I feel bad for derailing the switch debate now, as you were, kettle boiling!
I was enjoying it… supping my cup of tea here listening to a rather enjoyable recording of Eric Lu playing the piano… Chopin I think.
Playing with language is so much more fun that another debate about bloody switches. Pins in eyes…
Googling shows this:
Internet Group Management Protocol ( IGMP ; Defined in RFC 1112 ) is a protocol that allows a host to advertise its multicast group membership to neighboring switches and routers. IGMP is a standard protocol used by the TCP /IP protocol suite to achieve dynamic multicasting.
So I still do not understand how it could impact music streaming?
Not to mention there’s 3 versions of it, when will this madness end?
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That trouser / shoe combination looks dreadful. Must be an engineer.
Chinos in a rack room, I mean…
I think that’s a line from a Tom Wait’s track?
Nobody would wear chinos with black socks and shoes, not even in one of Tom’s songs. I bet they cost less than $29.
You can search back… I have written loads over the years… but in short
Multicast data is a form of data that goes from one to many hosts. The hosts can decide to join a specific group with a specific group IP address, so they can elect to receive and send data sent to that group… that is the multicast data being sent to the multicast group IP address. This group management and control uses a protocol called IGMP.
Now in order for switches and Wi-fi systems to learn which clients have elected to join a group they must listen in on these IGMP communications. This is called IGMP snooping. This will ensure that the group data is only sent to the correct devices on the switch and devices not joining a specific group are not sent or bombarded with another group’s data causing unnecessary processing and noise in connected devices.
Now cheaper consumer switches don’t often support these higher level functions, and simply broadcast out the multicast traffic to everyone irrespective of what groups the hosts wish to belong to… it all works still, but at the expense of reduced network efficiency and increased processing noise on all hosts not belonging to specific multicast groups … as they have to process the data to then decide they need to discard.
In audio devices on a network we want to reduce unnecessary processing load so as to reduce electrical noise / ground plane modulation in the host system.
Multicast data can be used IoT devices, home automation, status updates, broadcast IPTV, discovery etc. Clearly the benefit of IGMP snooping will depend what is happening on your home network.
I hope that helps.
But music streaming is using TCP or unicast? For example ROON is using RAAT, which is really TCP/IP, am I wrong?
My Linn ADSM can deal with both multicast and unicast (default is unicast), but it does not care regardless whether the music is being broadcast’ed or multicast’ed as long as the stream is good?
Anyway, thanks Simon for taking your time in explaining stuffs.
Yes media transfer uses unicast in UPnP … but we are talking about multicast traffic that exists on your LAN that might be nothing to do with your audio applications.
But even UPnP DLNA uses multicast for discovery and update messages… it uses the multicast IP group address 239.255.255.250.
From memory Roon uses two multicast group addresses of its own… possibly for discovery and status update.
However the point is about the streamer having to process to then discard somebody else’s group data. With a switch supporting IGMP snooping this should be prevented.
OK, so IGMP and multcasting stuffs do not really impact the SQ? All I am really concerned is a good stream of UDP packets being delivered (ie no random packets dropped or out of sequence packets) and how my streamers deal with them. In that sense, I think the ER or a good [Cisco] switch can be useful.
You might have mis typed… the point is multicast group data that is processed unnecessarily by a streamer will add noise…Ethernet noise and processing noise. If you believe or experience switches and Ethernet cables changing the SQ on your streamer, then processing in appropriate data sent to you will affect SQ too.
If you feel Ethernet cables and switches make no difference, and possibly WAV sounds the same and FLAC it is unlikely you will notice a SQ benefit in IGMP snooping… assuming there is other active multicast group data on your LAN.
BTW yes multicast uses UDP datagrams… but these are typically short messages, unless media is transferred, but most home audio applications (UPnP/DLNA/Roon) use regular TCP and flow control for media.
You are unlikely to drop UDP on ethernet LAN, but may be dropped in poor conditions on Wi-fi…possibly illustrated whete if you have a very weak or busy Wi-fi, discovery may take longer to work on the Naim app.
Now, I see your point, apart from the point-to–point unicast streaming between a source and the end-point (which is my streamer), there may be a whole lot of all kinds of multicast packets being sent to my streamer unnecessarily if the switch or router does not do the proper multicasting, meaning it does broadcast instead.
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Picking this up late due to travelling, I think poppycock is better - if only because it is more succinct, being usable as a one-word response.
Of course, you might say codswallop to that…
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Better late than never…
You missed the snooping alas.
Yes you actually need a switch. Like hifi, network gear is not magic, and there’s average-to-bad gear, and good-to-great gear.
Ubiquiti when set up properly, is my go-to. It’s a bit pro-sumer and takes a while to get your head around.
If you’re after a decent consumer-level good then Netgear Orbi works well. The 50 series usually does a great job. Sometimes there’s a need for an extra satellite, but it’s a well-thought out product.