NETWORK HARDWARENETWORK HARDWARE

CABLESCABLES

NETWORK INTERFACE CARD (NIC)NETWORK INTERFACE CARD (NIC)

CableCable

Cables are commonly used as a medium Cables are commonly used as a medium for transmitting data across networks. The for transmitting data across networks. The most commonly used cables are coaxial, most commonly used cables are coaxial, twisted-pair, and optical fiber cables.twisted-pair, and optical fiber cables.

NIC- Network Interface CardNIC- Network Interface Card

NIC is a hardware device that acts as an NIC is a hardware device that acts as an interface through which a computer connects to interface through which a computer connects to a network. NIC is usually an expansion card on a network. NIC is usually an expansion card on the computer with a port to plug in the network the computer with a port to plug in the network cable. NIC converts the data into cable. NIC converts the data into electrical/optical signals and transfers them electrical/optical signals and transfers them through cables from one computer to another on through cables from one computer to another on the network. On receiving the data, the NIC on the network. On receiving the data, the NIC on the destination computer converts the electrical the destination computer converts the electrical signals back to data.signals back to data.

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Internetworking devicesInternetworking devices

Increasing power and complexityIncreasing power and complexityRepeaters: HubsHubs BridgesBridges SwitchesSwitches RoutersRouters

Repeaters: Repeaters:

The signals transmitted can be attenuated due to The signals transmitted can be attenuated due to some problem in the transmission media or the some problem in the transmission media or the distance between the two locations. Attenuation of distance between the two locations. Attenuation of signal means the gradual weakening of signal signal means the gradual weakening of signal strength across long distances. A repeater is a strength across long distances. A repeater is a device that amplifies the incoming signals, create a device that amplifies the incoming signals, create a new copy of it, and transmits the signal back on the new copy of it, and transmits the signal back on the network. Repeaters are required in networks where network. Repeaters are required in networks where the computers are apart from each other that the the computers are apart from each other that the signal from the source computer attenuates, and signal from the source computer attenuates, and does not reach the destination computer.does not reach the destination computer.

Hub, Switch, Bridge, RouterHub, Switch, Bridge, Router

Hubs, switches, bridge and routers are all devices that let you connect one or more computers to other computers, networked devices, or even other networks.

Each has two or more connectors called ports into which you plug in the cables to make the connection.

HUBA A hubhub is typically the least expensive, least  is typically the least expensive, least intelligent, and least complicated of the four. intelligent, and least complicated of the four.

Its job is very simple – anything that comes in one Its job is very simple – anything that comes in one port is sent out to the others.port is sent out to the others.

A hub interconnects two or more workstations into a A hub interconnects two or more workstations into a local area network. local area network.

Hubs expand one Ethernet connection into many. For Hubs expand one Ethernet connection into many. For example, a four-port hub connects up to four machinesexample, a four-port hub connects up to four machines

Every computer connected to the hub “sees” Every computer connected to the hub “sees” everything that every other computer on the hub everything that every other computer on the hub sees. The computers themselves decide if they sees. The computers themselves decide if they are the targeted recipient of the message and are the targeted recipient of the message and when a message should be paid attention to or when a message should be paid attention to or not.not.

Here, the first computer prints to the laser printer, but the message is broadcast to all of the computers on the network. This causes more traffic and collisions over the network.

Hubs - contHubs - cont

Hubs operate at physical layer of the OSI model, Hubs operate at physical layer of the OSI model, simply repeating the information they receive.simply repeating the information they receive.

There are three types of hub:There are three types of hub:

Stand-alone hubsStand-alone hubs

Stackable hubsStackable hubs

Modular hubsModular hubs

Hubs - contHubs - cont

Stand-alone hubsStand-alone hubs

Small networksSmall networks

Final group segment of larger networksFinal group segment of larger networks

4-, 8- 12-, 16-, 24- and 32-ports4-, 8- 12-, 16-, 24- and 32-ports

CheaperCheaper

Hubs - contHubs - cont

Stackable hubsStackable hubs

Supports hierarchical structureSupports hierarchical structure

Maximum of four hubs or Maximum of four hubs or levels and five cable and five cable lengths between any workstation and the server for lengths between any workstation and the server for 10BaseT and maximum of two hubs or levels and 10BaseT and maximum of two hubs or levels and three cable lengths for 100BaseTthree cable lengths for 100BaseT

Similar to stand-alone hubs but can add ports at the Similar to stand-alone hubs but can add ports at the same level by joining the backplanes on the hubs same level by joining the backplanes on the hubs and acts as one huband acts as one hub

More expensive than stand-alone hubsMore expensive than stand-alone hubs

Hubs - contHubs - cont

Modular hubsModular hubs

Also called enterprise hubAlso called enterprise hub

Is a large chassis or cabinet with power supply and Is a large chassis or cabinet with power supply and backplane into which you can plug many different backplane into which you can plug many different boards, including hubs, switches, bridges, and routersboards, including hubs, switches, bridges, and routers

ExpensiveExpensive

SWITCHSWITCH

Like hub, has number of ports from 2 to 32Like hub, has number of ports from 2 to 32 An intelligent device that looks at the physical An intelligent device that looks at the physical destination address of the frame flowing into it and directs destination address of the frame flowing into it and directs the frame to the correct port for that destinationthe frame to the correct port for that destination Like bridges, segment a network to reduce the traffic Like bridges, segment a network to reduce the traffic and collisions, and ultimately increasing the throughputand collisions, and ultimately increasing the throughput

Using switches computers can talk with each other on private connections so multiple conversations can be carried on at the same time. Here, the first computer and laser printer make a private connection during printing, while the fourth computer transfers a file to the fifth computer over another connection. This reduces traffic and collisions over the network.

