Edit: I ended up using another way of sending an audio stream across the network to a remote Raspberry Pi with Pulseaudio - one that does not involve Avahi... So I lost interest in this question - don't bother answering it unless you find the problem extremely exciting. I'll leave it here anyway, in case my initial forays help anyone.
I am setting up a Rapsberry Pi as a Pulseaudio remote sink. On another host on the same LAN, 'export PULSE_SERVER="[2001:470:ca90:4:ba27:ebff:fee2:ada9]" && mplayer sound.mp3' lets me play music remotely - so far so good. It works well over IPv4 too. Client host is Debian Jessie, server host is Raspbian Jessie.
Pulseaudio works in system mode - a headless sink is one of the few cases where it is preferable. The additions to system.pa are as follow:
load-module module-native-protocol-tcp auth-ip-acl=127.0.0.1;10.4.0.0/24;2001:470:ca90:4:21b:21ff:feaa:99c9
load-module module-zeroconf-publish
I'll remove the 10.4.0.0/24 once in production - but for now I want to be able to test from any station on this subnet.
Selecting a remote Pulseaudio sink requires the server's avahi to advertise that service correctely. This is where we are now.
Locally on the server host, the Pulseaudio service seems advertised correctly:
root@hornwall:~# avahi-browse -a -t
+ eth0 IPv6 pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo PulseAudio Sound Sink local
+ eth0 IPv6 pulse@hornwall: bcm2835 ALSA Analog Stereo PulseAudio Sound Sink local
+ eth0 IPv4 pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo PulseAudio Sound Sink local
+ eth0 IPv4 pulse@hornwall: bcm2835 ALSA Analog Stereo PulseAudio Sound Sink local
+ eth0 IPv6 pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo PulseAudio Sound Source local
+ eth0 IPv4 pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo PulseAudio Sound Source local
+ eth0 IPv6 pulse@hornwall PulseAudio Sound Server local
+ eth0 IPv4 pulse@hornwall PulseAudio Sound Server local
+ eth0 IPv6 hornwall [b8:27:eb:e2:ad:a9] Workstation local
+ eth0 IPv4 hornwall [b8:27:eb:e2:ad:a9] Workstation local
But other hosts on the same network fail to see the Pulseaudio service:
root@Kitandara:/etc/pulse# avahi-browse -a -t
+ eth1 IPv6 amour Remote Disk Management local
+ eth1 IPv4 amour Remote Disk Management local
+ eth1 IPv6 amour [54:04:a6:67:9b:53] Workstation local
+ eth1 IPv6 Kitandara [00:1b:21:aa:99:c9] Workstation local
+ eth1 IPv4 amour [54:04:a6:67:9b:53] Workstation local
+ eth1 IPv4 Kitandara [00:1b:21:aa:99:c9] Workstation local
+ eth2 IPv6 Kitandara [00:1b:21:aa:99:cd] Workstation local
+ eth2 IPv4 Kitandara [00:1b:21:aa:99:cd] Workstation local
root@amour:~# avahi-browse -a -t
+ eth0 IPv6 amour Remote Disk Management local
+ eth0 IPv4 amour Remote Disk Management local
+ eth0 IPv6 amour [54:04:a6:67:9b:53] Workstation local
+ eth0 IPv6 Kitandara [00:1b:21:aa:99:c9] Workstation local
+ eth0 IPv4 amour [54:04:a6:67:9b:53] Workstation local
+ eth0 IPv4 Kitandara [00:1b:21:aa:99:c9] Workstation local
root@waga:~# avahi-browse -a -t
+ eth0 IPv6 waga Remote Disk Management local
+ eth0 IPv4 waga Remote Disk Management local
+ eth0 IPv6 waga [54:04:a6:67:9b:b7] Workstation local
+ eth0 IPv4 waga [54:04:a6:67:9b:b7] Workstation local
Those three examples are other workstations. Strangely, one of them does not even see the other workstations - though I believe it to be similarly configured.
All the four hosts involved (Raspberry Pi and four standard Intel computers) are on the same Ethernet segment with no router in-between. Both IPv6 and IPv4 connectivity are fine. No iptables on either host. All those hosts have a similar Avahi configuration, using both IPv4 and IPv6 on any interface available:
root@Kitandara:/etc/pulse# grep -v ^# /etc/avahi/avahi-daemon.conf
[server]
use-ipv4=yes
use-ipv6=yes
ratelimit-interval-usec=1000000
ratelimit-burst=1000
[wide-area]
enable-wide-area=yes
[publish]
[reflector]
[rlimits]
rlimit-core=0
rlimit-data=4194304
rlimit-fsize=0
rlimit-nofile=768
rlimit-stack=4194304
rlimit-nproc=3
Well... Now I'm stuck - which way should I be prodding ?
