Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

Can a router have 2 interface in the same subnet??

I'm pretty sure the answer to this is no.  I've read the routing FAQ and it states this cant be done, but is there anything creative that can be done to take 2 layer 2 connections from redundant switches that terminate into the same router and have them be on the same subnet.  On our ASA's we are able to configure a redundant interface and still enabling routing.  Is there something similar that can be done on a router?

Thanks in advance.

Hall of Fame Super Gold

Can a router have 2 interface in the same subnet??

Thats is done with IRB and BVIs. However the last time I tried on voice router, it caused the phones to loose registration periodically, without apparent reason or STP activity. So caveat emptor.

Super Bronze

Can a router have 2 interface in the same subnet??


The    Author of this posting offers the information contained within this    posting without consideration and with the reader's understanding that    there's no implied or expressed suitability or fitness for any   purpose.   Information provided is for informational purposes only and   should not  be construed as rendering professional advice of any kind.    Usage of  this posting's information is solely at reader's own risk.

Liability Disclaimer

In    no event shall Author be liable for any damages whatsoever  (including,   without limitation, damages for loss of use, data or  profit) arising  out  of the use or inability to use the posting's  information even if  Author  has been advised of the possibility of such  damage.


Besides what Paolo has suggested (bridging interfaces), if the router supports specific Ethernet modules, some will allow a virtual interface which you can route with.  Similarly, L3 switches support virtual interface routing.  The does allow multiple (Ethernet) interfaces on the same subnet.