I have a system with two physical interfaces, combined into a LACP
aggregation group. That LACP channel has two VLANs, one untagged (the
"native vlan") and one using VLAN tagging. This gives us:
lagg0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
options=19b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,TSO4>
ether 00:25:90:1d:fe:8e
inet 10.243.24.23 netmask 0xffffff00 broadcast 10.243.24.255
media: Ethernet autoselect
status: active
laggproto lacp
laggport: em1 flags=1c<ACTIVE,COLLECTING,DISTRIBUTING>
laggport: em0 flags=1c<ACTIVE,COLLECTING,DISTRIBUTING>
vlan0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
options=3<RXCSUM,TXCSUM>
ether 00:25:90:1d:fe:8e
inet 10.243.16.23 netmask 0xffffff80 broadcast 10.243.16.127
media: Ethernet autoselect
status: active
vlan: 610 parent interface: lagg0
Is it possible to set a 9K MTU on lagg0
while preserving the 1500
byte MTU on vlan0
? Normally I would simply try this out, but this
is actually on a vendor-supported platform and I am loathe to make
changes "behind the back" of their administration interface.
This system is roughly FreeBSD 7.3.
Best Answer
Yes, that is possible. The VLAN parent must be equal to or larger MTU than the VLAN itself.