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Network Devices• Hubs• Switches• Bridges• Routers• Gateways• CSU/DSU• Wireless access points (WAPs)• Modems• Network interface cards (NICs)• ISDN adapters• Transceivers• Firewalls

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Outline• Various Network Components• Hubs How a Hub Works Video Types of Hub Applications of Hub Merits/Demerits

• Switches How Switch Works Video Types of Switches Switching Methods Merits/Demerits

• Modems Types Video Modem Types Merits/Demerits

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HUBS

A workgroup hub. A high-capacity, or high density hub.

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HUB Hub is known as the most simplest amongst network devices. Less cost. In general, hub is the central part of a wheel where the spokes come

together. Hubs are used on a small networks where data transmission is not very

high. Types of Hubs:

1. Active2. Passive

It cannot filter data. As a network product, a hub may include a group of

Modem-cards : for dial-in user a gateway card : for connections to a local area network (LAN) and a connection

to a line

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How a Hub Works?

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Lets see how a Hub works?

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Hub, Switch or Router Network Devices Explained-0-0-0-0-0-0.mp4

Types of Hubs

• Active Hub:Active Hub is a hub which can amplify or regenerate the information signal.

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Passive Hub

• It is used for just creating a connection between various devices. It does not have the ability to amplify or regenerate any incoming signal.

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Intelligent Hub

• It can perform tasks of both Active and Passive buses.

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Application Of Hubs

Some Application of Networking Hub are given below:

• Hubs are used to create small Home Networks.• Hubs are used for monitoring the networks.• Hubs are used in Organizations and Computer Labs

for connectivity.• It makes one device or peripheral available

throughout the whole network.

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Merits

• Function• Cost Access• Shared Internet • Scalability(uplink)• Network Monitoring• Backward Compatibility(modem)

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Demerits

• Half-Duplex• Dedicated Bandwidth• Device Differentiation• Network Size

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Price :₹350 -₹20,000

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2. SWITCHES Looks more like a Hub. Switch has multiple ports.

A Switch forwards data only to the port on which the destination system is connected.

Switches can perform error checking before forwarding data. Usually, large networks use switches. Hybrid Switch:uses fiber-optic cable and UTP. Mechanism Used:

– Half Duplex – Full Duplex

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Internal Diagram

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How a Switch Works

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Lets see how a Switch works?

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Hub, Switch or Router Network Devices Explained-0-0-0-0.mp4

Different Types of Switches

1.LAN Switch or Active Hub

data switch or an Ethernet switch.blocks overlap of data(bandwidth)priority

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2.Unmanaged Network Switches

computer to computer or printer to computer in one location.

does not necessarily need to be configured or watched

simple and easy to set up

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3. Managed Switches

Enhance the functionality of a certain network.

SNMPTwo types of managed switches include smart

switches and enterprise managed switches.

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Switching Methods

Switches use three methods to deal with data as it arrives:

• Cut-through.• Store-and-forward.• Fragment-free.

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Merits

1) Reduces the number of Broadcast domains.2) Supports VLAN's which can help in Logical segmentation of ports[physical ports].Splitting up the broadcast domain.3) Intelliegent device[compared to Hub's] which can make use of CAM table for Port to MAC mapping4) Compared to Bridges ,Switches are more H/w oriented therefore operations are less CPU intense[Basic operations]

5) The cost to number of ports ratio is best .. i.e for a cheaper cost you get switches with more number of ports available than Routers.

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Demerits

1) Not as good as a router in limiting Broadcasts2) Communication b/w VLAN's need interVLAN routing [Router],but these days there are a number of Multilayer switches available in the market.3) Handling Multicast packets needs quite a bit of configuration & proper designing.4) At times switiches when in Promiscuos mode is a opening for Security attacks [Spoofing ip address or capturing Ethernet Frames using ethereal]

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Price ₹6000-₹20000

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COMPARISON HUBS AND SWITCHES

• Cost• Ports• Data Transfer• Error Checking• Use of MAC Address

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Working with Hubs and Switches

• Production Environments. • Hub and Switch Ports:Two types of ports: • Medium Dependent Interface (MDI) and • Medium Dependent Interface Crossed (MDI-X)

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Cables Connecting Hubs and Switches

Types of cables are used:1 . Pinouts for a straight-throughtwisted-pair cable

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2. Pinouts for a crossovertwisted-pair cable.

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• Hub and Switch Indicator Lights• Rack-Mount, Stackable, and Freestanding

Devices

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Hubs Vs SwitchesProperty Hubs SwitchLayer Physical layer. Hubs are

classified as Layer 1 devices per the OSI model.

