[c-nsp] Spanning tree compatibility with RSTP

[Alaerte.Vidali at nokia.com]

Hi Collins,

802.1w can revert back to 802.1D in order to interoperate with legacy
switches.
So, if Cisco does not understand the other switch you have it may try
speak old STP.

But I would recommend creating some loop and debug both switches to be
confortable they will handle the problem.

Besides creating loop, I would create single wire failure (for example,
cut wire 3 of UTP cable) to be aware of the behavior.

Good Luck,
Alaerte