On @grawity's suggestion, here is some insight into what goes across the ether...
Listening on the Pulseaudio sink's eth0, restarting the avahi daemon there unleashes a nice burst of the expected MDNS packets:
56 12.938605 2001:470:ca90:4:ba27:ebff:fee2:ada9 -> ff02::fb MDNS 450 Standard query 0x0000 ANY hornwall [b8:27:eb:e2:ad:a9]._workstation._tcp.local, "QM" question ANY pulse@hornwall._pulse-server._tcp.local, "QM" question
57 12.939394 10.4.0.202 -> 224.0.0.251 MDNS 430 Standard query 0x0000 ANY hornwall [b8:27:eb:e2:ad:a9]._workstation._tcp.local, "QM" question ANY pulse@hornwall._pulse-server._tcp.local, "QM" question
58 12.994690 2001:470:ca90:4:ba27:ebff:fee2:ada9 -> ff02::fb MDNS 849 Standard query 0x0000 ANY pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-source._tcp.local, "QM" question ANY pulse@hornwall: bcm2835 ALSA Analog Stereo._pulse-sink._tcp.local, "QM" question
59 12.995632 10.4.0.202 -> 224.0.0.251 MDNS 829 Standard query 0x0000 ANY pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-source._tcp.local, "QM" question ANY pulse@hornwall: bcm2835 ALSA Analog Stereo._pulse-sink._tcp.local, "QM" question
60 13.019775 2001:470:ca90:4:ba27:ebff:fee2:ada9 -> ff02::fb MDNS 652 Standard query 0x0000 ANY pulse@hornwall: bcm2835 ALSA Analog Stereo._pulse-sink._tcp.local, "QM" question ANY pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-sink._tcp.local, "QM" question
61 13.020848 10.4.0.202 -> 224.0.0.251 MDNS 632 Standard query 0x0000 ANY pulse@hornwall: bcm2835 ALSA Analog Stereo._pulse-sink._tcp.local, "QM" question ANY pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-sink._tcp.local, "QM" question
62 13.049454 2001:470:ca90:4:ba27:ebff:fee2:ada9 -> ff02::fb MDNS 738 Standard query 0x0000 ANY pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-sink._tcp.local, "QM" question
63 13.050227 10.4.0.202 -> 224.0.0.251 MDNS 718 Standard query 0x0000 ANY pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-sink._tcp.local, "QM" question
64 13.188819 2001:470:ca90:4:ba27:ebff:fee2:ada9 -> ff02::fb MDNS 450 Standard query 0x0000 ANY hornwall [b8:27:eb:e2:ad:a9]._workstation._tcp.local, "QM" question ANY pulse@hornwall._pulse-server._tcp.local, "QM" question
65 13.189735 10.4.0.202 -> 224.0.0.251 MDNS 430 Standard query 0x0000 ANY hornwall [b8:27:eb:e2:ad:a9]._workstation._tcp.local, "QM" question ANY pulse@hornwall._pulse-server._tcp.local, "QM" question
66 13.245302 2001:470:ca90:4:ba27:ebff:fee2:ada9 -> ff02::fb MDNS 849 Standard query 0x0000 ANY pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-source._tcp.local, "QM" question ANY pulse@hornwall: bcm2835 ALSA Analog Stereo._pulse-sink._tcp.local, "QM" question
67 13.246325 10.4.0.202 -> 224.0.0.251 MDNS 829 Standard query 0x0000 ANY pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-source._tcp.local, "QM" question ANY pulse@hornwall: bcm2835 ALSA Analog Stereo._pulse-sink._tcp.local, "QM" question
68 13.270384 2001:470:ca90:4:ba27:ebff:fee2:ada9 -> ff02::fb MDNS 652 Standard query 0x0000 ANY pulse@hornwall: bcm2835 ALSA Analog Stereo._pulse-sink._tcp.local, "QM" question ANY pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-sink._tcp.local, "QM" question
69 13.271250 10.4.0.202 -> 224.0.0.251 MDNS 632 Standard query 0x0000 ANY pulse@hornwall: bcm2835 ALSA Analog Stereo._pulse-sink._tcp.local, "QM" question ANY pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-sink._tcp.local, "QM" question
70 13.299927 2001:470:ca90:4:ba27:ebff:fee2:ada9 -> ff02::fb MDNS 738 Standard query 0x0000 ANY pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-sink._tcp.local, "QM" question
