[rbridge] Can we ever have pt-to-pt links?

[Radia Perlman]

Suppose the topology consisted only of RBridges with pt-to-pt links 
either to each other or
to endnodes, e.g., no bridges, no CSMA/CD. As specified,  we'd wind up 
creating
a pseudonode for each link. Not a total disaster, but it does seem 
suboptimal, especially
if we created a pseudonode for every port that contains an endnode.

I think we discussed this and said that there was no way of knowing for 
sure that a port
was a pt-to-pt link.

Do we want to try to optimize this case, for instance by:
a) allowing a port to be configured as "pt-to-pt", and freaking out (as 
in disabling
the port and declaring an error) if an RBridge sees multiple nodes on 
that port, or sees
a BPDU?
b) assuming if there is only one RBridge neighbors on a port that it is 
a pt-to-pt
link and there does not need to be a pseudonode? That makes me nervous 
because if
a third RBridge comes and goes, then things could get messy.
c) if there are zero RBridge neighbors on a port (just an endnode or
set of endnodes), do not create a pseudonode
for it
d) something else?

Or is it fine as is (if R1 and R2 are connected with a pt-to-pt link, R1 
will get elected DRB,
name the link R1.x, and issue two LSPs -- one for R1, one for R1.x, with 
R1.x claiming
connectivity to R1 and R2). Basically, there will be a pseudonode for 
every RBridge-RBridge
link. I hope we don't have to create a pseudonode for every port to 
every endnode.

Radia