Wired And Wireless LAN Question And Answer | letsbug

 Wired And Wireless LAN

1.  Answer the following questions in short.

1. What is IEEE standards?

    Answer: 

        The Institute for Electrical and Electronic Engineering developed an Ethernet standard know as IEEE standard 802.3. Ethernet is the most widely-installed Local Area Network technology. 

        This standard defines rules for configuring an Ethernet network and also specifies how the elements in an Ethernet network interacts with one another. By following IEEE standard, network equipment and network protocol can communicate efficiently.

2. Describe Fast Ethernet.

    Answer: 

         The Fast Ethernet standard (IEEE 802.3u) has been established for Ethernet networks that need higher transmission speeds. This standard raises the Ethernet speed limit from 10 mbps to 100 mbps with only minimal changes to the existing cable structure. Fast Ethernet provides faster throughput for video, multimedia, graphics, Internet surfing and stronger error detection and correction.              

3. What is network interface card?

    Answer: 

        A NIC is either an expansion card (the most  popular implementation) or built in to the motherboard of the computer. In the most cases, a NIC connects to the computer through expansion slots, which are special slots, which are specials slots located on a computer's motherboard that allow peripherals to be plugged directly into it. In some notebook, NIC adapters can be connected to the printer port or through a PC card slot.

4. What is wireless LAN?

    Answer: 

        A wireless LAN or WLAN is the linking of two or more computers or devices using spread-spectrum or OFDM modulation technology based to enable communication between devices in a limited area. This gives the mobility to move around within a broad coverage area and still be connected to the network.

5. What is Bluetooth in WLAN?

    Answer:

       Bluetooth is an open specification for short-range wireless transmission of voice and data. It provides  a simple, low-cost seamless wireless connectivity between Personal Digital Assistants (PDAs), cellular phones, laptops and portable handheld devices. 

        Bluetooth can be used for bridging data networks, connecting peripherals to devices and forming ad hoc connections between groups of information appliances.

2.  Define the following terms:

1. Ethernet

    Answer: 

        A system for connecting a number of computer systems to form a local area network, with protocols to control the passing of information and to avoid simultaneous transmission by two or more systems.

2. Start backbone

    Answer: 

       The backbone is simply a switch which is used to connect various LANs. The switch does the job of backbone are basically used as distribution backbone inside a building. 

3. Bus backbone

    Answer: 

      Bus backbone structure is used as a distribution backbone for connecting different buildings in an organization. Each building may have either a single LAN or another backbone which comes in start backbone. The structure is a bridge based (bridge is the connecting device) backbone with four LANs.

4. VLAN

    Answer: 

       In a traditional LAN, workstation are connected to each other by means of a hub or a repeater. These devices propagate any incoming data throughout the network. However if two people attempt to send information at the same time, a collision will occur and all the transmitted data will be lost. Once the collision has occurred, it will continue be propagated throughout the network by hubs and repeaters.

5. CSMA/CD

    Answer: 

        Carrier Sense Multiple Access with collision detection is a protocol used to sense whether a medium is busy before transmission but is the ability to detect whether a transmission has collided with another.

3.  Answer the following questions:

1. Write a short on IEEE standards 802.11.

    Answer: 

        IEEE has defined the specifications for wireless LAN, named IEEE 802.11, which covers both physical and data link layers. 

Architecture of 802.11(WLAN):

1. Each computer, mobile which is portable or fixed, is referred to as a station in 802.11 wireless networks. 
2. When two or more stations come together to communicate with each other, they form a Basic Service Set(BSS). 
3. The minimum BSS consists of two stations, 802.11 LANs use the BSS as the standard building block. The BSS can be either without AP (Access Point) or with AP.
4.  The BSS without AP can not send data to another BSS. So it is called as standalone or ad-hoc network. 
5. Two or more BSSs are interconnected using a Distribution System or DS. 
6. The concept of DS increases network coverage, which can be either wired or wireless. Entry to the DS is accomplished with the use of access points.

2. How Bluetooth works?

    Answer: 

1. Bluetooth supports transmission of voice and data over 2.4 GHz radio frequencies, using a frequency-hopping scheme with a maximum of 1600 hops per seconds, resulting in a new frequency being used to transmit each packet.
2. This scheme allows for smooth operation in spite of fading due to reflecting obstacles or excessive distance, and in spite of noise due to Electromagnetic Interference (EMI), such as that generated by microwave ovens.
3. In addition, Bluetooth uses short packets and fast acknowledgements to increase reliability and employs forward error correction to reduce the effects of random noise.
4. The range of transmission of Bluetooth is typically between 0.1 and 10 meters but can be as much as 100 meters using higher transmission power. The system's  automatic power adaptation adjusts transmission power to the minimum needed for reliable transmission in any given situation, which reduces the chance of eavesdropping.
5. Bluetooth also includes encryption and authentication mechanism. The entire Bluetooth technology is implemented in a single 9-millimeter-by-9-millimeter chip.
6. Bluetooth data transmission normally takes place over an asynchronous channel that provides 721 kbps in the forward direction and 57.6 kbps in both directions is also supported.

3. Write short notes on:

i) Scartternet architecture.

ii) Piconet architecture.

    Answer: 

Scartternet architecture:

1. Piconets can be combined to form what is called a scatternet.
2. A secondary station in one piconet can be the primary in another piconet. This station can receive message from the primary in the first piconet (as a secondary) and, acting as a primary, deliver them to secondaries in the second picont.
3. A station can be a member of two piconets.

Piconet architecture:

1. A bluetooth network is called piconet or a small net.
2. A piconet can have up to eight stations, one of which is called the primary; the rest are called secondaries.
3. All the secondary stations synchronize their clocks and hoping sequence with the primary. Note that a piconet can have only one primary station.
4. The communication between the primary and the secondary can be one-to-one or one-to-many.
5. Although a piconet can have a maximum of seven secondaries, an additional eight secondaries can be in the parked state.
6. A secondary in a parked state is synchronized with primary, but cannot take part in communication until it is moved from the parked state.
7. Because only eight stations can be active in a piconet, activating a station from the parked state means that an means that an active station must go to the parked state.