Ethernet port not working with a Gigabit switch

While our MacMini works fine in a Gigabit ethernet network, we have the same problem with an Imac Intel Core 2 Duo 2.4 Ghz. At 1000base-T speed the ethernet port is dead, regardless of the network settings, Imac reports "no ethernet cable plugged in". After manually switching back to 100base-T, the connection works fine.

I can safely say that the problem is not related to any network components and not only to the Mini. I replaced/exchanged cables (Cat5e, Cat6), switches (Dlink), routers and the position of computers in the network - all Gigabit equipped machines work fine, except for this Imac.

It did have Gigabit, BTW, for a short period right after we upgraded the network to 1000base-T, I can remember the bright green light on the switch. It lasted exactly till the next restart...

I'm seeing the same thing on this end. Have a brand new Mac Mini with 10.6.2 and it will ONLY connect with the ethernet cable if it is set to 10Base-T! This is crazy! I was using a 6 year-old G5 connected to my gigabit port and it worked (still does) just fine. But plugging this Mac Mini into the same port yields "Cable Not Connected". I've never had any issues getting any Mac on any network!! Will be calling about this later today. I'm now connecting using WiFi but this is not my desired solution. I've tried both CAT5 and CAT6 cables too . . . no go . . .

Hi,
Did you mean to say 100Base-T or does it really only work with 10Base-T? What gigabit switch are you connecting to?

10Base-T not 100!
We're on a Nortel Gigabit network . . .
Connects via Airport just fine but that isn't a long term solution for me at all . . .
One the phone with Apple right now.

Please refer them to this thread and also post your result.

Interesting. I have a new mini running OSX 10.6.2 and it connects fine to a gigabit port on my Time Capsule. Perhaps we should list our configurations: mac mini and router.

I do not believe that routers have anything to do with this. I actually have my switches cascaded. The fact that I get 100Base-T tells me the router is working correctly. The issue is that the negotiation between the two ethernet ports is not successful. The protocol that dictates the negotiation is called the 802.3 Nway protocol. {Remember when we used to have a different cable for uplink and downlink devices? NWay decides that now}. The fact that it works with the Time Capsule is not a surprise. I imagine Apple did QA against it's own products.

just want to weigh in and say that i have an Airport Extreme and my MiniMac has this problem. It is NOT the Airport Extreme or the cable. I've tested in every configuration you can think of to test this. It's the Mini. If I take the cable out of the mini and plug into my macbook, I get gigabit. All other machines get gigabit. ONLY the mini gets 100TX half-duplex. Any attempts to manually configure to anything other than the above results in a message that the cable isn't plugged in.
Just want to be clear, this happens between Apple products too.

C'mon Apple... FIX THIS.... it's been going on a while now!!!!!!!

i just say this from another thread:

http://support.apple.com/kb/TA24084

Some Gigabit Ethernet switches, using early versions of Broadcom 1000BASE-T PHY (Broadcom 5400), were manufactured and shipped before the IEEE 802.3ab specification was finalized and they do not comply with the final specification. These switches are not compatible with Intel-based Macintosh computers using the 1000BaseT setting.

Intel-based Macintosh computers will detect a link with some non-compliant switches, but can't interoperate with the switches at the 1000BaseT speed setting. You can change the settings on the Intel-based Mac to operate with these switches at the 100BaseTX setting instead.

Great find and interesting info about the support for IEEE 802.3ab!!! Thanks for posting that!!

However, my HP Procurve 1800-24G has IEEE 802.3ad, which from what I can gather, is post 802.3ab. I would think that I would be good to go, but unfortunately it is still failing.

If I knew for sure it would work with a different gigabit switch, I would buy a small one specifically for the mini, but I am skeptical that this would resolve the issue.

-Dave

That was a great find.
I checked and my switch IS 802.3a compliant.
http://www.linksysworks.com/SD2005.asp and the repackaged Cisco version: http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps10007/ps10008/datasheetc78-502060.html.

After working with Apple's GREAT Level 2 Support, we came to the conclusion that it was the switch. I went out this morning and bought the newer model of the same GigE Switch. Now I can use 1000Base-T and the "Automatic" setting.

Old Switch: Linksys SD2005 ver 2.1 = FAIL
New Switch: Linksys EG005W Ver 3 = WORKS

I too recently picked up a current gen mac mini. I cannot get it to connect at 1000mbit on my DLink 825 (revB) router. I can only get it to connect at 10baseT connection. Forcing it to connect at 100/1000 will get the "not connected" status. Using CAT5E...I have a windows7 and freebsd box hooked up to the router with no problem at 1000mbit.

well i just got a new router, the netgear wndr2700 and no go on gig. 5e cabling or cat 6. i guess im just gonna give up on ever getting gig on this machine. Just have to settle for wireless N

I doubt this switches are in question ! I have many ProCurve 1800/24G, when I connect an iMac late 2007 with Tiger, no problem in gigabit, but with a brand new iMac late 2009, I have to configure the ethernet port manually ! The Xserve and iMac don't have this problem in 10.6.2with the same switches, crazy thing...