There does not appear to be an issue with the switch. I would still recommend that all interfaces connected to computers/servers be in access mode. At this point I would check to see if it is an OS/driver issue, or a hardware problem. I would recommend booting to a Linux live DVD or some other OS that you can test the NIC's with. If you encounter the same problem with another operating system then there may be a firmware update that needs to be performed, or a hardware malfunction. If you do not encounter the same problem with another OS then it would appear to be an OS or driver issue. Given that this is a beta OS there is not much we can do with that. Here is our OMSA live DVD that you can use for testing. It is a distro of CentOS: [URL] Thanks
I just installed 2012 RC on my R815, it has 2 Intel x520-t2 nics on a PowerConnect 5548 Switch.  The NICS continue to "bounce" between connect/disconnect.  I was pointed to Dell since I purchased the nics through you.  I read the 2012 documents from Dell and these nics are said to have been tested and the inbox drivers should work.   Can someone please tell me if there's a config change that I need to make?   thanks.      
Intel x520-t2 NIC problem on Windows Server 2012 (Nic keeps 
disconnecting/reconnecting constantly)