[ovs-discuss] IGMP packets dropped

O'Reilly, Darragh darragh.oreilly at hpe.com
Tue Apr 26 16:43:38 UTC 2016


We have an application that we need to be able to restart quickly. It listens on a multicast address, so a restart causes IGMPv3 leave packets to be sent and join packets soon after. OVS250 receives the leave packet and removes the entry from the mdb, but ignores the join and the entry does not get re-added. It works if there is a 10 second delay between stopping and starting the app. OVS241 does not have this problem.

It can be reproduced on Ubuntu 16.04 with the OVS250 from its repo.

ovs-vsctl add-br br0
ovs-vsctl set Bridge br0 mcast_snooping_enable=true
ip link set dev br0 up
ip route add dev br0

## in another terminal
watch -n 1 ovs-appctl mdb/show br0

## in another terminal
watch -n 1 ovs-dpctl dump-flows

## start/stop/start... iperf with <10sec wait between
iperf -s -u -B

After processing an IGMP, this flow is present for 10sec which drops anymore IGMPs in that time:

recirc_id(0),in_port(1),eth(src=a6:58:9a:ab:19:4a,dst=01:00:5e:00:00:16),eth_type(0x0800),ipv4(frag=no), packets:1, bytes:54, used:7.972s, actions:drop

In OVS2.4.1 the flow ends in "slow_path(action)" instead of "actions:drop"


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