Re: [patch 2/6] [Network namespace] Network device sharing by view

jamal
2006-06-30T00:16:05Z

On Fri, 2006-30-06 at 09:07 +1200, Sam Vilain wrote:
> jamal wrote:

> > Makes sense for the host side to have naming convention tied
> > to the guest. Example as a prefix: guest0-eth0. Would it not
> > be interesting to have the host also manage these interfaces
> > via standard tools like ip or ifconfig etc? i.e if i admin up
> > guest0-eth0, then the user in guest0 will see its eth0 going
> > up.
>
> That particular convention only works if you have network namespaces and
> UTS namespaces tightly bound.

that would be one approach. Another less sophisticated approach is to
have no binding whatsoever, rather some translation table to map two
unrelated devices.

> We plan to have them separate - so for
> that to work, each network namespace could have an arbitrary "prefix"
> that determines what the interface name will look like from the outside
> when combined. We'd have to be careful about length limits.
>
> And guest0-eth0 doesn't necessarily make sense; it's not really an
> ethernet interface, more like a tun or something.
>

it wouldnt quiet fit as a tun device. More like a mirror side of the
guest eth0 created on the host side
i.e a sort of passthrough device with one side visible on the host (send
from guest0-eth0 is received on eth0 in the guest and vice-versa).

Note this is radically different from what i have heard Andrey and co
talk about and i dont wanna disturb any shit because there seems to be
some agreement. But if you address me i respond because it is very
interesting a topic;->

> So, an equally good convention might be to use sequential prefixes on
> the host, like "tun", "dummy", or a new prefix - then a property of that
> is what the name of the interface is perceived to be to those who are in
> the corresponding network namespace.
>
> Then the pragmatic question becomes how to correlate what you see from
> `ip addr list' to guests.

on the host ip addr and the one seen on the guest side are the same.
Except one is seen (on the host) on guest0-eth0 and another is seen
on eth0 (on guest).
Anyways, ignore what i am saying if it is disrupting the discussion.

cheers,
jamal