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there is nothing special about hub. It is a very simple device as it gets the signal and just forward it to everyone attached to it. It hopes that someone will pick it up.It means that if say computer A is sending something to computer B and computer C is also attached then not only computer B will receive the message but also computer C which means that the total traffic is being shared by all the devices attached to the hub the computer C will just discard the message. The simplicity of the hub is due to the fact that it was the first device developed to provide the central point to a ethernet for the distribution of signals to the rest of the network.It works on the layer 1 of the OSI model.
A bridge is a LAN interconnection device which operates at the data link layer layer 2. It may be used to join two LAN segments (A,B), constructing a larger LAN. A bridge is able to filter traffic passing between the two LANs (on the basis of MAC address)and may enforce a security policy separating different work groups located on each of the LANs. A bridge basically is used the divide a larger network into smaller collision domains to avoid the excessive collisions in one smaller domain.
Hubs, also known as concentrators or multiport repeaters, are used in star/hierarchical networks to connect multiple stations/cable segments. There are two main types of hubs: passive and active. An active hub takes the incoming frames, amplifies the signal, and forwards it to all other ports, a passive hub simply splits the signal and forwards it. Another type of hubs can be managed allowing individual port configuration and traffic monitoring, these are know as intelligent- or managed hubs.
Hubs operate on the physical layer of the OSI model and they are protocol transparent, that means they are not aware of the upper-layer protocols and such as IP, IPX nor MAC addressing
SWITCHES
To improve network performance even more switches were developed, switches are very similar to bridges; they also keep a table with MAC addresses per port to make switching decisions, operate in the OSI model and are protocol transparent.
Some of the main differences are:
- a switch has more ports than a bridge
- bridges switch in software whereas switches switch in hardware (integrated circuits)
- switches offer more variance in speed, an individual port can be assigned 10 Mb/s or 100 Mb/s or even more.
Added after 5 minutes:
i think no comparison between hub an switches coz hub layer first device an swtich layer two device similar to briges we use switches coz having asic processing its integrated circuits where in bridges software processing its slow an bridges haaving maximum 15 port where switches upto 500 ports i think its clear now
HUB has only sharing electrically. (common collision domain) like a cross of ROAD that need to wait to pass.
Bridge has both sharing of electrically and logically. (separate collision domain) like a cross over bridge of ROAD that no needs to wait.
Hubs are simple reapeter or Bus-in-Box device. Doesnt have any intelligance. works on L1(physical)
use : increase shared media size or collision domain
Bridge or switch : L2 inteligant device . doing 5 basic functions as 1.learning 2.Forwarding 3.flooding 4.filtering 5.aging (more details on howstuffworks.com)
Diff: hub only works in half duplex.
hub doesnt improve bandwidth utilization where as bridge does it by filtering feature.
brdige also provide security to some extent
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i think its clear now
