[Netkit.users] Tap Interface in Netkit Lab

Massimo Rimondini rimondin at dia.uniroma3.it
Sat Feb 2 13:09:33 CET 2008

Hi Michele,

both answers apply.

First, there is something improper in your configuration. In fact, you
cannot choose a collision domain on your own for TAP interfaces. Therefore,
the line router1[0]="A" is redundant, and indeed should be removed from your
lab.conf. The reason why Netkit does not detect the redundancy is that lines
in lab.conf that specify interfaces with an explicit name ([eth0]) are
simply considered as vstart command line arguments, and therefore are not
matched against interfaces specified with the standard syntax ([0]).

Second, your configuration reveals a bug which, fortunately, does not affect
your specific setting. At present, tap interfaces with a numbering higher
than 0 are not properly set up. In general, this should not be critical,
however I attach a patch that fixes the problem. To apply it, enter
$NETKIT_HOME and run 'patch -p1 < tap-not-first.diff'.

P.S. With the latest version of Netkit, TAP interfaces too can be configured
using the standard syntax for interface specification in lab.conf.
Therefore, I suggest to replace


> -----Original Message-----
> From: netkit.users-bounces a list.dia.uniroma3.it 
> [mailto:netkit.users-bounces a list.dia.uniroma3.it] On Behalf 
> Of Michele Di Mascolo
> Sent: Saturday, February 02, 2008 12:31 PM
> To: netkit.users a list.dia.uniroma3.it
> Subject: [Netkit.users] Tap Interface in Netkit Lab
> I've some trouble to start a Netkit Lab with vm_s that have tap
> interface configured at the start up to be capable to internet
> navigate.
> I configure in lab.conf file the interested vm as follow:
> router1[0]="A"
> router1[1]="B"
> router1[eth0]=tap,,
> When the router1 vm start, only the normal network interface come up
> with the address specified in router1.startup file. The tap interface
> instead doesn't go up and I can't navigate in internet with this vm.
> I want to know if this is a my bad configuration or if there is a bug
> in the lab start up when is present a vm with tap interface
> pre-configured.
> Thanks
> Michele Di Mascolo
> Specialistic Graduating in Telecommunications Engineering
> @ Università degli Studi di Roma "Tor Vergata"
> _______________________________________________
> Netkit.users mailing list
> Netkit.users a list.dia.uniroma3.it
> http://list.dia.uniroma3.it/mailman/listinfo/netkit.users
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