nanog mailing list archives

Re: two interfaces one subnet


From: Chris Meidinger <cmeidinger () sendmail com>
Date: Mon, 11 May 2009 23:59:18 +0200

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

On Mon, May 11, 2009 at 5:38 PM, Chris Meidinger
<cmeidinger () sendmail com> wrote:
For example, eth0 is 10.0.0.1/24 and eth1 is 10.0.0.2/24, 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 10.0.0.2 and the "administration" site to 10.0.0.1, 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.

Chris


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