FW: [Isis-wg] draft-ietf-isis-traffic-01.txt

[Tony Li]

Cristina,

I think we first need to be _very_ careful about what you mean by
"scoping".  

IS-IS TLVs by their very nature are not automatically exchanged between
areas or between levels.  This is no different for TE information and the
draft need not say anything specific about this.

The TLVs were not designed to carry topological information independent of
the LSP that they exist in, so their use in other areas or levels would be
non-trivial.  This was definitely not the intent.

That said, the topology information that one extracts out of the TE
information can be used independently of any area or level boundaries.  It
is simply a graph or 'map' if you like.

One possible application of this is to do multi-level traffic engineering.
Suppose that you had IS-IS areas interconnected using an OSPF (or IS-IS
level 2) backbone.  A traffic engineering path could compute a strict route
across one IS-IS area.  Then the boundary router between the protocols
would compute a strict path across the backbone, and the exit boundary
router would compute a strict path across the exit area.

Other wierd and wonderful things are also possible.  The spec is written
specifically to minimize future limitations while providing the
functionality that we want today.

Tony