Disclaimer
The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.
Liability Disclaimer
In no event shall Author be liable for any damages wha2tsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.
Posting
As Dennis already explained, if there are no L2 loops, you don't need STP. STP is one way to design L2 networks with intentional "extra" L2 links that would create loops. In insures there's only one active path.
Although loop free designs don't need STP, the general recommendation is to enable it to deal with any accidental loops.
BTW, Dennis mentions STP ". . . there is change that a loop occurs and thus SPT will kick in a shut down ports to prevent that loop." That's correct, STP can try to block a loop that becomes active, but this can be hit or miss. So, STP can also actually block ports becoming fully active until it determines activation of the port will not create a loop. The latter, though, can delay hosts coming on-line, which can cause other issues. I.e. as noted above, STP is recommended to be enabled "just-in-case", but choosing the "correct" flavor of STP, or using additional STP configuration options might be needed to optimize its behavior in your environment.
