Can someone enlighten me on circuit provisioning on the SP side of the house?

I'm wondering what a circuit looks like, from end to end, on the provider side of the house. Basically trying to educate myself, so I can talk shop better in certain situations.

So, for example, say Customer orders a 10 Mbps Internet Circuit from Provider. A few weeks later, eventually Carrier, who is the LEC for this circuit, and a different company from Provider, shows up, installs a Cienna box with a fiber uplink, and then feeds a single RJ45 copper port off that Cienna, that is our circuit.

Some cases, Provider will come and put their own box between that Cienna box and ours (Customer's) CPE router. In other cases, it just directly connects to Customer's router.

So... I'm well familiar with how this circuit looks on Customer's side. We set up our BGP or static route or whatever with Provider's PE-Router, usually the other side of either a /30 or /31 p2p connection. (Understanding that it's a virtual circuit traversing two different organization's equipment to get to said interface, but as far as our router cares, it looks like just a directly connected interface.) We configure a traffic shaper going egress on that interface. Ok, we ordered a 10Mbps circuit? We set the traffic shaper to like 9.8Mbps egress. That way we don't push 1Gbps of traffic and drop like 90% of our packets.

That's all fairly simple.

I'm just wondering from end-to-end how the configuration looks on Provider's and Carrier's equipment. I know the typical answer "it depends." Could be a bunch of different situations, I get that. What's one that you would say is the most basic or common.

What I'm most interested in are the following:

• Where (which interfaces) are Policers placed? Do both Provider and Carrier use ingress policers on their respective networks for this circuit?

• Do either Provider or Carrier employ any shapers for our circuit? Like, does Provider do a 10Mbps Shaper egress into Carrier's network, and Carrier has a matching policer on their side? Or is the link between Provider and Carrier just a big dumb line rate connection?

• For that matter, how does Provider connect to Carrier's (the LEC's) network? Do they use like maybe one dedicated connection in my city, that happen to have many other customer virtual circuits where Carrier happens to be the LEC for? Like is Provider's interface that we peer with just a sub-interface on said theoretical connection? How are those segmented on the hand-off from Provider to Carrier? Do they just use a trunk with VLAN's? Is it something more complex and provider'ey?

• What other technologies are used that lie in between like optical carrier stuff, (DWDM?) and is policing and shaping a thing on that side of the house?

• Once we are past Carrier's network and on Provider's back bone, our packets will then route to and from whatever Internet access point on Provider's network that they route us to. Is our traffic still tracked somehow (like kept in its own VRF?) and policied/shaped along this path, including at the Internet peering point? Or once we hit Provider's backbone, it's just all line rate?

Basically I'm just trying to understand how the magic happens when we get a circuit like that, and can only send 10Mbps and only receive 10Mbps on that circuit, and if we try to send faster than that, it gets dropped, and if somehow, either Provider or Carrier set something up wrong somewhere along that path and we try to RECEIVE faster than 10Mbps, some policer somewhere starts dropping packets.

Thanks! I'm really hoping to get a very clear picture of what this looks like from end to end, hopefully even someone will be nice and draw a crude diagram even. Would be very enlightening.