If you migrate from a Cisco 6500 to a Cisco Nexus switch, keep in mind that the ARP Default Timeout is very different. On the 6500’s it’s 4 Hours and on the Cisco Nexus it’s 25 Minutes.
Nexus 5K/7K:
ARP Default Timeout 1500 Seconds = 25 Minutes
MAC Address Aging 300 Seconds = 5 Minutes
6500:
ARP Default Timeout 14400 Seconds = 4 Hours
MAC Address Aging 300 Seconds = 5 Minutes
Changing the ARP Timeout & MAC Aging Time on Nexus:
ip arp timeout 14400 mac address-table aging-time 14400