--On 4. september 2001 02:32 -0400 "Natale, Robert C (Bob)"
<[EMAIL PROTECTED]> wrote:
> I do believe that the MPLS -> MPlS -> G-MPLS expansion to
> accommodate PSC and TDM -> LSC -> FSC devices is a beneficial
> and natural extension. The benefits offered by the traffic
> engineering opportunities would be hard to pass up too.
my personal (and largely irrelevant) belief about this evolution is that we
are reusing mechanisms (GMPLS, MPLS-TE, RSVP-TE, CR-LDP) that were
originally (?) evolved for MPLS tunnels to control other kinds of paths.
this is probably good (commonality is good).
However, I do not see how it validates tag-switching or the original MPLS
design.
To me, there is a fundamental difference between two classes of decisions:
- decisions taken at setup time (lambda allocation, routing computation,
path establishment, Strowger switch contact movement)
- decisions taken at packet switching time (IPv4 packet routing, ATM cell
switching, MPLS label switching)
I have heard argued that MPLS (the tag switching thing) was irrelevant on
the day that it was economically feasible to deploy 32-bit-wide associative
memory for routing table lookup in hardware. AND that the chief benefit of
the 6to4 and other 6-in-4 wrapper mechanisms is that you don't have to
develop 128-bit-wide associative memory for core switches (yet).
And arguments (like Bob's) that the benefits are real and present.
But I haven't yet figured out whether the latter class of argument applies
to the setup protocols or to the actual tag switching.
I'm sure I'll figure it out (sooner or later).
Harald
