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Consider that I need to connect 15 computers on different collision domains. I understand that each port on a switch has a separate collision domain. So, all I need to do is to connect 15 computers to a Switch. But I have only (say)10 ports on the Switch. So, adding a Hub to the Switch in order to connect the rest of the computers, would put those computers on the same collision domain. But I want all of them in different collision domains. So what should be done to just extend the number of ports on the switch?

P.S. I'm surprised I couldn't find an answer either in here or google. I'm also surprised that many still think that this could be achieved by just adding a hub to a switch, which is a complete blunder. I would appreciate any solution. Thanks!

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You're right, a hub wouldn't work. I'm not a networking professional, but the obvious answer seems to be "add another switch." – user55325 Aug 5 '13 at 6:52
Why not just get a switch with more ports? – David Schwartz Aug 5 '13 at 8:41
@DavidSchwartz I'm just trying to work with a presumptive situation. That is what most of networking is about, isn't it? Trying to figure out the best outcome using only available(affordable) devices. – Vishnu Vivek Aug 5 '13 at 10:00
@user55325 you're right! just what I was expecting. – Vishnu Vivek Aug 5 '13 at 10:01
16-port Gigabit switches are under $100. It's hard to imagine a situation where you need 15 collision domains but can't spend $100 to get it. – David Schwartz Aug 5 '13 at 10:10
up vote 4 down vote accepted

Connect another switch to your current switch. Either by cascading switches, where the uplink (if present) of the new switch is connected to a port on the original switch. Or by using stackable switches.

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Thanks! I believe this is the only cost-effective solution? – Vishnu Vivek Aug 5 '13 at 10:02
@VISHNUVIVEK - You could also simply replace the switch. Clearly using additional/different hardware is the only solution to a problem like this. – Ramhound Aug 5 '13 at 11:57
Cost/Needs are relative, based on the equipment you already have, bandwidth needs per machine, future expansion, etc. Remember, if you are cascading switches, the sum bandwidth total on the second switch will be limited to the speed of the port on the first switch. If this is not acceptable and your switch is not stackable, then you have to replace the switch with one with more ports. – Keltari Aug 5 '13 at 12:14

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