Port Mirroring STP Loop

[Fishmonger]

I've created a port mirror using the cli and when I plug it into another switch that I want to aggregate the span ports to I get a switching loop.  Switching-packet is disabled so I'm unsure why its trying to route traffic through the other switch, any idea?

[DPadula]

Hi Fishmonger,

If a L2 switch receive a frame where the destination MAC is not known it will broadcast the frame to each port that is up besides the port where the traffic was received. 

If you could you please provide a simple network diagram showing how the switches are connected, so we can have a better understanding would be great.