On Wed, 25 Mar 2015 11:01:57 +0200 Martin T <m4rtntns@xxxxxxxxx> wrote: > Hi, > > I have a network topology where in "Dell PE860" runs a Linux virtual-switch br0: > > http://s24.postimg.org/j1un2gs9h/virtual_bridge.png > > Now if I send an Ethernet frame to broadcast address from "IBM ThinkCentre": > > 17:10:23.569021 00:a1:ff:01:02:05 > ff:ff:ff:ff:ff:ff, ethertype IPv4 > (0x0800), length 34: 127.0.0.1 > 127.0.0.1: ip-proto-0 0 > > ..then I see this frame in both virtual-machines as I should. If I > send an Ethernet frame to MAC address which is not known in br0 MAC > address table, then the br0 also behaves correctly and floods the > frame to all ports expect to one where the frame came in(eth1 in this > example). However, if I send a multicast frame from "IBM ThinkCentre": > > 17:17:05.513283 00:a1:ff:01:02:05 > 01:33:44:55:66:77, ethertype IPv4 > (0x0800), length 34: 127.0.0.1 > 127.0.0.1: ip-proto-0 0 > > ..then for some reason Linux virtual-switch does not flood it to all > the ports(except the one where the frame came in from). Why is that > so? I would expect that switch handles multicast frames exactly like > broadcast frames. > > > thanks, > Martin Linux bridge does IGMP snooping (by default). Therefore you need an application that uses IGMP advertisements or manually disable this via sysfs.
