1 Oct
2012
1 Oct
'12
3:22 a.m.
think of a reason why the hardware MTU couldn't be set to 9000 on the physical interface, but that Linux just doesn't send packets larger than 1500 on eth0.
what? that makes no sense.
The MTU setting on an interface is what tells linux how large the packets can be before they have to be fragmented.
if you set the MTU to 9000, then you're telling Linux that packets up to that size are OK. it won't magically deduce that you really meant 1500 most of the time but sometimes 9000.
It makes perfect sense. Think of the physical interface as being separate from the eth0 interface, so eth0 is just another vlan: Physical interface MTU = 9000 (>= largest VLAN MTU) eth0 (vlan1, untagged) MTU = 1500 eth0.12 (vlan12, tagged) MTU = 9000 James