Repeated logs for entered/left allmulticast mode

Installing and Using OpenWrt
1

I just observed some repeated logs with dmesg on two of my OpenWRT devices running the latest 24.10.0. One is an Edgerouter-X, the other one an X86-based router (APU2C4), so different CPU arch and network drivers. The repeated logs look like:

[  255.296109] igb 0000:03:00.0 eth2: left allmulticast mode
[  255.413475] igb 0000:03:00.0 eth2: entered allmulticast mode
[  260.910925] igb 0000:03:00.0 eth2: left allmulticast mode
[  261.033485] igb 0000:03:00.0 eth2: entered allmulticast mode
[  261.073369] igb 0000:02:00.0 eth1: entered allmulticast mode
[  265.787921] igb 0000:03:00.0 eth2: left allmulticast mode
[  265.903506] igb 0000:03:00.0 eth2: entered allmulticast mode
[  265.909623] igb 0000:02:00.0 eth1: left allmulticast mode
[  266.073469] igb 0000:02:00.0 eth1: entered allmulticast mode
[  561.576850] igb 0000:03:00.0 eth2: left allmulticast mode
[  561.718932] igb 0000:03:00.0 eth2: entered allmulticast mode
[  561.724991] igb 0000:02:00.0 eth1: left allmulticast mode
[  561.818923] igb 0000:02:00.0 eth1: entered allmulticast mode

Same logs on Edgerouter-X with a different network driver.

Every 5 mins or so, all network interfaces seem to repeat the same left/entered allmulticast mode for no obvious reason. Network traffic does not seem impacted. Should I be worried? What could be causing those up/downs? Any advice appreciated, thanks!

2

Same to me

[   36.203235] br-lan: entered allmulticast mode
[   36.249380] br-lan: left allmulticast mode
[   36.367259] br-lan: entered allmulticast mode
[   40.962047] br-lan: left allmulticast mode
[   41.111655] br-lan: entered allmulticast mode
[ 3510.556749] br-lan: left allmulticast mode
[ 3510.701014] br-lan: entered allmulticast mode
[ 3611.578967] br-lan: left allmulticast mode
[ 3611.745631] br-lan: entered allmulticast mode
[42924.393607] br-lan: left allmulticast mode
[42927.151144] br-lan: entered allmulticast mode
[45136.328481] br-lan: left allmulticast mode
[45136.607559] br-lan: entered allmulticast mode
[45145.789253] br-lan: left allmulticast mode
[45788.614113] br-lan: entered allmulticast mode
[46570.695057] br-lan: left allmulticast mode
[46570.962996] br-lan: entered allmulticast mode
[46578.993948] br-lan: left allmulticast mode
[47549.909984] br-lan: entered allmulticast mode
[47988.934290] br-lan: left allmulticast mode
[47989.184200] br-lan: entered allmulticast mode
[69249.520609] br-lan: left allmulticast mode
[69252.122961] br-lan: entered allmulticast mode
[73591.762876] br-lan: left allmulticast mode
[73594.341932] br-lan: entered allmulticast mode
[73893.031034] br-lan: left allmulticast mode
[73893.331107] br-lan: entered allmulticast mode
[74925.932119] br-lan: left allmulticast mode
[74928.548648] br-lan: entered allmulticast mode
[75070.718983] br-lan: left allmulticast mode
[75070.982822] br-lan: entered allmulticast mode
[76229.397129] br-lan: left allmulticast mode
[76229.666824] br-lan: entered allmulticast mode
[76717.499711] br-lan: left allmulticast mode
[76717.793889] br-lan: entered allmulticast mode
[140012.819307] br-lan: left allmulticast mode
[140012.922146] br-lan: entered allmulticast mode
[141226.700293] br-lan: left allmulticast mode
[141226.813893] br-lan: entered allmulticast mode
3

At last I am not the only one :slight_smile:
Since I get the same behaviour no matter what router I use, I am starting to suspect something from my ISP (SFR). Do you have the same ISP by any chance?

4

The issue creeped up with 24.10 version. It doesn't appear so often in 24.10.1, don't know about 24.10.2 as I didn't try it yet.

nitroshift

5

Issue still present on 24.10.2. Testing on a Raspberry Pi 5 with PCI card, I can see both the native Ethernet and the PCI one logging every 5 minutes:

[ 9877.776220] macb 1f00100000.ethernet eth0: left allmulticast mode
[ 9877.910231] macb 1f00100000.ethernet eth0: entered allmulticast mode
[10181.668092] igc 0000:03:00.0 eth1: left allmulticast mode
[10181.760911] igc 0000:03:00.0 eth1: entered allmulticast mode
6

Thanks for confirming. We can rule out the ISP being the culprit since we live in different countries.

LE: Also found the fix: https://github.com/openwrt/openwrt/pull/18769

nitroshift

7

You sure about that fix? The issue you pointed to refers to a bug in the Realtek 83xx driver. I have those logs on a raspberry pi which has no Realtek hardware, in this case: the default RPi ethernet and an Intel i-226 on PCI bus.
Or maybe the bug comes from another device on my LAN running a Realtek NIC? Happy to know more :slight_smile:

8

I observe the same behavior on an x86 box with exclusively Intel e1000e-driven NICs. (But I do have an OpenWrt-powered switch feat. RTL8380M on the other end of the all-multicast-flapping port. Hmmm...)

9

Since I can't get to the bottom of this, as a workaround I installed igmpproxy package and after configuring it my system log is now clean.

nitroshift

10

Confirmed here: installing igmpproxy suppressed the logs. Thanks for sharing this workaround!

11

For what it’s worth: I just changed ISPs and took the opportunity to check the logs on a fresh new router running vanilla 24.10.2 (without igmpproxy). The multicast warnings were still present with the previous ISP, they disappeared with the new one. I suspect the previous ISP is blasting TV traffic on multicast UDP.

1 Like
12

Y'all are aware this message means a LAN device(or something) is trying to request a multicast, correct?

13

Weird. I have three OpenWRT devices on my LAN and the only one with those logs is the ISP-facing one. Any ideas how to trace the originator of those requests maybe?