In our existing environment we had migrated old firewall with new firewall after this activity . we had faced connectivity issue . From servers unable to reach other servers . Post clearing ARP table we are able to connect . Here i don't understand how ARP table clearing resolved this issue . throw some light here .
ARP maps (local) IP addresses to their MAC addresses. So, if you swap a device, reusing its IP address, incoming L2 frames are addressed incorrectly and subsequently ignored by the new device. Flushing the ARP cache requires a source device to run a new ARP request round and maps the IP address to its new MAC.