static nat questions related to arp entries

Unanswered Question
Nov 3rd, 2009
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Hi All,

I have configured a static NAT entry on 2800 Cisco router running 12.4. Can anyone explain why the router generates an arp entry on the "nat inside" interface for

the global address. For example I'm using the following static nat configuration

ip nat inside source static

with the later being the global address.

For some reason the router generates an arp entry and responds to arp requests for on the inside segment with the MAC address of the inside interface.

This arp entry is permanent and doesn't timeout as indicated by "-" in the sh arp command output.

Can anyone shed any light on why occurs. I can't see any reason why the router would need to respond to arp requests for the global outside address on the nat inside interface.

Would really like to work this one out.

Cheers :)

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