Regression in vr - not receiveing multicast

Pyun YongHyeon pyunyh at
Tue Dec 9 04:08:58 PST 2008

On Tue, Dec 09, 2008 at 10:40:17AM +0100, Goran Lowkrantz wrote:
 > Hi,
 > in July, vr had this problem and was fixed:
 > <>
 > <>
 > but now it's back again!

There was just one bug fix since then and I guess the fix is not
related with your issue.

 > On a system with the following:
 > 7.1-PRERELEASE FreeBSD 7.1-PRERELEASE #3: Thu Oct 16 12:31:04 UTC 2008
 > I have to set all vr interfaces in promisc to get routing info.
 > Using Quagga
 > # pkg_info -Ix uagga
 > quagga-0.99.10_3    Free RIPv1, RIPv2, OSPFv2, BGP4, IS-IS route software
 > on an inner network using RIPv2
 > # ifmcstat -i vr0
 > vr0:
 > 	inet
 > 		group
 > 			igmpv2
 > 			mcast-macaddr 01:00:5e:00:00:09 refcnt 1
 > 		group
 > 			mcast-macaddr 01:00:5e:00:00:01 refcnt 1
 > On the same box, we have some em devices also and they work without any 
 > problems.

There is fundamental differences between em(4) and vr(4). The
vr(4) for VT6105M takes advantage of perfect multicast filtering
feature which is not present on all em(4) interface. Perfect
multicast filtering can reduce unwanted multicast traffics such
that it could save a lot of CPU cycles. The downside is that vr(4)
cannot accept multicast frames for a multicast group without
joining the multicast group first.
For multicast routing purpose I guess 'options MROUTING' kernel
option should be enabled to accept all multicast frames.
Does your kernel have that option?

 > Let me know what I can do to help fix this.
 > /glz

Pyun YongHyeon

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