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

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Jun 17th, 2011
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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.

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Paolo Bevilacqua Fri, 06/17/2011 - 08:47
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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.

Joseph W. Doherty Fri, 06/17/2011 - 10:13
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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.


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