[CentOS-virt] proper bridging technoque

[aurfalien]

Sorry guys, I've tried and tried, no dice.

Seems like I am missing missing a vent1, vnet2, etc... to br0 association.

I can see were the vnet# gets created upon VM startup.

And based on how my VM xml file is set, will go to either br0, br1. br2, etc...

But in my case, the only interface that works is vnet0 for all my VMs.

In the CentOS virtual machine manager for whatever NIC you choose, there is a drop down option for virtual network interface.

For source device, I only ever see a vnet0 to br0.  For my other bridges, there is only eth# to vnet#.

The configs for this are rather simple and I don't know were else to look;

various /etc/sysconfig/network* files

and the VM xml config.

Everythings is set to the same MTU wether standard or jumbo, but no matter what, my VMs network interfaces work when set to vnet0 as its connected to br0.

I cannot get br6 to show with vnet2 for example.  Not even my vnet1 is connected to br1 but rather br0.

However in the UI as mentioned before, i do not see a vnet1 to br1 relationship.

Are there any other config files I can look at?

- aurf 
On Nov 21, 2013, at 5:52 PM, Digimer wrote:

> It's not so much hard as it is knowing all the hops in your network. If
> anything along the chain has a low MTU, the whole route is effectively
> reduced.
> 
> On 21/11/13 20:20, Nico Kadel-Garcia wrote:
>> This is int4eresting stuff. I do note that the "virt-manager" tool,
>> and NetworkManager, give *no* insight and detailed management
>> sufficient to resolve this stuff.  Note also that dancing through all
>> the hoops to get this working, end-to-end, is one of the big reasons
>> that most environments refuse to even *try* to use jumbo frames, as
>> helpful as they sometimes are to heavy data transfers.
>> 
>> On Thu, Nov 21, 2013 at 6:58 PM, Digimer <lists at alteeve.ca> wrote:
>>> 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.
>>> 
>>> --
>>> Digimer
>>> 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?
>>> _______________________________________________
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> 
> 
> -- 
> Digimer
> 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?
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