a network of metropolitan area networks. MAN is a relatively new range of networks. MAN is larger than a local area network and covers the area according to its name. MAN rarely extend beyond 100 KM and frequently comprise a combination of different hardware and transmission media. It can be a single network such as a cable TV network, or it can be a device for connecting a number of networks to a larger network .That means it can use a network to use a LAN and device.

                      
A MAN can be created as a single network such as Cable TV Network, covering the entire city or a group of several Local Area Networks. The resource network then can be transferred from LAN to LAN and from computer to computer also. In generally, MANs are owned by large organizations to interconnect its various branches across a city. 
MAN is based on IEEE 802.6 standard is called the Distributed Queue Dual Bus. Two DQDB unidirectional cables are used and all the computers are connected to these two buses. Each bus has a specialized device that initiates the transmission activity. This device is called head end. Data that sent to the computer on the right hand side of the sender will be sent to the upper bus. Data that is to be sent to the left hand side of the sender is transmitted on lower bus.

                            
The two main elements of MAN are security and standardization. Security is important because information is being shared between dissimilar systems. Standardization is needed to ensure the reliable data communication.

Normally MAN interconnects to a number of local area networks using a high-capacity backbone technology, such as fiber-optical links, and it provides up-link services to wide area networks and the Internet. 
Wide Area Networks 
A wide area network is a telecommunication network. A wide area network is simply a LAN of LANs or Network of Networks. WANs connect LANs that may be on opposite sides of a building, across the country or around the world. WANS are characterized by the most slow moving communication rates and the largest distances. There are two types of WANs: an enterprise WAN and Global WAN.

A wide range of computers are connected to common networks such as a telephone system. They can be connected through tax concessions or through satellite. The largest WAN is the Internet. Some of the features on the Internet, such as VPN-based antivirus, are the same as the WAN. In the end, most WANs are business or research networks that use rental rates. Numerous WANs have been constructed, including public packet networks, large corporate networks, military networks, banking networks, stock brokerage networks, and airline reservation networks.

Organizations of WANs using Internet Protocol are known as Network Service Providers. They are the core of the Internet.

By connecting the NSP WANs using internet Packet Interchanges a global communication infrastructure is created.

Computer network topology
A Network Topology is how a computer systems or network device interacts or interconnected. Topologies can define both physical and logical aspect of the network. A logical and physical observer can be the same and one or the same network.

Type of topology
Bus Topology
In case of Bus topology, all devices exchanged single communication line or cable. Bus topology may have problem while multiple hosts sending data at the same time. Therefore, if the bus pillar uses CSMA/CD technology or one carrier determines this problem host as the Bus Master. It is one of the simple forms of networking where a failure of a device does not affect the other devices. But failure of the shared communication line can make all other devices stop functioning.
Line terminator have Both ends of the shared channel. The data is sent in only one direction and as soon as it reaches the extreme end, the terminator removes the data from the line.

Star Topology
All hosts are connected to a central device in a Star Topology, called as hub device, using a point-to-point connection. That is, between hosts and hubs there exists a point to point connection.

Ring Topology
In ring topology, creating a circular network structure, each host machine connects to exactly two other machines. When one host tries to communicate or send message to a host which is not adjacent to it, the data travels through all intermediate hosts. To connect one more host in
The existing structure, the administrator may need only one more extra cable.

Mesh Topology
In this type of topology, a host is connected to one or multiple hosts. This topology has hosts in point-to-point connection with every other host or may also have hosts which are in point-to-point connection with few hosts only.

Tree Topology
This is also known as Hierarchical Topology, this is the most common form of network topology in use presently. This topology imitates as extended Star topology and inherits properties of Bus topology.

Daisy Chain
This topology connects all the hosts in a linear fashion. Similar to Ring topology, all hosts are connected to two hosts only, except the end hosts. Means, if the end hosts in daisy chain are connected then it represents Ring topology.

Hybrid Topology
A network structure whose design contains more than one topology is said to be hybrid topology. Hybrid topology inherits merits and demerits of all the incorporating topologies.

Network issues
Initial Configuration
This is a problem with your network, your systems, and resources. A complex network contains many parts, and its size and usage may be complicated and problematic. For the past ten years, hardware and software requirements have not been developed for the development of telecommunications and hardware or software, or many systems have not developed formal education on topics such as systems development, networking and security
Whether you are configuring and configuring Windows, or Linksys router, you need to be careful and make sure that you do it well. There are many ways to do things, therefore, the best practices should be considered. For example, a computer system that requires you to connect to the Internet. This simple example requires that you know the TCP / IP address scheme, the DHCP protocol and the cable (or wireless accessibility). Following this link, a great example of networking can be found. If you are already familiar with the principles, you can get an idea of the complexity of networking.

The biggest problems that your system handles is your problems such as losing your major power source, lost cable (or wireless configuration), poorly configured protocols (such as IPs) or configurable network services such as configuration systems. Another problem to consider is access to common resources, such as your client computer network service printing. In most cases, the ‘server’ will be used to provide a centralized access point, which will set the properties of the printer server, or the server on the server’s server on the server, the control team, or the server / server connection. This is an obstacle for those who work with networked Windows systems. The relationship of a client to the server it uses to work with shared resources. After the initial configuration and testing of your network, the next steps should be to document it correctly so that if problems do pop up, you have the phone number for your ISP handy, or the manuals (or Web links) to the systems you are working with.

People have found that muscular ulcers have only been worn by Brand AIDS. For example the major corporations using a packet of storage load tool to calculate the amount of bandwidth that runs online with a network monitor and to troubleshoot problems with applications, poor designs or otherwise.

