ARP (Address Resolution Protocol) is the method for finding a host’s hardware address when only its IP address is known. ARP is a Link Layer protocol (Layer 2) because it only operates on the local area network.
When you migrate an IP from a VM or an hypervisor to another one, you can sometime encounter strange network problems (like no traffic received to this IP for a while). The cause of theses problems is that some network equipment (router or firewall) on the path have a ‘expired’ ARP entry in their cache.
Refresh ARP cache
For a GNU/Linux or BSD host, check the current arp table with arp -a.
Then purge the value with arp -d <hostname>
For Cisco iOS use show arp for checking arp table and clear ip arp <ip> to purge an entry.
For equipment you don’t have the hand on, the solution is a little more tricky. You need to broadcast from your VM the correct ARP ‘value’, in order to make the remote device invalidate its existing cache entry. For this use the arping command:
arping -S <ip> -B