Low-lying Firmware issue on RV0XX?

Discussion in 'Cisco Small Business Routers and VPN Solutions' started by MiLe, Aug 29, 2012.

  1. MiLe

    MiLe Serious Server Member

    Dear Forum.

    Occasionally we experience problems with our internet connection. We are tracing this problem for quite some time now.

    Due to the fact that we are little far away from the DSLAM we do not have the fastest DSL. We are trying to compensate this with two DSL lines and therefore use Linksys/Cisco RV042 (v.1.1) routers.

    The effect is sort of loss of the ability to establich an internet connection. We first of all thought that this might have to do with our dual WAN environment. We've gone through the procedure to name the usual suspects like:

    ISP, Modem, Router, Cables, Setup.

    Our aim was to find a way to make it reproducible. Now we think that we have found a way to proof that this is a low-lying firmware problem. We've been using all available firmware for testing

    RV042 firmware,
    RV042 firmware and
    RV042 firmware

    and we've used different routers of the same model to make sure it is not hardware dependent.

    It cannot have to do with dual WAN setup, because we have physically disconnected the 2nd wan port and changed the setup so that the router should not have used this port.

    We have been able to see this problem with a computer that is directly connected to one of the RV042's LAN ports, no other network hardware inbetween.

    This problem can be seen on linux systems using traceroute only. We've tried on windows as well, but do not see this. We think that's either due to

    a) "The MS Windows tracert command uses ICMP echo request datagrams instead of UDP datagrams as probes." or

    b) timing, because the tracert program seems to be slower by default than traceroute.

    As you can see, slowing down traceroute by inserting "-z 500" makes the effect disappear.

    So does it have to do with load as well?

    There is no difference in the effect using traceroute with hostname or IP address. The effect is stable all the time.

    To make it very clear we've made a small video which can be watched here:

    When calling traceroute three times after another, on the third call we ever see a delay/timeout. To us it looks as if this occurs every 8th time!

    Does someone have an explanation for it? Any idea how to fix it? Can somebody check it on RV016 or RV082 routers?

    Help appreciated!

  2. Toxic

    Toxic Administrator Staff Member

    would it be an MTU issue? on the wan interfaces?
  3. MiLe

    MiLe Serious Server Member

    MTU issue: That's what my colleague thought first. We've played with WAN's MTU from 256 to 1500 without any effect.
  4. Toxic

    Toxic Administrator Staff Member

    are both WANs on ADSL or Fibre/Cable
  5. Toxic

    Toxic Administrator Staff Member

  6. MiLe

    MiLe Serious Server Member

    Both WAN ports are on ADSL (Modem) during normal operation. For the above mentioned test we stepped back to just one WAN port, because we wanted to see whether this effect could be caused by dual WAN setup.
  7. Toxic

    Toxic Administrator Staff Member

    are both WAN settings with Static IPs or Dynamic. also try setting both DNS's to the same, ie use OpenDNS

    IP address:
    IP address:
  8. Toxic

    Toxic Administrator Staff Member

    With DSL best to set MTU to 1492 or lower (settings of 8) ie 1492, 1484, 1476 etc etc.
  9. MiLe

    MiLe Serious Server Member

    Ok, we have heavily tested different MTU settings before. Our ISP suggests 1492 which is our default setting. We shall run TCP Optimizer to see whether that tool suggeste another value.

    We have dynamic IPs on both WAN ports (Remember: the test is done with one WAN port only!). By default we do use other DNS servers than that of our ISP (among them is, but as explained: "There is no difference in the effect using traceroute with hostname or IP address."

    As far as I see, using a dynamic IP on WAN (PPPoE) does not allow us to configure other DNS servers ON THE ROUTER than that provided by our ISP.

    We have exchanged RV042 against an old D-Link router (one WAN port only) for testing. Doing so, the effect disappears!
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