[114441] in North American Network Operators' Group
Re: two interfaces one subnet
daemon@ATHENA.MIT.EDU (Patrick W. Gilmore)
Mon May 11 17:49:14 2009
From: "Patrick W. Gilmore" <patrick@ianai.net>
To: NANOG list <nanog@nanog.org>
In-Reply-To: <4A08967C.7010901@ieee.org>
Date: Mon, 11 May 2009 17:47:43 -0400
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On May 11, 2009, at 5:19 PM, Alex H. Ryu wrote:
> Unless you configure Layer 2 for two interfaces, it's not going to
> work.
It can work. Of course it _may_ not, depending upon your
implementation, but then some implementations can't get a single
interface to work properly per subnet.
> It is invalid from networking principle.
You are confused, there is nothing invalid about the configuration.
> If you have to send the traffic for host in same subnet you
> configured,
> which interface it should send out ?
Pick an interface and send the packet. It's not rocket science. I
can come up with half a dozen algorithms off the top of my head while
typing the last sentence.
> Basically it may create broadcast storm loop by putting two ip
> addresses
> in same subnet in different interface.
That is an interesting statement. Could you explain how this can
happen without crafting an idiotic implementation spec (e.g. every
packet goes out both interfaces)?
> It may be allowed from host-level, but from router equipment, I don't
> think it was allowed at all.
Ever used HSRP / VRRP? Two interfaces in the same subnet. Works
fine. In fact, most people think it works _better_ than one interface
in the same subnet.
--
TTFN,
patrick
