Home » NETWORKING AND DATA COMMUNICATIONS

Category Archives: NETWORKING AND DATA COMMUNICATIONS

COMMUNICATIONS PROTOCOL

A protocol is a list of messages and rules that controls and enables communication between two or more systems or computers. It also responsible for the exchange of data or information between two systems. For communication between two or more system, there must be some set of protocols so that the systems can communicate properly with each other. If there are no protocols between the systems then there will be confusion and chaos. To accomplish any task on a network, we need protocols. For example if we want to print a document by a network printer then printer will need protocols to do that. If we want to send a file form one computer to another computer on a network then we need protocols. If we want to send a mail then we need protocols. If we want to access a file on a network then we need protocols. Therefore to do any job on a network we need protocols. More than one protocols can work together to accomplish a single job. Different protocols help each other to enhance the level of communication between computers. There are several types of protocols and these are listed below. Each protocol is also discussed separately.

(more…)

IP ADDRESS

IP address also known as Internet Protocol address is a numerical name given to each device of a network. Here the devices can be a computer, printer, scanner and other network devices. An IP address of a device server two purposes, one of its purpose to provide identification to the device in the network and its second purpose is to locate the device location. The IP address of a device can be a 32 bit binary number and this system of addressing in 32 bit number is called IPv4 or Internet Protocol version 4. Except IPv4 there is another system of addressing is IPv6 which is called Internet Protocol version 6 and it uses 128 bits for addressing. IP address of a device is unique. Thus two devices cannot have the same IP addresses at same time. If a device is connected to two different networks then it will have two different IP addresses.

(more…)

DATA TRANSMISSION

Data transmission refers to the transfer of data from one computer to another computer through guided or unguided media. There are two methods for data transmission between two or more computers and these are listed below.
  1. Serial Data Transmission
  2. Parallel Data Transmission

SERIAL DATA TRANSMISSION

BLOCK DIAGRAM FOR SERIAL DATA TRANSMISSIONIn serial data transmission there is a single communication line between computers. In this method bits are sent serially one by one from computer to computer. Each previous bit follows its next bit. In serial data transmission with each clock tick one bit is sent from sender system or computer to the receiver system or computer. Serial data transmission is used for long distance transmission between computers. Serial data transmission is further divided into two sub categories. These two categories are given below.

(more…)

WHAT IS LINK STATE ROUTING

Link state routing is one of the routing techniques. It a simple technique and the operation done during this routing technique can be divided into five stages. Each router of a network must follow the following operation.
  1. The router of the network must discover its neighbor routers and get their network address.
  2. The router of the network must calculate the time delay to each of its neighbor router.
  3. The router of the network must create a packet having all information it has got form other routers.
  4. The router has to send this packet to other neighbor routers.
  5. Finally computation of shortest path to every neighbor routers has to be done.

The above five points are discussed below one by one.

GETTING ADDRESS OF NEIGHBOR ROUTERS:

When a router is started or booted its first job is to know about its neighbor router and also get their network address. A router does this job by sending a special packet named HELLO to its neighbor routers. The other routers of the network are expected to send a reply telling who they are.
CALCULATION OF TIME DELAY:
Each routers of the network must know or at least have an estimate of the delay to each of its neighbor routers. To calculate time delay between two routers a special packet ECHO is to be sent from first router to the second router, the second router has to send back the packet immediately. Now by measuring the round trip time and dividing it by two the delay can be calculated. The most accurate value of delay can be found by sending the packet n times and taking the average of round trip time.
CREATING THE PACKET HAVING ALL INFORMATION:
Once the router have collected all information which is needed for the exchange between routers, the router has to create a packet which all these information. The packet starts with the identity of the sender, followed by a sequence number and age and a list of neighbor routers.
DISTRIBUTION OF PACKETS:
The next step of link state routing is to distribute the packet to all its neighbors. Flooding technique is used to distribute the packets. Each packet is given a sequence number and it incremented for the next packet. When a packet comes in it is checked against the list of packets already seen. If the packet is new then it is forwarded to all other routers if it is a duplicate packet then it is discarded.
COMPUTATION OF SHORTEST PATH:
The final step of link state routing is to find the shortest routes. Construction of shortest path is accomplished by Dijkstra’s algorithm. The results of this algorithm are stored in the routing tables and normal operations resumed.

URL: UNIFORM RESOURCE LOCATOR

URL also known as Uniform resource Locator of a website is an internet name of that website. It is a way to address data and information on the Internet. The URL of a site contains the following information.
  1. The URL contains the Internet name of the site which has the data and information.
  2. It contains the name of services used by the site for example HTTP and GOPHER.
  3. It contains the Internet port number of the service. If the port number is not given then it uses a commonly used value.
  4. And finally the locations of data or information in directory like structure.
The standard format of a website is given below. The structure of a URL is hierarchical and it follows from left to right.
STANDARD FORMAT:
Protocol service://server-name.domain-name.top-level-domain-name/directory-name/file name.html
Example of an URL is given below.
http://www.bscshortnote.com/DECODER/what-is-decoder-and-its-types.html
Protocol service : http
Server name : www
Domain name : bscshortnote
Top level domain name : com
Directory name : DECODE
File name : what-is-decoder-and-its-types.html

BANDWIDTH

The range of frequencies that can pass through a transmission medium is called the bandwidth of that medium. A medium cannot allow to pass or to block all the ranges of frequencies. Thus the bandwidth is a range and is normally the difference of the maximum and minimum frequencies that can pass through that medium. Hence it can be calculated by the given formula.

Bandwidth of a medium = Maximum frequency – Minimum frequency
As for example, suppose a medium can allow passing the signals whose frequencies are between 2000 to 5000 Hz then what is the bandwidth of the medium?
Here, the maximum frequency of the signal is 5000 Hz and minimum frequency is 2000 Hz. Thus
Bandwidth of a medium (B)
= Maximum frequency – Minimum frequency
= 5000 – 2000
= 3000 Hz

(more…)

TYPES OF NETWORK CONNECTION

A computer network is a set of several computers and devices connected through communication links. A communication link is a path among the computers and devices which is used to exchange information among them. Here information can be of any type like text, image, audio or video. In a network devices are also known nodes. A node in network can be a personal computer, printer, scanner or any other devices those who can exchange information. A connection is a link among nodes. For communication between two nodes or computer they must be linked to a common path at the same time. There are two types of network connection:
  1. POINT-TO-POINT CONNECTION
  2. MULTIPOINT CONNECTION
    a) SPATIALLY SHARED CONNECTION
    b) TIME SHARE CONNECTION

POINT-TO-POINT CONNECTION

In a point-to-point network connection only two nodes or computers are connected though a communication link. Here communication link can be a physical cable or it can be microwave or satellite link. In this connection the communication link reserved for transmission between the two connected nodes. In point-to-point connection channel capacity is not shared. A point-to-point connection is a dedicated connection. The dedicated connection means only the two nodes having point-to-point connection can see information. Television remote control and television control system is the example of point-to-point connection. Point-to-point connections are also used in mesh topology (FullyConnected topology), Star topology and Ring topology to connect nodes.

MULTIPOINT CONNECTION

Multipoint connection also known as Multidrop connection is used to connect more than two nodes to a single communication link. In multipoint connection channel capacity is shared among the nodes. Multipoint connection is used in bus topology. On the basis of sharing of channel capacity it is further divided as:

SPATIALLY SHARED CONNECTION

In spatially shared connection communication link is shared among all nodes at the same time.

TIME SHARE CONNECTION

In time share connection communication link is used by the nodes turn by turn.