Date: Mon, 31 Jul 2006 07:16:03 +0200 From: Ian FREISLICH <if@hetzner.co.za> To: pyunyh@gmail.com Cc: current@freebsd.org Subject: Re: em promiscuous mode bug? Message-ID: <E1G7Q8J-0003t9-LC@hetzner.co.za> In-Reply-To: Message from Pyun YongHyeon <pyunyh@gmail.com> of "Wed, 26 Jul 2006 11:22:35 %2B0900." <20060726022235.GB14991@cdnetworks.co.kr>
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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
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