Reaching pppoe 500/500 wan speed with EA8500

Hi. Let me introduce a bit my case...I had DD-WRT installed on my EA8500 during the last three years, working perfectly with my previous ISP (theorical 300/500 connection with DHCP, reaching 450/600 in my speedtests). Due to a DD-WRT bug that affected some EA8500 devices, any k4.x build was caussing not to be able to soft-reset the device, so I sticked to the newest k3.18 build (kong 37945m from 2018 FYI).

This week, I switched to a new ISP (500/500 connection with PPPoe auth). It was impossible for me to configure WAN tagging with id 20 (the one required by this new ISP) with DD-WRT because I read some article showing that ids between 16 and 21 were reserved for internal purposes. So, I installed Openwrt 19.07 in my EA8500 (kong's build to be precise).

The problem I am facing is that I can only reach 350/450 wan speeds with openwrt. With the router that my ISP supplied to me, I can reach 560/560. Tried enabling soft flow offloading also, but not much improvement. Are these speed results coherent with EA8500 cpu speed? I read somewhere that k3.18 provides faster WAN speeds than k4.x, is that true? Could another router help to reach the 560/560 speeds? Or maybe some config?. I also read around thia forum that pppoe can reduce wan speeds.....could this be the cause of the slowdown? Thank you for your help. Bye

I'm not sure what the CPU is on that device, but 500Mbps is a pretty heavy load on a cpu, and you should start looking for an x86 based solution. Some ARM based devices can hit 500+ but it's typically stretching.

@jeff has some posts evaluating the odroid H2 board very successfully.

It's a IPQ8064 device.

The curious thing is that this CPU managed to reach faster speeds with DD-WRT, so maybe is a kernel related thing?

assuming you're talking vlan id's;
"fixing" this maybe the path of least resistance for you.

but yea, ddwrt uses alot of optimizations to enhance performance, kong probably double so.
these usually also exlude the use of advanced qos mechanisms (sqm), so these optimisations are not really usefull for powerusers.
vanilla openwrt on embedded devices struggle after a few hundred mbps, pppoe will also take a significant toll.
but some core-i/ryzen based mini-pc or used enterprise desktop will cover you even with a full gbit.

Is that really the case?
If I understood you correctly, your previous ISP didn't require PPPoE, but worked over plain ethernet instead. Especially at high throughputs, PPPoE is a significant CPU hog, much more so than plain ethernet. It doesn't surprise me that your plain ethernet throughput is considerably faster than PPPoE, but by comparing the maximum routing speeds against each other, you're comparing apples with oranges.

IPQ806x (and I'm already basing this on the faster ipq8065 SOC, instead of your slightly slower ipq8064) is generally said to be good for around 400-450 MBit/s routing throughput, not more. Your ea8500 however adds another hardware obstacle. Contrary to all other known ipq806x devices, Linksys opted to only connect a single CPU port to the internal switch (instead of two, one for WAN, one for LAN), which reduces the theoretical throughput even further, as all traffic has to pass it twice (WAN <--> CPU <--> LAN, so even ignoring the SOC's actual performance, you're down to 500 at most, due to this unfortunate hardware design choice). So your figures are already better than expected for ipq8064 in general and the ea8500 in particular.

For more details, please see:

Kernel 4.19 (as used in current master snapshots, be aware that snapshots don't have the webinterface/ luci preinstalled) improves the maximum routing throughput significantly, but probably not enough for your needs either.

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You could run ddwrt with an external managed switch to apply / remove VLAN tags on the way to the modem. Maybe that's not practical in operation but it would be interesting for a speed test.

Thanks for the replies. I will give k4.19 a try and if speeds doesn't improve too much, I'll try to put a managed switch with DD-WRT and see what happens. Thank you

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