Re: em promiscuous mode bug?

Pyun YongHyeon wrote:
> On Tue, Jul 25, 2006 at 08:07:04AM +0200, Ian FREISLICH wrote:
>  > Hi
>  > 
>  > It seems that placing an em(4) interface into promiscuous mode the
>  > card stops doing hardware offload of 802.1Q tagging, in fact, it
>  > stops tagging entirely if vlanhwtag is enabled on the card.
>  > 
>  > With vlanhwtag:
>  > 15:40:48.050645 00:00:5e:00:01:02 > 01:00:5e:00:00:12, ethertype IPv4 (0x0
800), length 70: (tos 0x10, ttl 255, id 44821, offset 0, flags [DF], proto: VRR
P (112), length: 56) 196.30.82.61 > 224.0.0.18: VRRPv2, Advertisement, vrid 2, 
prio 10, authtype none, intvl 1s, length 36, addrs(7): 157.248.206.115,76.246.4
2.167,148.235.231.80,70.180.123.113,201.169.28.232,19.31.18.203,59.148.50.175
>  > 
>  > Without vlanhwtag:
>  > 15:40:57.419522 00:00:5e:00:01:02 > 01:00:5e:00:00:12, ethertype 802.1Q (0
x8100), length 74: vlan 1001, p 0, ethertype IPv4, (tos 0x10, ttl 255, id 44867
, offset 0, flags [DF], proto: VRRP (112), length: 56) 196.30.82.61 > 224.0.0.1
8: VRRPv2, Advertisement, vrid 2, prio 10, authtype none, intvl 1s, length 36, 
addrs(7): 157.248.206.115,76.246.42.176,8.148.142.115,171.178.137.11,211.216.40
.239,67.124.122.122,253.155.32.152
>  > 
>  > The interface is placed in promiscuous mode by the carp driver.
>  > 
>  > em0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> mtu 1500
>  >         options=cb<RXCSUM,TXCSUM,VLAN_MTU,POLLING,VLAN_HWCSUM>
>  >         ether 00:04:23:cf:50:00
>  >         media: Ethernet autoselect (1000baseTX <full-duplex>)
>  >         status: active
>  > 
>  > vlan1001: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> mtu 1
500
>  >         inet 196.30.82.62 netmask 0xfffffff0 broadcast 196.30.82.63
>  >         ether 00:04:23:cf:50:00
>  >         media: Ethernet autoselect (1000baseTX <full-duplex>)
>  >         status: active
>  >         vlan: 1001 parent interface: em0
>  > 
>  > carp1001: flags=49<UP,LOOPBACK,RUNNING> mtu 1500
>  >         inet 196.30.82.60 netmask 0xfffffff0 
>  >         carp: BACKUP vhid 2 advbase 1 advskew 0
>  > 
> 
> Hardware VLAN tagging was disabled in em(4) when it operates
> in promiscuous mode and em(4) will insert a VLAN tag in the
> driver.

Um, no.  When an em interface with hardware VLAN tagging enabled
is placed in promiscuous mode, it just _stops_ tagging.  Entirely.
The 802.1Q vlan just breaks.

Ian

--
Ian Freislich