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

[Laine Stump]

On 05/23/2014 03:02 PM, jiahu wrote:
>
> 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 at rhel6 ~]# ip link set name jiahu eth1
>> [root at 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 at 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 at rhel6 ~]# ip link set name jiahu eth1
> [root at 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 at rhel6 ~]# ifup jiahu
>
> Determining IP information for jiahu... done.

Neat! That's probably using the same netlink command that's used to
rename it at boot time. However, if you do what you suggest, the name
change won't be persistent across a system reboot.

I still say this is too low level for netcf to be messing with; it was
created to provide a standard way to manipulate the config files, not
mess with the hardware. (Note that it's also possible to change the mac
address of an ethernet device (ip link set $dev address $addr) , but we
don't support that either, and have no plans to do so.)