why vimage?

Jeremie Le Hen jeremie at le-hen.org
Fri Feb 29 15:48:56 UTC 2008

Hi Julian,

On Tue, Feb 26, 2008 at 08:53:52AM -0800, Julian Elischer wrote:
>  I can give a very simple example of something you can do trivially on 
>  vimage:
>  Make three virtual machines on yhour laptop:
>  The base machine and two others.
>  Have the first 'other' machine be assigned an IP address on
>  your HOME LAN.
>  have the second virtual machine have an IP adddress on
>  your WORK LAN.
>  use the base machine to run encrypted tunnels from where-ever
>  you happen to be to your work and home.. when you put the laptop to sleep 
>  (assuming the tcp sessions are quiescent (no keepalives))
>  then when you wake it up say an hour later.. as soon as the base machine has 
>  an IP address.. viola, your session on the virtual
>  machines are still alive.

On this post [1], Marko states:

% Each NICs is logically attached to one and only one network stack
% instance at a time, and it receives data from upper layers and feeds
% the upper layers with mbufs in exactly the same manner as it does on
% the standard kernel.  It is the link layer that demultiplexes the
% incoming traffic to the appropriate stack instance...

As I understand it, there is only one vimage per interface.  I'm surely
wrong or the setup you described wouldn't be possible.

Any explanation will be welcome :).

[1] http://lists.freebsd.org/pipermail/freebsd-current/2008-February/083908.html

Jeremie Le Hen
< jeremie at le-hen dot org >< ttz at chchile dot org >

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