[rbridge] IS-IS pseudonodes, nicknames, and rooted trees

[mike shand]

At 05:26 09/01/2007, Radia Perlman wrote:
>For RBridges, I think the answer to my question is that it does not
>matter -- I *think* the same
>tree would be calculated whether you chose as root the pseudonode or the
>DR.

I don't think that is true. Since the cost from the DR to the 
pseudonode is non-zero (although the cost from the pseudonode to the 
DR is zero), I think you could end up with a different tree depending 
on which is root. Of course in normal IS-IS you would never make the 
pseudonode the root, so the issue doesn't arise.

But I don't think it matters, since I agree with what you say below.

         Mike


>So it's probably better
>to say that pseudonodes do not request nicknames, and cannot be
>specified as the root of trees,
>and would never appear as the ingress or egress RBridge. I don't think
>it matters whether the
>endnode information appears to be advertised by the DR or the
>pseudonode. I think we can let the IS-IS
>people decide that detail.
>
>Radia