two interfaces one subnet

Chris Meidinger cmeidinger at
Mon May 11 16:59:18 CDT 2009

On 11.05.2009, at 23:48, Ben Scott wrote:

> On Mon, May 11, 2009 at 5:38 PM, Chris Meidinger
> <cmeidinger at> wrote:
>> For example, eth0 is and eth1 is, nothing  
>> like
>> bonding going on. The customers usually have the idea of running one
>> interface for administration and another for production (which is a  
>> _good_
>> idea) but they want to do it in the same subnet (not such a good  
>> idea...)
>  I just posted on this, but I didn't really address your original
> question, so: I'm not aware of anything in the RFCs or other standards
> which prohibits this.  But then, I haven't gone looking, because...
>  It *can* be made to work in practice, for certain scenarios.  For
> example, if you're talking a web server, and you bind the "production"
> site to and the "administration" site to, and
> configure policy routing (you said Linux, right?) to route
> appropriately, it should work.  It works because Apache can bind sites
> to individual interfaces.

Just to restate here, for people who have been responding both  
publicly and privately:

I know that *I* can make it work, and I know that *you* can make it  
work. But I also know that it's not likely to stay working.

One day, down the road, something will break. Then, my poor support  
team will spend days trying to diagnose the problem.

So I want to stop the customer from trying to force a round peg into a  
square hole, and just use separate subnets for the different  
interfaces. As someone said before, it's not rocket science.

Still though, thanks for all the input; it's really useful.


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