Packet with a source IP not in the routing table of the router

[F Martinez]

Hi,

I know this may seem a simple question but I just wanted to make sure. Here's it is.

Does a router drop a packet with a source IP address not in its routing table? If so, why?

Thanks in advance!

[Philip D'Ath]

Assuming this is a standard unicast packet not using reserved ranges - no it does not, unless you have configured reverse path forwarding or access control lists.

[F Martinez]

Thank you.

[e.ciollaro]

Hi

Philip is absolutely right; I just want to add a consideration: in that scenario if you have some king of returning traffic, it will be discarded having a destination ip address for which the router has no entry in routing table. So, not having the source ip in routing table could be a clue of some problem (may be asymmetric routing).

Bye,

enrico

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