If you decide to use wireless connections over wired ones, initial design and configuration must not be overlooked. The OSI Model is a great help in getting these issues resolved. Firstly, wires (or cables) are associated with problems at the physical level. The cable is either damaged or being affected by distance or electrical problems, is connected incorrectly (wrong type or grade), or possibly the fact that the cable is simply not fully connected. Signal Interference issues are common, especially when cables are laid over a light or power source, for example. Wireless connections are way more complicated, as they need multiple hardware as well as software components (such as drivers and applications software) to be configured, made to work and keep up and running. Many times, you need to configure an Access Point (AP), generally found on most home-based routers sold on the market today.

Network Performance
This is usually a common problem with networking. Functionality with Windows is influenced in many ways. For example if you build or purchase a computer network, you do not consider apps that run though the network. The most common applications are that the client needs a server connection. The data is transmitted over the network to run the installed server of the windows desktop. if the network performance is affected.

Either the network is too slow (very common term), or the application was not developed with the network in mind. It can be confusing to solve this type of issue and normally requires advanced analysis of the problem usually needing a tool such as a packet analyzer (known as a sniffer) to solve.

Speed and Latency issues can be the result of from a network that is saturated with data or slow connections. For example, if you use gigabit Ethernet between your hosts, cabled connections will give you up to 1000 Mbps of speed. Unbeknownst to some, switching to a wireless connection will drastically impact your network communication because today home-based wireless systems (even when teamed) will not produce more than about 54-100 Mbps of transfer. Add in interference and you will definitely feel the pinch. 

Also can cause major issues with speed and latency, using a hub instead of a network switch (that keeps a switching table in memory). Using non-hierarchical designs where the core of your network is operating at the fastest speed and the access layer into the core operating at a slower speed can and absolutely will create bottlenecks. Though this is not a common design for home-based networks, you would be surprised at how many SOHOs have grown in size to really need a good design to operate correctly. Mismatched speeds and duplex settings on NIC cards such as half-duplex to full duplex (and auto-sense) are also common issues that create a performance hit on your network. Lastly, using a switch and creating a loop will likely shut your network down completely if one exists.

Credential, Permission and Rights Problems

So, is it possible that you have correctly configured everything and connected all the systems without a problem? Anything and everything. The first problem with Windows systems is the authorization and ownership of credentials. In most cases, you can access the host and, because the reason is impossible … Yes, you can speculate it – they are not allowed to login or log in to access them after logging in.

Usually, a person with this area has prepared this for you. If you did, you really need to consider some things. First, the Windows system periodically forces you to change your password. Otherwise, forgotten accounts have been forgotten in periods of inaction. You can contact your administrator to fix this problem, or contact it automatically. To do this, visit your account and login information in Windows to set things up for simplicity. Also, you can use a working team without a centralized control source, and logging on to multiple systems for easy use of resources. This team does not recommend many network problems on computers with a network of 10 or more systems.

If you can access and check, you can use Windows Event Viewer to find your many problems in this region. It is recommended that when you store a password in a secure location when you forget, you never see a unique feature (username and password) that can be used to position you anywhere without your permission. Being unable to access resources through your network is a common problem and you can easily resolve an accident plan to overwrite forgotten credentials

TCP/IP and other Protocol Problems
There are several reasons for this problem. This can solve many problems with ISP-based protocols, DHCP, APIPA, DNS, IP addresses and / or TCP / TCP / IP on your network. A) Although there are several systems, your topology has an updated document.

It’s very useful when you’re trying to fix a grid so you can see a graphic, or add a new hosting to your network without causing a problem. If you are using DHCP, you can help search for things like search tools such as IP stroller, net stat, ping, and patching, but you can use them when dealing with TCP / IP problems.

Other protocols exist to provide the same functionality for testing them. At a higher level, IP packets send more troubles and links through multiple links and the gears you use. Routing tables can include duplicates, and the address space is not summed up correctly, it can cause large route tables, and any end user tries to download a business side and it also makes both performance problems. Other protocols do exist and tools are available to perform the same functions to test them. At a high level, IP packets are routed over multiple devices and links which takes the problem and multiplies it times the amount of gear you are using. Routing tables can get screwed up from duplicate entries, and if address space is not summarize correctly, could cause large route tables, both of this causing performance issues for any end-user just trying to download a spreadsheet from the corporate office location
General Security Concerns
A networking problem in dealing with Windows clients is the lack of basic security services and their flaws or shortcomings. For example, your system can get a virus that can fail the network, heavily binding your system resources so that you can not access a webpage. The network invades your network through many networks, or can easily be wirelessly connected. This can be seen with home-office offices and small companies that can not be found in enterprise security solutions that can be used to control, monitor and monitor wireless. It does not mean that your home computer or router can not be protected. The benefits nowadays from most of the hardware and software you’ve sold today are just one of the safest features you have now. The publishers now provide extensive notes about firewalls, unauthorized identifiers, and all that it travels through. Common form of invasion. An example will be to load your open area wirelessly and navigate your neighborhood.

Using wireless security is a convenient way to find easy to access privacy tools for uncomplicated WEP keying techniques online. Another way to secure a wireless network is to use the MAC addresses of its clients in your office. The site with the access is maintained only by those users. Again, bulletproof, but every little bit helps your system not be protected.

You should always use one as the hostname security, even though you use or use a third-party software release using Windows Firewall. Trend data is supported by network-based unauthorized detectors and can lock anything that can not be seen. Depending on the depth of security, this concept is easy to understand. When you apply different types of security, you have deeply engaged in security

There may be a router with other wireless IDS, wireless charging security features. Use them for your own advantage, always log in to see what is happening. This function can also be performed on the system firewall level