RE: MPLS,IETF, etc..
2001-09-09 23:50:03
--On 4. september 2001 02:32 -0400 "Natale, Robert C (Bob)"
<bnatale(_at_)lucent(_dot_)com> 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
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Harald Tveit Alvestrand <=
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