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If the host, for which an ARP table entry is present on the connected router, has changed its NIC(so that its MAC address has changed), what will happen when a packet is sent out on the link with the old MAC address by the router?

Will any kind of error message(like ICMP) be generated at layer2/3? If yes, what will be its SIP and DIP?

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Matches between MAC and IP are stores in the ARP cache. Unless you manually created a static entry these will time out. The time out period depends on your OS. (For modern windows installs this takes about 30 seconds according to support.microsoft.com/kb/949589 ). So nothing abnormal will happen if you can wait a short period after changing the NIC. (Not posted as an answer since I do not actually know what will happen if you do try this before the time out. I suspect it will depend on the operating systems involved. Or more precisely, on the used TCP/IP stack). –  Hennes Jun 10 '12 at 14:39

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Nothing will happen, the packet will be "lost", and time-out.

Depending on the implementation, the router will then try with arp again, get the new mac and then send the next* packet to the new address.

*with tcp, the lost packets will be retransmitted, with udp, it depends on the higher protocol (l7) - usually not

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