[ovs-discuss] VLAN tagging errors

rh ev watchlist at deltavm.com
Thu Sep 13 22:35:02 UTC 2012


Hello,

I am trying to get vlan tagging working and am running into some problems.
If I configure the switch with a vlan on the switch port I am able to
communicate through OVS. However once I change the port to be a trunk and
add the vlan tag to my OVS port I get a "bogus IP length" error when
pinging from my VM through OVS to my gateway. I found a post
http://openvswitch.org/pipermail/discuss/2012-March/006803.htmlfrom
earlier this year with the same problem but the resolution was never
posted. I am running OVS 1.7.1 on CentOS 6.3

Here is my config

 Bridge "br0"
        Port "br0"
            Interface "br0"
                type: internal
        Port "eth1"
            Interface "eth1"
        Port "vnet0"
            tag: 60
            Interface "vnet0"


I performed some captures. One on the switch and one on the host with OCS
from eth1.

If I look at the tcpdump from eth1 on the host when trying to ping the
gateway from the VM I can see that the vlan is set on the broadcast arp.

0000  ff ff ff ff ff ff 52 54  00 65 77 5c 81 00 00 3c  <--- 802.1Q vlan 60
0010  08 06 00 01 08 00 06 04  00 01 52 54 00 65 77 5c
0020  0a 0a 3c 04 00 00 00 00  00 00 0a 0a 3c 01

If you then follow the ARP to the switch capture the vlan is no longer set.

0000  ff ff ff ff ff ff 52 54  00 65 77 5c 08 06 00 01 <--- ARP no vlan
0010  08 00 06 04 00 01 52 54  00 65 77 5c 0a 0a 3c 04
0020  00 00 00 00 00 00 0a 0a  3c 01 00 00 00 00 00 00
0030  00 00 00 00 00 00 00 00  26 92 5b 34

There is also some other things going on that I can't explain like from the
switch the souce MAC for the ARP reply is 00:1b:d5:91:8d:ca. In the tcpdump
the source MAC is 00:1b:d5:91:00:01.

I'm not sure if this is a problem with my switch, openvswitch or my centos
install. Hopefully someone has seen a problem like this before and can help
me out.


Thanks,

Darcy
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