Hi Vittorio, Thank you very much for your detailed replies :)
On Fri, Nov 29, 2013 at 6:56 PM, Vittorio G (VittGam) <open...@vittgam.net> wrote: > Have you tried with stable AA? I have the same router but with AA, and I've > attached quite a lot of USB devices to it (one 32GB Cruzer Fit pendrive as > extroot, 2 powered hubs, 2 bus powered hard disks [one per hub], one self > powered hard disk, and one DVB-T TV card) and I experience no problems at > all. No, but it is on the list of things to do. The reason we have used trunk is that the support for QMI modems have improved quite a lot since kernel 3.8. We also currently rely on some patches to the 3.10 kernel. Fortunately, backporting shouldn't be too hard. > I also use a Huawei 3G dongle sometimes, and the coverage here is not so > good, but I never experienced this kind of problem. An interesting thing with this issue is that it seems to be more related to unstable coverage. We have driven through and stayed in areas with bad coverage and not experienced any trouble. However, when we move into areas where we are on a "coverage-border", i.e., the modem disconnects/connects on its own, we get this problem. Based on the QMI messages that are sent, it seems like the modem is connected to the network, but loses packet service. When looking at our phones in one of these areas, we see that we have reception but no data connection (or a very unstable one). One hunch I have is that the issue is caused, or at least provoked forward by, the firmware in the modem. When this happens, I see that the LED on the modem switches off for a long time before coming back on. So it seems like the modem disconnects, but this is information is never sent to the router. I also noticed that even though I used different modems, they are all based on the same chipset (MDM9200). So for my next set of tests I will include some other chipsets too. > Usually the USB bus on my router is quite busy, eg. at the same time there > can be a DVB recording from the card to one hard disk, a file transfer from > another hard disk to a LAN client via NFS, an incoming file transfer via > SFTP from the WAN port to the third hard disk, and also one WLAN client > using the 3G dongle when I need the 3G connection, and no problems occur at > all. Yes, I also tested this (pushing the USB hub) and did not see any issue. So probably it is not related to the amount of traffic, it is rather something in the communication between hub and modem(s). > Are you sure it is not power related? You said that you moved between > different areas during your tests, so if you are using some battery source > for your tests, you might want to check with a multimeter that you're giving > steady 12 V to the router and 5 V to the hub, even while there is the 1 A > load from the 3G dongle. Even if you're running from AC you might want to > check that the hub is really delivering the voltage and current requested, > or you might want to try to switch to a different hub. Yes, pretty sure. Our power supply is a car's 12V cigarette lighter and the supply seems stable. Also, when measuring the power of the modems, we see higher power usage in areas where the problem happens than in areas where it does. When this problem occurs, the average power consumption of the modem is around 0.3-0.4A, while we have seen averages of up to 0.7A-0.8A and no problems have occured. > > Also it could be a defective router; I once had a defective TL-MR3020 > (AR9330-based) router that crashed on a 3G dongle with many different hubs > and power adapters. I bought another router of the same model but more > recent hardware revision, and the problem disappeared. Yes, we have tried with both different WDR4300s and a Netgear WNDR4300, and they both have the same issue. The WDR4300s we have been testing with are version 1.6 Thanks again for the help! Kristian _______________________________________________ openwrt-devel mailing list openwrt-devel@lists.openwrt.org https://lists.openwrt.org/cgi-bin/mailman/listinfo/openwrt-devel