71 13.300792 10.4.0.202 -> 224.0.0.251 MDNS 718 Standard query 0x0000 ANY pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-sink._tcp.local, "QM" question
72 13.439241 2001:470:ca90:4:ba27:ebff:fee2:ada9 -> ff02::fb MDNS 450 Standard query 0x0000 ANY hornwall [b8:27:eb:e2:ad:a9]._workstation._tcp.local, "QM" question ANY pulse@hornwall._pulse-server._tcp.local, "QM" question
73 13.440068 10.4.0.202 -> 224.0.0.251 MDNS 430 Standard query 0x0000 ANY hornwall [b8:27:eb:e2:ad:a9]._workstation._tcp.local, "QM" question ANY pulse@hornwall._pulse-server._tcp.local, "QM" question
74 13.496557 2001:470:ca90:4:ba27:ebff:fee2:ada9 -> ff02::fb MDNS 849 Standard query 0x0000 ANY pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-source._tcp.local, "QM" question ANY pulse@hornwall: bcm2835 ALSA Analog Stereo._pulse-sink._tcp.local, "QM" question
75 13.497498 10.4.0.202 -> 224.0.0.251 MDNS 829 Standard query 0x0000 ANY pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-source._tcp.local, "QM" question ANY pulse@hornwall: bcm2835 ALSA Analog Stereo._pulse-sink._tcp.local, "QM" question
76 13.521724 2001:470:ca90:4:ba27:ebff:fee2:ada9 -> ff02::fb MDNS 652 Standard query 0x0000 ANY pulse@hornwall: bcm2835 ALSA Analog Stereo._pulse-sink._tcp.local, "QM" question ANY pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-sink._tcp.local, "QM" question
77 13.522523 10.4.0.202 -> 224.0.0.251 MDNS 632 Standard query 0x0000 ANY pulse@hornwall: bcm2835 ALSA Analog Stereo._pulse-sink._tcp.local, "QM" question ANY pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-sink._tcp.local, "QM" question
78 13.551102 2001:470:ca90:4:ba27:ebff:fee2:ada9 -> ff02::fb MDNS 738 Standard query 0x0000 ANY pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-sink._tcp.local, "QM" question
79 13.551881 10.4.0.202 -> 224.0.0.251 MDNS 718 Standard query 0x0000 ANY pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-sink._tcp.local, "QM" question
80 13.640087 10.4.0.202 -> 224.0.0.251 MDNS 243 Standard query response 0x0000 TXT, cache flush PTR hornwall [b8:27:eb:e2:ad:a9]._workstation._tcp.local SRV, cache flush 0 0 9 hornwall.local AAAA, cache flush 2001:470:ca90:4:ba27:ebff:fee2:ada9 A, cache flush 10.4.0.202 PTR _workstation._tcp.local
81 13.641352 2001:470:ca90:4:ba27:ebff:fee2:ada9 -> ff02::fb MDNS 247 Standard query response 0x0000 TXT, cache flush PTR hornwall [b8:27:eb:e2:ad:a9]._workstation._tcp.local SRV, cache flush 0 0 9 hornwall.local AAAA, cache flush 2001:470:ca90:4:ba27:ebff:fee2:ada9 PTR _workstation._tcp.local
82 13.683214 10.4.0.202 -> 224.0.0.251 MDNS 394 Standard query response 0x0000 TXT, cache flush PTR pulse@hornwall._pulse-server._tcp.local SRV, cache flush 0 0 4713 hornwall.local PTR _pulse-server._tcp.local
83 13.684306 2001:470:ca90:4:ba27:ebff:fee2:ada9 -> ff02::fb MDNS 414 Standard query response 0x0000 TXT, cache flush PTR pulse@hornwall._pulse-server._tcp.local SRV, cache flush 0 0 4713 hornwall.local PTR _pulse-server._tcp.local
84 13.700770 10.4.0.202 -> 224.0.0.251 MDNS 849 Standard query response 0x0000 TXT, cache flush PTR pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-source._tcp.local SRV, cache flush 0 0 4713 hornwall.local PTR _pulse-source._tcp.local PTR pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-source._tcp.local PTR pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-source._tcp.local
