> - Currently, the circuit where the user connects is arbitrarily decided by the demo user. In a real system with thousands of circuits, it'd be very difficult to properly assess which circuit the customer might connect to. When adding a new customer to a service, how does the operator decide, based on customer's location, which circuit to provide the service to ?

I'm not exactly sure what you're asking, but port allocation is, depending on the ISP's deployment model, either going to be fixed at the time the infrastructure was built, or whoever is doing the last metre install will choose a random available port on the switch. The subscriber will be assigned to that port in the RADIUS or equivalent database, and the BNG will query the subscriber based on DHCP Option 82 port information added by the switch. You could also map the subscriber based on MAC address, but this doesn't really work unless you don't support customer provided equipment on their end.

My access edge is injecting DHCP Option 82, and I'm mapping customers based on (bng_id + circuit_id + remote_id ). Say, a customer on Oakwood Drive ABC wants a service. What is the process of finding the right circuit between storing the customer's desired address and finding the best circuit to connect it to? Since, as mentioned in this thread, having connected to a wrong circuit can cause network noise for other customers too, how is the "cleanest" circuit + port assigned to a customer in a location ?

Depends on the access technology and environment. But usually there is not much choice to be made, by design. The cable or equivalent from the customer prem will go to exactly one aggregation location, and in that location, the choice of port generally doesn't matter. Among the potentially multiple cables or ports, they're all meant to be functionally the same. Maybe something is wrong with a cable or port, and that will hopefully come out in post-install testing, but there's not meant to be much of a decision to be made for commodity service like DSL or GPON (anything that'd use BNG). It's typically just going to be up to the last metre installer.

Metro ethernet services will be designed by an engineering team on a case-by-case basis, but they very rarely if ever use BNG.

Thank you! That answers my question. I appreciate your feedback.