On Wed, Apr 15, 2009 at 09:08:02PM -0500, Chris Adams wrote: > Once upon a time, Garry Dolley <gdolley@xxxxxxxxxxxxxxx> said: > > On Wed, Apr 15, 2009 at 07:53:04PM -0500, Chris Adams wrote: > > > If I run tcpdump in the VM and ping from the VM, I see: > > > > > > 19:02:04.443160 00:04:61:4a:ee:27 > Broadcast, ethertype ARP (0x0806), length 42: arp who-has 172.24.54.14 tell 172.24.54.207 > > > > > > > > > I swear I saw tagged packets within the VM earlier. :-( > > > > Are you running tcpdump in the VM on eth2? > > Yes. > > > If so, you won't see tagged packets on eth2. > > Huh, I didn't realize that. I set up a different test, and you are > right (confusing, but correct). > > However, if I (in the host) tcpdump tap2 or br2, the packets are > untagged there as well. So, either: > > - they are not being tagged in the VM Possibly. But your setup looks correct. > - qemu-kvm is stripping the tag Doubt it. > - the tap interface is stripping the tag My tap's pass tags w/o trouble, so it's probably not that. > > > Okay, if I watch eth2 and eth2.20 with the same tcpdump command as > > > above, I see incoming packets correctly. On eth2, I see the tag, and > > > then they show up on eth2.20 without the tag. It appears to only be a > > > problem with outbound packets not getting tagged (I see the same > > > untagged packets in the host with a tcpdump on tap2). > > > > Are you sure you see the tag on eth2? I woulda killed to see the > > tag on the physical int when doing my setup a few weeks ago. > > I only see it on traffic from the LAN, but yes, I do see it there. > > > I wonder if VLAN hardware acceleration has anything to do with it. > > Is that something that can be turned on/off within the VM? No, it is a hardware NIC issue. I heard you need to recompile the driver to turn it off (almost all NICs these days do hardware VLAN acceleration). > > Can you show a tcpdump on the host when pinging from inside the VM? > > # tcpdump -s0 -e -n -i tap2 > 20:55:30.927645 00:04:61:4a:ee:27 > Broadcast, ethertype ARP (0x0806), length 42: arp who-has 172.24.54.13 tell 172.24.54.207 > > # tcpdump -s0 -e -n -i br2 > 20:56:11.474010 00:04:61:4a:ee:27 > Broadcast, ethertype ARP (0x0806), length 42: arp who-has 172.24.54.13 tell 172.24.54.207 > > > Aha! Apparently, there's a fourth option to the above possible sources > of the problem: > > - the 8139 driver (either in the VM kernel or qemu-kvm) is stripping the > tag > > I switched qemu-kvm to emulate an Intel i82557b (using e100 driver in > the VM), and it all works! Ah!! Yup, I forgot that all my *BSD VMs use the e1000 driver, not the default 8139. I've heard the rtl8139 hardware is bad / broken, so emulating broken hardware in turn is broken ;) > Thanks for letting me know it _should_ work and helping me think through > it. Not a problem. -- Garry Dolley ARP Networks, Inc. | http://www.arpnetworks.com | (818) 206-0181 Data center, VPS, and IP Transit solutions Member Los Angeles County REACT, Unit 336 | WQGK336 Blog http://scie.nti.st -- To unsubscribe from this list: send the line "unsubscribe linux-net" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
