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How do hubs work? I mean if I have 5 port hub 10mbps. With all 5 pc connected via cat5. Say 1 PC is sending, All the other PCs are receiving the signal. Is the sending port working at max 10Mbps And are the othe ports receiving at 2 Mbps.

Is this correct? Now if 2 PCs are sending at same time, won't a collision occur? And what happens next? And what speed will the next operation be at? And what speed will the other pc be receiving

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closed as not constructive by Nifle, Diogo, slhck, random Dec 8 '11 at 14:34

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3 Answers 3

Is the sending port working at max 10mbps

Maybe. The rated speed of any link is based on max frame size. If the sender is using max frame size then the speed is 10Mbps.

And are the other ports receiving at 2 Mbps Is this correct

No. The incoming data stream is replicated to the other ports, at the same speed.

now if 2 pc are sending at same time Won't a collision occur

Yes.

And what happens next -

all devices will detect the collision and any device that wants to send will perform a random backoff, and then retry. You should look up CSMA/CD.

And what speed will the next operation be at And what speed will the other pc be receiving

Collisions do not change the speed.

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At the risk of offering a lazy answer, Google is your friend here:

http://en.wikipedia.org/wiki/Ethernet_hub

http://www.duxcw.com/faq/network/hubsw.htm

http://en.wikipedia.org/wiki/Collision_domain

I'd also recommend hopping on to Youtube and searching there, it's an invaluable resouce for information regarding networking.

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I would say, that is a bit of a lazy answer ;p –  Journeyman Geek Dec 8 '11 at 13:36
    
And you'd probably be right ;) –  Moif Murphy Dec 8 '11 at 13:42

A hub receives signals from clients and retransmits it to all clients. If two clients send messages to the hub at the same time, the hub merely ignores one, and since the client is not acknowledged, it resends it at a random time. If there are too many collisions from a specific client, the hub may ignore it.

Since clients need to send and listen for collisions, they can operate only at half duplex mode, and bandwith is shared between all the systems (see this link, stolen from moif murphy). All clients share the 10 mbps, and should heavy traffic go between two systems the rest will be affected

Should a port misbehave, it'll simply be disconnected from the shared connection.

Also, since the hub transmits all messages to all systems, you can listen into packets meant for other systems.

I'd note that in every way, except when network sniffing is required a switch is better - clients work at full duplex mode, there's no collisions, or promiscuous re transmission, and they work at better than 10mbps.

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