Editing: gaurav prajapati

Que:1: Explained HUBS:-

A Hub is a networking device which receives signal from the source, amplifies it and

send it to multiple destinations or computers. If you ever some across subject

'Computer Networking' then you must heard this word. Sometimes, hubs are also

called Ethernet Hub, Repeater Hub, Active Hub and Network Hub. Basically it is a

networking device which is used multiple devices like Computers, Servers etc. to

each other and make them work as a single network segment. Hubs are used in

'Physical Layer' of OSI Model.

Practically Hubs is a small box in rectangular shape which have multiple ports for

connecting various devices to it. It receives its power supply from auxiliary power

sources. The main work of Hub is to receive incoming data signals, amplify them in

the form of electrical signals and then send them to each connected device. A Hub

may contain a number of ports. Minimum amount of ports that a hub can have is 4

and it can have up to 24 ports for connecting various devices and peripherals to it.

Types of Hub :On the basis of its working methods, the Hubs can be divided into

three types, given as:1) Passive hub 2) Active hub 3) Intelligent hub

1) Active Hub: As its name suggests, Active Hub is a hub which can amplify or

regenerate the information signal. This type of hub has an advantage as it also

amplifies the incoming signal as well as forward it to multiple devices. This hub is

also known as Multiport Repeater. It can upgrade the properties if incoming

signal before sending them to destination.

2) Passive Hub: Passive Hub works like a simple Bridge. It is used for just creating

a connection between various devices. It does not have the ability to amplify or

regenerate any incoming signal. It receives signal and then forward it to multiple devices.

3) Intelligent Hub: This is the third and last type of hub. It can perform tasks of both

Active and Passive hub. Also, it can perform some other tasks like Bridging and

routing. It increases the speed and effectiveness of total network thus makes the performance of whole network fast and efficient.

2) Explain Network Interfaces card (NIC):

Short for Network Interface Card, the NIC is also referred to as an Ethernet

card and network adapter. It is an expansion card that enables a computer to

connect to a network; such as a home network, or the Internet using an Ethernet

cable with an RJ-45 connector.

Some NIC (Network Interface Card) cards are meant for wired networks while

others are for wireless network. Most widely used wired LAN Technology is

Ethernet. Ethernet based NIC (Network Interface Card) cards are available in

every local electronic hardware shops. Normal speed rating of Ethernet based

wired NIC (Network Interface Card) available these days are 10/100/1000 Mbps

(Megabits per second).

Every computer participating in network must have at least one NIC. Computers

can have more than one NIC card also NIC (network interface cards) also

provide a buffer for incoming and outgoing data, so that the computer can

compensate for latency issues. Many modern devices have network interface

cards built into them, as standards have made Ethernet and IEEE 802.11.

Every NIC (Network Interface Card) has a 48-bit globally unique identifier called

as MAC Address (Media Access Control Address) burned into its ROM chip.

This MAC address is used to deliver Ethernet Frames (packets) to a computer.

The NIC driver software passes the data between the Operating System and the

NIC. Latest Operating Systems include different NIC driver software for almost

all major NIC vendors. One NIC can handle a number of Ethernet connections

by attaching a switch or router to it. While most people are used to standalone

routers, many enterprise and server-grade routers are full servers attached to

switches. In some cases, two or more NICs might be used to provide more

through-put.

Que:3: explain modem

A modem is a type of hardware device that converts between analog and digital data in

real time for two-way network communication. The term is short for Modulator

DEmodulator

The first devices called modems converted digital data for transmission over analog telephone lines. The speed of these modems was historically measured in baud (a unit of measurement named after Emile Baudot), although as

computer technology developed, these measures were converted into bits per second (bps).

The first commercial modems supported a speed of 110 bps and were used by the U.S. department of defense, news services and some large businesses.

Traditional modems used on dialup networks convert data between the analog

form used on telephone lines and the digital form used on computers. An

external dial-up modem plugs into a computer and one end and a telephone line

on the other end. In the past, some computer makers also integrated internal

dial-up modems into their computer designs.

Types:

1) External:

This is the simplest type of modem to install because you don't have to

open the computer. External modems have their own power supply and

connect with a cable to a computer's serial port. The telephone line plugs

into a socket on the rear panel of the modem.

Because external modems have their own power supply, you can turn off

the modem to break an online connection quickly without powering down

the computer. Another advantage over an internal modem is that an

external modem's separate power supply does not drain any power from

the computer. You also can monitor your modem's connection activity by

watching the status lights

.

2) Internal:

Most internal modems come installed in the computer you buy. Internal

modems are more directly integrated into the computer system and,

therefore, do not need any special attention. Internal modems are

activated when you run a communications program and are turned off

when you exit the program. This convenience is especially useful for

novice users.

Internal modems usually cost less than external modems, but the price

difference is usually small. The major disadvantage with internal

modems is their location: inside the computer. When you want to

replace an internal modem you have to go inside the computer case to

make the switch.

3) PC card:

These modems, designed for portable computers, are the size of a

credit card and fit into the PC Card slot on notebook and handheld

computers. These modems are removed when the modem is not

needed. Except for their size, PC Card modems are like a

combination of external and internal modems. These devices are

plugged directly into an external slot in the portable computer, so no

cable is required other than the telephone line connection. The cards

are powered by the computer, which is fine unless the computer is

battery-operated. Running a PC Card modem while the portable

computer is operating on battery power drastically decreases the life

of your batteries.

