Xen users - Feb 2006 - understanding routed networking with xen 3.0

Hi,
I am a bit confused about how to set up routed instead of bridged
networking with xen 3.0.

In the xen 3.0 manual, routed networking is only mentioned "in the fine
print", multiple mails with questions about that topic in this list have
not been answered, and if I try the steps described in a mail on this
list, to which the xenwiki page about Networking points, I only get 
"Error: Device 0 (vif) could not be connected. Backend device not
found"
Besides that, The xend.log doesn''t tell anything that makes me
understand what''s happening.

I am a bit suspecting that routed networking support had been dropped in
xen 3.0, is it so? If not, what could I try, where could I look at to
get it going?

Henning


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BTW, some more infos on that:

What I exactly did before I got that error:
As described in the mentioned list mail, I disabled the network-bridge
and vif-bridge scripts, and enabled the *-route scripts in xend config.

Then I also added a (for bridged networking not needed) vif entry for
the network interface.

Another thing that looks strange to me: after destroying the
not-successfully started  vm (which appears in the output of "xm list"
anyway before I explicitly destroy it), I still have remaining vif<NR>.0
entries in ifconfig output. After multiple tries to start the vm I have
here about ten of them, which don''t seem to go away. Are they somehow
harmful?

Henning



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On Wed, 2006-02-01 at 13:37 +0100, Henning Sprang wrote:
> Hi,
> I am a bit confused about how to set up routed instead of bridged
> networking with xen 3.0.
> 
> In the xen 3.0 manual, routed networking is only mentioned "in the
fine
> print", multiple mails with questions about that topic in this list
have
> not been answered, and if I try the steps described in a mail on this
> list, to which the xenwiki page about Networking points, I only get 
> "Error: Device 0 (vif) could not be connected. Backend device not
found"
> Besides that, The xend.log doesn''t tell anything that makes me
> understand what''s happening.
> 
> I am a bit suspecting that routed networking support had been dropped in
> xen 3.0, is it so? If not, what could I try, where could I look at to
> get it going?
> 
> Henning
> 
> 
Routed is basically assigning the domU to an interface and the egress
for those packets is a different interface on the dom0. It is really
simplistic, hence the lack of documentation. 

Regards,
Ted




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On Wed, 2006-02-01 at 08:31 -0500, Ted Kaczmarek wrote:
> [...]
> Routed is basically assigning the domU to an interface and the egress
> for those packets is a different interface on the dom0. It is really
> simplistic, hence the lack of documentation. 
What do you mean by simplistic? If you mean, it "just works" then I
strongly disagree. It does definitely _not_ just work. Even if some very
experienced people get some things running very easily, for mere mortals
some things really need to be documented better (or, preferably, made
really "just work").

I do exactly what is described in the mail I mentioned on how to use
routed networking, but, as I tested that further,I get an error as soon
as I use the "ip=10.0.1.1" directive within the vif directive.
What''s
wrong with doing so? Is there a replacement?

What can be causing this?

Henning



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On Wed, Feb 01, 2006 at 04:00:43PM +0100, Henning Sprang
wrote:
> On Wed, 2006-02-01 at 08:31 -0500, Ted Kaczmarek wrote:
> > [...]
> > Routed is basically assigning the domU to an interface and the egress
> > for those packets is a different interface on the dom0. It is really
> > simplistic, hence the lack of documentation. 
> 
> What do you mean by simplistic? If you mean, it "just works" then
I
> strongly disagree. It does definitely _not_ just work. Even if some very
> experienced people get some things running very easily, for mere mortals
> some things really need to be documented better (or, preferably, made
> really "just work").
I think he means simplistic in the sense that Xen doesn''t actually do
anything out of the ordinary in a routed configuration. When you start a
routed domain new get a new interface in dom0 and then Xen pretty much
steps out of the way. If you read the scripts network-route (which is run
when you start xend) and vif-route (which is run whenever a new vif
interface is created) you''ll see just how little Xen does in routed
mode.
> I do exactly what is described in the mail I mentioned on how to use
> routed networking, but, as I tested that further,I get an error as soon
> as I use the "ip=10.0.1.1" directive within the vif directive.
What''s
> wrong with doing so? Is there a replacement?
> 
> What can be causing this?
If you read the vif-route script you''ll see that adding the ip
parameter to
the vif directive causes the vif-route script to try and add a route to the
routing table using the "ip" command. Perhaps you don''t have
it installed?
I don''t know what distro you are using, but it''s in the
iproute package in
Debian.

-- 
CJ van den Berg

mailto:cj@vdbonline.com
  xmpp:cj@vdbonline.com
   sip:8918316@sipgate.de

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