Eric:
I would phrase it differently. MPLS has a dual nature which tends to be a function of the control plane used.
Most of what you describe as non-CO stuff permits LSPs to mimic the topology generated by IP routing with as ruthlessly simple an implementation as possible, and that's OK, that was a design goal.
However if that were the only application of MPLS, I would delegate it to being a useless appendage on the IP forwarding plane. It only adds baggage and complexity to no net value. I require things like liberal label retention, supporting additional protocols (LDP), and lots of extra logic on the node to approach the reliability that IP routing by itself would be capable of without MPLS. This is because it adds steps after routing convergence so that MPLS can configure the forwarding table to mimic what the routing protocols have told it and that may include having to solicit new labels from neighbors, or remebering a lot of extra labels it would not otherwise need "just in case".
It is when I get into topology manipulation independent of dynamic IP routing that MPLS starts to add value and to claim this is not connection oriented use of MPLS forwarding IMHO smacks of the same "tunnel"/"layer" semantic debate that can also be said to waste much time.
I would also similarly invert the "saddled with CO mechanisms" statement as it would appear that bringing some CO properties to IP is what MPLS is all about. Otherwise IP without MPLS would be just fine....
cheers
Dave
> -----Original Message-----
> From: Eric Rosen [mailto:erosen@cisco.com]
> Sent: Tuesday, March 05, 2002 9:52 AM
> To: Shahram Davari
> Cc: 'Thomas D. Nadeau'; ccamp@ops.ietf.org
> Subject: Re: draft-bonica-tunneltrace-02
>
>
>
> Shahram> What is the difference between ATM, FR, or any CO
> technology and
> Shahram> MPLS
>
> Well, for one thing, MPLS isn't a CO technology. It's got
> lots of stuff
> that doesn't really make sense from a CO perspective. Of
> course, when the
> CO guys run across these features (multipoint-to-point,
> php, liberal
> retention, independent mode, equal cost load balancing,
> dynamic rerouting
> with no signaling, ttl, lack of packet sequencing, IP
> control plane, etc.,
> etc.) they assume that those features are there by mistake!
>
> This misconception that MPLS is a CO technology, shared
> as it is by the
> "pure IP" crowd and by the ITU/ATM crowd, is the source
> of much wasted
> time.
>
> MPLS is actually an IP-derived technology that facilitates
> the application
> of certain circuit-like characteristics to IP
> networks. As an IP
> technology, the usual IP diagnostic tools, such as ping
> and traceroute,
> should be applicable. That's what this whole useless
> discussion is about.
> One the one side are people who think that IP networks
> are inherently
> unmanageable (after all, they don't follow ITU standards),
> and on the other
> side are people who think that the IP-based paradigms are the best.
>
> It is true that MPLS can be used to provide something which
> is very like a
> CO network, but it doesn't have to be used this way, and
> usually isn't.
> Those of use who are not particularly interested in CO
> networks just don't
> want to be saddled with the legacy CO mechanisms.
> Presumably, if all these
> legacy CO mechanisms were so great there would not be such
> a great rush to
> IP.
>
>
>
>
>
>