How did an ethernet port (on Switch1) with Spanning Tree Protocol enabled bring another ethernet switch (Switch2) off-line when connected to it? Switch2 did not have spanning tree enabled.
I was setting up a new Wireless Controller (switch1) in our test lab. The test lab has an HP ProCurve Switch(Switch2). The Wireless Controller is essentially an Ethernet Switch with several Ethernet ports and a bit more functionality. Apparently the new Aruba Wireless Controller (Switch1) has all of its ethernet ports automatically enabled with Spanning Tree.
When I plugged the Spanning Tree Port 0/0/0 (switch1) into another Ethernet switch port (Switch2) in about 30 seconds … Switch2 became off-line. As a result aoof the other devices connected to Switch2 were off-line as well. When I un-lugged the Aruba Wireless Controller (Switch1) connection from Switch2 port that Switch came back on-line. The Aruba tech noticed that the Aruba (Switch1) port 0/0/0 was in 'Blocking' STP mode when it connected to the Switch2 so the Aruba Tech disabled the Spanning Tree Protocol for that interface port and then the problem went away.
I wish to understand how STP works and why did that switch port with STP enabled brought the other switch off-line. I have reviewed some material on-line: https://en.wikipedia.org/wiki/Spanning_Tree_Protocol
But I still have questions that I wish to clarify.
Question1: Am I to understand for STP to work correctly that every other switch on the network needs to have STP enabled as well?
Question2: Or am I to understand that STP is so unpredictable that it should only be enabled for Access/untagged ports that are connected directly to computers/devices and not
connected to other Ethernet switches?