19.07.1 - IPQ8064 low LAN-to-LAN throughput (iperf3)

[blinton]

Dear OpenWRT community,

Config:
I use two TP-LINK Archer c2600 (OpenWRT 19.07.1) as dumb AP's.

• using the tutorial on openwrt about dumb AP
• added a VLAN (guest ethernet and wireless)
• and installed irqbalance (and enabled), nano, iperf3 and
  i.e. very simple setup.Also verifed irqbalance is working (seems to have no impact on LAN speed).

Problem:
Therefore as using only LAN ports with iperf3 I realized I may have an issue ?

• c2600 to c2600 -> 250 MBit/s
• c2600 to bouygues.iperf.fr -> 250 to 350 MBit/s
• c2600 to my router or server -> 480 to 520 MBit/s
• router or server to c2600 -> 850 to 870 MBits/s
• router or server to bouygues.iperf.fr -> 930 to 940 MBit/s

My router (i7-3770, 4GB RAM, i210-T1 NIC's, OpenWRT 19.07.1) gets 933 MBit/s to bouygues.iperf.fr,
same for my server (i3-8100, headless Linux 4.19).

So I'm pretty puzzled, I thought LAN-to-LAN with firewall off should be at least 900 MBit/s ?
What's the problem, and how can I solve it ?
Can I find something in logs or should I turn off irqbalance etc ?

Many thanks ! and

cheers Blinton

[psherman]

Most consumer routers are designed to route traffic, but not to source or sink packets. It seems a bit counterintuitive, but the SoCs in those systems (the C2600s, for example), do not have the internal bandwidth necessary to saturate a gigabit link if the packets either originate or terminate at the device itself, but many can work at or near line-speed when the traffic passes through the device.

Your router has a full blown CPU (i7) that is capable of processing the packets at line speed.

[blinton]

Hi psherman,

Thanks a lot for the hint, I wasn't aware of that !
All is fine now (940 MBit/s achieved ).

Have a great weekend !

cheers Blinton