Network : Bridge over bonding

[Matthew Galgoci]

> Date: Thu, 22 Sep 2011 09:01:16 +0200
> From: Thierry Leurent <thierry.leurent at asgardian.be>
> Reply-To: redhat-sysadmin-list at redhat.com
> To: redhat-sysadmin-list at redhat.com
> Subject: Network : Bridge over bonding
>
> Hello,
>
> I'm configuring a server to use KVM.
> I want to have a redundant network connection. I a first time, I have
> create a bonding with eth0 and eth1. It's work but now I want install a
> bridge to use KVM and build a guest computer with an ip address in my
> normal address space (not NATed).
>
> But the bonding don't work. IFConfig give me informations about brigde0
> and lo.
> cat /proc/net/bonding/bond0 tell me that eth0 and eth1 are down.

You probably want to bond eth0 and eth1 into a mode 1 bond, which is
active/standby based on link status. You then want to make the bond0
interface a member of bridge0.

I caution you against bonding modes other than mode 1. You could easily
cause a loop in your layer2 network. I suggest consulting with your
networking folks about what to do here. As a network engineer, I would
highly recommend enabling spanning-tree on your bridge0 interface and a
short forwarding delay in your bridge. Switch side, you probably want to
have spanning-tree guard root on both ports to prevent your software bridge
from accidently becoming the root of your layer2 topology. You'll also
want to have bpduguard and bpdufilter both disabled.

Again, I would urge you to discuss spanning-tree and forwarding delays
with your network engineer as well as the implications of the proposed
failover bonding. A network engineer with a looped network is not a
happy network engineer.

Thanks,

Matt

-- 
Matthew Galgoci
Network Operations
Red Hat, Inc
919.754.3700 x44155
------------------------------
"It's not whether you get knocked down, it's whether you get up." - Vince Lombardi