Tue Dec 28, 2021 9:32 pm
Some chipsets support PPPoE hardware acceleration (such as Atheros IPQ806x). Don't know if MikroTik uses it though.
Most of the time you're running PPPoE at a payload MTU of 1492 so there will be packet fragmentation occurring on your router. That will be enough to prevent these packets being fasttracked and subsequently put strain on your CPU.
So one way to prevent that would be either running your PPPoE link at an MTU that allows for 1500 byte payload packets (that is, if your ISP even supports this (RFC 4638), 1508 would normally do it but MikroTik requires you to use 1520) or ensure packets destined for the internet reaching your router are already at a size of 1492 bytes, so that packet fragmentation is no longer being performed on the router.