Andrew is struggling with MPLS/VPN providers and sent me the following question:
Is "carriers carrier" a real service? I'm having a bit of an issue at the moment with too many MPLS providers […] Carrier’s carrier would be an answer to many of them, but none of the carriers admit to being able to do this, so I was wondering if it's simply that I'm speaking to the wrong people, or whether they really don't...
Short answer: I have yet to see this particular unicorn roaming the meadows of reality.
Carrier’s Carrier (CsC) seemed like a perfect idea for wholesale (transit) provides in the early days of MPLS – I know at least one of the big ones was pushing very hard to get it done. Transit providers could use CsC to offer their MPLS/VPN services as a transit MPLS backbone for other (smaller) MPLS/VPN providers.
However, even though CsC it was conceptually simple (all you had to do was to configure LDP or EBGP with labels on PE-CE link) I’ve never seen it working, and I’m guessing that most of the transit providers prefer offering VPLS (or other EoX) services – they’re way less hassle for the same money.
On the other hand, Carrier’s Carrier is nothing more than the ability to build your own MPLS/VPN service on top of someone else’s infrastructure, and probably won't solve your inter-provider issues. If you’re experiencing routing problems with your MPLS/VPN providers, stop bothering – use directly-connected subnets as transport endpoints, build GRE or MGRE tunnels on top of the providers’ MPLS/VPN network, and run your own routing protocols on top of them.