[rbridge] # of tree issues: default # of distribution trees, minimum acceptable supported # of trees

[Radia Perlman]

Easy question: what do you prefer the default # of trees to calculate be?

Harder question: What is the minimum acceptable # of trees an implementation
is willing to compute? (this is currently not specified in the spec. 
Should it be?)

Ugly question: What happens if R3 can only support, say, 3 trees and
the highest priority guy specifies, say, 5 trees? There are various
potential answers to this:

a) if we ignore the question, it will go away
b) we should put "number of trees I support" into the LSP, and
the highest priority RBridge is not allowed to specify a number
greater than the minimum supported by any RBridge
c) require RBridges to support as many trees as the highest
priority RBridge demands