85 13.702406 2001:470:ca90:4:ba27:ebff:fee2:ada9 -> ff02::fb MDNS 869 Standard query response 0x0000 TXT, cache flush PTR pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-source._tcp.local SRV, cache flush 0 0 4713 hornwall.local PTR _pulse-source._tcp.local PTR pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-source._tcp.local PTR pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-source._tcp.local
86 13.725697 10.4.0.202 -> 224.0.0.251 MDNS 643 Standard query response 0x0000 TXT, cache flush PTR pulse@hornwall: bcm2835 ALSA Analog Stereo._pulse-sink._tcp.local SRV, cache flush 0 0 4713 hornwall.local PTR _pulse-sink._tcp.local PTR pulse@hornwall: bcm2835 ALSA Analog Stereo._pulse-sink._tcp.local
87 13.727151 2001:470:ca90:4:ba27:ebff:fee2:ada9 -> ff02::fb MDNS 663 Standard query response 0x0000 TXT, cache flush PTR pulse@hornwall: bcm2835 ALSA Analog Stereo._pulse-sink._tcp.local SRV, cache flush 0 0 4713 hornwall.local PTR _pulse-sink._tcp.local PTR pulse@hornwall: bcm2835 ALSA Analog Stereo._pulse-sink._tcp.local
88 13.762306 10.4.0.202 -> 224.0.0.251 MDNS 784 Standard query response 0x0000 TXT, cache flush PTR pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-sink._tcp.local SRV, cache flush 0 0 4713 hornwall.local PTR pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-sink._tcp.local
89 13.763689 2001:470:ca90:4:ba27:ebff:fee2:ada9 -> ff02::fb MDNS 804 Standard query response 0x0000 TXT, cache flush PTR pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-sink._tcp.local SRV, cache flush 0 0 4713 hornwall.local PTR pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-sink._tcp.local
90 13.872390 10.4.0.202 -> 224.0.0.251 MDNS 187 Standard query response 0x0000 PTR, cache flush hornwall.local PTR, cache flush hornwall.local
91 13.873522 2001:470:ca90:4:ba27:ebff:fee2:ada9 -> ff02::fb MDNS 174 Standard query response 0x0000 PTR, cache flush hornwall.local
92 13.895013 10.4.0.202 -> 224.0.0.251 MDNS 93 Standard query response 0x0000 HINFO, cache flush ARMV6L LINUX
93 13.895711 2001:470:ca90:4:ba27:ebff:fee2:ada9 -> ff02::fb MDNS 113 Standard query response 0x0000 HINFO, cache flush ARMV6L LINUX
94 14.685743 10.4.0.202 -> 224.0.0.251 MDNS 243 Standard query response 0x0000 TXT, cache flush PTR hornwall [b8:27:eb:e2:ad:a9]._workstation._tcp.local SRV, cache flush 0 0 9 hornwall.local AAAA, cache flush 2001:470:ca90:4:ba27:ebff:fee2:ada9 A, cache flush 10.4.0.202 PTR _workstation._tcp.local
95 14.686990 2001:470:ca90:4:ba27:ebff:fee2:ada9 -> ff02::fb MDNS 247 Standard query response 0x0000 TXT, cache flush PTR hornwall [b8:27:eb:e2:ad:a9]._workstation._tcp.local SRV, cache flush 0 0 9 hornwall.local AAAA, cache flush 2001:470:ca90:4:ba27:ebff:fee2:ada9 PTR _workstation._tcp.local
96 14.727907 10.4.0.202 -> 224.0.0.251 MDNS 394 Standard query response 0x0000 TXT, cache flush PTR pulse@hornwall._pulse-server._tcp.local SRV, cache flush 0 0 4713 hornwall.local PTR _pulse-server._tcp.local
97 14.729184 2001:470:ca90:4:ba27:ebff:fee2:ada9 -> ff02::fb MDNS 414 Standard query response 0x0000 TXT, cache flush PTR pulse@hornwall._pulse-server._tcp.local SRV, cache flush 0 0 4713 hornwall.local PTR _pulse-server._tcp.local
98 14.745767 10.4.0.202 -> 224.0.0.251 MDNS 849 Standard query response 0x0000 TXT, cache flush PTR pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-source._tcp.local SRV, cache flush 0 0 4713 hornwall.local PTR _pulse-source._tcp.local PTR pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-source._tcp.local PTR pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-source._tcp.local
