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simple switch/hub port question

We have run out of wire runs. So to increase our network we will be putting a few hubs on different switch ports to increase the amount of pcs on the network. I have heard that it is important to make sure that any hub that is connected to a switch port that the port should be set to half duplex. Is this true? Also I have heard that port fast should be disabled. Are both of these suggestions valid? And are there any others that I should take head in?


  • Other Network Infrastructure Subjects

Re: simple switch/hub port question

Most hubs only function at 1/2 duplex so this might be the best setting for you. You might review the documentation for your hubs to ensure they are only 1/2 duplex capable. Go full if possible but don't mismatch settings.

Portfast being disabled is to help ensure there is never a bridging loop, since you are not supposed to connect any non-PC connection to a portfast enabled port. If you can ensure that your hubs will only have one connection to your switch you can leave it on... Best practices would disable this and allow STP to function on these hub connected ports.

Hope this helps,


Re: simple switch/hub port question


how could a hub (i.e. repeater) work in full-duplex?

My understanding is that running full-duplex disables collision detect. But all hub ports are in one collision domain so you have to be able to detect collisions.

So connecting to a hub you must use half-duplex.

Am I wrong?



Cisco Employee

Re: simple switch/hub port question

Yes a hub port can only be half-duplex but the uplink ports on some hubs can be configured for full-duplex.

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