[ovs-discuss] multicast GRE tunnel problems

[Mike Wray]

I'm trying to use openvswitch to bridge multicast GRE tunnels, but I can't
get it to work. This is my first go at using openvswitch, so I may be doing
something wrong.

*) First try: create GRE tunnels using standard linux commands on hosts A and B.

Host A:
ip tunnel add vtun2 mode gre remote 224.10.0.1 local 192.168.1.10 key 2
ifconfig vtun2 10.2.0.10/16

Host B:
ip tunnel add vtun2 mode gre remote 224.10.0.1 local 192.168.1.11 key 2
ifconfig vtun2 10.2.0.11/16

On B ping 10.2.0.10 works, and on A ping 10.2.0.11 does too. So the
tunnel is up. Now move one end of the tunnel onto a bridge:

Host A:
ifconfig vtun2 0.0.0.0
ovs-vsctl add-br vbr2
ovs-vsctl add-port vbr2 vtun2
ifconfig vbr2 10.2.0.10/16

Ping from B no longer works. Using tcpdump I can see GRE packets
coming into A on eth0 and I can see ARP requests coming out of vtun2,
but no replies, and no traffic going over vbr2.

*) Second try. Use an openvswitch GRE port. On host A clear everything up,
rmmod ip_gre and start again. Leave host B as-is.

Host A:
INTF=$(ovs-vsctl create interface name=vtun2 type=gre 
options="local_ip=192.168.1.10,remote_ip=224.10.0.1,key=2")
PORT=$(ovs-vsctl create port name=vtun2 interfaces=[${INTF}] )
ovs-vsctl add-br vbr2
ovs-vsctl add bridge vbr2 ports ${PORT}
ifconfig vbr2 10.2.0.10/16

Ping from B doesn't work. Using tcpdump I see GRE packets (ARP)
coming into A on eth0, but nothing on vbr2.
Doing ping from A I see GRE packets (ARP) coming into B on eth0,
but tcpdump on vtun2 shows strange stuff with ethertype 0x6558.
So there might be an interoperability problem.

*) Third try. Use openvswitch GRE ports at both ends.
Leave A as-is, setup GRE using ovs-vsctl on B.
Ping from B doesn't work. I see GRE packets (ARP) going out eth0 on B
and coming in eth0 on A but nothing on the vbr2 bridge.

Did I set something up wrong or is there some other problem?

Thanks,

Mike