Explain the OSI ( Open Systems Interconnection ) reference model with diagram?

Solution:-

OSI means open System Interconnect model. It was developed by the International organization for standardization in 1974. It consists of seven layer, each layer has specific processing function. Figure below.......

1. Application layer: It is responsible for providing network services to the user. It is also known as desktop layer.

2. Presentation layer: It is responsible for concerting data into standard format. eg. ASCII, JPG, MPG, BMP.

3. Session layer: It is responsible for establishing maintaining and terminating session. Session ID work at session layer.

RPC- Remote procedure call

SQL- Structured query language

NFS- Network File System

4. Transport layer: It is responsible for end- to- end connectivity. It is also known as the heart of OSI layers. Following tasks are performed at transport layer:

                i. Indentifying service

                ii. Multiplexing and De-multiplexing

                iii. Segmentation

                iv. Sequencing and reassembling

    v. Error correction

    vi. Flow control

5. Network layer: It is responsible for providing best path for data to reach the destination. Logical addressing works on this layer. Router is a Network layer device.

6. Data link layer: It is divided into two sub layers.

a. LLC: Logical link control which talks about WAN protocols.

b. MAC: Media Access Control which talk about physical address. It is responsible for error detection also.

7. Physical layer:  It is responsible for electrical mechanical and procedural checks. Data will be converted into Binary (i.e.) O's and I's devices working at physical layer are Hubs, Repeaters, cable, Modem etc.

What is switching? Explain the space-division switching and time-division switching.

Solution:-

               A communication network consists of a collection of devices (or nodes) that wish to communicate and inter-connect together. The primary objective in any communication network is simply moving information from one source to one or more destination nodes.

 

Space Division Switching:-

            In space-division switching each input takes a different physical path in the switch matrix depending on the out-put. Hence, when a connection is established through a space switch matrix, a permanent physical contact is made on the matrix of cross-points. The connection will be maintained throughout the call duration. This technology can be primarily developed to accommodate analog transmission. Figure Below.............

 

Time Division Switching:-

             Time division switch, the n input lines are scanned in sequence to build up an input frame with n slots. Each slot has k bits. For T1 switches, the slots are 8 bits, with 8000 frames processed per second. The heart of the time division switch is the time slot interchanger, which accepts input frames and produces output frames, in which the time slots have been reordered according to mapping table in the memory of the switch. Finally, the output frame is de-multiplexed with output slot 0 going to line 0, and so on. In essence, the switch moves data from input lines to output lines according to the mapping table even though there are no physical connections between these lines. Figure below.............

 

What is Internet Protocol Television (IPTV)? Describe Features.

Solution:-

                 Internet Protocol television (IPTV) is the process of transmitting and broadcasting television programs through the Internet using Internet Protocol (IP). IPTV gives dynamic features to the user to improve the user experience compared to a traditional television transmission such as radio frequency broadcast, satellite broadcast and/or cable television. A broadband connection is used as the medium of transmission for IPTV, which is very efficient compared to earlier transmission modes.

Main feature of  IPTV

1. VOD: Video on demand (VOD) is an option available to the users of IPTV. Each user is given the option to choose from a catalog of videos and watch them as many times as required. This feature uses unicast transmission, whereas normal TV broadcasts use multicast transmission. Real Time Streaming Protocol is used for VOD.
2. DVR: IPTV allows users to watch TV shows broadcast in the past using digital video recorder (DVR), which is also known as time shifted programming. Providers of IPTV allow users to watch recorded shows without DVR devices. There is a live DVR system at the provider’s end, making DVR more cost effective and efficient. Users can watch replays or start a TV program over from an interactive menu.
3. Live Television: IPTV allows users to watch live transmissions with minimal latency. It provides live television broadcasts either with or without interactivity, without being just like traditional TV broadcasts. The protocol used for live television is Internet Group Management Protocol (IGMP) version 2.