Re: [Xen-devel] Network still broken, new issue as well , 7468:17a9f111fa93

[Ewan Mellor <ewan@xxxxxxxxxxxxx>]

On Fri, Oct 21, 2005 at 10:26:30PM -0400, Ted Kaczmarek wrote:

> I see 2 vifs for a domU that has nics = 1 , this happens on 4 out of 10
> domU's. grepping my configs make me think that something has changed the
> way they are interpreted, all the the domU's using mac, bridge have 2
> vifs, where the one that ony have mac declared have 1 vif.
> 
> [Snip nics]
>
>  grep vif idom*

> idom1:vif = ['mac=AA:00:00:00:00:17','bridge=xen-br0']
> [Snip]
> idom10:vif = [ 'mac=AA:00:00:00:01:08, bridge=xen-br0' ]

Here, idom1 is declared using two strings, but idom10 is declared using just
one.  I'm guessing a little here, but from reading the code it looks like this
means that idom1 has two vifs, one with a default bridge and the given MAC,
and one with a random MAC and the given bridge, whereas idom10 has one vif,
with the given MAC and bridge.

I think this is fairly sensible behaviour.  Whether it is a regression or not,
I'm not sure.  It might actually have been a long-standing bug that has been
masked by other long standing bugs, and now we're doing things as intended.

The vifs= setting seems to only apply if the number of entries in vif= is less
than the number specified in vifs=.  In that case, the rest of the vifs are
created, with default details.  This is fairly barbaric, as you've found out.
We probably ought to have a "extra_vifs" setting or something, to make it
clear that they are separate from those configured using vif= and to make it
clear that this number is not a limit, to avoid the kind of confusion you've
suffered.

That said, I'm pushing back on configuration file format changes at the
moment, because we are trying to stabilise for release, and though the format
is pretty hideous, many people have stable configurations now, and I don't
want to break them without strong justification.

> idom5:vif = ['mac=AA:00:00"00"01:04' , 'bridge=xen-br0']

This MAC has quotation marks in it.  Lord only knows what that does, but it
can't be doing what you want, so I'd fix that ;-)


Regarding your other network problems, if you are still suffering once you've
changed your configuration, then please submit a full set of logs.  The
scripts involved have changed recently, as you know, but they are very
difficult to test, because we don't have a great variation of network
topologies available.  I'd be looking for

ifconfig
brctl show
cat /var/log/syslog
cat /var/log/debug
cat /var/log/xend.log

Ewan.

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