Re: [E1000-devel] discussion questions: SR-IOV, virtualization, and bonding

On 8/2/2012 4:01 PM, Jay Vosburgh wrote:

Chris Friesen [off-list ref] wrote:

quoted

On 08/02/2012 04:26 PM, Chris Friesen wrote:

quoted

On 08/02/2012 02:30 PM, Jay Vosburgh wrote:

quoted

quoted

The best long term solution is to have a user space API that
provides link state input to bonding on a per-slave basis, and then some
user space entity can perform whatever link monitoring method is
appropriate (e.g., LLDP) and pass the results to bonding.

I think this has potential. This requires a virtual communication
channel between guest/host if we want the host to be able to influence
the guest's choice of active link, but I think that's not unreasonable.

	Not necessarily, if something like LLDP runs across the virtual
link between the guest and slave, then the guest will notice when the
link goes down (although perhaps not very quickly).  I'm pretty sure the
infrastructure to make LLDP work on inactive slaves is already there; as
I recall, the "no wildcard" or "deliver exact" business in the receive
path is at least partially for LLDP.

Right we run LLDP over the inactive bond. However because LLDP
uses nearest customer bridge, nearest bridge, or neareast non-tpmr
addresses it should be dropped by switching components. The problem
with having VMs send LLDP and _not_ dropping the packets is it looks
like multiple neighbors to the peer. The point is there is really an
edge relay like component in the hardware with SR-IOV. So likely using
LLDP do to do this wouldn't work

If you happen to have the 2010 802.1Q rev section 8.6.3 "frame
filtering" has some more details. The 802.1AB spec has details on the
multiple neighbor case.

	Still, though, isn't "influence the guest's choice" pretty much
satisified by having the VF interface go carrier down in the guest when
the host wants it to?  Or are you thinking about more fine grained than
that?

Perhaps one argument against this is if the hardware supports loopback
modes or the edge relay in the hardware is acting like a VEB it may
still be possible to support VF to VF traffic even if the external link
is down. Not sure how useful this is though or if any existing hardware
even supports it.

Just in case its not clear (it might not be) an edge relay (ER) is
defined in the new 802.1Qbg-2012 spec. "An ER supports local relay
among virtual stations and/or between a virtual station and other
stations on a bridged LAN". Similar to a bridge but without spanning
tree operations.

.John