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

Dear OpenWRT community,

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).

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

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.

1 Like

Hi psherman,

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

Have a great weekend !

cheers Blinton

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