Network Engineering

IPv4      It is a logical network layer address used for identifying a network, host in a network, a group of host in a network or all the host in a network. IPv4 is 32 bit addressing scheme used as TCP/IP host addressing mechanism. It is divided into four octet. Each octet is represented in decimal format. Each octet is represented in decimal format. Each octet is separated with dots. eg: 192.168.0.254. IP addressing enables every host on the TCP/IP network to be uniquely identifiable. IPv4 provides hierarchical addressing scheme which enables it to divide the network into sub networks, each with well defined number of hosts. Based upon the first octet value, IP addresses are divided into five classes. Class A : It uses first octet for network addresses and last three octets for host addressing. Range : 0 - 127. Addresses range 1 - 126 are used. Address start with 0 is unknown network and address start with 127 is for Loop track testing (testing the TCP/IP stack...

      Wireless transmission is a form of unguided media. Wireless communication involves no physical link established between two or more devices, communicating wireless. Wireless signals are spread over in the air and are received and interpreted by appropriate antennas. When an antenna is attached to electrical circuit of a computer or wireless device, it converts the digital data into wireless signals and spread all over within its frequency range. The receptor on the other end receives these signals and converts them back to digital data.  Click here Radio Transmission      Radio frequency is easier to generate and because of its large wavelength, it can penetrate through walls and structures. Radio waves can have wavelength from 1 mm - 100,000 km and have frequency range from 3 Hz (Extremely Low Frequency) to 300 GHz (Extremely High Frequency). Radio frequencies are sub divided into six bands. Radio waves at lower frequencies can travel th...

TCP     The Transmission Control Protocol (TCP) is one of the most important protocol of Internet Protocol suite. It refers to a collection of communication protocols that governs data exchange process in the internet. It is most widely used protocol for data transmission in communication networks such as internet. A communication protocol can be defined as a rule or custom that helps in the orderly exchange of data within a computer network.  WorkFromHome Features TCP is reliable protocol. That is, the receiver always sends either positive or negative acknowledgement about the data packet to the sender, so that the sender always has bright clue about the data packet is reached the destination or it needs to resend it. TCP ensures that the data reaches intended destination in the same order it was sent. TCP is connection oriented. TCP requires that connection between two remote points be established before sending actual data. TCP provides error-checking an...

UDP      The User Datagram Protocol (UDP) is simplest Transport Layer communication protocol available of the TCP/IP protocol suite. It involves minimum amount of communication mechanism. UDP is said to be an unreliable transport protocol but it uses IP services which provides best effort delivery mechanism. In UDP, the receiver does not generate an acknowledgement of packet received and in turn, the sender does not wait for any acknowledgement of packet send. This shortcoming makes this protocol unreliable as well as easier on processing. We deploy UDP where the acknowledgement packets share significant amount of bandwidth along with the actual data. For example, in case of video streaming, thousands of packets are forwarded towards its users. Acknowledging all the packets is troublesome and may contain huge amount of bandwidth wastage. The best delivery mechanism of underlying IP protocol ensures best efforts to deliver its packets, but even if some packets in video...

IPv6      The exhaustion of IPv4 address gave birth to a next generation Internet Protocol. IPv6 address is nodes with 128 bit wide address, providing plenty of address space for future to be used on entire planet. IPv6 has introduced Anycast addressing but has removed the concept of broadcasting. IPv6 enables devices to self-acquire an IPv6 address and communicate within that subnet. This auto configuration removes the dependability of Dynamic Host Configuration Protocol ( DHCP ) servers. This way even if the DHCP server on that subnet is down, the hosts can communicate with each other. IPv6 provides new feature of IPv6 mobility. Mobile IPv6 equipped machines can roam around without the need of changing their IP addresses. IPv6 is still in transition phase and is expected to replace IPv4 completely in coming years. At present, there are few networks which are running on IPv6. There are some transition mechanisms available for IPv6 enabled networks to speak and roam a...

      Router is a layer 3 (Devices which work on Network Layer mainly focus on routing) device. It is used for interconnecting different networks. Router works based upon the logical address (IP address) to forward data to other network sections. It uses Access Control List for filtering packets. Router won't forward broadcast from one network to another, it creates multiple broadcast domains. Routers can provide interconnection between different VLANs (Virtual LANs). Each interface of a router will be in different networks. Internal Components of s Router    1. RSP : Route Switch Processor. It is the CPU inside the Router.   2. RAM : Random Access Memory. It is a temporary storage media. Its volatile. Router RAM includes the following : Running configuration : The list of configurations which are presently used by the router. Routing table : It is the list of all the network and path information known to the router. CDP (CISCO Discovery Pro...

Data Communication      Data communication is the exchange of data between two devices through some transmission mediums, like a cable wire in the form of 0's and 1's. The purpose of data communication is to exchange information between two agents (end stations or nodes). End station may be a general purpose computer, a workstation, a cell phone or a PDA (Personal Digital Assistant). Users depend on nodes for transmitting or receiving digital information. Digital techniques and digital equipments  are used in a data communication circuit. Transmission facilities are usually provided by a public telephone network (PTN) or Public Data Network (PDN). [ Source ] --- [ Transmitter ] --- [Transmission Channel] --- [Receiver] --- [Destination Software] Source      Source may be a digital equipment or an application software running on a computer through which the user enter data into communication system for transmission to a remote host. Examp...

Unguided Media      In unguided media transmission, messages or electromagnetic signals travel through air or space. Cables, connectors and other solid conductors are not required in unguided media systems. Wireless communication is particularly useful in those regions where cables are difficult to implement or install. The main types of unguided media are, Radio waves, Microwaves and Infrared waves. The three main types of wireless media are: Radio waves Microwaves Infrared waves Radio Wave Links      Electromagnetic waves in the frequency range of 3 kHz to 1 GHz are commonly known as radio waves. There are basically two types of configuration for electromagnetic wave transmission and reception, directional and omni-directional. In directional configuration, an antenna radiates electromagnetic e...

Data Transmission      There is a maximum limit to the amount of data that can be transmitted using any transmission medium (Shannon's Law). Each medium has its own maximum. Data transmitted as signals. The number of signals per second is the frequency of the signal. This is measured in Hertz (Hz). One cycle per second is 1 Hz. One million cycles per second is 1 MHz. Bandwidth      The maximum range of frequencies that can be transmitted is the bandwidth of the medium. This determines the maximum amount of data that can be transmitted. A coaxial cable might have a bandwidth of 10 to 100 MHz. An optic fiber has a bandwidth of up to 10^8 MHz. The higher the bandwidth the more data that can be transmitted per second, hence the popularity of optic fibers. In fact, computers cannot yet utilize the full capacity of optic fibers, that is , they cannot transmit at the speed which the fiber is capable of carrying. Channel Capacity     ...