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Half duplex or Full duplex

Hi Guys,

My network is 10/100 and have devices with NIC 10/100 and others with NIC 10, someone told me that when you have some device with 10 MBps with others with 10/100 in the same network all must be configured to half duplex, that is right ?



Community Member

Re: Half duplex or Full duplex

No that is incorrect. You can have ports setup for both. Currently we are running a 100 meg but most printers only run at 10 meg. So we setup the full and half duplex accordingly. Something else you may want to think about that some poeple don't know is that if you have ports on the switch or on the PC's setup as Auto detect they only detect at half duplex regardless if the port /NIC on the other side is setup as 100 full. You may want to look into that as well if you are having speed issues. We went from 34 meg per minute to over 300 meg per minute by just changing that setting. Wes


Re: Half duplex or Full duplex

That is one of the reasons people went to switches versus hubs which were generally a single speed , everyone now has their own pipe instead of sharing one and it can be 10 or 100 whatever you want to configure it for

Community Member

Re: Half duplex or Full duplex

duplex mismatch is only a problem in situations where the end devices are contending for access in the same collision domain e.g in a hub. In these situations half duplex is used with CSMA/CD media access, which actively looks out for lan collisions before transmitting. Full duplex mode disables CSMA/CD therefore if a half duplex and a fullduplex device were plugged in to a hub, collisions would occur as the full duplex device is not listening for other devices before it transmits. Switches, however act as a multiport bridge in that each port defines its own collision domain and is totally separate to other devices plugged into a switch. The only problem here would be a duplex mismatch between the switch port and the end device plugged into it, generally in these situations you would use full duplex (if the device supports it) as this increases the bandwidth available to the end user.

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