missing multicast traffic

[eowiin]

Hi everyone,

I'm currently working on a VM on proxmox 7.1-7 and have some issues with multicast traffic
i created a VM, with a network attached to it, on VM side it's eth2, on Host side it's eno4 and vmbr2.
If i make a tcpdump on host i see a lot of multicast traffic, but if i make the same inside VM, i don't have same traffic.

e.g : this on host "tcpdump -i eno dst 232.208.0.78" find traffic but "tcpdump -i eth2 dst 232.208.0.78" don't find anything.

i think problem is around the configuration of vmbr2, but i don't find it ...

Thanks in advance.

 

[Chris]

Hi everyone,

I'm currently working on a VM on proxmox 7.1-7 and have some issues with multicast traffic
i created a VM, with a network attached to it, on VM side it's eth2, on Host side it's eno4 and vmbr2.
If i make a tcpdump on host i see a lot of multicast traffic, but if i make the same inside VM, i don't have same traffic.

e.g : this on host "tcpdump -i eno dst 232.208.0.78" find traffic but "tcpdump -i eth2 dst 232.208.0.78" don't find anything.

i think problem is around the configuration of vmbr2, but i don't find it ...

Thanks in advance.

Hi,
do you have ip forwarding enabled? Please post the output of cat /etc/network/interfaces and ip route.

There is an example for a routed setup in the docs which you could use as reference, see https://pve.proxmox.com/pve-docs/pve-admin-guide.html#sysadmin_network_configuration

Edit: did you also setup the routes for multicast routing?

 

[eowiin]

Hi,
do you have ip forwarding enabled? Please post the output of cat /etc/network/interfaces and ip route.

There is an example for a routed setup in the docs which you could use as reference, see https://pve.proxmox.com/pve-docs/pve-admin-guide.html#sysadmin_network_configuration

Edit: did you also setup the routes for multicast routing?

Hi Chris,

here is the content of "etc/network/interface"

auto lo
iface lo inet loopback

iface eno1 inet manual

iface eno2 inet manual

iface eno3 inet manual

iface eno4 inet manual

auto vmbr0
iface vmbr0 inet static
        address 192.168.68.235/24
        gateway 192.168.68.4
        bridge-ports eno1
        bridge-stp off
        bridge-fd 0

auto vmbr1
iface vmbr1 inet manual
        bridge-ports eno2
        bridge-stp off
        bridge-fd 0

auto vmbr3
iface vmbr3 inet manual
        bridge-ports eno3
        bridge-stp off
        bridge-fd 0
#PAL2 10.17.2

auto vmbr2
iface vmbr2 inet manual
        bridge-ports eno4
        bridge-stp off
        bridge-fd 0

I think i'm missing something, in my case all traffic from eno4 should be forward on my vm on eth2 ? without any routing

 

[Chris]

Hi Chris,

here is the content of "etc/network/interface"

auto lo
iface lo inet loopback

iface eno1 inet manual

iface eno2 inet manual

iface eno3 inet manual

iface eno4 inet manual

auto vmbr0
iface vmbr0 inet static
        address 192.168.68.235/24
        gateway 192.168.68.4
        bridge-ports eno1
        bridge-stp off
        bridge-fd 0

auto vmbr1
iface vmbr1 inet manual
        bridge-ports eno2
        bridge-stp off
        bridge-fd 0

auto vmbr3
iface vmbr3 inet manual
        bridge-ports eno3
        bridge-stp off
        bridge-fd 0
#PAL2 10.17.2

auto vmbr2
iface vmbr2 inet manual
        bridge-ports eno4
        bridge-stp off
        bridge-fd 0

I think i'm missing something, in my case all traffic from eno4 should be forward on my vm on eth2 ? without any routing

Ah okay, you have attached the interface directly to the bridge as port. Can you ping the VM? Is there possibly a firewall interfering?

 

[eowiin]

Ah okay, you have attached the interface directly to the bridge as port. Can you ping the VM? Is there possibly a firewall interfering?

i can ping my VM yes, there is no firewall neither on the vm side or on proxmox.

I have 4 VM plugged on the same bridge, and they all have same problem, not all the fraffic is present.

 

[Chris]

Could it be that IGMP snooping is interfering with your multicast traffic? Is it enabled on your bridge? See https://pve.proxmox.com/wiki/Multicast_notes#Linux:_Disabling_Multicast_snooping_on_bridges

 

[eowiin]

Could it be that IGMP snooping is interfering with your multicast traffic? Is it enabled on your bridge? See https://pve.proxmox.com/wiki/Multicast_notes#Linux:_Disabling_Multicast_snooping_on_bridges

i have modified this already in order to get multicast traffic on it

cat /sys/class/net/vmbr2/bridge/multicast_snooping
0
cat /sys/devices/virtual/net/vmbr2/bridge/multicast_querier
1

i also disabled rp_filter

net.ipv4.conf.default.rp_filter = 0

stopped iptables and disabled selinux.
I think on my VM there is nothing now who can block traffic. (it's a standard centOS 6.5)