MTU problem and packet loss with vlan aware brige

[felipe]

hi,

i have changed our setup for the internet uplinks from access vlans to tagged vlans on the switch. around 200 vms perform normally. only one vm has the problem of a packet loss:

so traffick sniffing shows following for the old working setup:

eth0 -> smaller 1500 byte split in two packages
tap233i0 ->smaller 1500 byte split in two packages
fwbr165i0 -> bigger then 1500 byte in one package (why?)
vmbr0 -> bigger then 1500 in one package
bond0 -> smaller 1500 split again in two packages

on the new host with only tagged uplinks (nor more acces port on the switch) the same happens but on bond0 the packet is dropped

eth0 -> smaller 1500 byte split in two packages
tap233i0 ->smaller 1500 byte split in two packages
fwbr165i0 -> bigger then 1500 byte in one package (why?)
vmbr0 -> bigger then 1500 in one package
bond0 -> package dropped


-----------------------

config node1 (working):
the vm interface is not tagged as the switch has an acces vlan for 200

auto lo
iface lo inet loopback

auto eno4
iface eno4 inet manual

auto eno1
iface eno1 inet manual

auto eno2
iface eno2 inet manual

auto eno3
iface eno3 inet manual

auto bond0
iface bond0 inet manual
bond-slaves eno1 eno2
bond-miimon 100
bond-mode 802.3ad

auto bond1
iface bond1 inet manual
bond-slaves eno3 eno4
bond-miimon 100
bond-mode 802.3ad
bond-xmit-hash-policy layer2+3

auto vmbr0
iface vmbr0 inet static
address 192.168.11.11/24
gateway 192.168.11.254
bridge-ports bond0
bridge-stp off
bridge-fd 0
bridge-vlan-aware yes
bridge-vids 2-4094

auto vmbr1
iface vmbr1 inet static
address 192.168.10.11/24
bridge-ports bond1
bridge-stp off
bridge-fd 0

---------------

config on the host wehere the problem occurs:
the vm interface is tagged with vlan 200

auto lo
iface lo inet loopback

auto eth0
iface eth0 inet manual

auto eth1
iface eth1 inet manual

auto eth2
iface eth2 inet manual

auto eth3
iface eth3 inet manual

auto eth4
iface eth4 inet manual

auto eth5
iface eth5 inet manual

auto bond0
iface bond0 inet manual
bond-slaves eth0 eth1
bond-miimon 100
bond-mode 802.3ad
bond-xmit-hash-policy layer2+3

auto bond1
iface bond1 inet manual
address 192.168.13.4/24
bond-slaves eth2 eth4
bond-miimon 100
bond-mode 802.3ad

auto bond2
iface bond2 inet manual
bond-slaves eth3 eth5
bond-miimon 100
bond-mode 802.3ad

auto vmbr0
iface vmbr0 inet manual
bridge-ports bond0
bridge-stp off
bridge-fd 0
bridge-vlan-aware yes
bridge-vids 2-4094

auto vmbr1
iface vmbr1 inet static
address 192.168.10.104/24
bridge-ports bond2
bridge-stp off
bridge-fd 0

auto vmbr0.200
iface vmbr0.200 inet static
address 192.168.11.34/24


all running on latest 7.x proxmox
all interfaces report mtu 1500

 

[felipe]

to get better understanding i figured out following:

because of netfilter all packages > 1500 allways get reassebled on the bridgers (if turned on) the problem now in my case is - if the package is vlan taged on bridges with vlan-aware the packages are dropped by bond0 afterwards. if i switch back to "not vlan aware" it works. also i can increase the mtu of bond0 and it works. but that is not a solution because the packages should get fragementet again.
turning off netfilter (firewall & /proc/sys/net/bridge/bridge-nf-call-iptables = 0) packages dont get reassembled and irt works also.

what i dont know at the moment why are packages and how fragemented after being forwarded to bond0 normally by the bridge (and why not in may case with vlan aware)