[ovirt-users] vlan tagging issue

cmc iucounu at gmail.com
Wed Sep 14 15:08:18 EDT 2016


Hi,

I have modified my VM network to have multiple tagged networks. It used to
be an untagged network and it worked fine, but I needed to add more
networks on the host. The switch it is connected to has the port configured
as a trunk port with these VLANs. When a VM sends traffic out (to get a
DHCP address for instance), it reaches the server but does not get the DHCP
offer that the server sends. I did a tcpdump on the node that hosts the VM
and the packets going out do not have a VLAN tag. I assume the VM host
interface would should not have the tag present, but that the  p2p1.91
interface should put the VLAN tag on.

The relevant interface configuration on the node that the VM host is on
looks like:

27: sohonet_DMZ: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue
state UP
    link/ether a0:36:9f:2a:63:20 brd ff:ff:ff:ff:ff:ff
29: p2p1.91 at p2p1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue
master vmnet state UP
    link/ether a0:36:9f:2a:63:20 brd ff:ff:ff:ff:ff:ff
30: vmnet: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state
UP
    link/ether a0:36:9f:2a:63:20 brd ff:ff:ff:ff:ff:ff
    inet6 fe80::a236:9fff:fe2a:6320/64 scope link
       valid_lft forever preferred_lft forever
31: vnet0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast
master vmnet state UNKNOWN qlen 500
    link/ether fe:1a:4a:16:01:58 brd ff:ff:ff:ff:ff:ff
    inet6 fe80::fc1a:4aff:fe16:158/64 scope link
       valid_lft forever preferred_lft forever
32: vnet1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast
master vmnet state UNKNOWN qlen 500
    link/ether fe:1a:4a:16:01:5c brd ff:ff:ff:ff:ff:ff
    inet6 fe80::fc1a:4aff:fe16:15c/64 scope link
       valid_lft forever preferred_lft forever

where vnet1 is the VM interface, and p2p1.91 is the VLAN'd interface for
the network. The network the VM nic is on is vmnet, and the physical
interface is p2p1

Configuring an address manually does not help, nor does dropping the
firewall on the host.
I've run the vmnet interface in promiscuous mode to see if I can see
anything coming back, but the return traffic does not appear.

Any ideas as to why the network is not working?

Thanks for any help.

-Cam
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