Is PPPOE wan single-threaded?

RouterOS General
1

Hi guys,

Is PPPOE wan single-threaded?

I am testing out a ISP FTTH but uses PPPOE and looks like 1 core gets much higher than the others, I also have another ISP that I was thinking of replacing that is IPOE this uses all cores .

Thanks for any info

2

In ROS packets of single connections are handled by same CPU core. Which makes total sense as this way chances of out-of-order delivery are slim.

In case of IPOE, every client connection (TCP or UDP) counts as single connection, meaning that multiple users browsing internet will have many open connections and handling of those can be distributed across many cores.

In case of PPPoE, all WAN traffic becomes single PPPoE connection (L2 even) and due to timing reasons it will likely be handled by single core. Mind that this doesn’t mean that handling of IP packets (firewall, NAT, whatnot) doesn’t use all cores. Only PPPoE encapsulation uses one single CPU core. This is relatively light-weight operation but in case of high throughput (1Gbps) can still considerably load a CPU core.

I would not worry as long as none of cores get loaded higher than say 50%. Experience goes that load below around 70-80% doesn’t cause considerable performance drops …

3

Thanks for your well detailed and informative reply.
Just a little advice from you if I may :slight_smile: downloading torrents like linux ISO with the first ISP Fiber to the node then uses coax to the home/place kills all internet conection including the torrent itself, I tried qos but nothing, with the second ISP FTTH PPPOE I can download as many torrents at 1 time with no problems and no QOS, the only thing that is putting me off is PPPOE, Would it bother you?

4

I’ve got PPPoE at home as well (and IPoE at my parents’ and inlaws’ places) and that doesn’t bother me at all.

The only potential problem that PPPoE might cause is reduced MTU on this link. Which means that router has to do fragmentation of all full-sized packets (in uplink direction only) … which should not be a huge problem, because IP (both v4 and even more notably v6) has mechanism called “Path MTU discovery”, which should enable original sender to transmit packets small enough to fit any MTU bottle-neck between itself and server …

5

Thank you.
You really helped.

Regards

Chris

6

I experienced a behavior that I believe is related to what happened to you
billing server terminates sessions every 24 hours, and I have several sites with a large number of clients on a single router “ROSv6”. When clients’ sessions end and they attempt to reconnect, the router blacked out for 10 minutes.
and it solved by upgrading the router to ROSv7.