Miscellaneous ephemera…

Network Flooding on Ubuntu


I have been experiencing problems with my wifi LAN when playing music through mpd or watching movies. My upload speeds would climb to around 120-130Kb/s and my wifi would just go down.

Apart from being frustrating, this was inconvenient as it meant that if I was doing either of those things, my stereo in the living room couldn’t stream music from my squeezebox server, or other members of the family (or guests) couldn’t connect to the access point to get online.

After asking on Ask Ubuntu (which, like many of the Ubuntu-related fora is populated with people who are more well-intentioned than they are knowledgeable - which seems to me one of the fundamental problems the distro has; but I’ll save that rant for another day), one helpful user suggested I use wireshark to diagnose the network traffic.

I really should have thought of that myself. Nonetheless, it was immediately instructive. Wireshark quickly identified that, as soon as I started mpd, one of my ports was being flooded: 46560

lsof showed that pulse audio was the culprit:

pulseaudi 2190 jason 39u IPv4 14110 0t0 UDP mybox:56751->

Quelle surprise… When software engineers want a case study of opacity and abstraction from the user, this should be their first port of call.

Worse, it is a known bug. First logged in August, 2009. And apparently insufficiently serious to warrant any attention. Fair enough, I suppose, given the fix is easy enough if you know what you are trying to fix…

Install the Pulse audio preferences tool:

sudo apt-get install papref

…and disable Multicast/RTP.

Another example for me of Ubuntu’s fast waning utility as a distribution for people that want to be able to exercize some control over their system. It is only still installed on this machine because there isn’t an official Arch Linux mirror here and, with my international traffic capped to 30Kb/s until last month, I wasn’t prepared to try and run a distro on that sort of bandwidth. Now that has changed, I suspect that Ubuntu’s days are numbered on this box.