Difference Between Difference Between a Hub and a Switcha Hub and a Switch

The hub is basically the least expensive and The hub is basically the least expensive and the least intelligent. Basically, anything that the least intelligent. Basically, anything that comes to one port is sent out to the others.comes to one port is sent out to the others.

A switch does what a hub does, but way A switch does what a hub does, but way better. By paying attention to the traffic and better. By paying attention to the traffic and other things that come along, it can learn and other things that come along, it can learn and study where the addresses are.study where the addresses are.

BRIDGESBRIDGES

A A bridge is used to either segment a network or join two is used to either segment a network or join two networksnetworks

A bridge looks at the physical or MAC address in a frameA bridge looks at the physical or MAC address in a frame– if the frame address belongs to the other side of the if the frame address belongs to the other side of the

bridge, the frame is passed on to the other sidebridge, the frame is passed on to the other side– Otherwise ignoresOtherwise ignores

It operates at the Data Link layer of OSI model (one It operates at the Data Link layer of OSI model (one layer above the hub operates)layer above the hub operates)

Bridge - contBridge - cont

The purpose of a bridge is to reduce traffic in a network by The purpose of a bridge is to reduce traffic in a network by segmenting it, although it is still one networksegmenting it, although it is still one networkHub replacing a bridge – increasing collisions and Hub replacing a bridge – increasing collisions and decreasing the throughputdecreasing the throughputA bridge also allows additional hub layers above four-hub A bridge also allows additional hub layers above four-hub limit in a simple Ethernet networklimit in a simple Ethernet network– Cross the bridge and travel through four more hubsCross the bridge and travel through four more hubs

Simple device and is limited to a single network and to a Simple device and is limited to a single network and to a single cabling or media typesingle cabling or media type

Bridge allows additional hub layers

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Bridge interconnecting two identical LANs

2121

A bridge interconnecting two dissimilar LANs

ROUTERROUTER

A router can perform the same segmenting and joining A router can perform the same segmenting and joining functions as a bridge, but at a higher level using functions as a bridge, but at a higher level using logical addresslogical address. . – Routers connect separate networks, leaving them Routers connect separate networks, leaving them

independent with their own addressingindependent with their own addressing– Routers connect different types of networks; for Routers connect different types of networks; for

example, 100BaseF and 100BaseTexample, 100BaseF and 100BaseT– Routers select from among alternative routes a Routers select from among alternative routes a

through a complex network in order to get to an end through a complex network in order to get to an end destinationdestination

Basically, in a particular network, a router determines the fastest way possible,

which is also usually the shortest way possible.

Router - contRouter - cont

Routers clean up network traffic by Routers clean up network traffic by checking if a frame is corrupted or lost; if so, checking if a frame is corrupted or lost; if so, the frame is removed from the networkthe frame is removed from the network

For these reasons, routers are used to For these reasons, routers are used to connect to the Internet and within the Internet, connect to the Internet and within the Internet, and to connect a WAN to a LANand to connect a WAN to a LAN They are generally intelligent devices with a They are generally intelligent devices with a processor and memory.processor and memory. At the low end, routers process over 250,000 At the low end, routers process over 250,000 packets per secondpackets per second

Routers are called "smart" networking devices. Routers are called "smart" networking devices. Routers can assign IP addresses to computers, Routers can assign IP addresses to computers, filter websites, block unauthorized traffic and filter websites, block unauthorized traffic and route communication from one section of the route communication from one section of the network to another. network to another.

The router is used as a gateway between the The router is used as a gateway between the internal network and the Internet. It can help internal network and the Internet. It can help protect the internal network from hackers.protect the internal network from hackers.

Router - contRouter - cont

Wireless connections: Access Point as a BridgeWireless connections: Access Point as a Bridge

2525

Hardware Needed For LAN and WAN

Network Interface Card – connects the device to the network and allows communication between computers

Wireless Access Point (WAP) – connected to the network by a cable and positioned so that it can send and receive the wireless signal

Hub – joins lots of computers to the network via a single link. Signals received on any port are transmitted to all other ports.

Switch – receives data, examines it and then sends it to the appropriate port.

Hardware cont.

Gateway – A gateway is a device or service that translates communication protocols and enables two similar or dissimilar LANs, such as Ethernet and Token Ring, to communicate with each other.

Bridge – Connects and passes packets between two network segments that use the same communication protocols

Router – Sends info between networks using the topology by selecting the best path. Translates information between networks. Can connect a LAN to a WAN

Repeater – Used to strengthen a signal as it is passed along a network cable. Over a distance, a signal would degrade