99 14.747376 2001:470:ca90:4:ba27:ebff:fee2:ada9 -> ff02::fb MDNS 869 Standard query response 0x0000 TXT, cache flush PTR pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-source._tcp.local SRV, cache flush 0 0 4713 hornwall.local PTR _pulse-source._tcp.local PTR pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-source._tcp.local PTR pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-source._tcp.local
100 14.769576 10.4.0.202 -> 224.0.0.251 MDNS 629 Standard query response 0x0000 TXT, cache flush SRV, cache flush 0 0 4713 hornwall.local PTR _pulse-sink._tcp.local PTR pulse@hornwall: bcm2835 ALSA Analog Stereo._pulse-sink._tcp.local
101 14.770904 2001:470:ca90:4:ba27:ebff:fee2:ada9 -> ff02::fb MDNS 649 Standard query response 0x0000 TXT, cache flush SRV, cache flush 0 0 4713 hornwall.local PTR _pulse-sink._tcp.local PTR pulse@hornwall: bcm2835 ALSA Analog Stereo._pulse-sink._tcp.local
102 14.807296 10.4.0.202 -> 224.0.0.251 MDNS 841 Standard query response 0x0000 TXT, cache flush PTR pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-sink._tcp.local SRV, cache flush 0 0 4713 hornwall.local PTR pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-sink._tcp.local PTR pulse@hornwall: bcm2835 ALSA Analog Stereo._pulse-sink._tcp.local
103 14.809329 2001:470:ca90:4:ba27:ebff:fee2:ada9 -> ff02::fb MDNS 861 Standard query response 0x0000 TXT, cache flush PTR pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-sink._tcp.local SRV, cache flush 0 0 4713 hornwall.local PTR pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-sink._tcp.local PTR pulse@hornwall: bcm2835 ALSA Analog Stereo._pulse-sink._tcp.local
104 15.917331 10.4.0.202 -> 224.0.0.251 MDNS 231 Standard query response 0x0000 PTR, cache flush hornwall.local A, cache flush 10.4.0.202 PTR, cache flush hornwall.local AAAA, cache flush 2001:470:ca90:4:ba27:ebff:fee2:ada9
105 15.918460 2001:470:ca90:4:ba27:ebff:fee2:ada9 -> ff02::fb MDNS 202 Standard query response 0x0000 PTR, cache flush hornwall.local AAAA, cache flush 2001:470:ca90:4:ba27:ebff:fee2:ada9
106 15.939179 10.4.0.202 -> 224.0.0.251 MDNS 93 Standard query response 0x0000 HINFO, cache flush ARMV6L LINUX
107 15.942478 2001:470:ca90:4:ba27:ebff:fee2:ada9 -> ff02::fb MDNS 113 Standard query response 0x0000 HINFO, cache flush ARMV6L LINUX
108 16.730511 10.4.0.202 -> 224.0.0.251 MDNS 243 Standard query response 0x0000 TXT, cache flush PTR hornwall [b8:27:eb:e2:ad:a9]._workstation._tcp.local SRV, cache flush 0 0 9 hornwall.local AAAA, cache flush 2001:470:ca90:4:ba27:ebff:fee2:ada9 A, cache flush 10.4.0.202 PTR _workstation._tcp.local
109 16.731652 2001:470:ca90:4:ba27:ebff:fee2:ada9 -> ff02::fb MDNS 247 Standard query response 0x0000 TXT, cache flush PTR hornwall [b8:27:eb:e2:ad:a9]._workstation._tcp.local SRV, cache flush 0 0 9 hornwall.local AAAA, cache flush 2001:470:ca90:4:ba27:ebff:fee2:ada9 PTR _workstation._tcp.local
110 16.772372 10.4.0.202 -> 224.0.0.251 MDNS 394 Standard query response 0x0000 TXT, cache flush PTR pulse@hornwall._pulse-server._tcp.local SRV, cache flush 0 0 4713 hornwall.local PTR _pulse-server._tcp.local
111 16.773610 2001:470:ca90:4:ba27:ebff:fee2:ada9 -> ff02::fb MDNS 414 Standard query response 0x0000 TXT, cache flush PTR pulse@hornwall._pulse-server._tcp.local SRV, cache flush 0 0 4713 hornwall.local PTR _pulse-server._tcp.local
112 16.789610 10.4.0.202 -> 224.0.0.251 MDNS 835 Standard query response 0x0000 TXT, cache flush SRV, cache flush 0 0 4713 hornwall.local PTR _pulse-source._tcp.local PTR pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-source._tcp.local PTR pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-source._tcp.local
