I have used a revision A DGS-1216T for years with no problems in an STP setup with HP, SMC and 3COM switches.
I bought two revision D switches so i can dual-home my linux production servers with STP. The switches are interconnected on port 16, the server's NIC1 goes to switch1, NIC2 to switch2. Port 15 serves as uplinks to a Juniper router cluster. I have the exact same setup up and running with Blade Networks switches in an HP blade chassis.
Now, when I initially connect the two D-Link switches, the spanning tree builds fine, switch2 marks it's port 16 as the root port. When all servers are connected only to switch1, everything works fine. If I connect even one server to switch2, both ports become forwarding and I see a packet flood, most likely because of a loop somewhere, and the network segment goes down.
The server ports are untagged VLAN11 or VLAN14, port15-16 is tagged 11 and 14. In a Juniper JSRP cluster, the backup port acts as a blackhole, so that's not the source of the loop. STP enable on all ports, except port 15.
Kernel version: linux-image-2.6.26-1-amd64
Switch firmware: 4.21.01
Any ideas are appreciated!
Cheers,
Tamas