Unnamed Administration Sources Report that Criag Partidge said...
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MPLS has a genealogy that leaves it suspect (it descends from a vendor response to IP switching -- and IP switching turned out to be a fad) but a lot of careful work has gone into trying to make MPLS a sturdy technology. The issue is, has that work succeeded?
I'm actually not in a good place to say. I know some of the things people say about MPLS are clearly silly (the notion MPLS is faster to switch than IP reflects a poor knowledge of router innards, or a poor router design). Other statements have some credibility -- carriers have long wanted to do overlay networks to better track resources (witness how UUNET ran their backbone a few years ago) and MPLS apparently can help.
The scary thing is that the "speed" of MPLS-based networks is taken as gospel by an alarming number of engineers, mainly those who have come out of the large telco's (i.e. ILECs), and are still kind of mad that ATM didn't work out. These folks are more or less alarmed by IP, and desperately seek a more deterministic, switch-based model of data transmission for the Internet as a whole. The fact that there is no practical, real-world difference in forwarding speed between straight IP, and IP over MPLS is generally explained away by these guys in a fairly elaborate handwaving exercise. At least one major hardware vendor is not helping this, with some of their engineers convincing major customers that conventional IP routing is bad, and that anything MPLS is good. While I agree that MPLS has it's uses - i.e. TE as an exception handling mechanism for outages, and L2VPN technology as a FR/ATM replacement, some folks need to approach the technology with additional caution, and not blindly embrace it as a panacea. As the internet engineering community evolves, learning from things like ATM, becomes quite important. - Daniel Golding