VLANs and hardware options

[Pyun YongHyeon]

On Mon, Oct 13, 2008 at 05:26:04PM +0200, Ivan Voras wrote:
 > I have the following situation:
 > 
 > bce0: flags=8802<BROADCAST,SIMPLEX,MULTICAST> metric 0 mtu 1500
 > 	options=1bb<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,VLAN_HWCSUM,TSO4>
 > 	ether 00:14:5e:6d:2d:74
 > 	media: Ethernet autoselect (1000baseSX <full-duplex>)
 > 	status: active
 > 
 > vlan0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
 > 	options=3<RXCSUM,TXCSUM>
 > 	ether 00:14:5e:b3:2a:38
 > 	inet xx.xx.xx.xx netmask 0xffffff00 broadcast xx.xx.xx.255
 > 	media: Ethernet autoselect (1000baseSX <full-duplex>)
 > 	status: active
 > 	vlan: 250 parent interface: bce1
 > 
 > e.g. the network card is directly on a trunked network, and I have the
 > vlan interface with actual IP address. My question is: since this setup
 > mixes various network&protocol layers, are the TSO capabilities of the
 > card used? I guess not and that only RXCSUM & TXCSUM are used (for
 > IP-level packets).
 > 

Correct. I believe almost all gigabit controllers can handle TSO
with VLAN tagging. Unfortunately there is no official way to inform
TSO capability of parent interface to VLAN layer in FreeBSD. Just
adding a new flag to if_capabilities and minor patch to vlan(4)
would make TSO work on vlan interface. But I haven't had time to
implement this as my working environment does not involve VLANs.

-- 
Regards,
Pyun YongHyeon