[libvirt] oVirt considers using macTableManager='libvirt'

Ido Barkan ibarkan at redhat.com
Sun Nov 1 13:52:21 UTC 2015

Hi guys,

We, at oVirt, are considring using the automatic bridge management
feature of libvirt for our hosts
I could find any discussion in the mailing list archives about the
motivation for this feature.
  (was there?). If there wasn't I would like to start a new one, about
the possible trade offs it would
  have in oVirt.
  Specifically I have a few questions:

1) The obvious performance motivation is clear: considering N hosts
with M vms each connected to
   the same LAN, the first packet to any unknown yet host will flood
all the vms in all N bridges.
      -- was there any other motivation that I do not understand
(apart from slightly better security?
2) oVirt uses TC for port mirroring, in case this is requested by
users, to mirror traffic from a chosen
   bridge to a chosen NIC in the host. I could not understand if
macTableManager will interfere
   with it, or not.
3) Are there any drawbacks to enabling this feature?
4) We aim for rhel7.2. Will the feature be supported (or partially
supported) for kernels older then
    3.17? And if so, in what way?
5) oVirt currently builds its own bridges and tell libvirt about them.
Does that have any affect on the
    functionality of that feature?
6) are there any plans to support OVS for this feature in the future?

Ido Barkan

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