We are making heavy use of macvlan interfaces (in VEPA mode) on-top of virtual functions, under VMs being managed by oVirt.  In this scenario IPv6 is not playing nicely, with no traffic going through, and messages about neighbor solicitation.  There are some pointers out there indicating the issue stems from the fact IPv6 utilizing multicast for neighbor solicitation, but nothing we have tried seems to work around this issue.

The problem is made all the most bizarre by the fact that on the same hardware libvirt + virt-manager works perfectly fine.  I have looked at the corresponding xml for the guests, and nothing seems to point to the underlying cause for oVirt to fail, but libvirt to succeed.

* Intel XL710 40G NICs (i40e/i40evf drivers)

* CentOS 7.1 (fully up-to-date)

* oVirt 3.6

* libvirt-1.2.17

* virt-manager-1.2.1-8

Thanks for any pointers folks can provide.

- jkt