[Verizon Galaxy Note 3 Q&A, Help & Troubleshooting] bftb0:
I ran a different multicast experiment yesterday.

I moved both the multicast source and the receiver so that they were both on the the same WiFi segment (with the N3 connected to the same AP/SSID). I did this mostly to try to pump up the traffic rate. (The way I did it in the first trial, the sender was on one subnet, and multicasts had to traverse *two* ancient routers to get to the receiver along a wired path. I was having a significant throughput issues of unknown origin - maybe because the sender was in a VM, or maybe because "mint" sends all it's packets per second in an immediate burst instead of pacing them). In that trial, I couldn't do much better than 40 kbps.

The best I could do with both sender/receiver on the same WiFi segment was with the sender emitting about 1 Mbit/sec of traffic, and the receiver successfully getting about 0.7 Mbit/sec of multicast traffic. So anyway, this meant that the N3 would be sitting there (passively) listening to about 1.7 Mbit/sec of radio traffic most all of which was multicast.

I ran this way for about 3 hours, and the N3 lost 6% of battery (Airplane mode, but WiFi on) - 2%/hr. That is substantially more than when my home WiFi network is quiet, but still nowhere as bad as you are seeing. I also had a WiFi-only Nexus 7 tab sitting there the same way, and it lost a similar amount of battery. I didn't see any evidence that the N3 was "staying awake" at that time.

So, I don't know what to make of it. It sounds sort of reasonable, but the question is - why 3 watts of power dissipation? (For comparison, the PA - Power Amplifier - chips at the front end of cell radio transmitters are usually spec'ed to max out around 2W - and everybody knows how fast a cell phone will drain if it is left on in a zero-service area, or how much shorter "talk time" is than standby time - and your device seems to be using even more power than that!) I certainly believe you are experiencing exactly the symptoms that you describe. But it also does sort of sound like it is something a bit more subtle than just simply "is multicast in use?" - probably it is also something specific about the way your employer's network is utilized or configured or the exact nature of the traffic in use. (Some protocols are incredibly noisy when it comes to broadcasts - the old Novell netware comes to mind)

In IPv4 multicast the destination MAC address can be either individual hosts' MACs or a MAC constructed from a IANA prefix plus a slightly-ambiguous mapping of the IPv4 group multicast address. Interestingly, the Wikipedia page for "IP multicast" makes this comment:

and then goes on to describe circumstances (dumb switches or dumb routers that don't understand IGMP) how multicast can lead to traffic flooding.

I asked about an App on your phone because there was the possibility that you were using a BYOD device with an institution-supplied App (that might be a multicast receiver).

Anyway, I can't help you get Samsung/Google's attention; about the only way I know that I can help personally is the following: I recently built tcpdump for ARM (tcpdump-4.5.1 plus libpcap-1.5.2) - I can provide it for you via PM if you want a copy (let me know). You'll have to run it from a terminal emulator (as root I suppose). But by doing that, you can capture the output to a file (tcpdump -i wlan0 -s 1600 -w packet_logfile.pkts) and then move that file afterwards to a honest-to-goodness computer and look at the packet capture using Wireshark. I tried this last night with a small sample, and it seems to work correctly. (In my experience, trying to use a Android device for reviewing massive amounts of data - like packet logs - is a horrible experience; you can't see the forest for the trees.)

Note: I don't know if the WiFi radio in the N3 can be operated in "monitor" mode... meaning that you might only see traffic that the radio is collecting based on it's own MAC plus however it deals with multicast... but that latter condition might just be exactly what you need to figure out what exactly is going on.

$.02