Bridged & Bonded Interfaces? Confusion

slimjim · 06-12-2012, 06:34 AM

Hi.

I'm moving some of our servers to a new data centre shortly. The rack will have two network feeds for redundancy, each providing a separate switch.

The servers each have two ethernet interfaces, so they'll be cabled to one switch each.

That's more or less the setup we have at the moment in the old data centre.

The trouble is - the data centre have told me that the network interfaces on the servers can't be bridged. Unfortunately, I think they are. But I'm not that experienced with bridged and bonded network cards. Can someone please tell me what's going on here (output from ifconfig -a follows)

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)

.. I've changed / masked some of the addresses to protect the innocent. But can someone confirm for me that the two ethernet ports are bridged, as well as bonded?

It's a Redhat machine. The following is in /etc/sysconfig/networking/devices/ifcfg-bond0:

Code:

DEVICE=bond0
USERCTL=no
BOOTPROTO=none
ONBOOT=yes
BRIDGE=br0

It's actually a vm host for some KVM virtual machines. I'm thinking that maybe has something to do with it.

illusion88 · 06-13-2012, 02:01 PM

Run:

Code:

brctl show

And this should list any bridges and which interfaces are in the bridge.

slimjim · 06-14-2012, 04:36 AM

Thank-you!

This is what I get:

Code:

[root@kvmhost1 ~]# brctl show
bridge name	bridge id		STP enabled	interfaces
br0		8000.00145e579d8c	no		vnet1
							bond0
virbr0		8000.000000000000	yes		
[root@kvmhost1 ~]#

This actually makes me a bit hopeful, in that it seems to show that the interfaces that are bridged are vnet1 and bond0, which are not the two physical interfaces.

bond0 represents the two ethernet interfaces, bonded together.

vnet1 is presumably a virtual interface used by the virtualisation solution somehow, although I can't see where it's defined - there's nothing in /etc/sysconfig/network-scripts.

So based on this, I'm going to say, tentatively, that the two ethernet interfaces aren't bridged.

Sound reasonable?