113 16.791221 2001:470:ca90:4:ba27:ebff:fee2:ada9 -> ff02::fb MDNS 855 Standard query response 0x0000 TXT, cache flush SRV, cache flush 0 0 4713 hornwall.local PTR _pulse-source._tcp.local PTR pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-source._tcp.local PTR pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-source._tcp.local
114 16.814388 10.4.0.202 -> 224.0.0.251 MDNS 714 Standard query response 0x0000 TXT, cache flush SRV, cache flush 0 0 4713 hornwall.local PTR _pulse-sink._tcp.local PTR pulse@hornwall: bcm2835 ALSA Analog Stereo._pulse-sink._tcp.local PTR pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-source._tcp.local
115 16.815894 2001:470:ca90:4:ba27:ebff:fee2:ada9 -> ff02::fb MDNS 734 Standard query response 0x0000 TXT, cache flush SRV, cache flush 0 0 4713 hornwall.local PTR _pulse-sink._tcp.local PTR pulse@hornwall: bcm2835 ALSA Analog Stereo._pulse-sink._tcp.local PTR pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-source._tcp.local
116 16.850830 10.4.0.202 -> 224.0.0.251 MDNS 827 Standard query response 0x0000 TXT, cache flush SRV, cache flush 0 0 4713 hornwall.local PTR pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-sink._tcp.local PTR pulse@hornwall: bcm2835 ALSA Analog Stereo._pulse-sink._tcp.local
117 16.852697 2001:470:ca90:4:ba27:ebff:fee2:ada9 -> ff02::fb MDNS 847 Standard query response 0x0000 TXT, cache flush SRV, cache flush 0 0 4713 hornwall.local PTR pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-sink._tcp.local PTR pulse@hornwall: bcm2835 ALSA Analog Stereo._pulse-sink._tcp.local
118 16.891486 10.4.0.202 -> 224.0.0.251 MDNS 147 Standard query response 0x0000 PTR pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-sink._tcp.local
119 16.892429 2001:470:ca90:4:ba27:ebff:fee2:ada9 -> ff02::fb MDNS 167 Standard query response 0x0000 PTR pulse@hornwall: Sound Blaster X-Fi Go! Pro Analog Stereo._pulse-sink._tcp.local
Packets directed ff02::fb and 224.0.0.251 on port 5353 are just what should be happening in theory - so that is nice.
But meanwhile, no other station has seen anything - not a single MDNS packet.
A few moments later on a workstation:
root@amour:~# tshark -i eth0 -f "port 5353"
1 0.000000 2001:470:ca90:4:21b:21ff:feaa:99c9 -> ff02::fb MDNS 140 Standard query 0x0000 PTR _pulse-sink._tcp.local, "QM" question PTR _non-monitor._sub._pulse-source._tcp.local, "QM" question
2 0.000031 10.4.0.124 -> 224.0.0.251 MDNS 120 Standard query 0x0000 PTR _pulse-sink._tcp.local, "QM" question PTR _non-monitor._sub._pulse-source._tcp.local, "QM" question
And on the local router:
root@arua:~# tshark -i vlan4 -f "port 5353"
1 0.000000 2001:470:ca90:4:21b:21ff:feaa:99c9 -> ff02::fb MDNS 140 Standard query 0x0000 PTR _pulse-sink._tcp.local, "QM" question PTR _non-monitor._sub._pulse-source._tcp.local, "QM" question
2 0.000135 10.4.0.124 -> 224.0.0.251 MDNS 120 Standard query 0x0000 PTR _pulse-sink._tcp.local, "QM" question PTR _non-monitor._sub._pulse-source._tcp.local, "QM" question
But the Pulseaudio sink avertised here belongs to another station, not to the Raspberry pi that broadcast the large burst above. If I restart avahi on that other sink-advertising station, the correct MDNS burst is seen on both of the preceeding hosts (amour & arua)... But not on the other workstation (waga) nor on the Raspberry Pi (hornwall). This is strange because amour and waga are extremely similarly configured, though something might conceivably have diverged.
Now why doesn't any other station see the MDNS packets that the Raspberry Pi seems to be broadcasting ? Why do only two stations see the sink-advertising MDNS packets broadcast by the other station ? Can there be misconfiguration on the receiving side ?
