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Shibby v104 Bug - E2500 throughput on 5 GHz.

Discussion in 'Tomato Firmware' started by rafwes, Dec 27, 2012.

  1. rafwes

    rafwes Serious Server Member

    Hello!

    I have noticed that due to high CPU load (95% for [events/0]), the 5 GHz performance of E2500 gets bottlenecked at about 7 MB/s (no encryption, 40 MHz channel). I tried changing almost every possible wl setting for eth2 without success. For the 2.4 GHz radio, CPU usage is very low and its throughput is most of the time even higher with 20 MHz channels compared to the 40 MHz channel at 5GHz.

    Stock firmware works fine, there the performance comes close to the maximum of 100 Mbit/s of the wired links. Since I do not know where to file bug reports for Shibby, I'm posting it here.

    Thanks!
     
  2. ipse

    ipse LI Guru Member

  3. VirtualLarry

    VirtualLarry Serious Server Member

    Perhaps this is the problem that I am encountering. I just flashed several E2500 routers with Shibby 104, and am using them in a 5Ghz WDS configuration. I am only seeing 30Mbit/sec throughput, even though the link rate is showing as 130. Doesn't seem to matter if I'm using 40Mhz or 20Mhz channels.

    In my case, I AM using encryption, WPA2-PSK/AES between WDS nodes.

    If this is a bug, hopefully it can get fixed soon. I was thinking it was some sort of configuration problem on my end.
     
  4. rafwes

    rafwes Serious Server Member

    Unfortunately, encryption is not the root of the problem. I can observe the same behaviour using wpa2/aes only.
     
  5. rafwes

    rafwes Serious Server Member

    @VirtualLarry: Putting into mind that WDS overhead is 50% thanks to retransmission (on top of the average wifi overhead), the throughput you are experiencing is about the same as mine. Looks like it's not only on my hardware. Thanks for the report.
     
  6. VirtualLarry

    VirtualLarry Serious Server Member

    I don't think point-to-point WDS should incur any 50% retransmission overheat, if packets are going from the LAN, to the wireless, out to the other wireless router, and then back onto the LAN.

    I'm not running in WDS + AP mode, I'm only running in WDS mode, with wired clients (mostly). I do have a laptop connecting to the 2.4Ghz at times on the primary WDS router, but that radio is set to AP mode, not WDS + AP. So there should be no retransmission overhead.
     
  7. rhester72

    rhester72 Network Guru Member

    Why would there be no retransmission overhead? WiFi isn't full-duplex...at any given point in time, the transceiver is either receiving or transmitting. To retransmit, it must do both...separately. Thus, speed is automatically cut in half.

    Rodney
     
  8. VirtualLarry

    VirtualLarry Serious Server Member

    I meant that there should be no retransmission of wireless frames. Ethernet frame comes in on LAN of router 1, goes out wireless of router 1, comes in wireless of router 2, goes out to the ethernet of router 2 LAN connection.

    Yes, actual throughput of wireless is around half of the link rate, but that's not due to re-transmissions.

    In my case, throughput is like one quarter of link rate, which is why I think something funny is going on.
     
  9. VirtualLarry

    VirtualLarry Serious Server Member

    Hmm, I reconfigured the primary WDS router as just a 5Ghz AP, using 40Mhz channel width, channel 40.
    Then I reconfigured one of my secondary WDS routers as wireless ethernet bridge.

    Now I'm getting 36Mbit/sec down, 28Mbit/sec, instead of 23/23.

    It's an improvement, but I was hoping by using 40Mhz channel width, I might be seeing numbers like 60/30.
     
  10. ceevee

    ceevee LI Guru Member

    I am getting this as well on the E2500 as access point linked to another E2500 as wireless ethernet bridge. All using 5 ghz. It won't go past 30mbit/sec on Shibby 112 on my E2500. I reflashed stock on the access point, and the throughput is better. However, the wireless ethernet bridge is still tomato.
     

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