I'm trying to get a vlan interface on a bonded nic (Centos 5.5) and whilst the interface has been very happily created with vconfig I'm seeing no traffic on it at all. Running tcpdump and tshark on the underlying eth0 I see no sign at all of vlan tags in the traffic, and I'm wondering if there's somethign I'm missing on the server side as the network dept say they are sending me the tagged data. I've got the 8021q module loaded, however under lsmod it shows it's only being used by the cxgb3 module, for an unused onboard iSCSI card, whereas my nics (on an HP DL380 G7) are driven by bnx2 and e1000e modules. Should these modules be listing 8021q as used module? should I have something conrete in /etc/modprobe.conf?



  • Much more likely than not, the network/switch is not sending tagged traffic. – Chris S Jan 10 '11 at 13:51
  • Well that's my line, but the catos configs I'm being shown suggest it should be working, mostly need to cover my back. – Chris Phillips Jan 10 '11 at 13:57

Chris, Did you check /etc/sysconfig/network-scripts/ifcfg-bondedinterface-name and make sure that VLAN=Yes is entered as an option? Perhaps that's why the modprobe is skipping those interfaces.


  • Turned out it was all fine. I have vlan interfaces, but they still don't say the module is directly used by the driver. Nice and clear... – Chris Phillips Jan 14 '11 at 8:42

Turned out it was all correct at this level. lsmod output was normal, if confusing.

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