Stephen, thanks! Once I disabled multicast snooping under /sys/devices/virtual/net/br0/bridge/multicast_snooping, then bridge started to forward multicast Ethernet frames. Martin On 3/25/15, Stephen Hemminger <stephen@xxxxxxxxxxxxxxxxxx> wrote: > 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. >
