Re: [Xen-users] newbie in trouble with CentOS Xen

[Dave Stevens <geek@xxxxxxxxxxxx>]

Quoting Alexandre Kouznetsov <alk@xxxxxxxxxx>:

> El 05/04/13 10:13, Greg Woods escribió:
> > On Fri, 2013-04-05 at 10:05 -0600, Alexandre Kouznetsov wrote:
> >
> > > It seems like, Dom0's IP connectivity is not done directly via the
> > > actual device. Instead it creates a vif0.2 and maps it as eth2 to Dom0,
> > > as it would do with any other Dom.
> > > Seems much cleaner than the setup I described before, as "old ways",
> > > when a eth was renamed to peth and a bridge called eth was created.
> > We're getting a bit away from the original topic,
> The original topic is still discussed on another branch of this thread (:
>
> > We've got the ethX devices
> > which are the physical device, same as any non-Xen system,
> No. While Dom0 is booted, it's virtualized. See all that vif0.X,  
> they are interfaces exported to a Domain with ID 0.
> > and the
> > xenbrX devices, which are the actual bridges.
> Right, they communicate the backend vif's with the physical network.
>
> > The pethX devices don't
> > seem to serve any real purpose. I would hazard a guess that the pethX
> > devices aren't really needed at all, and are just there for historical
> > compatibility.
> Yes they do serve a purpose. ethX devices you see in your Dom0  
> (note, this seems to be CentOS specific Xen stuff) are not real  
> network interfaces. They are virtualized, just like any other  
> network interface in any other DomU. They are backed by a  
> corresponding vif0.X device. Just as in case of DomU, vif0.X devices  
> are bridged together with a physical interface within Dom0. That is  
> where pethX comes into play, it links the bridge to the physical  
> network. Also, it's used to interact with the physical card, for  
> MTU, error correction settings, WOL, firmware, etc.
> So the topology is like this:
>
> -----------
>  Dom0 eth0
> -----------
>      |
>  Xen PV VIF
>      |
> -----------
>    vif0.0
>      |
>   xenbr0
>      |
>    peth0
> -----------
>      |
> physical port
>
> Greetings.
>
> --
> Alexandre Kouznetsov
Alexandre,

I don' know if I can send an attachment to this list, but I'll see if  
one comes through, also pasted in below. A diagram of the original  
"supposed to be like this" setup.
Dave

      LAN0                                                  LAN1
       |                                                     |
 +-----+-----------------------------------------------------+-----+
 |     |                                                     |     |
 | +---+-------------------------+ +-------------------------+---+ |
 | |   |                         | |                         |   | |
 | | peth0            xenbr0     | |      xenbr1           peth1 | |
 | |                             | |                             | |
 | | vif0.0       vif1.0  vif1.1 | |  vif2.0  vif2.1      vif0.1 | |
 | |   |            |       |    | |    |       |            |   | |
 | +---+------------+-------+----+ +----+-------+------------+---+ |
 |     |            |       |           |       |            |     |
 |     |     +------+-------+-----------+-------+------+     |     |
 |     |     |      |       |           |       |      |     |     |
 |     |     | +----+-------+----+ +----+-------+----+ |     |     |
 |     |     | |    |       |    | |    |       |    | |     |     |
 |   eth0    | |  eth0    eth1   | |  eth0    eth1   | |   eth1    |
 |     |     | |    |       |    | |    |       |    | |     |     |
 |   +-+-+   | |  +-+-+   +-+-+  | |  +-+-+   +-+-+  | |   +-+-+   |
 |   |   |   | |  |   |   |   |  | |  |   |   |   |  | |   |   |   |
 |  www ssh  | | www ssh ftp pop | | www ssh ftp pop | |  ftp pop  |
 |           | |                 | |                 | |           |
 |  Domain0  | |     Domain1     | |     Domain2     | |  Domain0  |
 +-----------+ +-----------------+ +-----------------+ +-----------+



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--
The problem with being cynical is you can't keep up!

-- anon. philosopher

Attachment: diagram of multi-bridged dom0
Description: Text document

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