A few of the service tags i have on the bench right now are :
The topology is very simple.
switch ports 1-2 (client),9-12 (uplink GbE) all set to trunk all vlans, untagged vlan1 default
switch addresses 192.168.99.41,42
pc plugged into 41/1
switches linked 41/9 to 42/9
when in this arrangement, i can ping 192.168.99.41 , but cannot ping 192.168.99.42
if i change pc to 42/1, i can ping 192.168.99.42 but not 192.168.99.41
if i connect a dumb switch 3 ports to PC, 41/9 and 42/9 , i can ping both switches.
if i connect 41/1 to 42/1 , PC into 41/2 or 42/2 , i can ping both switches
it's like the UPLINK ports have a different behaviour completely to the client ports