Data Link Layer. Network switches operate at Layer 2 of the OSI model.

Function To connect a network of personal computers together, they can be joined through a central hub.

Allow to connect multiple device and port can be manage, Vlan can create security also can apply

Ports 4/12 ports Switch is multi port Bridge. 24/48 ports

Data Transmission form

Electrical signal or bits Frame (L2 Switch) Frame & Packet (L3 switch)

Spanning-Tree No Spanning-Tree Many Spanning-tree Possible

Used in (LAN, MAN, WAN) LAN LAN

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Hubs Vs SwitchesProperty Hubs Switch

Collisions Collisions occur commonly in setups using hubs.

No collisions occur in a full-duplex switch.

Manufacturers Sun Systems, Oracle and Cisco

Cisco and D-link Juniper

Transmission Type Hubs always perform frame flooding; may be unicast, multicast or broadcast

First broadcast; then unicast & multicast as needed.

Device Type Passive Device (Without Software)

Active Device (With Software) & Networking device

Table A network hub cannot learn or store MAC address.

Switches use content accessible memory CAM table which is typically accessed by ASIC (Application Specific integrated chips).

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3. MODEMS abbreviation for Modulator – Demodulator. data transfer from one computer network to another

computer network through telephone lines. modulates an analog signal to encode into the digital signals

and also demodulates it to transmit the information. example is a voice band modem

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Modulator-Demodulators, or Modems (Bits and Bytes, Episode 5).mp4

TYPES OF MODEMS

• Internal MODEM: i)Dial Up

ii)Wireless

• External MODEM Ex. DSL MODEM (Broadband Connections)

• PC Card MODEM

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MODULATION

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Modulator-Demodulators, or Modems (Bits and Bytes, Episode 5).mp4

INTERNAL MODEM

• a network device that is contained on an expansion board that plugs into the motherboard.

• contains no lights to inform the user of its current function or changing modem states.

• also known as on-board modems.• two types: dial-up and wireless

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Dial Up Modem• Dial-up modems require a connection with a telephone line,

network access phone number and username and login ID.• ses the facilities of the public switched telephone network

(PSTN) to establish a connection to an Internet service provider (ISP) by dialing a telephone number on a conventional telephone line.

• maximum theoretical transfer speed of 56 kbit/s (using the V.90 or V.92 protocol), although in most cases 40–50 kbit/s is the norm.

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Wireless Modem• bypasses the telephone system• prebuilt into smartphones, mobile phones and personal data

assistants (PDAs),Usb• Wi-Fi and WiMAX standards may also be used for wireless

firewall, serial and USB modems operating at microwave frequencies.

• Ex. flash modems, express card modems and PC card modems.

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External Modems• An external modem is a network device that is in a self-

contained enclosure external to a computer• Some types of external modems include:

• USB • Cable • DSL• External wireless modems

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USB dial up

• A USB (universal serial bus) modem connect to any available USB port on a computer.

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External dial up• reliable early on in dial up networking history.• hardware controlled.• need an external AC power supply. • Wireless modem consists of modem and antenna. • It is also known as radio frequency modem. It transmits the data signals

through air. This type of modem is used with laptop computer

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DSL,ADSL &SDSL• Asymmetric digital subscriber line, type of DSL broadband

communications technology. • lines ,compared to traditional modem lines. a micro filter, is installed on

subscriber's telephone line . • ADSL requires ADSL modem and close to the provider's central office to

receive ADSL service. radius of 2 -2.5 miles. data rates of from 1.5 to 9 Mbps downstream rate 16 to 640 Kbps as upstream rate.

• SDSL bandwidth in both directions

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Merits & Demerits• DSL Advantages• - Cheap hardware with easy setup.

- low cost effective services.- Good ISPs offer high speed and low latency.- Strong coverage.- Well supported.

• DSL Disadvantages• - Speed degrades over longer distances.

- Variable service quality from many UK ISPs.- Switching ISP can be confusing due to different platforms.- Complicated to troubleshoot.

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Price

₹ 550- 5000

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ReviewDevice Function/Purpose Key Points

Hub Connects devices on a Ethernet twisted-pair network.

A hub does not perform any tasks besidessignal regeneration.

Switch Connects devices on a twisted-pair network.

A switch forwards data to its destination byusing the MAC address embedded in each packet

Modem Provides serial communicationcapabilities across phone lines.

Modems modulate the digital signal into analog at. the sending end and perform the reverse function atthe receiving end.

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Thank You!!

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