The other bug has been closed, so I'm starting a new one. The other Bug is https://sourceforge.net/tracker/?func=detail&atid=782616&aid=2820846&group_id=151951
While it's great that the freeBSD documenation states "The MTU of the first interface to be added is used as the lagg MTU. All
additional interfaces are required to have exactly the same value." at http://www.freebsd.org/cgi/man.cgi?query=lagg&apropos=0&sektion=0&manpath=FreeBSD+7.2-RELEASE&format=html, at the minimum, this language needs to be added to the GUI somewhere.
freenas:~# ifconfig
em0: flags=8802<BROADCAST,SIMPLEX,MULTICAST> metric 0 mtu 1500
options=19b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,TSO4>
ether 00:1d:09:84:71:52
media: Ethernet autoselect
status: no carrier
em1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
options=9b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM>
ether 00:1b:21:13:e2:5c
media: Ethernet autoselect (1000baseTX <full-duplex>)
status: active
lagg: laggdev lagg0
em2: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
options=9b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM>
ether 00:1b:21:13:e2:5c
media: Ethernet autoselect (1000baseTX <full-duplex>)
status: active
lagg: laggdev lagg0
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384
inet6 fe80::1%lo0 prefixlen 64 scopeid 0x4
inet6 ::1 prefixlen 128
inet 127.0.0.1 netmask 0xff000000
lagg0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
options=9b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM>
ether 00:1b:21:13:e2:5c
inet 192.168.1.148 netmask 0xffffff00 broadcast 192.168.1.255
media: Ethernet autoselect
status: active
laggproto lacp
laggport: em2 flags=1c<ACTIVE,COLLECTING,DISTRIBUTING>
laggport: em1 flags=1c<ACTIVE,COLLECTING,DISTRIBUTING>
freenas:~# ifconfig em1 mtu 9000
ifconfig: ioctl (set mtu): Invalid argument
freenas:~# ifconfig em2 mtu 9000
ifconfig: ioctl (set mtu): Invalid argument
freenas:~# ifconfig lagg0 mtu 9000
ifconfig: ioctl (set mtu): Invalid argument
freenas:~#
After deleting the lagg:
freenas:~# ifconfig
em0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 8192
options=19b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,TSO4>
ether 00:1d:09:84:71:52
inet 192.168.1.172 netmask 0xffffff00 broadcast 192.168.1.255
media: Ethernet autoselect (100baseTX <full-duplex>)
status: active
em1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 8192
options=9b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM>
ether 00:1b:21:13:e2:5c
inet 192.168.1.180 netmask 0xffffff00 broadcast 192.168.1.255
media: Ethernet autoselect (1000baseTX <full-duplex>)
status: active
em2: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 8192
options=9b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM>
ether 00:1b:21:13:e2:5b
inet 192.168.1.181 netmask 0xffffff00 broadcast 192.168.1.255
media: Ethernet autoselect (1000baseTX <full-duplex>)
status: active
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384
inet6 fe80::1%lo0 prefixlen 64 scopeid 0x4
inet6 ::1 prefixlen 128
inet 127.0.0.1 netmask 0xff000000
I'm not even sure that em0 should be supporting the high mtu as it's not a gigabit interface.
What shall i say. The MTU is set the FreeBSD way in the /etc/rc.conf file. If it does not work then it is a FreeBSD problem and there my sphere of influence ends. I think this is a driver problem, maybe in the lagg or em driver.