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What is the difference between a hub and a switch?

I have Cisco 2900 catalyst. And i have other hardwares for networking. But what is the difference between HUB and Switch? Which is strong and whats the main differences?

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migrated from stackoverflow.com Apr 12 '11 at 19:34

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marked as duplicate by sysadmin1138 Apr 12 '11 at 19:37

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As others have stated, the main difference is that a hub broadcasts incoming packets on all other ports:

A network hub is a fairly unsophisticated broadcast device. Hubs do not manage any of the traffic that comes through them, and any packet entering any port is regenerated and broadcast out on all other ports. Since every packet is being sent out through all other ports, packet collisions result—which greatly impedes the smooth flow of traffic.

The same Wikipedia article also suggests some uses for a hub:

  • For inserting a protocol analyzer into a network connection, a hub is an alternative to a network tap or port mirroring.

  • When a switch is accessible for end users to make connections, for example, in a conference room, an inexperienced or careless user (or saboteur) can bring down the network by connecting two ports together, causing a loop. This can be prevented by using a hub, where a loop will break other users on the hub, but not the rest of the network. This hazard can also be avoided by using switches that can detect and deal with loops, for example by implementing the spanning tree protocol.

  • A hub with a 10BASE2 port can be used to connect devices that only support 10BASE2 to a modern network. The same goes for linking in an old 10BASE5 network segment using an AUI port on a hub (individual devices that were intended for thicknet can be linked to modern Ethernet by using an AUI-10BASE-T transceiver).

There are potential security implications as well, which are hinted at above. If a hub is deployed, someone with access to a single machine on the hub can monitor traffic going to all of the other machines on the hub. In general, a switch does not have this attack vector.

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A hub takes a message from one port and broadcasts it to all the other ports.

A switch takes that same message, and through internal tables and knowledge of who is listening at the other ports, only sends it to the ports that need it. This results in less utilization on the part of the rest of the hosts, and results in higher total aggregate throughput.

About.com - Network switch

About.com - Network hub

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Network hubs work at the the physical layer (layer 1) of the OSI model.

A network switch processes and routes data at the data link layer (layer 2) of the OSI model. Switches that additionally process data at the network layer (Layer 3) and above are often referred to as Layer 3 switches or multilayer switches.

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