[CentOS-virt] proper bridging technoque

Thu Nov 21 23:58:30 UTC 2013
Digimer <lists at alteeve.ca>

On 21/11/13 18:20, aurfalien wrote:
> On Nov 21, 2013, at 2:45 PM, Digimer wrote:
>> The 'vnetX' number doesn't relate to the interface, bridge or anything
>> else. The vnetX number is a simple sequence that increments each time a
>> VM is started. So don't think that you need 'vnet6'... it can be anything.
>> The 'brctl show' output from earlier showed that both vnet0 and vnet1
>> were connected to br0. You can try using the bridge utils to remove them
>> from br0 and connect them to br6 as a test.
>> -- 
>> Digimer
> Well, when I remove vnet1 from br0 and add vnet1 to br1, I loose connectivity with my VMs.
> No biggy so I reboot my entire host.
> Then vnet1 show back under br0.
> I just don't understand enough about this to get a clue, depressing.
> - aurf

Think of each bridge as if it were a physical switch.

When you detached vnet1 from br0, you unplugged it from a switch. When
you attached it to br1, you plugged it into another switch.

If there is no connection out to your network/internet on a given
switch, then anything plugged into that switch will go nowhere. Same
with bridges.

You seemed to indicate earlier that the main connection was on br6. Is
this true? If so, then "switch" br6 is the switch with the "uplink" to
your network. Plug a VM into it and you can route out through it.

When you rebooted the VM, the hypervisor read the definition file. That
definition file says to plug in the server to br0. So it makes sense
that the reboot reconnected it to br0.

If you want to use jumbo frames on the br0 switch, you need to set the
larger MTU on the interfaces are all set to your desired MTU size.

Papers and Projects: https://alteeve.ca/w/
What if the cure for cancer is trapped in the mind of a person without
access to education?