MPLS totally sucks. It's the X.25 of the new
millenia, just as ATM was the X.25 of the 90's.
Why? It's a CIRCUIT SWITCH methodology on top
of a PACKET SWITCHING network. Dumb! It's
another thing to manage and break from a network
engineering point of view. That, and most
vendors implementations don't work worth a damn
today. [snip]
This would be enough for a person with an average
education in MPLS to judge how much you (don't)
know about MPLS. I am doing MPLS-oriented
research for the last 1.5 years so let me
try clearing some of the "bad air" around the
issue:
1) MPLS is NOT circuit switching ON TOP of packet
switching. If you would care to do some minimal
reading before you flame a subject, you would
find out that MPLS is not ISO layer >= 3 but it
is a "layer 2.5" technology. In other words IP
datagrams are carried on top of MPLS frames
pretty much the way ATM worked.
2) The reasons behind MPLS are too complex to
describe here (for the intrested reader, take a
look at RFC3031). But basically it was
acknowledged that despite ATM being "evil"
circuit switched technology does offer some
advantages. That's why you can (_very_ roughly)
characterize MPLS as an "IP friendly ATM", minus
some of ATM's design shortcomings (that were
present there due to the technology limitations
at that time and ATM's intended use).
But to rebute your misconception, MPLS is NOT
about "routing IP datagrams fast", nor "replacing
CIDR". Again, if you care to skim the mentioned
RFC it is acknowledged that this _were_ some
advantages few MPLS proponents claimed but this
is simply not true, as you correctly state:
Efficient algorithms for IP address lookup and
routing are implemented in hardware by several
vendors (incl. cisco, btw...) so MPLS doesn't
have any edge there.
3) About "Traffic Engineering being a load of
crap" I would say that few of the top 10 largest
carriers in US might disagree a bit. Get a hold
of an educated MCI network operations
engineering (say MCI/UUNET) and ask how much improvement (and revenue) TE gives them. And yes, the reaction is "WOW".
And QoS... Same deal- load of crap.
4) Well, QoS is too broad a topic to
disuss in any relevance here. But in saying that
you automatically excluded _all_ mechanisms for
traffic differentiation in a network. Enough said.
Also, to end this, MPLS is _not_ only about TE/QoS/IP fast switching. It is used for fast network restoration, it is extended for supporting WDM in a similar manner (see "Generalized"MPLS), etc. People w/ some network education might care to take a look here for a overall view on the MPLS-related topics.
All in all I would dare to say that your posting
is the worst kind of mis-information:It contains
a grain of truth and mixes completely different and unrelated subjects as "comparisons" (OPenGL w/ CIDR)
For the rest of the readers, the necessary grain
of salt when reading the linked article: In IETF
there is a lot of politics around MPLS (disguised
in "technical debates") -- surprise,surprise. For example if someone
cares to browse the MPLS mailing list archives
Mr. Randy Bush long opposed BGP/MPLS VPNs
(described initially in RFC2547.IIRC there is
also draft updating it). Which happen to be a
technology cisco pushes very hard and which Mr.
Bush opposes violently.
What particular agenda Mr. Bellovin has escapes
me. But I assume (again, this is _speculation_)
since AT&T made a _huge_ investment in ATM in
the past do not see MPLS (which is simply a
better competening technology) so favorably.
All in all, remember that the most competent
answer is "I don't know.It depends".
Slashdot Mirror
MPLS totally sucks. It's the X.25 of the new millenia, just as ATM was the X.25 of the 90's. Why? It's a CIRCUIT SWITCH methodology on top of a PACKET SWITCHING network. Dumb! It's another thing to manage and break from a network engineering point of view. That, and most vendors implementations don't work worth a damn today.
[snip]
This would be enough for a person with an average education in MPLS to judge how much you (don't) know about MPLS. I am doing MPLS-oriented research for the last 1.5 years so let me try clearing some of the "bad air" around the issue:
1) MPLS is NOT circuit switching ON TOP of packet switching. If you would care to do some minimal reading before you flame a subject, you would find out that MPLS is not ISO layer >= 3 but it is a "layer 2.5" technology. In other words IP datagrams are carried on top of MPLS frames pretty much the way ATM worked.
2) The reasons behind MPLS are too complex to describe here (for the intrested reader, take a look at RFC3031). But basically it was acknowledged that despite ATM being "evil" circuit switched technology does offer some advantages. That's why you can (_very_ roughly) characterize MPLS as an "IP friendly ATM", minus some of ATM's design shortcomings (that were present there due to the technology limitations at that time and ATM's intended use).
But to rebute your misconception, MPLS is NOT about "routing IP datagrams fast", nor "replacing CIDR". Again, if you care to skim the mentioned RFC it is acknowledged that this _were_ some advantages few MPLS proponents claimed but this is simply not true, as you correctly state: Efficient algorithms for IP address lookup and routing are implemented in hardware by several vendors (incl. cisco, btw...) so MPLS doesn't have any edge there.
3) About "Traffic Engineering being a load of crap" I would say that few of the top 10 largest carriers in US might disagree a bit. Get a hold of an educated MCI network operations engineering (say MCI/UUNET) and ask how much improvement (and revenue) TE gives them. And yes, the reaction is "WOW".
And QoS... Same deal- load of crap.
4) Well, QoS is too broad a topic to disuss in any relevance here. But in saying that you automatically excluded _all_ mechanisms for traffic differentiation in a network. Enough said.
Also, to end this, MPLS is _not_ only about TE/QoS/IP fast switching. It is used for fast network restoration, it is extended for supporting WDM in a similar manner (see "Generalized"MPLS), etc. People w/ some network education might care to take a look here for a overall view on the MPLS-related topics.
All in all I would dare to say that your posting is the worst kind of mis-information:It contains a grain of truth and mixes completely different and unrelated subjects as "comparisons" (OPenGL w/ CIDR)
For the rest of the readers, the necessary grain of salt when reading the linked article: In IETF there is a lot of politics around MPLS (disguised in "technical debates") -- surprise,surprise. For example if someone cares to browse the MPLS mailing list archives Mr. Randy Bush long opposed BGP/MPLS VPNs (described initially in RFC2547.IIRC there is also draft updating it). Which happen to be a technology cisco pushes very hard and which Mr. Bush opposes violently.
What particular agenda Mr. Bellovin has escapes me. But I assume (again, this is _speculation_) since AT&T made a _huge_ investment in ATM in the past do not see MPLS (which is simply a better competening technology) so favorably.
All in all, remember that the most competent answer is "I don't know.It depends".
My $0.02
Florian-Daniel Otel
http://www.ce.chalmers.se/staff/otel