Hi, we have a new build where we're going to offer internet service via PPPOE to various clients within a large building. A simplified view of the network is RTR -> Switch Stack -> PPPOE Clients.
Simplified Overview: The switch stack will also be used for other things but I'm focused here on the L2 design for the PPPOE clients.

I've been thinking about three different L2 designs and wanted to get a general opinion on the best way to go, or I'm open to any other approaches I've not thought of.

First is a shared L2, no separation between clients all on the same vlan 100. A single PPPOE instance serving all clients: Second is separate vlans for each client (MSTP on the switch stack) those vlan interfaces on the router all bridged together and a common bridge horizon set. A single PPPOE server instance serving all clients: Third is separate vlans for each client (MSTP on the switch stack) separate PPPOE server instance for each client on each vlan interface:
I guess the crux for me is: one PPPOE server instance or multiple and how hard should I be trying to protect each users L2 segment from each other.

Any advice gratefully received, many thanks.
Sam

I would build a highly available BRAS for PPPoE and use x86 +CHR. We wrote an article on how to design it

https://stubarea51.net/2018/04/23/pppoe ... atorsbras/

Great article, thank you very much!

I have not included it here for simplicity, but we actually will have two AC's on site and it's my intention to make them both available to all clients. Since we won't have very many, possibly 10-20 PPPOE clients in the building, I had thought to just let each client negotiate the AC it was happiest with, but your article has made me consider that if I setup a PPPOE instance per client I can have much more control over their affinity by padding the pado-delay accordingly.

Do you think it's worth the effort to Vlan each client into it's own L2 domain or how would you feel about having just two Vlan's and two PPPOE instances per AC for simplicity (half the clients in one vlan and half in the other, pado-delay padded accordingly on the ACs). I'm unsure how concerned I should be about protecting each client's L2 from each other? For some reason it niggles me as inelegant to have a PPPOE server instance for each and every client (per AC), but I am strongly considering it.

Many thanks,

Sam