xen discuss - May 2008 - Cannot get second network interface working in Linux guest

Hi,
I''m running snv_89 on an X4150 with a CentOS-5 guest.  I cannot seem to
get my
second network interface to work properly.  I followed the virt-install
instructions, and even saw the FAQ entry about adding a second network instance
in the XML config.  I see my second device in the guest but it''s either
connected to the wrong interface or not at all.

I''d like to understand how xVM connects the virtual devices to physical
ones-- I
understand about the default-nic property of the xend service, but what about
subsequent additions?

In my dom0 I''m using e1000g0 and g1.  g0 is the default-nic, which is
on my
internal private net.  g1 is connected to my public DMZ net.  I have tried
pinging from within the domU, but don''t see the traffic when snooping
in dom0 on
either interface.

Thanks in advance,
Eric

Eric Sproul wrote:
> Hi,
> I''m running snv_89 on an X4150 with a CentOS-5 guest.  I cannot
seem to get my
> second network interface to work properly.  I followed the virt-install
> instructions, and even saw the FAQ entry about adding a second network
instance
> in the XML config.  I see my second device in the guest but it''s
either
> connected to the wrong interface or not at all.
> 
> I''d like to understand how xVM connects the virtual devices to
physical ones-- I
> understand about the default-nic property of the xend service, but what
about
> subsequent additions?
> 
In a Solaris dom0, guests OSes get virtual nics which
sits on top of a real NIC.

in dom0, if you do a dladm show-link, you will see the
real nics and virtual nics currently in your system.
For the virtual NICs, you will see which NIC they are
using.

You can do the following to see which vnics map to you
domains

# /usr/lib/xen/bin/xenstore-ls /local/domain/0/backend/vif

you can snoop on the vnic to get more info, e.g.
# snoop -d vnic1


if you want to specify a guest to NIC mapping, put the following in
the vif configuration.


vif =[ ''bridge=e1000g1,...'', ...]



MRJ

> In my dom0 I''m using e1000g0 and g1.  g0 is the default-nic, which
is on my
> internal private net.  g1 is connected to my public DMZ net.  I have tried
> pinging from within the domU, but don''t see the traffic when
snooping in dom0 on
> either interface.

Mark Johnson wrote:
> in dom0, if you do a dladm show-link, you will see the
> real nics and virtual nics currently in your system.
> For the virtual NICs, you will see which NIC they are
> using.
> 
> You can do the following to see which vnics map to you
> domains
Awesome, Mark, this is exactly what I needed.  I now see the problem:

$ sudo dladm show-link
Password:
LINK        CLASS    MTU    STATE    OVER
e1000g2     phys     1500   unknown  --
e1000g0     phys     1500   up       --
e1000g1     phys     1500   up       --
e1000g3     phys     1500   unknown  --
vnic11      vnic     1500   unknown  e1000g0
vnic12      vnic     1500   unknown  e1000g0

Both vnics are on g0.
> if you want to specify a guest to NIC mapping, put the following in
> the vif configuration.
> 
> 
> vif =[ ''bridge=e1000g1,...'', ...]
Can you point me to where I set that?  I haven''t been able to locate
any config
files, and that format doesn''t look like something that goes in the
domU XML
definition.  Is the vif config part of xenstored?

Thanks,
Eric

Eric Sproul wrote:
> Mark Johnson wrote:
>> in dom0, if you do a dladm show-link, you will see the
>> real nics and virtual nics currently in your system.
>> For the virtual NICs, you will see which NIC they are
>> using.
>>
>> You can do the following to see which vnics map to you
>> domains
> 
> Awesome, Mark, this is exactly what I needed.  I now see the problem:
> 
> $ sudo dladm show-link
> Password:
> LINK        CLASS    MTU    STATE    OVER
> e1000g2     phys     1500   unknown  --
> e1000g0     phys     1500   up       --
> e1000g1     phys     1500   up       --
> e1000g3     phys     1500   unknown  --
> vnic11      vnic     1500   unknown  e1000g0
> vnic12      vnic     1500   unknown  e1000g0
> 
> Both vnics are on g0.
> 
>> if you want to specify a guest to NIC mapping, put the following in
>> the vif configuration.
>>
>>
>> vif =[ ''bridge=e1000g1,...'', ...]
> 
> Can you point me to where I set that?  I haven''t been able to
locate any config
> files, and that format doesn''t look like something that goes in
the domU XML
> definition.  Is the vif config part of xenstored?
The are a few different ways you can do this, but the
quickest and dirtiest way is to

shutdown the domain

  # xm list -l <domainname> > /tmp/<domainname>.sxp

edit /tmp/<domainname>.sxp and add in thee
bridge.
     (device
         (vif
             (bridge e1000g1)  <****
             (mac ...

refresh the domain config,
  # xm new -F /tmp/<domainname>.sxp


Make sure it got updated.
  # xm list -l  <domainname>




MRJ

Mark Johnson wrote:
> shutdown the domain
> 
>  # xm list -l <domainname> > /tmp/<domainname>.sxp
> 
> edit /tmp/<domainname>.sxp and add in thee
> bridge.
Sweet, that''s done it.  Thanks Mark!

Eric