[ovs-dev] Support for MCAST_Snooping

[Flavio Leitner]

On Tue, Dec 09, 2014 at 06:49:36PM +0530, Aman Kumar wrote:
> Now i got why ovs2 is not able to snoop the vm1's(running on ovs1) igmp
> request, it's because action for patch-tun is not normal.
> 
> But for action= NORMAL ovs is not sending the igmp report (or any packet)
> to patch-tun. Port patch-tun is on bridge br-int and it's connected to
> bridge br-tun(on same ovs).
> ovs does not have learning capacity for the port patch-tun, so can you
> implement and fix this issue for the next release of ovs, so that ovs can
> also learn the port which is connected to another bridge.

Why would one forward a IGMP Report? It's meant to say to the local
bridge that there is a host interested in receiving multicast traffic.
The only reason I see is to enable sending multicast traffic through
a port that doesn't have a host behind.  For that there is the port's
option mcast-snooping-flood=true.  Once you enable that on a port, all
multicast traffic (but not Reports) will be sent over that port and the
other side is free to decide what to do with them (snooping or not).

ovs-vsctl set Port <port> other_config:mcast-snooping-flood=true

Notice that you need to do that in both ends for tunnel/patch ports
and in your case in the intermediate tunnel/patch ports too.

If the above is correct, check the packet's TTL.

fbl


> Please refer diagram mailed by me on  10:28pm 8th dec (GMT + 5:30)
> 
> On Tue, Dec 9, 2014 at 6:34 PM, Aman Kumar <amank3107 at gmail.com> wrote:
> 
> > Hi,
> >
> >     It is a openstack setup that we are using. To be more clear with the
> > configuration:
> >
> >      -> we have set  *mcast_snooping_enable=true* on *br-int* of OVS on
> > both the compute nodes.
> >
> >      -> *mcast-snooping-flood=true *for *Patch-tun* port of br-int on
> > both compute nodes ( so that the multicast traffic reaches the compute node
> > 2 via br-tun through patch-tun).
> >
> > we can see that the igmp membership report is recieved on *br-int* (via
> > patch-tun) of compute node 2 ,which may be sent via vm1 or vm2( Acting as
> > Recievers) .Flows on* br-int *of the compute nodes have "*normal*"
> > action. An *mdb/show* on the first compute node shows that the packets
> > have been snooped. The same is not true for the second compute node. Is
> > there something amiss here?
> >
> > On Tue, Dec 9, 2014 at 9:51 AM, Neethi Shashidhar <neethi209 at gmail.com>
> > wrote:
> >
> >> Hi,
> >>
> >>     It is a openstack setup that we are using. To be more clear with the
> >> configuration:
> >>
> >>      -> we have set  *mcast_snooping_enable=true* on *br-int* of OVS on
> >> both the compute nodes.
> >>
> >>      -> *mcast-snooping-flood=true *for *Patch-tun* port of br-int on
> >> both compute nodes ( so that the multicast traffic reaches the compute node
> >> 2 via br-tun).
> >>
> >> we can see that the igmp membership report is recieved on *br-int* (via
> >> br-tun) of compute node 2 ,which may be sent via vm1 or vm2( Acting as
> >> Recievers) .Flows on* br-int *of the compute nodes have "*normal*"
> >> action. An *mdb/show* on the first compute node shows that the packets
> >> have been snooped. The same is not true for the second compute node. Is
> >> there something amiss here?
> >>
> >> Regards,
> >> Neethi
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >> On Tue, Dec 9, 2014 at 1:04 AM, Flavio Leitner <fbl at redhat.com> wrote:
> >>
> >>> On Mon, Dec 08, 2014 at 10:28:14PM +0530, Aman Kumar wrote:
> >>> > Hi all,
> >>> >
> >>> > Thanks again, because of your help it is working fine but i have a
> >>> problem
> >>> > with 2 compute nodes(each one is having different OVS),
> >>> > below is the complete scenario.
> >>> > [image: Inline image 1]
> >>> >
> >>> > Here, when receiver VM1 sends IGMP v2 reports, it reaches to OVS2 also
> >>> but
> >>> > only OVS1 is able to Snoops that but OVS2 is not able to snoop.
> >>> > So, Now my question is that does ovs snoops only to those ports which
> >>> is
> >>> > connected to host?
> >>> > Can't it snoop the other port which is not connected to host but IGMP
> >>> > report is coming from there?
> >>> > here br-tun and br-int is bridges on ovs, i have enabled the snooping
> >>> on
> >>> > br-int
> >>>
> >>> I am confused with your problem description.  If you configured the
> >>> port as multicast flood port or if it is a multicast router port, then
> >>> the bridge will not learn any Report coming there because they are
> >>> automatically used to send multicast packets anyway.  Flood ports are
> >>> configured by the admin.  The mcast router port is automatically set
> >>> when a Query is received (you can check in the mdb).
> >>>
> >>> Other than that, the bridge should snoop any packet passing through it
> >>> using the action NORMAL regardless if it's connected to a host or not.
> >>>
> >>> fbl
> >>>
> >>>
> >>>
> >>
> >