It is a corner case design. Most SPs would buy lambdas on someone else's DWDM network or MPLS L2VPN etc. Routing at layer 3 through another SP overcomplicates the design.
It's the same as like Inter-AS MPLS L3VPN option C. Just because you *can* do it doesn't mean you *should* do it.
Personally I've never seen any SP run option C, and I've seen many many large implementations. I'm sure it's out there and maybe someone here on the list has seen it but the amount of politics and interoperability that's needed between the providers is the limiting factor.
From a technology standpoint CSC and option C L3VPN are more scalable than dark fiber or DWDM or L2VPN AToM or VPLS, but from an operational point of view a lot of time they're just not practical.
Brian McGahan, CCIE #8593 (R&S/SP/Security)
bmcgahan_at_INE.com
Internetwork Expert, Inc.
http://www.INE.com
On Dec 29, 2012, at 8:00 PM, "John Neiberger" <jneiberger_at_gmail.com> wrote:
> I'm watching some videos for the SP track and I just started one on CSC
> using L3VPN. It seems awfully complicated. I haven't even really gotten
> into the configuration of it yet, so maybe I'll be able to answer my own
> question shortly, but why not just use L2VPN for this? It seems like you
> could accomplish basically the same thing with MPLS pseudowires or
> something like that. Or maybe even VPLS or whatever. Not sure about that
> since I haven't done VPLS yet. :-)
>
> So, what's the deal? What advantage does CSC via L3VPN bring that would
> make it worth all the configuration hassle?
>
> Heck, why not just run MPLS over GRE?
>
> I'll keep watching the video and reading about it. There is probably some
> huge advantage that I am completely missing. I'm a noob to some of this, so
> go easy on me. :)
>
> John
>
>
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Received on Sat Dec 29 2012 - 21:23:13 ART
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