[c-nsp] Maximum spannig tree instances

[A.L.M.Buxey at lboro.ac.uk]

Hi,

> ... but it doesn't say anything about the number of STP instances.

things go wonky when you have more than 1800 virtualports per slot
(which you didnt quite reach) (1200 on older eg 100mbit blades)
with 13,000 in total (PVST+), 10,000 in total (RPVST+) 

however, with MST, you can have 6000 virtual ports per blade and 50,000
in total (yay!)

however, this is all about logical interfaces. you want to know the
STP instance? 

regarding maximum STP instances... I believe theres a platform limit
of 1024 because of the MAC to VLAN bridge mapping on the platform -
but, from the values above, you can see that virtual ports would
hit you quite quickly without appropriate control of the VLANs

alan