Physical host of KVM VMs with bonded interface

slimjim · 06-13-2012, 10:09 AM

Hi,

I have a RedHat machine running a number KVM VM guests. Its two ethernet interfaces are bonded, for redundancy - each running to a separate switch in the data centre.

I inherited this server. It's evident, although I'm not entirely sure, that the ethernet interfaces are bridged as well as bonded. Which is fine, since it all seems to work nicely.

However I'm moving it, along with a number of other servers, to a new data centre soon. The new data centre tells me that in order to use the two network feeds into the rack, I can't have the two interfaces bridged.

So my question is - is the bridging necessary for KVM hosts? I know there's an internal, "virtual" bridge, but do the physical interfaces have to be bridged as well, for some reason?

From ifconfig -a:

Code:

bond0     Link encap:Ethernet  HWaddr XX:XX:XX:XX:XX:XX  
          UP BROADCAST RUNNING MASTER MULTICAST  MTU:1500  Metric:1
          RX packets:1410305578 errors:14927 dropped:0 overruns:0 frame:14927
          TX packets:671693186 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:1116561859775 (1.0 TiB)  TX bytes:566748542669 (527.8 GiB)

br0       Link encap:Ethernet  HWaddr XX:XX:XX:XX:XX:XX  
          inet addr:200.99.99.75  Bcast:200.99.99.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:1221480801 errors:0 dropped:0 overruns:0 frame:0
          TX packets:352449231 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:1016259239672 (946.4 GiB)  TX bytes:490177928634 (456.5 GiB)

eth0      Link encap:Ethernet  HWaddr XX:XX:XX:XX:XX:XX  
          UP BROADCAST RUNNING SLAVE MULTICAST  MTU:1500  Metric:1
          RX packets:1382952331 errors:14927 dropped:0 overruns:0 frame:14927
          TX packets:671693186 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:1113483862074 (1.0 TiB)  TX bytes:566748542669 (527.8 GiB)
          Interrupt:185 Memory:e4000000-e4012800 

eth1      Link encap:Ethernet  HWaddr XX:XX:XX:XX:XX:XX  
          UP BROADCAST RUNNING SLAVE MULTICAST  MTU:1500  Metric:1
          RX packets:27353247 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:3077997701 (2.8 GiB)  TX bytes:0 (0.0 b)
          Interrupt:185 Memory:e2000000-e2012800 

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:35685773 errors:0 dropped:0 overruns:0 frame:0
          TX packets:35685773 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:2800744716 (2.6 GiB)  TX bytes:2800744716 (2.6 GiB)

virbr0    Link encap:Ethernet  HWaddr 00:00:00:00:00:00  
          inet addr:192.168.122.1  Bcast:192.168.122.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:274 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:0 (0.0 b)  TX bytes:57713 (56.3 KiB)

vnet1     Link encap:Ethernet  HWaddr XX:XX:XX:XX:XX:XX  
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:1146411 errors:0 dropped:0 overruns:0 frame:0
          TX packets:97725361 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:500 
          RX bytes:194260293 (185.2 MiB)  TX bytes:14792144821 (13.7 GiB)

dyasny · 06-13-2012, 03:08 PM

Why can't you have bridged interfaces?

In any case, the bridge is essentially like a virtual switch, that has a leg (in your case it's a bond) into the physical network, and into which VMs plug in as well.

You can, instead, use NAT, but it's usually not recommended, especially because of the extra diffculty with managing the port forwarding