[pve-devel] corosync, multicast problem because of vmbr multicast_snooping enabled

Alexandre DERUMIER aderumier at odiso.com
Sun Mar 3 18:11:41 CET 2013

Also, I use corosync in my vms for some virtuals cluster, and I also have problems because of vmbrX igmp_snooping

I also found a redhat bugzilla about it here:


----- Mail original ----- 

De: "Alexandre DERUMIER" <aderumier at odiso.com> 
À: pve-devel at pve.proxmox.com 
Envoyé: Dimanche 3 Mars 2013 18:02:15 
Objet: [pve-devel] corosync, multicast problem because of vmbr multicast_snooping enabled 


I had worked on a problem this week, 

Since some month, I have corosync random failures. 
Thanks to omping, I had check the multicast layer, and it seem that sometime it's hanging. 

Also, I have had a strange thing, shutdown down a node had killed multicast between all my others nodes .... 

I had found article here: 

Telling that multicast_snooping on bridge can lead to problems. 
(Multicast snooping is used to filter multicast, listen igmp packet to create groups, and avoid to send multicast to all ports). 

I don't known how exactly it's works with linux bridge, But as my proxmox host ip is on vmbr0 (the default proxmox setup), 

echo 0 > /sys/class/net/vmbr0/bridge/multicast_snooping 

has resolved all my problems. 

I'm not sure, but I think we should disable multicast_snooping by default. (Don't known if it can cause regression ?) 

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