I use eth6 as a pppoe server for almost one hundred customers and some of them ( always the same ) have problem to download and surfing is slow .
Is there a problem or have i too many customers on the same interface ?
If he has 500 on RB1200, then you can probably have 1000I have a RB1100.
I use mangle rules and queue tree ( cpu load 19% max )
I also use nat to redirect customers to my squidbox