[TriLUG] Networking and Fedora

[Justis Peters]

Ouch. I offer both my sympathy and my apologies. I didn't realize you
were troubleshooting remotely, but I also didn't think it would blow up
like that. I hope the fix is easy.

Kind regards,
Justis

Joseph Tate wrote:
> Well, that went poorly.
>
> As soon as I issued the brctl command my whole network went dark.  The
> shell I was working in hung, and I forcefully disconnected to the top
> level ssh shell instead of the sub shell.  Now I can't connect to that
> host machine, or even the other machine that I was using to connect
> through it.  I guess it'll have to wait until I get home to fix it up.
>  That'll teach me to troubleshoot network issues remotely... :/
>
> On Wed, May 26, 2010 at 2:50 PM, Justis Peters <jtrilug at indythinker.com> wrote:
>   
>> Jeff Schornick wrote:
>>     
>>> Preparing to make a fool of myself...
>>>
>>>       
>>>> 10.2.2.0        0.0.0.0         255.255.255.0   U     0      0        0 eth0
>>>> 10.2.2.0        0.0.0.0         255.255.255.0   U     0      0        0 br0
>>>>
>>>>         
>>> You appear to have two routes to the same destination subnet, equal
>>> metric to two different interfaces.  Since eth0 and br0 aren't
>>> currently bridged, I'd imagine this would lead to rather inconstant
>>> delivery.  I'm honestly not sure how the kernel choses which route to
>>> use under these circumstances, but I'm 99% sure it won't deliver each
>>> packet to both.
>>>
>>> Do you perhaps want eth0 part of the br0 bridge group?
>>>
>>>       
>> Didn't see your reply before I sent mine. I think you've got it nailed,
>> Jeff. I hadn't noticed that eth0 is not yet attached to br0.
>>
>> The way that Xen users frequently do this is to rename the "real" eth0
>> to peth0 and then name the bridge itself eth0. You would then add peth0
>> to the bridge, along with all the virtual interfaces for the guest VMs.
>> Some people find this confusing; others like it.
>>
>> Joseph: The quick way to test our theory would be to remove the second
>> route and then add eth0 to the br0 bridge. The commands should look
>> something like this:
>>  route del -net 10.2.2.0/24 br0
>>  brctl addif br0 eth0
>>
>> I'm not sure of the preferred way to make those changes persistent in
>> Fedora, but I'm sure the answer is online and easy to find. Also note
>> that you probably want to run them in the order listed above. I suspect
>> that reversing the order might create a feedback loop between the
>> routing table and the bridge.
>>
>> Best of luck and let us know how it goes.
>>
>> Kind regards,
>> Justis
>> --
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>>
>>     
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