To force a gratuitous arp on an interface you can use the following command:
# arping -q -c 3 -A -I eth11 172.16.1.7
We were also able to isolate the issue using tcpdump and looking specifically for ARP requests:
# tcpdump -nni eth11 arp
These commands allow for sending and monitoring gratuitous ARP's out for an address in Linux which is extremely helpful when trouble shooting layer 2 issues.