routing table look up for directly connected interfaces.

[sarahr202]

Hi everybody,

Does a router perform route-look up for a packet destined to one of its directly connected interfaces say loop back ?

or

since router is already aware of its directly connected interfaces therefore it is already actively listening on those IP configured on its interfaces so no route look up is performed.

Much appreciated.

Have a great day !!

[Joseph W. Doherty · Accepted solution]

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Posting

By default, a router should route between networks on directly connected interfaces.  NB: Some L3 switches you can disable routing, and if you do, it won't route between networks on directly connected interfaces.

Such routing between connected interface networks has nothing to do with "listening" for the IP on those interfaces.  For example, even if there's no routing, those interfaces should normally respond to ARPs for their IPs.