On the other side, the tcpdump show:
[2.4.5-RELEASE][admin@pf1-tos.domain]/root: tcpdump -i xn0.10 ether host c8:df:84:c1:16:37 -nn
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on xn0.10, link-type EN10MB (Ethernet), capture size 262144 bytes
18:05:55.841165 ARP, Request who-has 172.16.80.241 tell 172.16.80.242, length 42
18:05:55.841190 ARP, Reply 172.16.80.241 is-at 00:16:3e:19:25:5f, length 28
18:05:56.850828 ARP, Request who-has 172.16.80.241 tell 172.16.80.242, length 42
18:05:56.850855 ARP, Reply 172.16.80.241 is-at 00:16:3e:19:25:5f, length 28
i can't run it on the origin otherwise the ping start working...