Dropping Gigabit Ethernet connection

Question

Hello,
I found out a strange issue on my mac mini 2011 with Gigabit Ethernet port and what I see that it is works on automatic mode, in 100 mbit speed, but today I bought cisko 1 gbit switch and I still see in network utility 100 mbit. If I force the 1 gbit speed in seeting I will get error message like cable was unplugged.
Don't tell me that I have broken logic board. My varanty finished 2 months ago.
Thank you.

Answer 1

OK ****! - was I wrong...
After the above entry I packed up my MacBook, headed out to the Mac store and dropped it for repair; they had it overnight. "The Genius" called me to pick it up the next day. The answer:
There's nothing wrong with your MacBook. They copied files back and fourth between my MacBook and many other hosts on their network; it performed as expected.
I gave him a short history of the problem, and he said, "OOOOOooohhh, it's the Belkin." I brought my baby home, did a little research, found that others had a similar problem and found an acceptable fix. I ordered the new switches, a 5-port for my desk and an 8-port for the servers in the back room; incidentally, these items were inexpensive.
I swapped out the Belkin F4G0500 for the TrendNet TEG-S50g and everything started popping:
The MacBook received (and retained) a DHCP lease
Files copied between the Mac and other hosts at gigabit speeds
I should say the rest of my gear, 3 Linux Servers, a Linux Desktop/Laptop, and printer all made use of the Belkin at gigabit speeds (100MB file between Host A <--> Host B in 2 seconds), it was only the Mac that had trouble with the Belkins.
I split this evenly between Belkin and Apple as a responsibility to fix for we the buyers. It's 2012, we should have layer 3 (switching) sorted out by now. This was minor but pricey pain in the ***.
Troubleshooting Techniques:
Create Files of a Specific Size
You can use the "dd" (Unix) program to create files of a specific size. To test gigabit speeds, specific file sizes take the guessing out of the equation.
Open the Terminal (Utilities directory)
To create test files, enter both of the following lines (line one, then line two, giving each time to finish):
dd if=/dev/zero of=~/Desktop/output_100MB.dat bs=1M count=100   # Creates a 100MB file
dd if=/dev/zero of=~/Desktop/output_1GB.dat   bs=1M count=1000  # Creates a 1GB   file
The files created in Step 3 will now be on your desktop ready for transfer/testing.
Quit the Terminal.
File Transfer Calculator
This calculator will give you an approximation of what transfer times should be; at least it's close enough for me. There will be a little flux due to various (network) conditions, within 2-3 seconds it seems, but generally these estimations should hold.
For my problem, I wanted to test a 100MB & 1GB file transfer between 2 computers (both with Gigabit Network Cards) on the same switch.
EG: for the 2 files, I fill in the calculator:
100MB file: Size: 100; Size Lable: MB; Speed Lable: -none ; Select Speed by interface: Wired Lan Gigabit Ethernet --> click Calculate = estimated 2 seconds.
1GB file: Size: 1; Size Lable: GB; Speed Lable: -none ; Select Speed by interface: Wired Lan Gigabit Ethernet --> click Calculate = estimated 9 seconds.
Verify Gigabit Speeds on the Switch
The Trendnet ports will light up GREEN for each port that is functioning at gigabit (1000 Mbit/s) speeds; ports that are only running at Fast Ethernet speeds (100 Mbit/s) will light up AMBER. Transfers must occur between any 2 computers lit green on the switch.
When I copy the files to another (host) computer I see transfer times for:
The 100MB file is on the money: 100MB   50.0MB/s  00:02 seconds.
The 1GB file takes a little longer: 1000MB  47.6MB/s  00:21
Here we see approximately 50.0MB/s transfer times for both. The File Transfer Calc estimate was off by 12 seconds but I did notice that the transfer degraded slightly (in speed) the longer it persisted; even though that's true, the MB/s is similar.
If you have a similar setup as me (1 switch under your desk, and 1 in the server room), repeat the transfers to (hosts) computers in the back room with a green light on the switch. The transfers should be similar if not the same. 
It's not perfect but it's a week later and I'm almost $200 down; it's close enough for jazz and better than what I had before. I'm tired of screwing with it.
Cheers all,
TT