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Re: vifs not working?

der Mouse wrote:
I guess my thought is, without an ethernet device nor a bridge, how
is a vif to communicate?  What exactly are you pinging?

The dom0 and the domU communicate with one another.

dom0# ifconfig vif3.0
domU# ifconfig xennet0
dom0# ping
domU# ping

The documentation says that the xennet interface and the vif interface
are effectively like a crossover cable between two Ethernet ports.
Except for the issue that they don't stay around because the "hotplug
scripts", whatever they are, aren't working, that's exactly how they
seem to be behaving.

I didn't realise that. I had assumed the vifs were independent and had to be bound to something. In that case it seems quite plausible they should function as you expect, maybe it's just an untested scenario ...

I don't see what PCI access has to do with it; nothing says there's
a PCI bus anywhere in sight.
No ... but if you were to opt out of a bridge, then you'd usually
choose a physical interface.  Unless there is some other way to
emulate the physical layer that I'm unaware of (quite possibly).

I don't see why you'd need to.  The xennet interface in the domU seems
to communicate with its corresponding vif interface in the dom0 just
fine.  Whether the vif interface happens to be a member of a bridge is,
as far as I can see, entirely orthogonal to this - or, at least, it
should be; I can't see why a vif being a member of a bridge would
matter to anything.

It's highly likely that it doesn't matter. As stated, I haven't ventured much outside standard config and can only identify differences in yours. From what I've seen on the list, most people expose their domus and apply vlan tagging using dom0 as router. Yours may be a considerably less tested scenario.

The whole auto-bridging thing seems to be built around the assumption
that you want the domUs and the dom0 to, effectively, share a physical
interface.  If you do, this is fine, but if you don't - if you'd rather
have the domUs form one or more small private networks with the dom0 as
a router between them and the real network, or if you don't want the
domUs to communicate with anything beyond the dom0 - I can't see why
that should be a problem.

No it probably shouldn't. Hopefully this is something Manuel has tested and can respond to. Alternatively, anyone else have this type of setup?

The bridge is merely required to emulate the use of a physical

I don't see why.  The xennet/vif pair seems to emulate two physical
interfaces connected to one another just fine.  If I happen to want to
bridge a vif with a real interface, great, but I can't see any reason I
should have to if I'd rather not.

Well I was clearly wrong, see above. Your problem may not have anything to do with bridging what-so-ever ... but as it's the one exception in our configs, maybe it's worth trying to isolate the problem a little bit? At the least, if it doesn't work then it's highly likely a bug.


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