Que:4: Explain repeater:

Network repeaters regenerate incoming electrical, wireless or optical

signals. With physical media like Ethernet or Wi-Fi, data

transmissions can only span a limited distance before the quality of

the signal degrades. Repeaters attempt to preserve signal integrity

and extend the distance over which data can safely travel.

Actual network devices that serve as repeaters usually have some

other name. Active hubs, for example, are repeaters. Active hubs are sometimes

also called "multiport repeaters," but more commonly they are just "hubs." Other types of "passive hubs" are not repeaters. In Wi-Fi, access points function as repeaters only when operating in so-

called "repeater mode." Higher-level devices in the OSI

model like switches and routers generally do not incorporate the functions of a repeater. All repeaters are technically OSI physical layer devices.

Que: 5: Explain Switch:-

A switch is a piece of a physical circuitry component that governs

the signal flow on network. (not write: Having a switch or toggle switch allows a connection to

be opened or closed. When opened the switch allows a signal or

power to flow through the connection. When closed the switch stops the flow and breaks the circuit connection.

On a network, ) A switch is a hardware device

that filters and forwards network packets, but often not capable of

much more. The first network device that was added on Internet was a switch called the IMP, which helped send the first message on

October 29, 1969. A network switch is more advanced than a hub but not as advanced as a router.

The picture shows an example of a NETGEAR5 port switch.

Type:

1) Unmanaged Network Switches

Unmanaged network switches are frequently used in home

networks and small companies and businesses. It permits devices on the network to connect with each other, such as computer to computer or printer to computer in one location. An unmanaged switch does not

necessarily need to be configured or watched. They are simple and easy to set up and needs only small cable connections.

2) Managed Switches

Managed switches can be customized to enhance the functionality of a certain network. They are achieved by setting a simple network management

protocol or SNMP. Two types of managed switches include smart switches and enterprise managed switches.

Smart switches have a limited set of management features which provide a web interface and accept configuration of basic settings, such as

virtual LAN or VLANs, port-bandwidth and duplex. Smart switches are ideally used in fast and constant LANs, which support gigabit data transfer and

allocations. Enterprise managed switches are also known as fully managed switches.

They have a wide ranging of management features which includes a web

interface SNMP agent and command-line interface. Also, its features include the capability to fix, copy, transform and display different network configurations.

They are found in large companies which contained of a large number of connections and nodes, switches and ports. Enterprise managed switches have more features that can be modified or enhanced, and are usually more expensive

than traditional smart switches.

Que:6 : Explain Bridge:

A network bridge helps to join two otherwise separate computer

networks together to enable communication between them. Bridge devices are used with local area networks (LANs) for extending their reach to cover

larger physical areas. To improve the performance, usually networks are divided in smaller

segments. Bridge used to divide large network in smaller segments

Break large network in smaller segments.

Join different media types such as UTP and Fiber optic

Join different network architecture such as Ethernet with token ring A bridge can connect two different types of media or network architecture but

it cannot connect two different types of network layer protocol such as TCP/IP or IPX. Bridge requires same network layer protocol in all segments.

There are three types of bridge:-

Local Bridge:-This bridge connects two LAN segments directly. In Ethernet Implementation it is known as Transparent bridge. In

Token Ring network it is called Source-Routed bridge.

Remote Bridge:- This bridge connects with another bridge over the WAN link.

Wireless Bridge:- This bridge connects with another bridge without

wiring between them.

In OSI Layer model Bridge works at physical layer and data link

layer. Bridges have following issues :- Bridges have limited ports.

In bridge forward decision are made through the software which slow down overall performance of

network. Bridges use age old technology which is not capable

to fulfi ll the requirement of modern networks

effectively.

Que: 7:- Network Router:

A router is a network device which is responsible for routing traffic from one to another network. These two networks could be a private company network

to a public network. You can think of a router as a traffic police who directs different network traffic to different directions.

Router is a layer three device which forwards data packet from one logical network segment to another. Router forwards packets on the bases of their destination address. For this router keeps record of the path that packets can

use as they move across the network. These records are maintained in a database table known as routing table. Routing table can be built statically or

dynamically Basically routers are used:-

To connect different network segments.

To connect different network protocols such as IP and IPX.

To connect several smaller networks into a large network (known

as internetwork)

To break a large network in smaller networks (Known as subnet

usually created to improve the performance or manageability)

To connect two different media types such as UTP and fiber

optical.

To connect two different network architectures such as token ring and Ethernet.

To connect LAN network with Telco company’s office (Known as DTE device).

To access DSL services (known as DSL Router).

Que: 8 :- Explain Brouter

Brouters are the combination of router and bridge. It can be used as a bridge or router. Brouters are the earlier implementation of the routers.

At layer two it’s a fairly expensive device. which cost more than other high end switches that work much faster than it. At layer three it has a lot of

complexity. Due to these drawbacks it is rarely used. Gradually it has been replaced by high end switch at layer 2 and by router at layer three.