When I enable module-rtp-send either by ticking [x] Enable Multicast/RTP sender in paprefs or adding something like 

load-module module-null-sink sink_name=rtp
load-module module-rtp-send

to /etc/pulse/default.pa, pulseaudio starts flooding the packet with more than 100 UDP packets per second. My router can't handle that and fails to serve any other devices. The network is practially DOS'd by pulseaudio.

Output from tcpdump -i eth0, as soon as the [x] Enable Multicast/RTP sender checkbox in paprefs is ticket, starts about 2 seconds later:

13:15:37.872284 IP 192.168.1.7.42051 > 224.0.0.56.sapv1: UDP, length 236
13:15:40.106404 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.113622 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.120879 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.128150 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.135305 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.142550 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.149782 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.157019 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.164254 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.171478 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.178687 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.185959 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.193206 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.200402 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.207614 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.214899 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.222118 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.229332 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.236563 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.243806 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.251050 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.258285 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.265471 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.272692 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.279998 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.287151 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.294461 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.301695 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.308892 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.316144 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.323376 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.330585 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.337884 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.345098 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.352285 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.359539 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.366760 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.374038 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.381829 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.388471 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.395700 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
13:15:40.402964 IP 192.168.1.7.53698 > 224.0.0.56.46808: UDP, length 1292
(...)


Some info:

pulseaudio -vvvvv says nothing interesting at all when enabling RTP.

[root@tachychineta shapeshifter]# uname -a
Linux tachychineta 3.1.5-1-ARCH #1 SMP PREEMPT Sun Dec 11 06:26:14 UTC 2011 i686 Intel(R) Core(TM)2 CPU T5600 @ 1.83GHz GenuineIntel GNU/Linux

[root@tachychineta shapeshifter]# pacman -Qi $(pacman -Qq | grep pulse) | grep -e "Name" -e "Version"
Name           : libcanberra-pulse
Version        : 0.28-2
Name           : libpulse
Version        : 1.1-2
Name           : pulseaudio
Version        : 1.1-2
Name           : pulseaudio-alsa
Version        : 1-2
Name           : pulseaudio-equalizer-bzr
Version        : 4-4

[root@tachychineta shapeshifter]# grep -v "^#" /etc/pulse/default.pa | grep -v "^$"
.nofail
.fail
load-module module-device-restore
load-module module-stream-restore
load-module module-card-restore
load-module module-augment-properties
.ifexists module-udev-detect.so
load-module module-udev-detect
.else
load-module module-detect
.endif
.ifexists module-jackdbus-detect.so
.nofail
.fail
.endif
.ifexists module-bluetooth-discover.so
load-module module-bluetooth-discover
.endif
.ifexists module-esound-protocol-unix.so
load-module module-esound-protocol-unix
.endif
load-module module-native-protocol-unix
.ifexists module-gconf.so
.nofail
load-module module-gconf
.fail
.endif
load-module module-default-device-restore
load-module module-rescue-streams
load-module module-always-sink
load-module module-intended-roles
load-module module-suspend-on-idle
.ifexists module-console-kit.so
.nofail
load-module module-console-kit
.fail
.endif
load-module module-position-event-sounds
load-module module-cork-music-on-phone
load-module module-filter-heuristics
load-module module-filter-apply
.ifexists module-dbus-protocol.so
load-module module-dbus-protocol
.endif