gig switch not work but 100mb will

Posted on 2015-01-14
Last Modified: 2015-03-12
i have an imac computer and when i connect it to a gig switch, there is no connection. when i connect it to a 10/100 switch it works. can anyone tell me why?
this also happened when i tried to connect a 10/100 to a gig switch.
Question by:stevekee65
LVL 13

Expert Comment

by:Mark Galvin
ID: 40549117
So, in summary:
iMac does not work on gig switch
iMac works on 10/100 swtich

When you state 'this also happened when i tried to connect a 10/100 to a gig switch' what test/s are you referring to?

What model (year) is the iMac?
LVL 13

Expert Comment

by:Mark Galvin
ID: 40549122
PS all macs since g4 come with gigbit as Apple was an early adopter.

Author Comment

ID: 40549175
when i connect a linksys 24 port switch to the gig switch and it would act as if there were no connection. i believe it is one of the aluminum imacs.
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LVL 13

Expert Comment

by:Mark Galvin
ID: 40549176
So really, anything you plug into the gig switch doesnt work?

Author Comment

ID: 40549183
there are other computers connected to that gig switch. i connected the imac to all of the gig switches we have and nothing. i connect it to a 10/100 switch and it works
LVL 13

Accepted Solution

Mark Galvin earned 250 total points
ID: 40549203
I would check the speed & duplex setting on the iMac. All gig switches should be set to auto/auto. It might be that the iMac has been hard set to 100/full or something which would mean conencting to to a gig switch would mean no auto neg.

What version of Mac OS is this on?
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Expert Comment

by:Mark Galvin
ID: 40549235
Here is a link that would help for Mavericks
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Assisted Solution

by:Lee W, MVP
Lee W, MVP earned 250 total points
ID: 40549339
Check your cabling.  Gig ethernet requires Cat5e or better cabling, patch panels, and connectors.  If any of these are older, you can have problems - I've seen issues where things don't connect, they do connect but fail to negotiate and just keep saying connecting.... (Windows), and go out intermittently.  First thing I'd do is verify your cabling.

Expert Comment

by:nader alkahtani
ID: 40549754
Check cable if it compatible with GIG and the connectors

Expert Comment

by:corey tauriac
ID: 40601695

   Looks like this has been an issue for quite a while.  Most people were able to solve it by having the logic board changed out, but if this is an older model obviously that probably wouldn't so useful, but at least it works at 10/100.  For the most part and majority ruled on this one being most likely an issue with the logic board.

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