@librecast I was asked what supporting F = 0 means from the CHANGELOG.
You've heard me say that when a tree 
falls in a #multicast forest and no one is listening, no data is sent?
Now imagine there was no tree! 
In #RaptorQ, F is the size of the object we are encoding. F = 0 means we are encoding no data. This is completely valid under RFC6330. F must be non-negative, but it can be zero.
So, @schenklradio wäre jetzt testweise auch mal im @ffhl per #multicast mit @videolan verfügbar. @tokudan: vll. könnte das ja eine kleine Motivation sein, um mal multicast routing zwischen @ffhl und @FreifunkHamburg einzurichten :-)?
Remember, when a tree falls in a #multicast forest, and no one is listening, no data is sent.
Was hier in Lübeck mit @ffhl auch geht: Am Strand das einzig wahre #vibe_coding, mit Mate, Musik per #multicast aus dem #MeshNetzwerk vom mobilen LTE Freifunk Knoten mit @videolan hören und per #MPD für alle moderieren :D.
Die Bilder wurden bequem und lokal fix ohne Volumenbelastung via #Syncthing vom Handy auf den Laptop kopiert, auch dank der #multicast basierten #LocalPeerDiscovery von Syncthing, die hier bei uns im @ffhl geht.
@ffhl @videolan die technische Hintergrund der neuen Streams:
Statt #IPv6 / UDP / #RTP / #Opus. Ist es jetzt: IPv6 / UDP / #MPEG2TS / RTP / Opus.
Es ist also noch ein gaaanz toller (Sarkasmus), proprietärer, unnötiger Protokollheader dazwischen gekommen, der nur das Paket aufbläht. VLC v3 kann aber noch nicht das #IETF #RFC standardisierte, native RTP-Opus, das kann erst der nightly/v4.
Sobald VLC endlich mal releasen sollte, schmeiß ich das MPEG-TS auch ganz schnell wieder weg.
Die #Multicast streams im @ffhl sind jetzt zusätzlich auch mit dem @videolan v3 unter "Local Netzwork -> Network streams (SAP)" find- und abspielbar. Nur die mit "(v4)" markierten brauchen noch den #VLC v4/nightly. Den v4 nightly zum Laufen zu bekommen, schien bei vielen noch eine zu große Hürde zu sein. Würde mich sehr über Feedback freuen, ob es jetzt auch bei anderen geht im @ffhl geht.
#Multicast ist auch wieder im #Mesh aktiv. Wurde jetzt auch reboot-fest auf unseren Gateways eingerichtet.
With Alonso's "help", I merged in restricted channel support to @librecast today.
This lets a receiver set a filter on an inbound #multicast channel with a keyring and capabilities.
Any traffic arriving must be cryptographically signed and have a token signed by a key on the filter keyring, and have the required capability bits set, otherwise it is silently dropped by standard API recv calls like lc_channel_recvmsg().
yeah. :-/ Latest iOS simulators somehow can not use multicast anymore. Working fine on real device ¯\_(ツ)_/¯ `nw_browser_fail_on_dns_error_locked [B1] nw_browser_dns_service_browse_callback failed: PolicyDenied(-65570)`
#IETF RFC 9777 was released last month, replacing RFC 3810 for #Multicast Listener Discovery ( #MLD2 ).
Reviewing this, aside from a bunch of textual clarifications and fixes, the only real technical change to speak of was an adjustment to the Multicast Address Listening Interval (MALI).
I've patched #libmld and #librecast with the new timer value and the change will be included in the next release.
So, one more switch arrived, the GS1900-24E, the non-#PoE variant of the #ZyXEL switch that I got before. And without PoE it was even about half the price on #Kleinanzeigen, just 35€. I wanted to have one that I could install at our hackspace, the #Nobreakspace, for production and one for development on #multicast.
This also means that things are getting more serious now, I think I have nearly all code changes/fixes now. Will need to clean them up a bit and submit pull requests then.
In the classic, non-DSA #Linux bridge the philosophy so far is: No matter in what combination you enable/disable multicast_snooping+ multicast_querier: The bridge ensures you don't break any network protocol, it detects per protocol family if #multicast snooping is applicable. That together with #RFC4541 I think is the only way to regain trust for #IGMP / #MLD snooping imo.
And now things like #DSA or #switchdev come along with non-foolproof solutions, diverging between each driver...
@joemj sehr schöner, gut zusammefassender Beitrag. Würde höchstens noch den "neuen" Ansatz "#AirtimeFairness" hinzupacken: Dass jede Station gleichviel Sendezeit statt gleichviel "Bandbreite"/Durchsatz bekommt, wie es unter #Linux seit einer Weile mehrere #WLAN Treiber machen. Das sollte den letzten Punkt am Ende bzgl. Nachteile von #multicast-to-unicast stark abschwächen.
Auch in #ForwardErrorCorrection durch zB #RaptorQ für #RTP streams sehe ich große Chancen und es geht schon mit @gstreamer
for the former case it is broken when you have devices/listeners with #IGMP v1/v2 or #MLD v1, instead of IGMPv3 / MLDv2. The issue you'll then potentially run into is IGMP / MLD report suppression. The big thing which #RFC4541 specifies an ugly workaround for... this whole report suppression has lead to so many hard to debug, subtle breakages for decades and now seems to continue with #Linux #DSA / #switchdev...
#multicast #igmpsnooping #mldsnooping
and Jan's reply on the #OpenWrt forum also lead me to this observation, that several #switchdev drivers seem to try to emulate a multicast router port by mirroring all known #multicast listener entries onto these mc router ports... https://patchwork.ozlabs.org/project/openwrt/cover/20230303214846.410414-1-jan@3e8.eu/#3074983
Which makes me scream, this is broken in so many scenarios... like when you use multiple #IGMP / #MLD snooping switches. Or if you don't have a listener for that group, only a sender, whose packets still need to go to multicast routers.
on the other hand, unfortunately, it seems that #DSA in #Linux (and by that this downstream #rtl83xx driver) so far seems to repeat the mistakes we did in the Linux #bridge and fixed during the last decade... it's not following #RFC4541, DSA does not seem to have an option to set multicast router ports yet... which overall breaks #IGMP / #MLD snooping and by that #multicast in many scenarios... will be interesting if that is fixable or a limitation of #rtl83xx based #switch chips.
My reading for @librecast has arrived!
Much #Matrix #Mathematics and #Multicast to come! 
So, coding session 2 of trying to get #OpenWrt running on this D-Link DGS-1210-10P B1 switch (which I hoped it would before buying it for 40€ on kleinanzeigen.de - but of course only variant F1 is supported by OpenWrt...). Last time I got at least an OpenWrt initramfs booted (without any networking or flash). And still hoping that it might be #DSA capable and would do #IGMP / #MLD snooping in kernelspace with hardware #multicast forwarding support.
@skalabyrinth und wenn man die Nachrichten komplett lokal behalten möchte, dass die den PC nicht verlassen, dann nimmt man z.B. eine #IPv6 #multicast Adresse mit Interface-local scope. Z.B. "mcchat ff01::123 1234 wlp1s0". Die erste 1 in ff01::123 sagt, dass nicht raus darf. Nimmt man eine 2, z.B. ff02::123, darf es raus, aber nicht geroutet werden.
Könnte man alles bestimmt noch schöner in einem richtigen Bash Skript abstrahieren :D.
