Full Duplex and Hub
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Posted by Benjamin M. Stocks on April 13, 2006, 5:53 pm
Please log in for more thread options Greetings all, I've searched the archive but did not find the answer to this question: if I have exactly 2 stations on a hub, is there any reason they cannot use full duplex? If I understand logically how the hub works for exactly 2 stations it should be the same as a cross over cable, right? This is not for some real issue, more an intellectual curiosity that came to me. Thanks, Ben | |||||||||||||||||||||||||||||||||||||||||||||||||
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Posted by glen herrmannsfeldt on April 13, 2006, 7:41 pm
Please log in for more thread options While 'hub' is often used in place of 'repeater', in the more general sense, and often as found for sale, it includes switches. In normal operation a repeater will detect collisions on any port and properly signal that collision on all ports. There is usually only one datapath in the internal logic, and only enough buffer for a small number of bits. A repeater will always run half duplex, even when only two stations are active. A switch will normally negotiate half or full and operate in that mode the whole time. -- glen | |||||||||||||||||||||||||||||||||||||||||||||||||
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Posted by Stuart Robinson on April 14, 2006, 3:01 am
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> If I understand logically how the hub works for
> exactly 2 stations it should be the same as a cross over cable, right? > > This is not for some real issue, more an intellectual curiosity that > came to me. Regardless of the confusion that often occurs between hub and switch, I think I see the point your making. If you assuming that 2 stations connected as if they were on a swap over cable, will not experience collisions, then you would be wrong. Stuart. | |||||||||||||||||||||||||||||||||||||||||||||||||
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Posted by Robert Redelmeier on April 14, 2006, 10:00 am
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> I've searched the archive but did not find the answer to this question:
> if I have exactly 2 stations on a hub, is there any reason they cannot > use full duplex? If I understand logically how the hub works for > exactly 2 stations it should be the same as a cross over cable, right? No. A hub has only one channel, like coax. So cannot do full duplex. A crossover cable has two channels. -- Robert | |||||||||||||||||||||||||||||||||||||||||||||||||
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Posted by q_q_anonymous@yahoo.co.uk on April 23, 2006, 9:10 am
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Robert Redelmeier wrote: > > I've searched the archive but did not find the answer to this question:
> > if I have exactly 2 stations on a hub, is there any reason they cannot > > use full duplex? If I understand logically how the hub works for > > exactly 2 stations it should be the same as a cross over cable, right? >
> No. A hub has only one channel, like coax. So cannot do full duplex. > A crossover cable has two channels. > > -- Robert Agreed. There are some wrong answers here, but I think you and albert have it. I guess that if a comp tries to send while it's receiving(i..e. acts full duplex) , then it'll prob cause a collision in the hub, propagated to all comps, but undetected by comps 'cos they're running full duplex. | |||||||||||||||||||||||||||||||||||||||||||||||||
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> I've searched the archive but did not find the answer to this question:
> if I have exactly 2 stations on a hub, is there any reason they cannot
> use full duplex? If I understand logically how the hub works for
> exactly 2 stations it should be the same as a cross over cable, right?