A router is a networking device that connects at least two networks and forwards data packets along networks using headers and forwarding tables to determine the best path. A switch filters and forwards packets between network segments at the data link layer, using MAC addresses to identify which device is connected to each port. A hub copies packets arriving at one port to all other ports so all network segments can see all traffic, but it does not distinguish intended ports and bandwidth is shared, impacting performance when multiple devices broadcast.

1. 1. Hub
A common connection point for devices in a network. Hubs are commonly used to connect
segments of a LAN. A hub contains multiple ports. When a packet arrives at one port, it is
copied to the other ports so that all segments of the LAN can see all packets.
2. Switch
In networks, a device that filters and forwards packets between LAN segments. Switches operate
at the data link layer (layer 2) and sometimes the network layer (layer 3) of the OSI Reference
Model and therefore support any packet protocol. LANs that use switches to join segments are
called switched LANs or, in the case of Ethernet networks, switched Ethernet LANs.
3. A device thatforwards data packetsalongnetworks.A routerisconnectedtoat leasttwonetworks,
commonlytwo LANsor WANsor a LAN and its ISP.snetwork.Routersare locatedat gateways,the
placeswhere twoor more networksconnect.Routersuse headers andforwardingtablestodetermine
the bestpath for forwardingthe packets,andtheyuse protocols suchasICMP to communicate with
each otherand configure the bestroute betweenanytwohosts.
Difference b/wrouter switch hub
1.hub- 1. In a hub,a frame ispassedalongor "broadcast"to everyone of itsports. Itdoesn'tmatter
that the frame is onlydestinedforone port.The hub hasno way of distinguishingwhichporta frame
shouldbe sentto.
2. Additionally,a10/100Mbps hub mustshare its bandwidth witheachandeveryone of its ports.So
whenonlyone PCis broadcasting,itwill have accesstothe maximumavailable bandwidth.If,however,
multiple PCsare broadcasting,thenthatbandwidthwill needtobe dividedamongall of those systems,
whichwill degrade performance.
2.switchA switch,however,keepsarecordof the MAC addresses of all the devicesconnectedtoit.With
thisinformation,aswitchcanidentifywhichsystemissittingonwhichport.Sowhena frame is
received,itknowsexactlywhichportto senditto, withoutsignificantlyincreasingnetworkresponse
times.And,unlikeahub,a 10/100Mbps switchwill allocate afull 10/100Mbps to each of itsports.
Data center A datacenteris a facilityusedtohouse computersystemsandassociatedcomponents,
such as telecommunicationsandstorage systems. Itgenerallyincludesredundantorbackup power
supplies,redundantdatacommunicationsconnections,environmentalcontrols(e.g.,airconditioning,
fire suppression) andvarioussecuritydevices.