[Desire HD Q&A, Help & Troubleshooting] pnomandk:
I've got a significant problem with my DHD when running any of the latest JB releases I've tested -- the problem appears with the JellyTime, codefireX, pipelinerard's CM and also the AOKP ROM's I've tested, even on a clean install (complete wipe of everything but the radio, install only the ROM; gapps not needed to cause the issue). The problem is however not manifest in IceColdSandwich, so I suspect something is broken in the way JB uses the WiFi network compared to how ICS did it. Maybe that triggers a bug somehow in the radio or misses some important radio settings?

To some/many people, it may not be immediately visible, but if you have this problem and use your phone on a large network, you might get banned/kicked off the network if they use rules similar to what e.g. Princeton recently implemented. You may also experience this as intermittent network problems with some hosts being unavailable from time to time.

Here is what happens:

Whenever the phone sleeps (i.e. the screen is off), it sends out bogus ARP message every 15.1 seconds (give and take 10mS or so). The message typically announces "IP x.y.z.v is at MAC ii:ii:ii:ii:ii:ii:ii" where the MAC address is the one of the phone and the IP addresses seems to come from some predetermined list and/or the routers IP -- or it might be 0.0.0.0.

On my network, when using one of the AP's, it will send out seemingly "real" IP addresses that will clog up the main router, trigger additional traffic to poll the ARP addresses and eventually cause misfunction and loss of connectivity also for other clients on the network -- it will however heal itself after some minutes, when the ARP cache times out, just to reappear again later randomly.

On the other AP it will always announce an IP of 0.0.0.0, which is obviously incorrect -- but doesn't cause any direct malfunction.

From time to time, I've also seen incorrectly formatted ARP packages.

I've debugged this with wireshark and pcap's on my network (as I started to wonder about more frequent network problems after using this phone).

I've also tried running tcpdump on the phone itself, and have inspected the pcap from the locally captured file. That pcap does NOT contain the ARP messages, so somehow somewhere deep down the kernel or in the radio, ARP messages are triggered to be sent out (i.e. below the capture interface).

To see if you have this problem, you need to run wireshark on another device and check for traffic from your phone's MAC address. It is easy to see if you know what to look for. You cannot know if you have this problem unless you check for it -- but you might suffer weird connectivity issues from time to time also on other devices/PC's, depending on the rest of your network components, that are not immediately discernable as related to the phone.

Technically this looks similar to ARP spoofing/flooding, with similar symptoms.

Does anyone have any ideas how to fix this? I think this requires someone with kernel/network knowledge, and it is likely related to how parts of the legacy parts (binaries) are being used.

I'm initialy trying to figuring out what runs every 15 seconds on the phone, and would then like to start tracing/bisect ICS vs JB code here.

Would also be nice if someone else could confirm this -- even though the specific symptoms apparently depend on certain WiFi related parameters.

Any ideas?

For reference, I'm using the latest radio 12.69.60.29_26.17.14.11_M. But as ICS does not have this problem, it might not be related to the radio version directly.