I am running a LXC container, which has a veth type interface (if_veth), linked with a bridge (if_bridge) which is in the host(outside of the container). When I sent multicast packets (UDP) from if_bridge, I could observe ethernet frames from if_veth, when I capture the packets with Wireshark. However, if I listen the if_veth interface, by opening a UDP socket, I could not observe the multicast packets. So I think multicast packets are dropped.
Unicast is OK, routing entries in the host machine is OK. Additionally only multicast address which could be received is 220.127.116.11, which is interesting.
I checked for the root cause,
- netstat -u -s output in the LXC container
InCsumErrors are more than 0.
- I observe skb:kfree_skb events excessively, when I checked “perf” tool output.
I am using CentOS8 kernel 4.18, LXC version 1.0.11