[libvirt] [RFC] [PATCH 3/3 v2] vepa+vsi: Some experimental code for 802.1Qbh

[Dave Allan]

On Sat, May 22, 2010 at 06:47:19PM -0700, Scott Feldman wrote:
> On 5/22/10 6:24 PM, "Dave Allan" <dallan at redhat.com> wrote:
> 
> >>> Mostly I'm concerned about the failure case: how would the user know
> >>> that something has gone wrong, and where would information to debug
> >>> the problem appear?
> >> 
> >> Think of it as equivalent to waiting to get link UP after plugging in a
> >> physical cable into a physical switch port.  In some cases negotiation of
> >> the link may take on the order of seconds.  Depends on the physical media,
> >> of course.  A user can check for link UP using ethtool or ip cmd.
> >> Similarly, a user can check for association status using ip cmd, once we
> >> extend ip cmd to know about virtual ports (patch for ip cmd coming soon).
> > 
> > That's the way I was thinking about it as well.  The difference I see
> > between an actual physical cable and what we're doing here is that if
> > you're in the data center and you plug in a cable, you're focused on
> > whether the link comes up.  Here, the actor is likely to be an
> > automated process, and users will simply be presented with a VM with
> > no or incorrect connectivity, and they will have no idea what
> > happened.  It's just not supportable to provide them with no
> > indication of what failed or why.
> 
> What can we do in libvirt to provide async status of port-profile
> association?  How could an aynsc status be reported to the user via libvirt?
> In the virt-manager GUI, for example, on the details sheet for the NICs, can
> we display the status of the backing virtual port?  Kind of like the status
> on the basic details overview sheet.  Actually, if we could display the
> other virtual port settings like port-profile name of VSI-* tuple along with
> status, then the user would have some good info to start troubleshooting.

It's not impossible to do what you're suggesting here, but what's the
benefit?  Is it a problem to poll for even 10 or 20 seconds?

Dave