Problem with TP-Link Switches

[guterkerl]

I have 2 TP-Link Managed Switches model TL-SG3216 and TL-SL3452. We've been having problems with the connection and it has gotten worse lately.

3216
–- pfsense
--- file servers
--- uplink

3452
--- workstations
--- uplink

My servers including pfsense are connected to the 3216. All the workstations are connected to the 3452. The problem starts whenever I plug in the uplink of the 3452 to the 3216. The 3216 now loses connection and all the lights are flashing fast. When I remove the uplink connection everything goes back to normal and the 3216 replies to ping requests.

One thing I noticed in wireshark is that the pfsense somehow broadcasts ICMPv6 whenever I plug in the 3452.

Any help would be appreciated. Thanks

[doktornotor]

=> http://forum.tp-link.com/forumdisplay.php?22-L2-Managed-Switches

[almabes]

You have a switching loop somewhere.

[johnpoz]

With dok, how is this have even the slightest thing to do with pfsense at all?

So do you get the problem if there is nothing plugged into the 3452 other than the link to your 3216?

Have you enabled loop detection?

From the manual for the 3452
5.1.5
Loopback Detection
With loopback detection feature enabled, the switch can detect loops using loopback detection packets. When a loop is detected, the switch will display an alert or further block the corresponding port according to the port configuration.
Choose the menu Switching→Port→Loopback Detection to load the following page.

Start plugging in 1 port at a time after uplink - when does it start happening?

[almabes]

It's either a loop, or RSTP blowing up after a topology change. (just bit me!)
I'll bet the MAC address on the 3452 is lower than the 3216, and trying to take over as RSTP root bridge.  Blammo!  Nothing works.

The fix is to set the STP root bridge pirority lower on the 3216, preferably 0 instead of the default 32768.