This still seems to be a problem for me. I'm running the 2.2-BETA (amd64) Fri Oct 24 12:17:25 CDT 2014 build. I have 4 vlan interfaces atop a lagg interface. Each vlan interface has the MTU set to 9000. Yet, all of the vlan interfaces, the lagg interface, and the underlying igb interfaces all still show an MTU of 1500, even after multiple applications/reboots.
[2.2-BETA][admin]/root: ifconfig
...
igb2: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
options=407bb<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,VLAN_HWCSUM,TSO4,TSO6,LRO,VLAN_HWTSO>
ether 00:90:0b:33:e2:40
nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
media: Ethernet autoselect (1000baseT <full-duplex>)
status: active
igb3: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
options=407bb<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,VLAN_HWCSUM,TSO4,TSO6,LRO,VLAN_HWTSO>
ether 00:90:0b:33:e2:40
nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
media: Ethernet autoselect (1000baseT <full-duplex>)
status: active
...
lagg0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
options=407bb<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,VLAN_HWCSUM,TSO4,TSO6,LRO,VLAN_HWTSO>
ether 00:90:0b:33:e2:40
inet6 fe80::290:bff:fe33:e240%lagg0 prefixlen 64 scopeid 0xb
nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
media: Ethernet autoselect
status: active
laggproto lacp lagghash l2,l3,l4
laggport: igb3 flags=1c<ACTIVE,COLLECTING,DISTRIBUTING>
laggport: igb2 flags=1c<ACTIVE,COLLECTING,DISTRIBUTING>
lagg0_vlan3: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
options=303<RXCSUM,TXCSUM,TSO4,TSO6>
ether 00:90:0b:33:e2:40
inet6 fe80::290:bff:fe33:e240%lagg0_vlan3 prefixlen 64 scopeid 0xc
inet 192.168.3.1 netmask 0xffffff00 broadcast 192.168.3.255
nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
media: Ethernet autoselect
status: active
vlan: 3 vlanpcp: 0 parent interface: lagg0
lagg0_vlan6: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
options=303<RXCSUM,TXCSUM,TSO4,TSO6>
ether 00:90:0b:33:e2:40
inet6 fe80::290:bff:fe33:e240%lagg0_vlan6 prefixlen 64 scopeid 0xd
inet 192.168.6.1 netmask 0xffffff00 broadcast 192.168.6.255
nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
media: Ethernet autoselect
status: active
vlan: 6 vlanpcp: 0 parent interface: lagg0
lagg0_vlan9: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
options=303<RXCSUM,TXCSUM,TSO4,TSO6>
ether 00:90:0b:33:e2:40
inet6 fe80::290:bff:fe33:e240%lagg0_vlan9 prefixlen 64 scopeid 0xe
inet 192.168.9.1 netmask 0xffffff00 broadcast 192.168.9.255
nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
media: Ethernet autoselect
status: active
vlan: 9 vlanpcp: 0 parent interface: lagg0
lagg0_vlan7: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
options=303<RXCSUM,TXCSUM,TSO4,TSO6>
ether 00:90:0b:33:e2:40
inet6 fe80::290:bff:fe33:e240%lagg0_vlan7 prefixlen 64 scopeid 0xf
inet 192.168.7.1 netmask 0xffffff00 broadcast 192.168.7.255
nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
media: Ethernet autoselect
status: active
vlan: 7 vlanpcp: 0 parent interface: lagg0
Manually trying to set the MTU via ifconfig results in the same errors shown above.
[2.2-BETA][admin]/root: ifconfig lagg0 mtu 9000
ifconfig: ioctl (set mtu): Invalid argument
[2.2-BETA][admin]/root: ifconfig igb2 mtu 9000
ifconfig: ioctl (set mtu): Invalid argument
[2.2-BETA][admin]/root: ifconfig igb3 mtu 9000
ifconfig: ioctl (set mtu): Invalid argument
I originally reported MTU issues with 2.2 at #3744, but that was closed in favor of this bug. I assumed this fix to this bug would have fixed my issues as well, but it appears to not be so. Maybe an issue with combining vlans + lagg + jumbo frame MTUs?
Thoughts?