How To Bring Down A Single NIC In ESX? • Technodrone

I was installing a new ESX Host today, and before putting it into Production, I wanted to test that the Network Failover was working correctly.

Now instead of going over to the server and pulling out network cables, I started to think, there must be a way to do this (like all good administrators do) from the comfort of my desk.

Easiest would be – Log into the switch and shutdown the port. I agree, but what happens when your the Virtualization Team do not control the Physical network (my situation)? That was not an option.

I started to look if I could bring the interface down.

With regular Linux you would – ifdown eth0

[root@esx1 ~]# ifdown eth0  
usage: ifdown <device name>

So that did not work! Pretty obvious why though… There is no eth0 interface.

[root@esx1 ~]# ifconfig  
lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0  
          UP LOOPBACK RUNNING  MTU:16436  Metric:1  
          RX packets:784233 errors:0 dropped:0 overruns:0 frame:0  
          TX packets:784233 errors:0 dropped:0 overruns:0 carrier:0  
          collisions:0 txqueuelen:0  
          RX bytes:3017478364 (2877.6 Mb)  ...:3017478364 (2877.6 Mb)

vmnic0    Link encap:Ethernet  HWaddr 00:1A:64:E5:31:38  
          UP BROADCAST MULTICAST  MTU:1500  Metric:1  
          RX packets:6602129 errors:0 dropped:0 overruns:0 frame:0  
          TX packets:237757 errors:0 dropped:0 overruns:0 carrier:0  
          collisions:0 txqueuelen:1000  
          RX bytes:1130250120 (1077.8 Mb) ..es:195027359 (185.9 Mb)  
          Interrupt:113 Memory:92000000-92012100

vmnic1    Link encap:Ethernet  HWaddr 00:1A:64:E5:31:3A  
          UP BROADCAST MULTICAST  MTU:1500  Metric:1  
          RX packets:505 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:303685 (296.5 Kb)  TX bytes:0 (0.0 b)  
          Interrupt:201 Memory:94000000-94012100

vswif0    Link encap:Ethernet  HWaddr 00:50:56:4C:43:11  
          inet addr:1.1.1.1  Bcast:1.1.1.255  Mask:255.255.255.0  
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1  
          RX packets:2490053 errors:0 dropped:0 overruns:0 frame:0  
          TX packets:260404 errors:0 dropped:0 overruns:0 carrier:0  
          collisions:0 txqueuelen:1000  
          RX bytes:664363188 (633.5 Mb)  TX bytes:196222902 (187.1 Mb)

So I tried..

[root@esx1 ~]# ifdown vmnic0  
usage: ifdown <device name>

And that did not work either.

I did not want to shutdown the whole vSwitch – because then I would lose the connectivity (of course there is the possibility of creating the second Service Console – but this was not the case here)

The only way to do this is to manipulate the NIC’s directly. So what can you do with the physical NIC’s?

[root@esx1 ~]# esxcfg-nics  
esxcfg-nics <options> [nic]  
   -s|--speed <speed>      Set the speed of this NIC to one of 10/100/1000/10000.  
                           Requires a NIC parameter.  
   -d|--duplex <duplex>    Set the duplex of this NIC to one of 'full' or 'half'.  
                           Requires a NIC parameter.  
   -a|--auto               Set speed and duplexity automatically.  Requires a NIC parameter.  
   -l|--list               Print the list of NICs and their settings.  
   -r|--restore            Restore the nics configured speed/duplex settings (INTERNAL ONLY)  
   -h|--help               Display this message.**

So you cannot shut down the device, but you do the next best thing – set it to 10 Half-Duplex.

That will bring the port down.

[root@esx1 ~]#esxcfg-nics -s 10 -d half vmnic2

And to bring it back up

[root@esx1 ~]#esxcfg-nics -a vmnic2

Now unless there is a good reason – your ports should always be set to Auto-Negotiate, and in this casem when the nic was reset to auto – then it came back up without any issues.

The failover worked – so my experiment was successful.

Some might call it being a lazy Bum – I call it being a Good Administrator!!

Hope you enjoyed the ride!