RE: MPLS VPNs or not?

["Daniel Golding" <dan () netrail net>]

Unnamed Administration Sources Report that Criag Partidge said...
>

{snip}

> 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