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

[Radia Perlman]

In IS-IS, a shared link is treated as a "pseudonode" -- as if it were 
another router. The purpose of
this is because the routing algorithm scales as the number of links, so 
a link with n router neighbors
becomes n+1 nodes with n links rather than fully connected, order of n^2 
links.

The Designated Router gives the pseudonode a name (in IS-IS, a 7-byte ID 
consisting of
a 6-byte EUI owned by the DR, plus an extra byte to differentiate among 
links that that router
is DR for), and generates an LSP on behalf of the pseudonode.

Anyway, the question is -- should we allow/require pseudonodes to be 
assigned RBridge nicknames?
There are two reasons for obtaining an RBridge nickname

1) to be specified as the egress RBridge of a data packet -- I don't 
think this will ever be relevant
to pseudonodes
2) to be specified as the root of a tree

My inclination is to say pseudonodes cannot be egress RBridges, or 
specified as tree roots, and
therefore pseudonodes will not be given nicknames.

Comments?

Radia