a forum user have reported strange bug with ovs + mtu9000 when
switching between 2 ovs bridge with different mtu. (1500 vs 9000)
https://forum.proxmox.com/threads/ovs-problem-with-mtu-9000-on-vms-assigned-to-vmbr0.105172/
I have found 2 bugs:
1) ovsint port mtu need to be set with ""ovs-vsctl set mtu-request"
(ip link set mtu 9000 don't seem to do nothing on ovs-int port, maybe this have
change with last ovs version.)
fresh start of a vm 100 + firewall on ovs with mtu 9000:
153: tap100i0: <BROADCAST,MULTICAST,PROMISC,UP,LOWER_UP> mtu 9000 qdisc
pfifo_fast master fwbr100i0 state UNKNOWN group default qlen 1000
link/ether 62:42:32:cc:a2:24 brd ff:ff:ff:ff:ff:ff
154: fwbr100i0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state
UP group default qlen 1000
link/ether 46:f6:b7:95:23:86 brd ff:ff:ff:ff:ff:ff
155: fwln100o0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master
fwbr100i0 state UNKNOWN group default qlen 1000
2) when switching between 2 bridges or ovs with differents mtu, mtu are not
updated on existing interfaces (veth,tap, fwbr, fwnl)
vm start : vmbr0 mtu=1500 + firewall
-----------------------------
200: tap100i0: <BROADCAST,MULTICAST,PROMISC,UP,LOWER_UP> mtu 1500 qdisc
pfifo_fast master fwbr100i0 state UNKNOWN group default qlen 1000
link/ether 62:42:32:cc:a2:24 brd ff:ff:ff:ff:ff:ff
206: fwbr100i0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state
UP group default qlen 1000
link/ether 46:f6:b7:95:23:86 brd ff:ff:ff:ff:ff:ff
207: fwpr100p0@fwln100i0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc
noqueue master vmbr0 state UP group default qlen 1000
link/ether 0a:2e:f5:f4:22:e3 brd ff:ff:ff:ff:ff:ff
208: fwln100i0@fwpr100p0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc
noqueue master fwbr100i0 state UP group default qlen 1000
link/ether 96:0e:94:11:c1:45 brd ff:ff:ff:ff:ff:ff
switch to vmbr1 mtu=9000 + firewall
--------------------------------------
200: tap100i0: <BROADCAST,MULTICAST,PROMISC,UP,LOWER_UP> mtu 1500 qdisc
pfifo_fast master fwbr100i0 state UNKNOWN group default qlen 1000
link/ether 62:42:32:cc:a2:24 brd ff:ff:ff:ff:ff:ff
209: fwbr100i0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state
UP group default qlen 1000
link/ether 46:f6:b7:95:23:86 brd ff:ff:ff:ff:ff:ff
210: fwpr100p0@fwln100i0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9000 qdisc
noqueue master vmbr3 state UP group default qlen 1000
link/ether 0a:2e:f5:f4:22:e3 brd ff:ff:ff:ff:ff:ff
211: fwln100i0@fwpr100p0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9000 qdisc
noqueue master fwbr100i0 state UP group default qlen 1000
link/ether 96:0e:94:11:c1:45 brd ff:ff:ff:ff:ff:ff
Alexandre Derumier (1):
network: tap_plug: fix mtu
src/PVE/Network.pm | 30 ++++++++++++++++++++----------
1 file changed, 20 insertions(+), 10 deletions(-)
--
2.30.2
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