libvirt users - May 2014 - Re: [netcf] Why netcf can not rename a existing physical interface dynamically by itself?

Hi All,

I have a usage question about netcf. Why netcf can not rename a existing
physical interface dynamically by itself? If you have any other method, please
share to me, or can we add support for it in netcf? You can see the following
steps for details.

Version:
netcf-0.2.4-1.el6.x86_64
kernel-2.6.32-431.el6.x86_64

1. Select a existing NIC from host, for example eth1.
[root@rhel6 ~]# ncftool list --all
eth0
eth1
lo
[root@rhel6 ~]# ncftool dumpxml eth1
<?xml version="1.0"?>
<interface type="ethernet" name="eth1">
  <start mode="none"/>
  <mac address="00:1B:21:27:4E:CE"/>
  <protocol family="ipv4">
    <dhcp/>
  </protocol>
</interface>

[root@rhel6 ~]# ifconfig eth1
eth1      Link encap:Ethernet  HWaddr 00:1B:21:27:4E:CE  
          BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

[root@rhel6 ~]# ncftool ifup eth1
Interface eth1 successfully brought up

2. Undefine eth1 from host
[root@rhel6 ~]# ncftool ifdown eth1
Interface eth1 successfully brought down
[root@rhel6 ~]# ncftool undefine eth1
eth1 undefined
[root@rhel6 ~]# ncftool list --all
eth0
lo

3. Prepare another xml with same MAC and a new name "jiahu"
[root@rhel6 ~]# cat jiahu.xml 
<interface type="ethernet" name="jiahu">
 <start mode="none"/>
  <mac address="00:1B:21:27:4E:CE"/>
  <protocol family="ipv4">
    <dhcp/>
  </protocol>
</interface>

4. Define the "jiahu", and start it.
[root@rhel6 ~]# ncftool define jiahu.xml 
Defined interface jiahu
[root@rhel6 ~]# ncftool dumpxml jiahu
<?xml version="1.0"?>
<interface type="ethernet" name="jiahu">
  <start mode="none"/>
  <mac address="00:1B:21:27:4E:CE"/>
  <protocol family="ipv4">
    <dhcp/>
  </protocol>
</interface>

[root@rhel6 ~]# ifconfig jiahu
jiahu: error fetching interface information: Device not found
         
[root@rhel6 ~]# cat /etc/sysconfig/network-scripts/ifcfg-jiahu 
DEVICE=jiahu
HWADDR=00:1B:21:27:4E:CE
ONBOOT=no
BOOTPROTO=dhcp
[root@rhel6 ~]# ncftool ifup jiahu
Interface jiahu bring-up failed!
error: failed to execute external program
error: Running 'ifup jiahu' failed with exit code 1: Device jiahu does
not seem to be present, delaying initialization.

[root@rhel6 ~]# ll /sys/class/net/
total 0
lrwxrwxrwx. 1 root root 0 May 23 11:32 eth0 ->
../../devices/pci0000:00/0000:00:19.0/net/eth0
lrwxrwxrwx. 1 root root 0 May 23 11:35 eth1 ->
../../devices/pci0000:00/0000:00:1e.0/0000:02:00.0/net/eth1
lrwxrwxrwx. 1 root root 0 May 23 11:32 lo -> ../../devices/virtual/net/lo
lrwxrwxrwx. 1 root root 0 May 23 11:32 virbr0 ->
../../devices/virtual/net/virbr0
lrwxrwxrwx. 1 root root 0 May 23 11:32 virbr0-nic ->
../../devices/virtual/net/virbr0-nic

5. Reboot the host OS, the jiahu interface appeared.
[root@rhel6 ~]# ifconfig jiahu
jiahu     Link encap:Ethernet  HWaddr 00:1B:21:27:4E:CE  
          BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

BR,
Jianwei

On 05/23/2014 06:46 AM, Jianwei Hu wrote:
> Hi All,
>
> I have a usage question about netcf. Why netcf can not rename a existing
physical interface dynamically by itself?
The name of a physical interface is determined by lower levels of the
operating system, and can't be modified by netcf. the configuration that
is setup by netcf can only reference an *existing* physical device name,
it can't rename it.
> If you have any other method, please share to me, or can we add support for
it in netcf?
One source of information is here:

 
http://www.freedesktop.org/wiki/Software/systemd/PredictableNetworkInterfaceNames/

(although that only completely applies to systems running recent
systemd, e.g. Fedora 20, but not to RHEL6 as you appear to be running)

There is a reference there of how to change an interface name in a
system that isn't using "predictable network interface names" (or
biosdevname, which was a short-lived alternative attempt at a solution
to the same problem): modify the file
/etc/udev/rules.d/70-persistent-net.rules. You'll need to reboot the
system for this to take effect.

On 05/23/2014 04:56 PM, Laine Stump wrote:
> On 05/23/2014 06:46 AM, Jianwei Hu wrote:
>> Hi All,
>>
>> I have a usage question about netcf. Why netcf can not rename a
existing physical interface dynamically by itself?
> The name of a physical interface is determined by lower levels of the
> operating system, and can't be modified by netcf. the configuration
that
> is setup by netcf can only reference an *existing* physical device
nam[root@rhel6 ~]# ip link set name jiahu eth1
> [root@rhel6 ~]# ifconfig jiahu
> jiahu     Link encap:Ethernet  HWaddr 00:1B:21:27:4E:CE
>            BROADCAST MULTICAST  MTU:1500  Metric:1
>            RX packets:0 errors:0 dropped:0 overruns:0 frame:0
>            TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
>            collisions:0 txqueuelen:1000
>            RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)
>
> [root@rhel6 ~]# ifup jiahu
>
> Determining IP information for jiahu... done.
> e,
> it can't rename it.
OK, thanks, but I think we can use ip command line to rename existing NIC.

[root@rhel6 ~]# ip link set name jiahu eth1
[root@rhel6 ~]# ifconfig jiahu
jiahu     Link encap:Ethernet  HWaddr 00:1B:21:27:4E:CE
           BROADCAST MULTICAST  MTU:1500  Metric:1
           RX packets:0 errors:0 dropped:0 overruns:0 frame:0
           TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
           collisions:0 txqueuelen:1000
           RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

[root@rhel6 ~]# ifup jiahu

Determining IP information for jiahu... done.
>> If you have any other method, please share to me, or can we add support
for it in netcf?
> One source of information is here:
>
>   
>
http://www.freedesktop.org/wiki/Software/systemd/PredictableNetworkInterfaceNames/
>
> (although that only completely applies to systems running recent
> systemd, e.g. Fedora 20, but not to RHEL6 as you appear to be running)
>
> There is a reference there of how to change an interface name in a
> system that isn't using "predictable network interface names"
(or
> biosdevname, which was a short-lived alternative attempt at a solution
> to the same problem): modify the file
> /etc/udev/rules.d/70-persistent-net.rules. You'll need to reboot the
> system for this to take effect.
>